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1. Nanocatalysts for High Selectivity Enyne Cyclization: Oxidative Surface Reorganization of Gold Sub-2-nm Nanoparticle Networks

Author: Houssein O. Nasrallah, Yuanyuan Min, Emmanuel Lerayer, Tuan-Anh Nguyen, Didier Poinsot, Julien Roger, Stéphane Brandès, Olivier Heintz, Pierre Roblin, Franck Jolibois, Romuald Poteau, Yannick Coppel, Myrtil L. Kahn, Iann C. Gerber, M. Rosa Axet, Philippe Serp, and Jean-Cyrille Hierso
Subjects: Chemistry, QD1-999
Published: 2021
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2. Bidimensional lamellar assembly by coordination of peptidic homopolymers to platinum nanoparticles

Author: Ghada Manai, Hend Houimel, Mathilde Rigoulet, Angélique Gillet, Pier-Francesco Fazzini, Alfonso Ibarra, Stéphanie Balor, Pierre Roblin, Jérôme Esvan, Yannick Coppel, Bruno Chaudret, Colin Bonduelle, and Simon Tricard
Subjects: Science
Abstract: Precise organization of nanoparticles and polymers for the design of hybrid materials remains a challenging task. Here, the authors show a convenient way to organize nanoobjects by preorganization of inorganic particles in presence of a functional peptidic homopolymer.
Published: 2020
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3. The asymmetric binding of PGC-1α to the ERRα and ERRγ nuclear receptor homodimers involves a similar recognition mechanism.

Author: Maria Takacs, Maxim V Petoukhov, R Andrew Atkinson, Pierre Roblin, François-Xavier Ogi, Borries Demeler, Noelle Potier, Yassmine Chebaro, Annick Dejaegere, Dmitri I Svergun, Dino Moras, and Isabelle M L Billas
Subjects: Medicine, Science
Abstract: BackgroundPGC-1α is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERRα and ERRγ) in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1α and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al) that PGC-1α binds in a strikingly different manner to ERRγ ligand-binding domains (LBDs) compared to its mode of binding to ERRα and other nuclear receptors (NRs), where it interacts directly with the two ERRγ homodimer subunits.Methods/principal findingsHere, we show that PGC-1α receptor interacting domain (RID) binds in an almost identical manner to ERRα and ERRγ homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1α RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1α RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1α/ERRα LBDs and PGC-1α/ERRγ LBDs complexes share an identical architecture with an asymmetric binding of PGC-1α to homodimeric ERR.Conclusions/significanceThese studies provide the molecular determinants for the specificity of interactions between PGC-1α and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.
Published: 2013
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4. Synthesis and emission dynamics of sub-3 nm single-emitter upconversion nanoparticles

Author: Baptiste Amouroux, Ali Eftekhari, Clément Roux, Jean-Claude Micheau, Pierre Roblin, Mathieu Pasturel, Fabienne Gauffre, Christian Würth, Ute Resch-Genger, Michel Sliwa, Aude Bouchet, and Christophe Coudret
Abstract: Reducing the size of upconversion nanoparticles (UCNPs) down to a few nm yields unique luminescent materials containing a very small number of emitters. Considering the bottom limit of one activator per particle, such ultrasmall UCNPs offer an unprecedented platform to study the contributions of the different energy transfer processes at play in upconversion luminescence, especially the role of cross relaxation. Maintaining detectable emission despite the limited number of emitting ions and the high surface-to-volume ratio requires suitable particle architectures. The preparation of Na(Gd-Yb)F4:Tm emissive sub-3 nm diameter -phase UCNPs was achieved using a gadolinium-rich composition, in situ mixing of the precursors NaOH and NH4F, and a microwave high-temperature cycling sequence that allowed precise control of the particle size and dispersity. These nanoparticles contain only a single Tm3+ activator ion, while coating of these cores with a NaGdF4 inert shell was performed to minimize the deleterious influence of surface quenching. The role of cross relaxation in upconversion luminescence was examined by time-resolved luminescence measurements using a combination of standard NIR excitation of the Yb3+ sensitizer and direct UV excitation of the Tm3+ activator. The fine tuning of the number of activators per particle via an optimized synthesis pathway along with an appropriate excitation scheme enabled us to select the operating cross relaxation processes and provide an accurate analysis of the different mechanisms at play in these model nanoparticles.
Published: 2023
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5. Pyrophosphate-stabilised amorphous calcium carbonate for bone substitution: toward a doping-dependent cluster-based model

Author: Marion Merle, Jérémy Soulié, Capucine Sassoye, Pierre Roblin, Christian Rey, Christian Bonhomme, and Christèle Combes
Subjects: General Materials Science, General Chemistry, Condensed Matter Physics
Abstract: Multiscale and multitool advanced characterisation of pyrophosphate-stabilised amorphous calcium carbonates allowed building a cluster-based model paving the way for tunable biomaterials.
Published: 2022
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6. Simple Synthesis of Monodisperse Ultrasmall Au Icosahedral Nanoparticles

Author: Ezgi Yildirim, Raj Kumar Ramamoorthy, Rohan Parmar, Pierre Roblin, Jorge A. Vargas, Valeri Petkov, Ana Diaz, Stefano Checchia, Isaac Rodriguez Ruiz, Sébastien Teychené, Lise-Marie Lacroix, Guillaume Viau, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Universidad Autonoma de Zacatecas [Autonomous University of Zacatecas] (UAZ), Central Michigan University (CMU), Paul Scherrer Institute (PSI), European Synchroton Radiation Facility [Grenoble] (ESRF), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-21-CE09-0019,NIMRod,Nucléation, croissance par ensemencement et intégration de nanofils magnétiques(2021), and ANR-17-EURE-0009,NanoX,Science et Ingénierie à l'Echelle Nano(2017)
Subjects: General Energy, [CHIM.MATE]Chemical Sciences/Material chemistry, Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials
Abstract: International audience; Ultra-small metal nanoparticles (NPs) with a mean diameter below 2 nm are being intensively studied due to their unique structural and chemical properties. At such small sizes, metal particles can appear as various polyhedra with different atomic structures depending on whether electronic effects, surface energy or the nucleation mechanism govern their crystallization. Therefore, the synthesis of monodisperse nanoparticles of a very small size and well-defined structure requires a good understanding of the different steps of the crystallization process, which can be achieved by conducting and coupling in situ studies at different length and time scales. In this article, we describe the synthesis of ultra-small gold NPs by reduction of HAuCl4 in solution of oleylamine (OY) in hexane using trialkylsilanes as reducing agents. Thanks to time-resolved in situ small angle X-ray scattering and X-ray absorption spectroscopy kinetic studies, a competition between nucleation of Au NPs from a solution containing Au(III) clusters and crystallization of a lamellar phase of composition OY-Au(I)-Cl was revealed. In situ X-ray diffraction and Pair Distribution Function analysis (PDF) showed that the first chemical pathway leads to icosahedral NPs while the reduction of OY-Au(I)-Cl leads to fcc NPs.
Published: 2023
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7. Synthesis and emission dynamics of ultrasmall (sub-3 nm) UCNPs containing a reduced number of emitters

Author: Baptiste Amouroux, Ali Eftekhari, Clément Roux, Pierre Roblin, Mathieu Pasturel, Ute Resch-Genger, Christian Würth, Fabienne Gauffre, Michel Sliwa, Aude Bouchet, and Christophe Coudret
Abstract: Reducing the size of rare earth, alkali metal fluoride crystals formulated as upconverting nanoparticles (UCNP) down to few nm can lead to unique luminescent devices due to a reduced number of emitters. The synthesis of such Na(Gd-Yb)F4:Tm nanocrystals is still challenging. The most critical issue is to keep detectable emission despite the high surface to volume ratio and the limited number of emitting ions. The preparation of sub-3 nm diameter emissive, ꞵ-phase UCNPs with few emitters was achieved using a gadolinium-rich composition, an in-situ mixing of the precursor (NaOH and NH4F), and a microwave high-temperature cycling sequence which allowed the precise control of the particle size and dispersity. Such particles can contain only a single activator ion (Tm3+). Coating of these core particles with a NaGdF4 inert shell was carried-out in order to moderate the surface quenching deleterious influence. The reduced number of activators offers an unprecedented platform to study the role of cross relaxation in the global luminescence. This was tackled by time resolved luminescence measurements using an original combination of standard Yb3+ sensitizer NIR-excitation and direct Tm3+ activator UV-excitation.
Published: 2022
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8. BioSAXS on the SWING beamline at Synchrotron SOLEIL

Author: Javier Pérez, Aurélien Thureau, and Pierre Roblin
Subjects: Materials science, Spectrometer, business.industry, Instrumentation, Detector, Column (database), General Biochemistry, Genetics and Molecular Biology, Synchrotron, Light scattering, law.invention, Software, Optics, Beamline, law, business
Abstract: Small-angle X-ray scattering (SAXS) of proteins in solution has become a key tool for biochemists and structural biologists, thanks especially to the availability of beamlines with high-throughput capabilities at synchrotron sources. Despite the large spectrum of scientific disciplines tackled on the SWING beamline since its opening in 2008, there has always been a strong commitment to offering state-of-the-art biological SAXS (BioSAXS) instrumentation and data reduction methods to the scientific community. The extremely reliable in-vacuum EigerX-4M detector allows collection of an unlimited number of frames without noise. A small beamstop including a diamond diode-based monitor enables measurements of the transmitted intensity with 0.1% precision as well as a q max/q min ratio as large as 140 at a single distance. The parasitic scattering has been strongly reduced by the installation of new hybrid blades. A new thermally controlled in-vacuum capillary holder including fibre-optics-based spectroscopic functionalities allows the simultaneous use of three spectroscopic techniques in addition to SAXS measurements. The addition of a second high-performance liquid chromatography (HPLC) circuit has virtually eliminated the waiting time associated with column equilibration. The easy in-line connection of a multi-angle light scattering spectrometer and a refractometer allows for an independent determination of the molecular mass and of the concentration of low-UV-absorption samples such as detergents and sugars, respectively. These instrumental improvements are combined with important software developments. The HPLC injection Agilent software is controlled by the SAXS beamline acquisition software, allowing a virtually unlimited series of automated SAXS measurements to be synchronized with the sample injections. All data-containing files and reports are automatically stored in the same folders, with names related to both the user and sample. In addition, all raw SAXS images are processed automatically on the fly, and the analysed data are stored in the ISPyB database and made accessible via a web page.
Published: 2021
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9. Heterogeneous Oxysulfide@Fluoride Core/Shell Nanocrystals for Upconversion-Based Nanothermometry

Author: Qilin Zou, Cécile Marcelot, Nicolas Ratel-Ramond, Xiaodong Yi, Pierre Roblin, Florian Frenzel, Ute Resch-Genger, Ali Eftekhari, Aude Bouchet, Christophe Coudret, Marc Verelst, Xueyuan Chen, Robert Mauricot, Clément Roux, Interactions moléculaires et réactivité chimique et photochimique (IMRCP), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), IDeAS - Interfaces Dynamiques et Assemblages Stimulables (IDeAS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Federal Institute for Materials Research and Testing - Bundesanstalt für Materialforschung und -prüfung (BAM), Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Chinese Academy of Agricultural Sciences (CAAS)
Subjects: General Engineering, General Physics and Astronomy, [CHIM]Chemical Sciences, General Materials Science
Abstract: International audience
Published: 2022
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10. Top-down synthesis of luminescent microplastics and nanoplastics by incorporation of upconverting nanoparticles for environmental assessment

Author: Nadiia Yakovenko, Baptiste Amouroux, Magali Albignac, Fabrice Collin, Clément Roux, Anne-Françoise Mingotaud, Pierre Roblin, Christophe Coudret, Alexandra ter Halle, Interactions moléculaires et réactivité chimique et photochimique (IMRCP), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), IDeAS - Interfaces Dynamiques et Assemblages Stimulables (IDeAS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT), BIBAC - Chimie analytique et interactions biomolécules - matière molle biomimétique (BIBAC), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), SMODD - Systèmes Moléculaires Organisés et Développement Durable (SMODD), Université Toulouse III - Paul Sabatier, Centre National de la Recherche Scientifique, and ANR-15-CE09-0020, Agence Nationale de la Recherche
Subjects: [CHIM.POLY]Chemical Sciences/Polymers, Materials Science (miscellaneous), General Environmental Science
Abstract: International audience; The occurrence of micro- and nanoplastics is a major environmental problem. Especially for nanoplastics due to their easy bioavailability and unknown impact on living organisms. The monitoring of these extremely small particles during their ingestion, tissue translocation and transfer through the trophic chain remains very challenging. This study aims to develop an environmentally relevant model of luminescent micro- and nanoplastics. Lanthanide based upconverting nanophosphors able to convert highly penetrating and benign near infrared light into visible one were selected as luminescent tag for the plastic particles. First, lanthanide-based upconverting nanophosphors (20 nm) were incorporated in bulk polyethylene without modification of the polymer structure or morphology. Second, micrometric and nanometric particles were obtained after powdering. Two fractions were obtained with cascade filtration with average sizes of 5 μm and 150 nm and characterized in terms of size distribution, morphology and surface charge. The particles are very polydisperse with an irregular shape and a global negative charge; they exhibit morphological characteristics similar to those formed in the environment. Their luminescent properties upon NIR excitation at 980 nm open the possibility to track them in the tissues of organisms. The powdering method is very simple and compatible with many polymers pure or formulated. As a perspective, the use of weathered materials is possible with the proposed method and will allow the preparation of particles sharing additional properties with environmental micro- and nanoplastics.
Published: 2022
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11. Wet spinning of a library of carbohydrate low molecular weight gels

Author: Christophe Coudret, Delphine Bordignon, Laurent Malaquin, Pierre Joseph, Juliette Fitremann, Pierre Roblin, Anaïs Chalard, Barbara Lonetti, Interactions moléculaires et réactivité chimique et photochimique (IMRCP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Laboratoire de Génie Chimique (LGC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Équipe Micro-Nanofluidique pour les sciences de la vie et de l’environnement (LAAS-MILE), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), IDeAS - Interfaces Dynamiques et Assemblages Stimulables (IDeAS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole)
Subjects: Materials science, Supramolecular chemistry, Carbohydrates, Biocompatible Materials, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Biomaterials, Colloid and Surface Chemistry, molecular gel, Molecule, Spinning, Alkyl, chemistry.chemical_classification, injectable, saccharide, Biomaterial, Hydrogels, self-assembly, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, LMWG, Molecular Weight, chemistry, Chemical engineering, Self-healing hydrogels, Printing, Three-Dimensional, aldonamide, Self-assembly, 0210 nano-technology, wet spinning, Linker, supramolecular
Abstract: International audience; Hypothesis Recently, a low molecular weight hydrogel based on a carbohydrate alkyl amide has been successfully used as biomaterial for neuron cell culture and for 3D printing. Varying the molecular structure should make it possible to extend the library of carbohydrate low molecular weight hydrogels available for these applications and to improve their performances. Experiments Thirteen molecules easy to synthetize and designed to be potentially biocompatible were prepared. They are based on gluconamide, glucoheptonamide, galactonamide, glucamide, aliphatic chains and glycine. Their gelation in water was investigated in thermal conditions and wet spinning conditions, namely by dimethylsulfoxide-water exchange under injection. Findings Nine molecules give hydrogels in thermal conditions. By wet spinning, six molecules selfassemble fast enough, within few seconds, to form continous hydrogel filaments. Therefore, the method enables to shape by injection these mechanically fragile hydrogels, notably in the perspective of 3D printing. Depending on the molecular structure, persistent or soluble gel filaments are obtained. The microstructures are varied, featuring entangled ribbons, platelets or particles. In thermal gelation, molecules with a symmetrical polar head (galacto, glucoheptono) give flat ribbons and molecules with an asymmetrical polar head (gluco) give helical ribbons. The introduction of an extra glycine linker disturbs this trend.
Published: 2021
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12. The Jo-In protein welding system is a relevant tool to create CBM-containing plant cell wall degrading enzymes

Author: Guy Lippens, Pierre Roblin, Cedric Montanier, Thomas Enjalbert, Immacolata Venditto, Michael J. O’Donohue, Louise Badruna, Vincent Burlat, Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Dynamique et Evolution des Parois cellulaires végétales, Laboratoire de Recherche en Sciences Végétales (LRSV), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), Laboratoire de Génie Chimique (LGC), Newcastle University [Newcastle], Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDV.BIO]Life Sciences [q-bio]/Biotechnology, Protein domain, Carbohydrates, CBM family 3, Bioengineering, Computational biology, Welding, CBM family 2, Protein Engineering, law.invention, Substrate Specificity, 03 medical and health sciences, 0302 clinical medicine, law, Cell Wall, Catalytic Domain, Plant Cells, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, Molecular Biology, 030304 developmental biology, chemistry.chemical_classification, Flexibility (engineering), 0303 health sciences, beta-xylanase, Endo-1,4-beta Xylanases, Substrate (chemistry), General Medicine, Ligand (biochemistry), Spatial proximity, Enzyme, chemistry, Bio Molecular Welding, Xylanase, 030217 neurology & neurosurgery, Function (biology), Biotechnology
Abstract: International audience; Irrespective of their biological origin, most proteins are composed of several elementary domains connected by linkers. These domains are either functionally independent units, or part of larger multidomain structures whose functions are defined by their spatial proximity. Carbohydrate-degrading enzymes provide examples of a range of multidomain structures, in which catalytic protein domains are frequently appended to one or more non-catalytic carbohydrate-binding modules which specifically bind to carbohydrate motifs. While the carbohydrate-binding specificity of these modules is clear, their function is not fully elucidated. Herein, an original approach to tackle the study of carbohydrate-binding modules using the Jo-In biomolecular welding protein pair is presented. To provide a proof of concept, recombinant xylanases appended to two different carbohydrate-binding modules have been created and produced. The data reveal the biochemical properties of four xylanase variants and provide the basis for correlating enzyme activity to structural properties and to the nature of the substrate and the ligand specificity of the appended carbohydrate-binding module. It reveals that specific spatial arrangements favour activity on soluble polymeric substrates and that activity on such substrates does not predict the behaviour of multimodular enzymes on insoluble plant cell wall samples. The results highlight that the Jo-In protein welding system is extremely useful to design multimodular enzyme systems, especially to create rigid conformations that decrease the risk of intermodular interference. Further work on Jo-In will target the introduction of varying degrees of flexibility, providing the means to study this property and the way it may influence multimodular enzyme functions.
Published: 2021
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13. Pearl-necklace assembly of human serum albumin with the poly(acrylic acid) polyelectrolyte investigated using small angle X-ray scattering (SAXS)

Author: Pierre Roblin, Charaf Eddine Merzougui, Yung Chang, Antoine Venault, Pierre Aimar, Patrice Bacchin, Christel Causserand, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Chung Yuan Christian University - CYCU (TAIWAN), Laboratoire de Génie Chimique - LGC (Toulouse, France), Chung Yuan Christian University, Laboratoire de génie chimique [ancien site de Basso-Cambo] (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: SAXS, Interaction, Acrylic Resins, Serum Albumin, Human, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, chemistry.chemical_compound, [CHIM.GENI]Chemical Sciences/Chemical engineering, X-Ray Diffraction, Ionic strength, Scattering, Small Angle, medicine, Humans, Génie chimique, Molecule, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Génie des procédés, Human Serum Albumin, Poly(acrylic acid), Acrylic acid, pH, Chemistry, Small-angle X-ray scattering, X-Rays, General Chemistry, Hydrogen-Ion Concentration, biochemical phenomena, metabolism, and nutrition, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Human serum albumin, Polyelectrolytes, Polyelectrolyte, 0104 chemical sciences, body regions, Crystallography, embryonic structures, Radius of gyration, 0210 nano-technology, Macromolecule, medicine.drug
Abstract: International audience; In this comprehensive study, the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA) was explored using small angle X-ray scattering (SAXS) combined with chromatography. The results revealed the formation of a complex between HSA macromolecules and PAA chains but solely under some specific conditions of the ionic strength and pH of the medium. In fact, this binding was found to take place only at pH close to 5 and at low ionic strength (0.15 M). Otherwise, for a higher pH and a salt concentration of 0.75 M the HSA–PAA complex tends to dissociate completely showing the reversibility of the complexation. The assessment of the influence of the HSA/PAA molar ratio on the radius of gyration of the complex suggests that 4 HSA molecules could bind to each 100 kDa PAA chain. In addition, the Porod volume evaluation for the same range of the HSA/PAA ratio confirms this assumption. Finally, an all-atom SAXS modelling study using the BUNCH program was conducted to find a compatible model that fits the HSA–PAA complex scattering data. This model allows us to portray the HSA/PAA complex as a pearl-necklace assembly with 4 HSA molecules on the 100 kDa PAA chain.
Published: 2020
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14. New exploration of the γ-gliadin structure through its partial hydrolysis

Author: Hélène Rogniaux, Adeline Boire, Alexandre Giuliani, Denis Renard, Line Sahli, Véronique Solé-Jamault, Pierre Roblin, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Laboratoire de Génie Chimique - LGC (Toulouse, France), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: Partial hydrolysis, Peptide, 02 engineering and technology, Intrinsically disordered proteins, Biochemistry, Gliadin, Domain (software engineering), 03 medical and health sciences, Protein Domains, Structural Biology, Enzymatic hydrolysis, Wheat storage proteins, Chymotrypsin, Génie chimique, Génie des procédés, Molecular Biology, Triticum, 030304 developmental biology, 2. Zero hunger, chemistry.chemical_classification, 0303 health sciences, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], biology, Small-angle X-ray scattering, Hydrolysis, food and beverages, General Medicine, 021001 nanoscience & nanotechnology, 3D structure modelling, Template, chemistry, Biophysics, biology.protein, 0210 nano-technology
Abstract: International audience; The partial enzymatic hydrolysis of wheat gliadins constitutes an interesting tool to unravel their structural specificity. In this work, the structure and conformation of γ-gliadin were investigated through its limited chymotrypsic digestion. Using a combination of computational, biochemical and biophysical tools, we studied each of its N and C terminal domains. Our results reveal that γ-gliadin is a partially disordered protein with an unfolded N-terminal domain surprisingly resistant to chymotrypsin and a folded C-terminal domain. Using spectroscopic tools, we showed that structural transitions occured over the disordered N-terminal domain for decreasing ethanol/water ratios. Using SAXS measurements, low-resolution 3D structures of γ-gliadin were proposed. To relate the repeated motifs of the N-terminal domain of γ-gliadin to its structure, engineered peptide models PQQPY/F were also studied. Overall results demonstrated similarities between the N-terminal domain and its derived model peptides. Our findings support the use of these peptides as general templates for understanding the wheat protein assembly and dynamics.
Published: 2020
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15. 2D and 3D Ruthenium Nanoparticle Covalent Assemblies for Phenyl Acetylene Hydrogenation

Author: Andrea Falqui, Beatriz María Illescas Martínez, Pierre Roblin, M. Rosa Axet, Philippe Serp, Thomas Theussl, Silverio Coco, Nazario Martín, Hervé Martinez, Yuanyuan Min, Pierre Lecante, María Barcenilla, Alberto Casu, Bruno F. Machado, Faqiang Leng, Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia (LSRE-LCM), Universidade do Porto = University of Porto, Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université de Pau et des Pays de l'Adour (UPPA), King Abdullah University of Science and Technology (KAUST), Universidad de Valladolid [Valladolid] (UVa), Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Instituto IMDEA Nanociencia [Madrid], Instituto Imdea Nanociencia, Centre National de la Recherche Scientifique (CNRS), Institut National Polytechnique (INP), ANR-16-CE07-0007,ICARE_1,Nanostrucutres métal@carbone innovante pour une catalyse durable(2016), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Universidade do Porto, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), King Abdullah University of Science and Technology - KAUST (SAUDI ARABIA), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Universidad Complutense de Madrid - UCM (SPAIN), Université de Pau et des Pays de l'Adour - UPPA (FRANCE), Universidade do Porto - UP (PORTUGAL), and Centre d'Elaboration de Matériaux et d'Etudes Structurales - CEMES (Toulouse, France)
Subjects: Triphenylene, chemistry.chemical_element, Nanoparticle, 010402 general chemistry, 01 natural sciences, Ruthenium, Catalysis, Styrene, Inorganic Chemistry, chemistry.chemical_compound, [CHIM.GENI]Chemical Sciences/Chemical engineering, Génie chimique, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Génie des procédés, Covalent assembly, 010405 organic chemistry, Combinatorial chemistry, Acetylene hydrogenation, 0104 chemical sciences, Metallic nanoparticles, chemistry, Phenylacetylene, Covalent bond, Selectivity, Confinement effect
Abstract: International audience; The bottom‐up covalent assembly of metallic nanoparticles (NP) represents one of the innovative tools in nanotechnology to build functional heterostructures, with the resulting assemblies showing superior collective properties over the individual NP for a broad range of applications. The ability to control the dimensionality of the assembly is one of the major challenges in designing and understanding these advanced materials. Here, two new organic linkers were used as building blocks in order to guide the organization of Ru NP into two‐ or three‐dimensional covalent assemblies. The use of a hexa‐adduct functionalized C60 leads to the formation of 3D networks of 2.2 nm Ru NP presenting an interparticle distance of 3.0 nm, and the use of a planar carboxylic acid triphenylene derivative allows the synthesis of 2D networks of 1.9 nm Ru NP with an interparticle distance of 3.1 nm. The Ru NP networks were found to be active catalysts for the selective hydrogenation of phenylacetylene, reaching good selectivity toward styrene. Overall, we demonstrated that catalyst performances are significantly affected by the dimensionality (2D vs. 3D) of the heterostructures, which can be rationalize based on confinement effects.
Published: 2020
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16. Spray-drying-derived amorphous calcium phosphate: a multi-scale characterization

Author: Christian Rey, Pierre Roblin, Yannick Coppel, Pierre Lecante, Sylvain Le Grill, Fabien Brouillet, Jérémy Soulié, Ghislaine Bertrand, Olivier Marsan, Cédric Charvillat, Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Chimique (LGC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de génie chimique [ancien site de Basso-Cambo] (LGC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), and Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Subjects: Multi scale characterization, Materials science, multi scale characterization, Matériaux, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Apatite, [CHIM.GENI]Chemical Sciences/Chemical engineering, Phase (matter), Génie chimique, General Materials Science, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Amorphous calcium phosphate, Génie des procédés, Spray drying derived, Mechanical Engineering, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Amorphous solid, Characterization (materials science), Chemical engineering, Mechanics of Materials, Spray drying, visual_art, Scientific method, visual_art.visual_art_medium, 0210 nano-technology, Reactive material, amorphous calcium phosphate
Abstract: International audience; Amorphous calcium orthophosphates (ACP) are bioactive compounds presenting high interest as bone substitute. However, the synthesis of such metastable products requires special attention as they can rapidly evolve into a crystalline phase during the elaboration process. The resulting increased stability generally leads to less bioactive reactive materials. Among the various strategies developed to obtain stable form of ACP, the use of spray drying is an effective and reproducible route. Compared to previous works, this study aims to demonstrate for the first time the feasibility of ACP elaboration by spray drying directly from a single solution of selected precursors. Moreover, structuration of the spray-dried powders was determined at different length scales, demonstrating a hierarchical organization from nanometric clusters to particles aggregates. These complementary analyses highlighted a thorough mechanism of particles formation during processing. The effect of the initial composition of the solution was observed, and it was demonstrated that there is a correlation with the purity of the final product that may be modulated. In addition, ACP powders were found to be highly reactive in aqueous medium and their fast transformation into low crystalline apatite suggests a good suitability for biomedical use.
Published: 2020
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17. Bidimensional lamellar assembly by coordination of peptidic homopolymers to platinum nanoparticles

Author: Mathilde Rigoulet, Bruno Chaudret, Angélique Gillet, Colin Bonduelle, Yannick Coppel, Simon Tricard, Pierre Roblin, Ghada Manai, Jérôme Esvan, Stéphanie Balor, Pier-Francesco Fazzini, Hend Houimel, Alfonso Ibarra, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Instituto de Nanociencia de Aragón [Saragoza, España] (INA), University of Zaragoza - Universidad de Zaragoza [Zaragoza], Centre de Biologie Intégrative (CBI), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Chimique (LGC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Laboratoire de Chimie des Polymères Organiques (LCPO), Université de Bordeaux (UB)-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-18-CE09-0007,MOSC,Chimie supraparticulaire orientée par des molécules(2018), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux (UB)-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Team 3 LCPO : Polymer Self-Assembly & Life Sciences, Université de Bordeaux (UB)-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Bordeaux INP - BINP (FRANCE), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de Bordeaux (FRANCE), and Universidad Zaragoza (SPAIN)
Subjects: Materials science, Polymers, Science, Metal Nanoparticles, General Physics and Astronomy, Nanoparticle, Nanotechnology, 02 engineering and technology, 010402 general chemistry, Platinum nanoparticles, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, Polymerization, Copolymer, Génie chimique, Molecular self-assembly, Lamellar structure, [CHIM.COOR]Chemical Sciences/Coordination chemistry, lcsh:Science, Polymer, Platinum, chemistry.chemical_classification, Mesoscopic physics, Multidisciplinary, Photoelectron Spectroscopy, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Polymères, 0104 chemical sciences, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Nanoparticles, lcsh:Q, Peptides, 0210 nano-technology, Hybrid material, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract: A key challenge for designing hybrid materials is the development of chemical tools to control the organization of inorganic nanoobjects at low scales, from mesoscopic (~µm) to nanometric (~nm). So far, the most efficient strategy to align assemblies of nanoparticles consists in a bottom-up approach by decorating block copolymer lamellae with nanoobjects. This well accomplished procedure is nonetheless limited by the thermodynamic constraints that govern copolymer assembly, the entropy of mixing as described by the Flory–Huggins solution theory supplemented by the critical influence of the volume fraction of the block components. Here we show that a completely different approach can lead to tunable 2D lamellar organization of nanoparticles with homopolymers only, on condition that few elementary rules are respected: 1) the polymer spontaneously allows a structural preorganization, 2) the polymer owns functional groups that interact with the nanoparticle surface, 3) the nanoparticles show a surface accessible for coordination., Precise organization of nanoparticles and polymers for the design of hybrid materials remains a challenging task. Here, the authors show a convenient way to organize nanoobjects by preorganization of inorganic particles in presence of a functional peptidic homopolymer.
Published: 2020
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18. Characterisation of the Effect of the Spatial Organisation of Hemicellulases on the Hydrolysis of Plant Biomass Polymer

Author: Thomas Enjalbert, Claire Dumon, Pierre Roblin, Marion De La Mare, Louise Badruna, Cedric Montanier, Thierry Vernet, Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Toulouse White Biotechnology (TWB), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de biologie structurale (IBS - UMR 5075), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), internal grant from the Toulouse White Biotechnology and the Région Occitanie., Commissariat à l'Energie Atomique et aux énergies alternatives - CEA (FRANCE), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: 0106 biological sciences, 0301 basic medicine, Oligosaccharides, Xylose, Protein Engineering, 01 natural sciences, Enzyme engineering, lcsh:Chemistry, chemistry.chemical_compound, X-Ray Diffraction, Biomass, lcsh:QH301-705.5, Spectroscopy, Plant Proteins, 2. Zero hunger, chemistry.chemical_classification, Hydrolysis, General Medicine, Plants, Computer Science Applications, Reducing sugar, Xylosidases, xylosidase, Xylanase, Glycoside Hydrolases, Recombinant Fusion Proteins, Context (language use), spatial proximity, Xylosidase, Article, Catalysis, Carbon Cycle, Inorganic Chemistry, 03 medical and health sciences, Protein Domains, 010608 biotechnology, synergism, Scattering, Small Angle, Génie chimique, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, Physical and Theoretical Chemistry, Génie des procédés, Molecular Biology, xylanase, Organic Chemistry, Synergism, Substrate (chemistry), Protein engineering, Xylan, Spatial proximity, enzyme engineering, 030104 developmental biology, chemistry, lcsh:Biology (General), lcsh:QD1-999, Bio Molecular Welding, Biophysics
Abstract: International audience; Synergism between enzymes is of crucial importance in cell metabolism. This synergism occurs often through a spatial organisation favouring proximity and substrate channelling. In this context, we developed a strategy for evaluating the impact of the geometry between two enzymes involved in nature in the recycling of the carbon derived from plant cell wall polymers. By using an innovative covalent association process using two protein fragments, Jo and In, we produced two bi-modular chimeric complexes connecting a xylanase and a xylosidase, involved in the deconstruction of xylose-based plant cell wall polymer. We first show that the intrinsic activity of the individual enzymes was preserved. Small Angle X-rays Scattering (SAXS) analysis of the complexes highlighted two different spatial organisations in solution, affecting both the distance between the enzymes (53 Å and 28 Å) and the distance between the catalytic pockets (94 Å and 75 Å). Reducing sugar and HPAEC-PAD analysis revealed different behaviour regarding the hydrolysis of Beechwood xylan. After 24 h of hydrolysis, one complex was able to release a higher amount of reducing sugar compare to the free enzymes (i.e., 15,640 and 14,549 µM of equivalent xylose, respectively). However, more interestingly, the two complexes were able to release variable percentages of xylooligosaccharides compared to the free enzymes. The structure of the complexes revealed some putative steric hindrance, which impacted both enzymatic efficiency and the product profile. This report shows that controlling the spatial geometry between two enzymes would help to better investigate synergism effect within complex multi-enzymatic machinery and control the final product.
Published: 2020
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19. The Crystal Structure of Gurmarin, a Sweet Taste–Suppressing Protein: Identification of the Amino Acid Residues Essential for Inhibition

Author: Pierre Legrand, Pierre Roblin, Christophe Charron, Anne Brockhoff, Loïc Briand, Maud Sigoillot, Wolfgang Meyerhof, Christine Belloir, Nicolas Poirier, Fabrice Neiers, Centre des Sciences du Goût et de l'Alimentation [Dijon] (CSGA), Institut National de la Recherche Agronomique (INRA)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Université Bourgogne Franche-Comté [COMUE] (UBFC), German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE), Synchrotron SOLEIL, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and ANR Sweetprot
Subjects: 0301 basic medicine, Protein Conformation, Physiology, Crystal structure, Crystallography, X-Ray, 03 medical and health sciences, Behavioral Neuroscience, GPCR, sweet taste, taste receptor, Physiology (medical), goût sucré, Animals, Humans, G protein-coupled receptor, Amino Acids, Binding site, Receptor, Nuclear Magnetic Resonance, Biomolecular, Plant Proteins, Gurmarin, inhibiteur, 030102 biochemistry & molecular biology, biology, Chemistry, Mutagenesis, Cystine knot, Gymnema sylvestre, Sweet taste, biology.organism_classification, Recombinant Proteins, Sensory Systems, Rats, 3. Good health, inhibitor, HEK293 Cells, 030104 developmental biology, Biochemistry, knottin, [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition, Hydrophobic and Hydrophilic Interactions
Abstract: International audience; Gurmarin is a highly specific sweet-taste suppressing protein in rodents that is isolated from the Indian plant Gymnemasylvestre. Gurmarin consists of 35 amino acid residues containing three intramolecular disulfide bridges that form a cystine knot. Here, we report the crystal structure of gurmarin at a 1.45 Å resolution and compare it with previously reported NMR solution structures. The atomic structure at this resolution allowed us to identify a very flexible region consisting of hydrophobic residues. Some of these amino acid residues had been identified as a putative binding site for the rat sweet taste receptor in a previous study. By combining alanine-scanning mutagenesis of the gurmarin molecule and a functional cell-based receptor assay, we confirmed that some single point mutations in these positions drastically affect sweet taste receptor inhibition by gurmarin.
Published: 2018
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20. Biophysical analysis of Arabidopsis protein-only RNase P alone and in complex with tRNA provides a refined model of tRNA binding

Author: Philippe Giegé, Anthony Gobert, Claude Sauter, Catherine Birck, Aurélien Thureau, Pablo Fernandez-Millan, Cédric Schelcher, Franziska Pinker, Pierre Roblin, Architecture et réactivité de l'ARN (ARN), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Architecture et Réactivité de l'ARN (ARN), Institut de biologie moléculaire et cellulaire (IBMC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie moléculaire des plantes (IBMP), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), French CNRS, University of Strasbourg, Agence Nationale de la Recherche (ANR) Blanc 'PRO-RNase P' Research Grant [ANR-11-BSV8-008-01/02], LabEx consortium 'MitoCross' in the frame of the French National Program 'Investissement d'Avenir' [ANR-11-LABX-0057_MITOCROSS], French Infrastructure for Integrated Structural Biology (FRISBI) [ANR-10-INSB-05], Sauter, Claude, and Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)
Subjects: 0301 basic medicine, precursor tRNA (pre-tRNA), ribonuclease P (RNase P), RNA processing, small-angle X-ray scattering (SAXS), X-ray crystallography, PRORP, pentatricopeptide repeat (PPR), tRNA maturation, RNase P, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Biology, Biochemistry, RNase PH, 03 medical and health sciences, 0302 clinical medicine, Protein structure, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, tRNA, Molecular Biology, Ribonucleoprotein, Nuclear RNase P, Prorp, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, Cell Biology, Molecular biology, TRNA binding, RNase MRP, 030104 developmental biology, Transfer RNA, tRNA maturation tRNA, 030217 neurology & neurosurgery
Abstract: RNase P is a universal enzyme that removes 5′ leader sequences from tRNA precursors. The enzyme is therefore essential for maturation of functional tRNAs and mRNA translation. RNase P represents a unique example of an enzyme that can occur either as ribonucleoprotein or as protein alone. The latter form of the enzyme, called protein-only RNase P (PRORP), is widespread in eukaryotes in which it can provide organellar or nuclear RNase P activities. Here, we have focused on Arabidopsis nuclear PRORP2 and its interaction with tRNA substrates. Affinity measurements helped assess the respective importance of individual pentatricopeptide repeat motifs in PRORP2 for RNA binding. We characterized the PRORP2 structure by X-ray crystallography and by small-angle X-ray scattering in solution as well as that of its complex with a tRNA precursor by small-angle X-ray scattering. Of note, our study reports the first structural data of a PRORP–tRNA complex. Combined with complementary biochemical and biophysical analyses, our structural data suggest that PRORP2 undergoes conformational changes to accommodate its substrate. In particular, the catalytic domain and the RNA-binding domain can move around a central hinge. Altogether, this work provides a refined model of the PRORP–tRNA complex that illustrates how protein-only RNase P enzymes specifically bind tRNA and highlights the contribution of protein dynamics to achieve this specific interaction.
Published: 2017
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21. 3D Ruthenium Nanoparticle Covalent Assemblies from Polymantane Ligands for Confined Catalysis

Author: Philippe Serp, Pierre Roblin, Yann Tison, Hervé Martinez, Pierre Lecante, Andrea Falqui, Yuanyuan Min, Iker del Rosal, Romuald Poteau, Jean-Cyrille Hierso, Didier Poinsot, M. Rosa Axet, H. Nasrallah, Iann C. Gerber, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Institut National de la Santé et de la Recherche Médicale - INSERM (FRANCE), King Abdullah University of Science and Technology - KAUST (SAUDI ARABIA), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE), Université de Bourgogne - UB (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de Pau et des Pays de l'Adour - UPPA (FRANCE), Laboratoire de Physique et Chimie des Nano-Objets - LPCNO (Toulouse, France), Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire de l'Université de Bourgogne [Dijon] (ICMUB), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-Institut de Chimie du CNRS (INC), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Université de Pau et des Pays de l'Adour (UPPA), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Chimique (LGC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, King Abdullah University of Science and Technology (KAUST), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Bourgogne (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), CNRS, Université de Bourgogne, Conseil Régional de Bourgogne (plan d'actions régional pour l’innovation PARI), Fonds européen de développement régional (FEDER programs), and ANR-16-CE07-0007,ICARE_1,Nanostrucutres métal@carbone innovante pour une catalyse durable(2016)
Subjects: General Chemical Engineering, Carboxylic acid, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, 010402 general chemistry, Ligands, 01 natural sciences, Catalysis, chemistry.chemical_compound, [CHIM.GENI]Chemical Sciences/Chemical engineering, Organic acids, Materials Chemistry, Génie chimique, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Amines, Génie des procédés, chemistry.chemical_classification, Catalysts, Ligand, Decarbonylation, General Chemistry, 021001 nanoscience & nanotechnology, Combinatorial chemistry, 0104 chemical sciences, Ruthenium, chemistry, Phenylacetylene, Metals, Density functional theory, 0210 nano-technology
Abstract: International audience; The synthesis of metal nanoparticle (NP) assemblies stabilized by functional molecules is an important research topic in nanoscience, and the ability to control interparticle distances and positions in NP assemblies is one of the major challenges in designing and understanding functional nanostructures. Here, two series of functionalized adamantanes, bis-adamantanes, and diamantanes, bearing carboxylic acid or amine functional groups, were used as building blocks to produce, via a straightforward method, networks of ruthenium NPs. Both the nature of the ligand and the Ru/ligand ratio affect the interparticle distance in the assemblies. The use of 1,3-adamantanedicarboxylic acid allows the synthesis of three-dimensional (3D) networks of 1.7–1.9 nm Ru NPs presenting an interparticle distance of 2.5–2.7 nm. The surface interaction between Ru NPs and the ligands was investigated spectroscopically using a 13C-labeled ligand, as well as theoretically with density functional theory (DFT) calculations. We found that Ru species formed during the NP assembly are able to partially decarbonylate carboxylic acid ligands at room temperature. Decarbonylation of a carboxylic acid at room temperature in the presence of dihydrogen usually occurs on catalysts at much higher temperatures and pressures. This result reveals a very high reactivity of ruthenium species formed during the network assembly. The Ru NP networks were found to be active catalysts for the selective hydrogenation of phenylacetylene, reaching good selectivity toward styrene. Overall, we demonstrated that catalyst activity, selectivity, and NP network stability are significantly affected by Ru NP interparticle distance and electronic ligand effects. As such, these materials constitute a unique set that should allow a better understanding of the complex surface chemistry in carbon-supported metal catalysts.
Published: 2020
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22. The role of pre-nucleation clusters in the crystallization of gold nanoparticles

Author: Valeri Petkov, Lise-Marie Lacroix, Ezgi Yildirim, Jorge A. Vargas, Raj Kumar Ramamoorthy, Philippe Decorse, Sébastien Teychené, Pierre Roblin, Guillaume Viau, Enguerrand Barba, Isaac Rodríguez-Ruiz, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Laboratoire de Génie Chimique (LGC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Central Michigan University (CMU), Universidad Autonoma de Zacatecas [Autonomous University of Zacatecas] (UAZ), Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Central Michigan University - CMU (USA), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE), Universidad Autónoma de Zacatecas - UAZ (MEXICO), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de Paris - U-Paris (FRANCE), and Interfaces, Traitements, Organisation et Dynamique des Systèmes - ITODYS (Paris, France)
Subjects: Materials science, Nucleation, Nanoparticle, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, chemistry.chemical_compound, Oleylamine, law, Génie chimique, [CHIM]Chemical Sciences, Gold nanoparticles, General Materials Science, Crystallization, Génie des procédés, ComputingMilieux_MISCELLANEOUS, X-ray absorption spectroscopy, Small-angle X-ray scattering, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, Chemical engineering, Colloidal gold, Particle size, 0210 nano-technology
Abstract: International audience; The syntheses of metal nanoparticles by reduction in apolar solvents in the presence of long chain surfactants have proven to be extremely effective in the control of the particle size and shape. Nevertheless, the elucidation of the nucleation/growth mechanism is not straightforward because of the multiple roles played by surfactants. The nucleation stage, in particular, is very difficult to describe precisely and requires in situ and time-resolved techniques. Here, relying on in situ small angle X-ray scattering (SAXS), X-ray absorption spectroscopy (XAS) and high-energy X-ray diffraction (HE-XRD), we propose that ultra-small gold particles prepared by reduction of gold chloride in a solution of oleylamine (OY) in hexane with triisopropylsilane do not follow a classical nucleation process but result from pre-nucleation clusters (PNCs). These PNCs contain Au(III) and Au(I) precursors; they are almost stable in size during the induction stage, as shown by SAXS, prior to undergoing a very fast shrinkage during the nucleation stage. The gold speciation as a function of time deduced from the XAS spectra has been analyzed through multi-step reaction pathways comprising both highly reactive species, involved in the nucleation and growth stages, and poorly reactive species acting as a reservoir for the reactive species. The duration of the induction period is related to the reactivity of the gold precursors, which is tuned by the coordination of OY to the gold complexes, while the nucleation stage was found to depend on the size and reactivity of the PNCs. The role of the PNCs in determining the final particle size and structure is also discussed in relation to previous studies. The multiple roles of OY, as the solubilizing agent of the gold salt, the ligand of the gold complexes determining both the size of the PNCs and the reactivity of the gold precursors, and finally the capping agent of the final gold particles as oleylammonium chloride, have been clearly established. This work opens new perspectives to synthesize metal NPs via metal–organic PNCs and to define new synthesis routes for nanoparticles that may present structure and morphologies different from those obtained by the classical nucleation routes.
Published: 2020
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23. Nanoscale Metal Phosphide Phase Segregation to Bi/P Core/Shell Structure. Reactivity as a Source of Elemental Phosphorus

Author: Lorena Soria, Nicolas Mézailles, Julian Sklorz, Montserrat Gómez, Yannick Coppel, Pierre Roblin, Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie de coordination (LCC), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université Fédérale Toulouse Midi-Pyrénées, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)
Subjects: Materials science, Phosphide, General Chemical Engineering, Phosphorus, Inorganic chemistry, chemistry.chemical_element, Nanoparticle, 02 engineering and technology, General Chemistry, Structure reactivity, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Bismuth, Metal, chemistry.chemical_compound, chemistry, Phase (matter), visual_art, Materials Chemistry, visual_art.visual_art_medium, [CHIM]Chemical Sciences, 0210 nano-technology, Nanoscopic scale
Abstract: International audience; We report for the first time the synthesis of well-defined bismuth/ phosphorus nanoparticles (Bi/P NPs) based on silyl-halide elimination by reaction of BiX 3 (X = I, Cl) and P(SiMe 3) 3 in the presence of different types of stabilizing ligands, such as cinchonidine, 4-(3-phenylpropyl)pyridine, and polyvinylpyrroli-done. This synthetic approach led to spherical, small, and monodisperse NPs [mean diameter ca. 2.0−2.5 nm determined by transmission electron microscopy (TEM)]. Wide-ranging characterization of these NPs, including TEM, powder X-ray diffraction, and small-angle X-ray scattering, and several spectroscopic techniques, such as X-ray fluorescence, IR, and solid-state NMR, proved the formation of a core/shell structure constituted by a crystalline Bi(0) core and amorphous P-containing shells, representing a unique case of phase segregation for metal/phosphorus materials reported in the literature. The assessed reactivity of the as-prepared Bi/P NPs evidenced their potential application in the synthesis of phosphine (PH 3) in a safer way than the conventional approach using P 4 (white phosphorus) and in a sharp contrast with the reported reactivity of amorphous red phosphorus. ■ INTRODUCTION Bulk metal phosphides (M x P y) are nowadays receiving intense attention in the field of materials due to their wide scope of properties and applications in metallurgy and semiconductors for electronics or optics, among others. 1−9 The structure and composition of these M x P y binary species have been accurately analyzed for almost all combinations with metals, except with the heavy elements of group 15 (As, Sb, Bi). 10 Among them, bismuth phosphide is particularly appealing because it is isoelectronic with PbS, a well-known intrinsic semiconductor used for an extensive range of applications, but exhibiting strong environmental constraints. 11−17 Concerning its preparation, two synthetic approaches have been reported to obtain Bi x P y. The first methodology relied on the dissolution of phosphorus in molten bismuth, which however did not lead to the desired compound but to the segregation of the elements into their pure form, leading to the synthesis of black and violet allotropes of P and Bi(0). 18,19 Based on the successful syntheses of other metal phosphides, M x P y , under milder conditions via the formation of Me 3 SiX (X = Cl, Br, I) as concomitant products, we pursued this strategy for the synthesis of Bi x P y. 20 Notably, the generation of the strong Si−X bond acts as a driving force for the reaction. Following this strategy, Allen and co-workers reported the formation of an insoluble black material at room temperature from the reaction of BiCl 3 with P(SiMe 3) 3. 21 A range of analyses were carried out to characterize this material, including scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), thermogravimetric analysis and differential scanning calorimetry (TGA and DSC), as well as conductivity measurements. These analyses prompted the authors to propose the formation of amorphous hybrid "BiP" materials. However, the characterization of the as-prepared materials did not provide unequivocal evidence for the formation of the expected product, whose precise structure remains unknown. From another standpoint, molecular compounds featuring discrete Bi/P bonds are rather rare. Their synthesis also relies on substitution reactions between reagents containing P−Si (or P−Li) and Bi−X bonds. More importantly for the present study, the stability of the Bi/P bond appears to vary in these molecular species. Indeed, Coles and co-workers reported in 2016 that the compound "Bi(NON R) (PPh 2)" (NON R = [O(SiMe 2 NR) 2 ], where R = tBu, 2,6-iPr 2 C 6 H 3) was unstable and readily evolved to form a P−P bond (Ph 2 P−PPh 2) and a Bi−Bi bond, whereas the related Bi(NON R)(PCy 2) was a stable compound at room temperature. 22 Between molecules and bulk material domains, nanoparticles (NPs) may provide a field of interesting and distinctive properties. In this context, the case of "BiP" is particularly appealing for two reasons. First, a fundamental question can be asked: are Bi/P bonds strong enough in nanoalloys versus Bi− Bi and P−P bonds in the elemental materials? In other words
Published: 2020
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24. Injection time controls the final morphology of nanocrystals during in situ-seeding synthesis of silver nanodisks

Author: Yannick Hallez, Jeffrey F. Morris, Pierre Roblin, Martine Meireles, Cecilia Gestraud, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), City University of New-York - CUNY (USA), Laboratoire de génie chimique [ancien site de Basso-Cambo] (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), City University of New York [New York] (CUNY), Laboratoire de Génie Chimique (LGC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP)
Subjects: Materials science, Nucleation, Nanoparticle, 02 engineering and technology, 010402 general chemistry, Borohydride, 01 natural sciences, chemistry.chemical_compound, Sodium borohydride, [CHIM.GENI]Chemical Sciences/Chemical engineering, Génie chimique, General Materials Science, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Génie des procédés, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Ascorbic acid, Silver nanodisks, 0104 chemical sciences, Nanocrystals, Silver nitrate, chemistry, Chemical engineering, Nanocrystal, 0210 nano-technology, Dispersion (chemistry)
Abstract: International audience; We investigate an in situ-seeding synthesis of silver nanodisks based on the sequential addition of weak and strong reducing agents, ascorbic acid and sodium borohydride respectively, to silver nitrate at room temperature and in the presence of polyvinylpyrrolidone. Well-defined silver nanodisks with a uniform thickness of 8 nm and a distribution of diameters around a mean of 22 nm can thus be prepared, the diameter being tunable. We report and explain the influence of important experimental control parameters on the quality of the nanoparticle dispersion synthesized. In particular, we show that a dispersion containing exclusively nanodisks can only be obtained if the second reducer is injected in a specific time window at room temperature. The rapid injection of concentrated borohydride triggers a burst nucleation creating seeds with structural defects. Seeds are then grown from silver atoms produced by the reduction of remaining silver ions by ascorbic acid. When the rate of production of these atoms is slow enough, seeds grow along the seed defects and only nanodisks are obtained. The ability to maintain a slow enough production rate after burst nucleation is thus essential. This critical reduction rate depends on the injection time as the latter determines the amount of reactants remaining after nucleation. The influence of temperature is subtle as it affects both reaction kinetics and adatom diffusion on the nanoparticle surfaces. Provided these subtle kinetic effects are understood and under control, the present in situ-seeding synthesis yields good quality nanodisk dispersions in only a few minutes. These results suggest realistic and robust pathways for a scalable production of silver nanodisks in continuous flow reactors most suited to industrial needs.
Published: 2020
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25. Biochemical characterization of the respiratory syncytial virus N0-P complex in solution

Author: Jean-François Eléouët, Sébastien Brûlé, Charles-Adrien Richard, Pierre Roblin, Jenna Fix, Camille Esneau, Marie Galloux, Bertrand Raynal, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut Pasteur (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Unité de recherche Virologie et Immunologie Moléculaires (VIM (UR 0892)), Institut National de la Recherche Agronomique (INRA), Centre de Ressources et de Recherche Technologique - Center for Technological Resources and Research (C2RT), Institut Pasteur [Paris], Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), French Agence Nationale de la Recherche, specific program ANR Blanc ANR-13-IVS3-0007, Institut Pasteur [Paris] (IP), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Unité de recherche Virologie et Immunologie Moléculaires (VIM), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Institut National Polytechnique de Toulouse - INPT (FRANCE), Eleouet, Jean Francois, and Galloux, Marie
Subjects: 0301 basic medicine, Biochimie, Biologie Moléculaire, Respiratory syncytial virus, Biochemistry, Virus, 03 medical and health sciences, Human metapneumovirus, N0-P complex, Viral replication, Génie chimique, Nucleoprotein N, Mononegavirales, Génie des procédés, Molecular Biology, protein folding, structural model, small-angle X-ray scattering (saxs), mutagenesis, analytical ultracentrifugation, n0-p complex, nucleoprotein n, respiratory syncytial virus, structure-function, viral replication, 030102 biochemistry & molecular biology, biology, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], Structure-function, Chemistry, RNA, Cell Biology, biology.organism_classification, Nucleoprotein, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], 030104 developmental biology, Phosphoprotein, [SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology, Protein folding
Abstract: International audience; As all the viruses belonging to the Mononegavirales order, the non-segmented negative strand RNA genome of respiratory syncytial virus (RSV) is encapsidated by the viral nucleoprotein N. N protein polymerizes along the genomic and anti-genomic RNAs during replication. This requires the maintenance of the neosynthesized N protein in a monomeric and RNA-free form by the viral phosphoprotein P that plays the role of a chaperone protein, forming a soluble N0-P complex. We have previously demonstrated that residues 1-30 of P specifically bind to N0. Here, to isolate a stable N0-P complex suitable for structural studies, we used the N-terminal peptide of P (P40) to purify truncated forms of the N protein. We show that to purify a stable N0-P-like complex, a deletion of the first 30 N-terminal residues of N (NΔ30) is required to impair N oligomerization, whereas the presence of a full-length C-arm of N is required to inhibit RNA binding. We generated structural models of the RSV N0-P with biophysical approaches, including hydrodynamic measurements and small-angle X-ray scattering (SAXS), coupled with biochemical and functional analyses of human RSV (hRSV) NΔ30 mutants. These models suggest a strong structural homology between the hRSV and the human metapneumovirus (hMPV) N0-P complexes. In both complexes, the P40-binding sites on N0 appear to be similar, and the C-arm of N provides a high flexibility and a propensity to interact with the N RNA groove. These findings reveal two potential sites to target on N0-P for the development of RSV antivirals.
Published: 2019
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26. Biochemical characterization of the respiratory syncytial virus N

Author: Camille, Esneau, Bertrand, Raynal, Pierre, Roblin, Sébastien, Brûlé, Charles-Adrien, Richard, Jenna, Fix, Jean-François, Eléouët, and Marie, Galloux
Subjects: Models, Molecular, Solutions, Viral Proteins, Binding Sites, Nucleoproteins, Protein Conformation, Surface Properties, Respiratory Syncytial Virus, Human, Mutation, Protein Structure and Folding, DNA-Directed RNA Polymerases
Abstract: As all the viruses belonging to the Mononegavirales order, the nonsegmented negative-strand RNA genome of respiratory syncytial virus (RSV) is encapsidated by the viral nucleoprotein N. N protein polymerizes along the genomic and anti-genomic RNAs during replication. This requires the maintenance of the neosynthesized N protein in a monomeric and RNA-free form by the viral phosphoprotein P that plays the role of a chaperone protein, forming a soluble N(0)-P complex. We have previously demonstrated that residues 1–30 of P specifically bind to N(0). Here, to isolate a stable N(0)-P complex suitable for structural studies, we used the N-terminal peptide of P (P40) to purify truncated forms of the N protein. We show that to purify a stable N(0)-P–like complex, a deletion of the first 30 N-terminal residues of N (N(Δ30)) is required to impair N oligomerization, whereas the presence of a full-length C-arm of N is required to inhibit RNA binding. We generated structural models of the RSV N(0)-P with biophysical approaches, including hydrodynamic measurements and small-angle X-ray scattering (SAXS), coupled with biochemical and functional analyses of human RSV (hRSV) N(Δ30) mutants. These models suggest a strong structural homology between the hRSV and the human metapneumovirus (hMPV) N(0)-P complexes. In both complexes, the P40-binding sites on N(0) appear to be similar, and the C-arm of N provides a high flexibility and a propensity to interact with the N RNA groove. These findings reveal two potential sites to target on N(0)-P for the development of RSV antivirals.
Published: 2018

27. Dystrophin's central domain forms a complex filament that becomes disorganized by in-frame deletions

Author: Olivier Delalande, Angélique Chéron, Céline Raguénès-Nicol, Mirjam Czjzek, Arnaud Bondon, Christophe Tascon, Jean-François Hubert, Nicolas Ferey, Elisabeth Le Rumeur, Emmanuel Giudice, Aurélie Nicolas, Émeline Pollet, Marc Baaden, Javier Pérez, Raphael Dos Santos Morais, Marine Guilbaud, Pierre Roblin, Anne-Elisabeth Molza, Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), European Synchrotron Radiation Facility (ESRF), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre de recherche en Myologie – U974 SU-INSERM, Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Informatique pour la Mécanique et les Sciences de l'Ingénieur (LIMSI), Université Paris-Sud - Paris 11 (UP11)-Sorbonne Université - UFR d'Ingénierie (UFR 919), Sorbonne Université (SU)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Saclay (COmUE), Laboratoire de biochimie théorique [Paris] (LBT (UPR_9080)), Institut de biologie physico-chimique (IBPC (FR_550)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Laboratoire de Biologie Intégrative des Modèles Marins (LBI2M), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU), Association Francaise Contre les Myopathies, AFM-Telethon, Conseil Regional de Bretagne, RTR Biologie-Sante of the Universite Europeenne de Bretagne, Grand Equipement National de Calcul Intensif-GENCI Program (DYSIM Project), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche en myologie, Université Pierre et Marie Curie - Paris 6 (UPMC)-Association française contre les myopathies (AFM-Téléthon)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), AP-HP - Hôpital Cochin Broca Hôtel Dieu [Paris], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Delalande, Olivier, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Université Paris-Saclay-Sorbonne Université - UFR d'Ingénierie (UFR 919), Sorbonne Université (SU)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Saclay (COmUE), Centre National de la Recherche Scientifique (CNRS)-Institut de biologie physico-chimique (IBPC), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Unité de Recherche sur les Biopolymères leurs Interactions et Assemblages (URBIA), Sorbonne Universités, Institut de recherche en santé, environnement et travail (Irset), Université d'Angers (UA)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Biochimie et Génétique Moléculaire, Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Cochin [AP-HP], Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université Paris Saclay (COmUE)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université - UFR d'Ingénierie (UFR 919), Sorbonne Université (SU)-Sorbonne Université (SU)-Université Paris-Saclay-Université Paris-Sud - Paris 11 (UP11), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut de biologie physico-chimique (IBPC (FR_550)), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Jonchère, Laurent
Subjects: 0301 basic medicine, Reading Frames, multiresolution modeling, Duchenne muscular dystrophy, [SDV]Life Sciences [q-bio], small-angle X-ray scattering (SAXS), Small angle X-ray scattering, Nitric Oxide Synthase Type I, Biochemistry, Exon, 0302 clinical medicine, dystrophin central domain, X-Ray Diffraction, dystrophin, molecular docking, muscular dystrophy, nitric oxide synthase, Becker muscular dystrophy, Spectrin, Muscular dystrophy, biology, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], Molecular Bases of Disease, Exons, musculoskeletal system, Phenotype, Cell biology, Nitric oxide synthase, Molecular Docking Simulation, Solutions, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], medicine.symptom, Dystrophin, Muscle contraction, musculoskeletal diseases, congenital, hereditary, and neonatal diseases and abnormalities, [SDV.BBM.BS] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], 03 medical and health sciences, Protein Domains, Scattering, Small Angle, medicine, Humans, Molecular Biology, Binding Sites, neuronal Nitric Oxide Synthase, Cell Biology, medicine.disease, Muscular Dystrophy, Duchenne, 030104 developmental biology, multi resolution modeling, biology.protein, 030217 neurology & neurosurgery, Gene Deletion
Abstract: International audience; Dystrophin, encoded by the DMD gene, is critical for maintaining plasma membrane integrity during muscle contraction events. Mutations in the DMD gene disrupting the reading frame prevent dystrophin production and result in severe Duchenne muscular dystrophy (DMD); in-frame internal deletions allow production of partly functional internally deleted dystrophin and result in less severe Becker muscular dystrophy (BMD). Many known BMD deletions occur in dystrophin's central domain, generally considered to be a monotonous rod-shaped domain based on the knowledge of spectrin family proteins. However, the effects caused by these deletions, ranging from asymptomatic to severe BMD, argue against the central domain serving only as a featureless scaffold. We undertook structural studies combining small-angle X-ray scattering and molecular modeling in an effort to uncover the structure of the central domain, as dystrophin has been refractory to characterization. We show that this domain appears to be a tortuous and complex filament that is profoundly disorganized by the most severe BMD deletion (loss of exons 45–47). Despite the preservation of large parts of the binding site for neuronal nitric oxide synthase (nNOS) in this deletion, computational approaches failed to recreate the association of dystrophin with nNOS. This observation is in agreement with a strong decrease of nNOS immunolocalization in muscle biopsies, a parameter related to the severity of BMD phenotypes. The structural description of the whole dystrophin central domain we present here is a first necessary step to improve the design of microdystrophin constructs toward the goal of a successful gene therapy for DMD
Published: 2018
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28. Tetramerization and interdomain flexibility of the replication initiation controller YabA enables simultaneous binding to multiple partners

Author: Liza Felicori, Magali Ventroux, Transito Garcia-Garcia, Laurent Terradot, Franck Molina, Anthony J. Wilkinson, Mark J. Fogg, Philippe Noirot, Katie H. Jameson, Alexandre Bazin, Mickaël V. Cherrier, Marie Francoise Noirot-Gros, Pierre Roblin, Sysdiag CNRS Bio-Rad UMR 3145, Cap Delta/Parc Euromédecine, Centre National de la Recherche Scientifique (CNRS), Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), York Structural Biology Laboratory, Department of Chemistry, University of York [York, UK], MICrobiologie de l'ALImentation au Service de la Santé (MICALIS), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Institut de biologie structurale (IBS - UMR 5075), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Informatique, de Modélisation et d'Optimisation des Systèmes (LIMOS), Ecole Nationale Supérieure des Mines de St Etienne-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Sysdiag-Modélisation et Ingénierie des Systèmes Complexes Biologiques pour le Diagnostic (SysDiag ), BIO-RAD-Centre National de la Recherche Scientifique (CNRS), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Institut de biologie structurale (IBS - UMR 5075 ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Ecole Nationale Supérieure des Mines de St Etienne-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), European integrated project, BaSysBio, Biotechnology and Biological Sciences Research Council, UK, EU-Marie Curie Project AMBER FP7-People [317338], CIBLE program from the region Rhones-alpes, MICALIS INRA, Felicori, Liza, Jameson, Katie H., Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Microbiologie moléculaire et biochimie structurale / Molecular Microbiology and Structural Biochemistry (MMSB)
Subjects: Models, Molecular, 0301 basic medicine, Protein Conformation, Amino Acid Motifs, Intracellular Space, dnaN, MESH: DNA Replication, Plasma protein binding, MESH: Amino Acid Sequence, MESH: Zinc, MESH: Amino Acid Motifs, Protein structure, MESH: Structure-Activity Relationship, MESH: Protein Conformation, Structural Biology, Protein Interaction Mapping, MESH: Bacterial Proteins, Genetics, DNA clamp, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], MESH: Protein Multimerization, DNA-Binding Proteins, Protein Transport, Zinc, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], MESH: Intracellular Space, MESH: Models, Molecular, Bacillus subtilis, Protein Binding, DNA Replication, MESH: Protein Transport, MESH: Mutation, Molecular Sequence Data, MESH: Sequence Alignment, Biology, Structure-Activity Relationship, 03 medical and health sciences, Bacterial Proteins, Position-Specific Scoring Matrices, MESH: Protein Binding, Protein Interaction Domains and Motifs, Amino Acid Sequence, Homology modeling, MESH: Protein Interaction Domains and Motifs, Binding Sites, MESH: Molecular Sequence Data, MESH: Protein Interaction Mapping, DNA replication, MESH: Position-Specific Scoring Matrices, MESH: Bacillus subtilis, MESH: Multiprotein Complexes, DnaA, 030104 developmental biology, MESH: Binding Sites, Replication Initiation, Multiprotein Complexes, Mutation, Biophysics, Protein Multimerization, Sequence Alignment, MESH: DNA-Binding Proteins
Abstract: International audience; YabA negatively regulates initiation of DNA replication in low-GC Gram-positive bacteria. The protein exerts its control through interactions with the initiator protein DnaA and the sliding clamp DnaN. Here, we combined X-ray crystallography, X-ray scattering (SAXS), modeling and biophysical approaches, with in vivo experimental data to gain insight into YabA function. The crystal structure of the N-terminal domain (NTD) of YabA solved at 2.7 Å resolution reveals an extended α-helix that contributes to an intermolecular four-helix bundle. Homology modeling and biochemical analysis indicates that the C-terminal domain (CTD) of YabA is a small Zn-binding domain. Multi-angle light scattering and SAXS demonstrate that YabA is a tetramer in which the CTDs are independent and connected to the N-terminal four-helix bundle via flexible linkers. While YabA can simultaneously interact with both DnaA and DnaN, we found that an isolated CTD can bind to either DnaA or DnaN, individually. Site-directed mutagenesis and yeast-two hybrid assays identified DnaA and DnaN binding sites on the YabA CTD that partially overlap and point to a mutually exclusive mode of interaction. Our study defines YabA as a novel structural hub and explains how the protein tetramer uses independent CTDs to bind multiple partners to orchestrate replication initiation in the bacterial cell.
Published: 2016
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29. In-Situ Quantitative and Multiscale Structural Study of Starch-Based Biomaterials Immersed in Water

Author: Corinne Rondeau-Mouro, Pierre Roblin, Laurent Chaunier, Chloé Chevigny, Denis Lourdin, Ruzica Ferbus, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National de la Recherche Agronomique - INRA (FRANCE), Institut national de Recherche en Sciences et Technologies pour l'Environnement et l'Agriculture - IRSTEA (FRANCE), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Optimisation des procédés en Agriculture, Agroalimentaire et Environnement (UR OPAALE), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de génie chimique [ancien site de Basso-Cambo] (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: In situ, Materials science, Polymers and Plastics, Starch, MICROIMAGING, Bioengineering, RX, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, Biomaterials, chemistry.chemical_compound, [CHIM.GENI]Chemical Sciences/Chemical engineering, X-Ray Diffraction, law, TRANSFERT D'EAU, Materials Chemistry, Génie chimique, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Diffusion (business), Génie des procédés, Potato starch, Solanum tuberosum, Molecular Structure, Scattering, SYNCHROTRON, Water, 021001 nanoscience & nanotechnology, Magnetic Resonance Imaging, Fick's laws of diffusion, Synchrotron, 0104 chemical sciences, Amorphous solid, Chemical engineering, chemistry, BIOMATÉRIAUX, 0210 nano-technology, ETUDE STRUCTURALE, MRI
Abstract: International audience; The behavior upon immersion in water of two types of starchy materials of biomedical relevance, amorphous potato starch and glycerol-plasticized potato starch, is analyzed in depth. Synchrotron X-ray scattering, specifically wide-angle X-ray scattering (WAXS), and magnetic resonance microimaging (MRμI) are used as very precise and nondestructive quantitative methods to monitor water transfers and structure changes in the samples, with refined spatial and kinetics results. The ingress of water in the cylinder-shaped samples can be inferred from both techniques, and from this, a diffusion mechanism is deduced for each sample type. Qualitatively, scattering and imaging give comparable results: plasticized samples are shown to behave close to a Fickian diffusion case, amorphous samples close to a case II. WAXS results also provide an in-depth knowledge of the crystalline structures associated to each step of the water ingress, and these are in turn correlated to water diffusion. To refine these observations, a recrystallized starch sample is also analyzed via WAXS. This study gives better insight into the structure of a material with a huge biomedical potential (as implants, for example), and for such applications, the behavior upon immersion in water is particularly relevant.
Published: 2018
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30. Enzymatic synthesis of polysaccharide-based copolymers

Author: Pierre Roblin, Florent Grimaud, Laurence Tarquis, Xavier Falourd, Denis Lourdin, Pauline Faucard, Sandrine Morel, Agnès Rolland-Sabaté, Magali Remaud-Simeon, S. Le Gall, Sandra Pizzut-Serin, Gabrielle Potocki-Véronèse, Claire Moulis, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Sécurité et Qualité des Produits d'Origine Végétale (SQPOV), Institut National de la Recherche Agronomique (INRA)-Avignon Université (AU), Region Midi-Pyrenees, European Regional Development Fund, ANR 14-CE27-0011-02, ANR-11-INBS-0012, Avignon Université (AU)-Institut National de la Recherche Agronomique (INRA), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), ANR-11-INBS-0012,PHENOME,Centre français de phénomique végétale(2011), Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: copolymère, glucane, [SDV.BIO]Life Sciences [q-bio]/Biotechnology, Stereochemistry, Biotechnologies, 02 engineering and technology, Degree of polymerization, 010402 general chemistry, medicine.disease_cause, 01 natural sciences, Chemical synthesis, Dextransucrase, Leuconostoc citreum, medicine, Copolymer, synthèse chimique, Environmental Chemistry, copolymer, biology, Chemistry, glucan, 021001 nanoscience & nanotechnology, biology.organism_classification, Pollution, Alternansucrase, 0104 chemical sciences, enzyme, Polymerization, Leuconostoc mesenteroides, 0210 nano-technology, chemical synthesis
Abstract: The design of enzymatic routes for the production of biosourced copolymers represents an attractive alternative to chemical synthesis from fossil carbon. In this paper, we explore the potential of glycosynthesizing enzymes to produce novel block copolymers composed of various covalently-linked α-glucans with contrasting structures and physicochemical properties. To this end, various glucansucrases able to synthesize α-glucans with different types of α-osidic bonds from sucrose were tested for their ability to elongate oligosaccharide and polysaccharide acceptors with different structures from the native polymer synthesized by each enzyme. We showed that two enzymes – namely, the alternansucrase from Leuconostoc mesenteroides NRRL B-1355 (specific for α(1 → 6)/α(1 → 3)-linked alternan synthesis) and the dextransucrase DSR-MΔ1 from Leuconostoc citreum NRRL B-1299 (specific for α(1 → 6)-linked dextran formation) – were able to elongate α(1 → 4)-linked amylose and α(1 → 6)/α(1 → 3)-linked alternan respectively. Carrying out stepwise acceptor reactions, and after optimization of the acceptor size and donor/acceptor ratio, two types of diblock copolymers were synthesized – a dextran-b-alternan and an alternan-b-amylose – as well as the triblock copolymer dextran-b-alternan-b-amylose. Their structural characterization, performed by combining chromatographic, NMR and permethylation analyses, showed that the copolymer polymerization degree ranged from 29 to 170, which is the highest degree of polymerization ever reported for an enzymatically synthesized polysaccharide-based copolymer. The addition of dextran and alternan blocks to amylose resulted in conformational modifications and related flexibility changes, as demonstrated by small angle X-ray scattering.
Published: 2018
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31. Ibuprofen loading into mesoporous silica nanoparticles using Co-Spray drying: A multi-scale study

Author: Mallorie Tourbin, Pierre Roblin, Yannick Coppel, Christine Frances, Jérémy Soulié, Fabien Brouillet, Lucas Ruffel, Université Fédérale Toulouse Midi-Pyrénées, Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Subjects: Materials science, Matériaux, Mesoporous silica nanoparticles, Spray-drying, Nanoparticle, 02 engineering and technology, Drug loading, 010402 general chemistry, 01 natural sciences, Suspension (chemistry), [SPI]Engineering Sciences [physics], Nano, Génie chimique, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, General Materials Science, spray-drying, drug loading, Génie des procédés, ComputingMilieux_MISCELLANEOUS, General Chemistry, Mesoporous silica, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Chemical engineering, Mechanics of Materials, Spray drying, Surface modification, Nanomedicine, 0210 nano-technology, Mesoporous material
Abstract: International audience; Mesoporous Silica Nanoparticles (MSN) are used in an increasing number of applications in nanomedicine. Their synthesis and external/internal functionalization have been extensively studied as well as their biological properties. Nevertheless, the conventional drug loading processes of MSN (such as impregnation), do not enable sufficient efficiency and are difficult to consider on an industrial scale. To overcome these limitations, we implemented an innovative co-spray-drying process, using a nano spray-dryer, to load MSN with ibuprofen molecules. In this contribution, complementary techniques were used to perform a multi-scale characterization of the loaded particles. Spray-dried powders have been analysed from aggregates size and morphology to pore loading and ibuprofen conformation. This study demonstrates that ibuprofen/silica weight ratio in the initial suspension strongly affects the location (into 2 mesopores or external) and the conformation (crystallized, amorphous or liquid-like) of ibuprofen. The quantification of each phase has allowed calculating precise loading rates and demonstrate tunable pore filling.
Published: 2020
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32. Biophysical analysis of

Author: Franziska, Pinker, Cédric, Schelcher, Pablo, Fernandez-Millan, Anthony, Gobert, Catherine, Birck, Aurélien, Thureau, Pierre, Roblin, Philippe, Giegé, and Claude, Sauter
Subjects: Models, Molecular, RNA, Transfer, Cys, Arabidopsis Proteins, Protein Conformation, Recombinant Fusion Proteins, Amino Acid Motifs, Arabidopsis, Biophysical Phenomena, Peptide Fragments, Recombinant Proteins, Ribonuclease P, Amino Acid Substitution, Solubility, RNA, Plant, Catalytic Domain, Enzyme Stability, Mutation, RNA Precursors, Nucleic Acid Conformation, RNA, Protein Interaction Domains and Motifs, Nucleotide Motifs, RNA Processing, Post-Transcriptional
Abstract: RNase P is a universal enzyme that removes 5′ leader sequences from tRNA precursors. The enzyme is therefore essential for maturation of functional tRNAs and mRNA translation. RNase P represents a unique example of an enzyme that can occur either as ribonucleoprotein or as protein alone. The latter form of the enzyme, called protein-only RNase P (PRORP), is widespread in eukaryotes in which it can provide organellar or nuclear RNase P activities. Here, we have focused on Arabidopsis nuclear PRORP2 and its interaction with tRNA substrates. Affinity measurements helped assess the respective importance of individual pentatricopeptide repeat motifs in PRORP2 for RNA binding. We characterized the PRORP2 structure by X-ray crystallography and by small-angle X-ray scattering in solution as well as that of its complex with a tRNA precursor by small-angle X-ray scattering. Of note, our study reports the first structural data of a PRORP–tRNA complex. Combined with complementary biochemical and biophysical analyses, our structural data suggest that PRORP2 undergoes conformational changes to accommodate its substrate. In particular, the catalytic domain and the RNA-binding domain can move around a central hinge. Altogether, this work provides a refined model of the PRORP–tRNA complex that illustrates how protein-only RNase P enzymes specifically bind tRNA and highlights the contribution of protein dynamics to achieve this specific interaction.
Published: 2017

33. Investigations on the Determinants Responsible for Low Molar Mass Dextran Formation by DSR-M Dextransucrase

Author: Marion Claverie, Guy Lippens, Pierre Roblin, Magali Remaud-Simeon, Nelly Monties, Marlène Vuillemin, Claire Moulis, Gianluca Cioci, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Laboratoire de Génie Chimique (LGC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, French Ministry of Higher Education and Research, Agence Nationale de la Recherche (ANR), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut National de la Recherche Agronomique - INRA (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: 0301 basic medicine, crystal structure, Sucrose, [SDV.BIO]Life Sciences [q-bio]/Biotechnology, carbohydrate-binding protein, Population, medicine.disease_cause, Catalysis, Dextransucrase, sucrose 6-glucosyltransferase, 03 medical and health sciences, chemistry.chemical_compound, [CHIM.GENI]Chemical Sciences/Chemical engineering, polymère, Leuconostoc citreum, medicine, Génie chimique, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, education, Génie des procédés, chemistry.chemical_classification, dextran, education.field_of_study, Molar mass, Chemistry, glucan-binding domain, dextransucrase, Substrate (chemistry), General Chemistry, glucansucrases, dextransucrases, 030104 developmental biology, Enzyme, Dextran, Biochemistry, nonprocessive polymerization, GH70 family
Abstract: International audience; Certain enzymes of the GH70 family dextransucrases synthesize very high molar mass dextran polymers, whereas others produce a mixed population of very high and low molar mass products directly from sucrose substrate. Identifying the determinants dictating polymer elongation would allow the tight control of dextran size. To explore this central question, we focus on the recently discovered DSR-M enzyme from Leuconostoc citreum NRRL B-1299, which is the sole enzyme that naturally, exclusively, and very efficiently produces only low molar mass dextrans from sucrose. Extensive biochemical and structural characterization of a truncated form of DSR-M (DSR-MΔ2, displaying the same biochemical behavior as the parental enzyme) and X-ray structural analysis of complexes with sucrose and isomaltotetraose molecules together with accurate monitoring of the resulting polymer formation reveal that DSR-MΔ2 adopts a nonprocessive mechanism attributed to (i) a high propensity to recognize sucrose as a preferred acceptor at the initial stage of catalysis, (ii) an ability to elongate oligodextrans irrespective of their size, and (iii) the presence of a domain V showing a weak ability to bind to the growing dextran chains. In this study, we present the 3D structure with the largest defined domain V reported to date in the GH70 family and map sugar binding pockets on the basis of the structure of the complex obtained with isomaltotetraose. Altogether, these findings give insights into the interplay between the domain V and the catalytic site during polymerization. They open promising strategies for GH70 enzyme engineering aiming at modulating glucan size.
Published: 2017
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34. C-terminal region of bacterial Ku controls DNA bridging, DNA threading and recruitment of DNA ligase D for double strand breaks repair

Author: Philippe Noirot, Pierre Roblin, Sonia Baconnais, Jean-Baptiste Charbonnier, Pierre Nicolas, Héloïse Simonson, François Lecointe, Olivier Piétrement, Stephen McGovern, Eric Le Cam, Pascal Drevet, MICrobiologie de l'ALImentation au Service de la Santé (MICALIS), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Interactions moléculaires et cancer (IMC (UMR 8126)), Centre National de la Recherche Scientifique (CNRS)-Institut Gustave Roussy (IGR)-Université Paris-Sud - Paris 11 (UP11), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Unité Mathématique, Informatique et Génome (MIG), Institut National de la Recherche Agronomique (INRA), Institute for Integrative Biology of the Cell, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Enveloppe Nucléaire, Télomères et Réparation de l’ADN (INTGEN), Département Biochimie, Biophysique et Biologie Structurale (B3S), Institut de Biologie Intégrative de la Cellule (I2BC), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Biologie Intégrative de la Cellule (I2BC), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, Signalisation, noyaux et innovations en cancérologie (UMR8126), Université Paris-Sud - Paris 11 (UP11)-Institut Gustave Roussy (IGR)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut Gustave Roussy (IGR)-Centre National de la Recherche Scientifique (CNRS), Mathématiques et Informatique Appliquées du Génome à l'Environnement [Jouy-En-Josas] (MaIAGE), Université Paris-Sud - Paris 11 (UP11)-Institut Gustave Roussy (IGR)-Centre National de la Recherche Scientifique (CNRS), ANR-12-BSV8-0012,NHEJ-complexes,Etudes structurales et fonctionnelles des complexes multi-protéiques de la voie NHEJ humaine(2012), European Project: 244093,EC:FP7:KBBE,FP7-KBBE-2009-3,BASYNTHEC(2010), Institut Gustave Roussy (IGR), and Lecointe, Francois
Subjects: 0301 basic medicine, Genetics, chemistry.chemical_classification, DNA ligase, Ku80, 030102 biochemistry & molecular biology, [SDV]Life Sciences [q-bio], DNA Ligases, Bacillus subtilis, Biology, Genome Integrity, Repair and Replication, biology.organism_classification, Cell biology, 03 medical and health sciences, chemistry.chemical_compound, 030104 developmental biology, chemistry, Threading (protein sequence), Ligation, DNA polymerase mu, DNA
Abstract: International audience; Non-homologous end joining is a ligation process repairing DNA double strand breaks in eukaryotes and many prokaryotes. The ring structured eukaryotic Ku binds DNA ends and recruits other factors which can access DNA ends through the threading of Ku inward the DNA, making this protein a key ingredient for the scaffolding of the NHEJ machinery. However, this threading ability seems unevenly conserved among bacterial Ku. As bacterial Ku differ mainly by their C-terminus, we evaluate the role of this region in the loading and the threading abilities of Bacillus subtilis Ku and the stimulation of the DNA ligase LigD. We identify two distinct sub-regions: a ubiquitous minimal C-terminal region and a frequent basic C-terminal extension. We show that truncation of one or both of these sub-regions in Bacillus subtilis Ku impairs the stimulation of the LigD end joining activity in vitro. We further demonstrate that the minimal C-terminus is required for the Ku-LigD interaction, whereas the basic extension controls the threading and DNA bridging abilities of Ku. We propose that the Ku basic C-terminal extension increases the concentration of Ku near DNA ends, favoring the recruitment of LigD at the break, thanks to the minimal C-terminal sub-region.
Published: 2016
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35. Characterization of Intersubunit Communication in the Virginiamycin trans-Acyl Transferase Polyketide Synthase

Author: Kira J. Weissman, Jonathan Dorival, Benjamin Chagot, Sabrina Collin, Thibault Annaval, Christophe Jacob, Pierre Roblin, Arnaud Gruez, Fanny Risser, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), ANR JCJC 2011 PKS-PPIs to K.J.W.Centre National de la Recherche Scientifique (CNRS)Université de Lorraine (UL)Lorraine Region (Bonus Qualité Recherche (BQR) grants to K.J.W. and B.C, ANR-11-JSV8-0003,PKS-PPIs,Les polykétide synthases (PKS) de type 'trans AT' : Etude des modes d'interactions entre les 'acyl carrier' protéines et leur différents partenaires enzymatiques (en cis/trans)(2011), and Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0301 basic medicine, Models, Molecular, Magnetic Resonance Spectroscopy, Stereochemistry, Plasma protein binding, 01 natural sciences, Biochemistry, Virginiamycin, Catalysis, 03 medical and health sciences, chemistry.chemical_compound, Polyketide, Colloid and Surface Chemistry, Biosynthesis, Polyketide synthase, medicine, Transferase, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], biology, 010405 organic chemistry, General Chemistry, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], 0104 chemical sciences, Acyl carrier protein, 030104 developmental biology, chemistry, Docking (molecular), biology.protein, Polyketide Synthases, Acyltransferases, [SDV.MHEP]Life Sciences [q-bio]/Human health and pathology, medicine.drug
Abstract: International audience; Modular polyketide synthases (PKSs) direct the biosynthesis of clinically valuable secondary metabolites in bacteria. The fidelity of chain growth depends on specific recognition between successive subunits in each assembly line: interactions mediated by C- and N-terminal ``docking domains'' (DDs). We have identified a new family of DDs in trans-acyl transferase PKSs, exemplified by a matched pair from the virginiamycin (Vir) system. In the absence of C-terminal partner (VirA (DD)-D-C) or a downstream catalytic domain, the N-terminal DD (VirFG (DD)-D-N) exhibits multiple characteristics of an intrinsically disordered protein. Fusion of the two docking domains results in a stable fold for VirFG NDD and an overall protein protein complex of unique topology whose structure we support by site-directed mutagenesis. Furthermore, using small-angle X-ray scattering (SAXS), the positions of the flanking acyl carrier protein and ketosynthase domains have been identified, allowing modeling of the complete intersubunit interface.
Published: 2016
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36. How a single residue in individual β-thymosin/WH2 domains controls their functions in actin assembly

Author: Dominique Didry, Pierre Roblin, Maud Hertzog, Marie-France Carlier, Anna M Eswara Moorthy, Javier Pérez, François-Xavier Cantrelle, Eric Guittet, Christophe Le Clainche, Clotilde Husson, Louis Renault, and Carine van Heijenoort
Subjects: 0303 health sciences, General Immunology and Microbiology, Small-angle X-ray scattering, General Neuroscience, 030302 biochemistry & molecular biology, macromolecular substances, Plasma protein binding, Biology, Actin cytoskeleton, Intrinsically disordered proteins, General Biochemistry, Genetics and Molecular Biology, Protein filament, 03 medical and health sciences, Biochemistry, Biophysics, biology.protein, Actin-binding protein, Molecular Biology, Peptide sequence, Actin, 030304 developmental biology
Abstract: β-Thymosin (βT) and WH2 domains are widespread, intrinsically disordered actin-binding peptides that display significant sequence variability and different regulations of actin self-assembly in motile and morphogenetic processes. Here, we reveal the structural mechanisms by which, in their 1:1 stoichiometric complexes with actin, they either inhibit assembly by sequestering actin monomers like Thymosin-β4, or enhance motility by directing polarized filament assembly like Ciboulot βT. We combined mutational, functional or structural analysis by X-ray crystallography, SAXS (small angle X-ray scattering) and NMR on Thymosin-β4, Ciboulot, TetraThymosinβ and the long WH2 domain of WASP-interacting protein. The latter sequesters G-actin with the same molecular mechanisms as Thymosin-β4. Functionally different βT/WH2 domains differ by distinct dynamics of their C-terminal half interactions with G-actin pointed face. These C-terminal interaction dynamics are controlled by the strength of electrostatic interactions with G-actin. At physiological ionic strength, a single salt bridge with actin located next to their central LKKT/V motif induces G-actin sequestration in both isolated long βT and WH2 domains. The results open perspectives for elucidating the functions of βT/WH2 domains in other modular proteins.
Published: 2011
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37. Multifunctionality of the β-thymosin/WH2 module: G-actin sequestration, actin filament growth, nucleation, and severing

Author: Louis Renault, Dominique Didry, Javier Pérez, Kim Ho Diep Le, Eric Guittet, Clotilde Husson, Pierre Roblin, Marie-France Carlier, Carine van Heijenoort, and François-Xavier Cantrelle
Subjects: 0303 health sciences, biology, Small-angle X-ray scattering, General Neuroscience, Nucleation, Arp2/3 complex, macromolecular substances, Fusion protein, General Biochemistry, Genetics and Molecular Biology, Protein filament, 03 medical and health sciences, Crystallography, 0302 clinical medicine, History and Philosophy of Science, Tandem repeat, Polymerization, biology.protein, Biophysics, 030217 neurology & neurosurgery, Actin, 030304 developmental biology
Abstract: The beta-thymosin/WH2 actin-binding module shows an amazing adaptation to multifunctionality. The beta-thymosins are genuine G-actin sequesterers of moderate affinity for G-actin, allowing an efficient regulation of the G-actin/F-actin ratio in cells by amplifying changes in the critical concentration for filament assembly. In contrast, the first beta-thymosin domain of the protein Ciboulot makes with G-actin a complex that supports filament growth, such as profilin-actin. We illustrate how the use of engineered chimeric proteins, actin-binding and polymerization assays, crystallographic, NMR, and SAXS structural approaches complement each other to decipher the molecular basis for the functional versatility of these intrinsically disordered domains when they form various 1:1 complexes with G-actin. Multifunctionality is expanded in tandem repeats of WH2 domains present in WASP family proteins and proteins involved in axis patterning like Cordon-Bleu and Spire. The tandem repeats generate new functions such as filament nucleation and severing, as well as barbed end binding, which add up to the G-actin sequestering activity. Novel regulation pathways in actin assembly emerge from these additional activities.
Published: 2010
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38. Structural bases for N-glycan processing by mannoside phosphorylase

Author: Gabrielle Potocki-Véronèse, Simon Ladevèze, Samuel Tranier, Pierre Roblin, Gianluca Cioci, Lionel Mourey, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Institut de pharmacologie et de biologie structurale (IPBS), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, French Ministry of Higher Education and Research, French National Institute for Agricultural Research (INRA, 'Meta-omics of Microbial Ecosystems'research program), European Project: 283570,EC:FP7:INFRA,FP7-INFRASTRUCTURES-2011-1,BIOSTRUCT-X(2011), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées, Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Tranier, Samuel, and Potocki-Veronese, Gabrielle
Subjects: Models, Molecular, Glycan, Cristallography, Phosphorylases, Stereochemistry, Protein Conformation, Molecular Sequence Data, Mannose, N-glycans, 03 medical and health sciences, chemistry.chemical_compound, Glycogen phosphorylase, Protein structure, N-glycan processing, X-Ray Diffraction, Structural Biology, Polysaccharides, human gut microbiota, Scattering, Small Angle, [CHIM.CRIS]Chemical Sciences/Cristallography, Transferase, Amino Acid Sequence, Peptide sequence, 030304 developmental biology, Mannan, GH130 enzymes, 0303 health sciences, biology, Sequence Homology, Amino Acid, 030302 biochemistry & molecular biology, General Medicine, Research Papers, 3. Good health, Cristallographie, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], chemistry, Biochemistry, biology.protein, glycoside phosphorylases
Abstract: Crystal structures of the GH130 enzyme Uhgb_MP in the apo form and in complex with mannose and N-acetylglucosamine are described and the structural determinants of the functional specificities of the enzymes involved in N-glycan breakdown by human gut bacteria are identified., The first crystal structure of Uhgb_MP, a β-1,4-mannopyranosyl-chitobiose phosphorylase belonging to the GH130 family which is involved in N-glycan degradation by human gut bacteria, was solved at 1.85 Å resolution in the apo form and in complex with mannose and N-acetylglucosamine. SAXS and crystal structure analysis revealed a hexameric structure, a specific feature of GH130 enzymes among other glycoside phosphorylases. Mapping of the −1 and +1 subsites in the presence of phosphate confirmed the conserved Asp104 as the general acid/base catalytic residue, which is in agreement with a single-step reaction mechanism involving Man O3 assistance for proton transfer. Analysis of this structure, the first to be solved for a member of the GH130_2 subfamily, revealed Met67, Phe203 and the Gly121–Pro125 loop as the main determinants of the specificity of Uhgb_MP and its homologues towards the N-glycan core oligosaccharides and mannan, and the molecular bases of the key role played by GH130 enzymes in the catabolism of dietary fibre and host glycans.
Published: 2015
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39. In vitro digestion of emulsions: high spatiotemporal resolution using synchrotron SAXS

Author: Sébastien Marze, Cédric Gaillard, Pierre Roblin, Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), and Synchrotron SOLEIL
Subjects: Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Models, Biological, law.invention, Digestion (alchemy), Spatio-Temporal Analysis, X-Ray Diffraction, law, Scattering, Small Angle, [SDV.IDA]Life Sciences [q-bio]/Food engineering, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Intestinal Mucosa, Triglycerides, Chemistry, Small-angle X-ray scattering, Vesicle, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, In vitro digestion, Synchrotron, 0104 chemical sciences, Kinetics, Chemical engineering, Emulsion, Digestion, Emulsions, Absorption (chemistry), 0210 nano-technology, Lipid digestion, Synchrotrons
Abstract: International audience; Although the biochemical processes of lipid digestion are well-known, the biophysical ones, responsible for the assembly of molecules into functional structures, lack studies resolving both time and space scales. About 35 years ago, the seminal microscopy study of Patton and Carey constituted a major advance to reach this goal. Nowadays, new perspectives arise from the availability of large facilities scattering techniques, able to monitor the dynamics of multi-scale assemblies with unprecedented resolutions. The present small angle X-ray scattering (SAXS) study focused on the roles of the emulsifier and triglyceride in the formation of lipid assemblies during emulsion digestion in vitro. By developing several interpretations of the data in the whole space range (qualitative, shape-dependent and shape-independent models), the characteristic size of the assemblies and their transition times were obtained, which depended on the triglyceride, but not on the emulsifier. The major assembly formed was found to be a spherical mixed micelle, but vesicle was also found to coexist throughout the digestion, although in a lower proportion. The quantitative determination of the sizes and proportions of these assemblies, as well as the evolution of these characteristics during digestion are precious information for nutritional sciences, as these assemblies are the vehicles of lipophilic nutrients and micronutrients towards their absorption site.
Published: 2015
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40. A salmonella type three secretion effector/chaperone complex adopts a hexameric ring-like structure

Author: Pierre Roblin, Coralie Bompard, Vincent Villeret, Frédérique Dewitte, Emanuele G. Biondi, Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Unité de Glycobiologie Structurale et Fonctionnelle UMR 8576 (UGSF), Institut National de la Recherche Agronomique (INRA)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), CNRS (Centre National de la Recherche Scientifique, CNRS/USTL, France) Region Nord Pas-de-Calais CPER CIA, and Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: Models, Molecular, Salmonella typhimurium, ATPase, Virulence, Sigma Factor, Bioinformatics, Microbiology, 03 medical and health sciences, Bacterial Proteins, Sigma factor, Commentaries, Scattering, Small Angle, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Secretion, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Molecular Biology, Bacterial Secretion Systems, 030304 developmental biology, 0303 health sciences, biology, 030306 microbiology, Effector, NEEDLE COMPLEX, SMALL-ANGLE SCATTERING, EPITHELIAL-CELLS, biochemical phenomena, metabolism, and nutrition, Cell biology, Protein Structure, Tertiary, SYSTEM EXPORT APPARATUS, Cytoplasm, III SECRETION, Chaperone (protein), biology.protein, Chaperone complex, bacteria, STRUCTURE PREDICTION, VIRULENCE FACTORS, HOST-CELLS, TYPHIMURIUM INVASION, PROTEIN EXPORT, Molecular Chaperones
Abstract: Many bacterial pathogens use type three secretion systems (T3SS) to inject virulence factors, named effectors, directly into the cytoplasm of target eukaryotic cells. Most of the T3SS components are conserved among plant and animal pathogens, suggesting a common mechanism of recognition and secretion of effectors. However, no common motif has yet been identified for effectors allowing T3SS recognition. In this work, we performed a biochemical and structural characterization of the Salmonella SopB/SigE chaperone/effector complex by small-angle X-ray scattering (SAXS). Our results showed that the SopB/SigE complex is assembled in dynamic homohexameric-ring-shaped structures with an internal tunnel. In this ring, the chaperone maintains a disordered N-terminal end of SopB molecules, in a good position to be reached and processed by the T3SS. This ring dimensionally fits the ring-organized molecules of the injectisome, including ATPase hexameric rings; this organization suggests that this structural feature is important for ATPase recognition by T3SS. Our work constitutes the first evidence of the oligomerization of an effector, analogous to the organization of the secretion machinery, obtained in solution. As effectors share neither sequence nor structural identity, the quaternary oligomeric structure could constitute a strategy evolved to promote the specificity and efficiency of T3SS recognition.
Published: 2015
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41. Molecular Dynamics at the Root of Expansion of Function in the M69L Inhibitor-Resistant TEM β-Lactamase from Escherichia coli

Author: Yun Zhang, Sergei B. Vakulenko, Samy O. Meroueh, Dasantila Golemi, Shahriar Mobashery, Pierre Roblin, Jean-Pierre Samama, and Laurent Maveyraud
Subjects: chemistry.chemical_classification, Mutation, Base Sequence, Mutant, General Chemistry, medicine.disease_cause, Biochemistry, beta-Lactamases, Catalysis, Amino acid, Dissociation constant, Kinetics, Molecular dynamics, Colloid and Surface Chemistry, Enzyme, chemistry, Escherichia coli, medicine, Peptide bond, Enzyme Inhibitors, beta-Lactamase Inhibitors, DNA Primers
Abstract: Clavulanate, an inhibitor for beta-lactamases, was the very first inhibitor for an antibiotic resistance enzyme that found clinical utility in 1985. The clinical use of clavulanate and that of sulbactam and tazobactam, which were introduced to the clinic subsequently, has facilitated evolution of a set of beta-lactamases that not only retain their original function as resistance enzymes but also are refractory to inhibition by the inhibitors. This article characterizes the properties of the clinically identified M69L mutant variant of the TEM-1 beta-lactamase from Escherichia coli, an inhibitor-resistant beta-lactamase, and compares it to the wild-type enzyme. The enzyme is as active as the wild-type in turnover of typical beta-lactam antibiotics. Furthermore, many of the parameters for interactions of the inhibitors with the mutant enzyme are largely unaffected. The significant effect of the inhibitor-resistant trait was a relatively modest elevation of the dissociation constant for the formation of the pre-acylation complex. The high-resolution X-ray crystal structure for the M69L mutant variant revealed essentially no alteration of the three-dimensional structure, both for the protein backbone and for the positions of the side chains of the amino acids. It was surmised that the difference in the two enzymes must reside with the dynamic motions of the two proteins. Molecular dynamics simulations of the mutant and wild-type proteins were carried out for 2 ns each. Dynamic cross-correlated maps revealed the collective motions of the two proteins to be very similar, yet the two proteins did not behave identically. Differences in behavior of the two proteins existed in the regions between residues 145-179 and 155-162. Additional calculations revealed that kinetic effects measured experimentally for the dissociation constant for the pre-acylation complex could be mostly attributed to the electrostatic and van der Waals components of the binding free energy. The effects of the mutation on the behavior of the beta-lactamase were subtle, including the differences in the measured dissociation constants that account for the inhibitor-resistant trait. It would appear that nature has selected for incorporation of the most benign alteration in the structure of the wild-type TEM-1 beta-lactamase that is sufficient to give the inhibitor-resistant trait.
Published: 2002
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42. Speciation of a group I intron into a lariat capping ribozyme

Author: Vincent Olieric, Mélanie Meyer, Henrik Nielsen, Steinar Johansen, Pierre Roblin, Eric Westhof, Benoît Masquida, Université de Strasbourg (UNISTRA), University of Copenhagen = Københavns Universitet (KU), Institut Paul Scherrer (IPS), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, University of Tromsø (UiT), Centre National de la Recherche Scientifique, University of Strasbourg, L'Agence Nationale de la Recherche [ANR-10-BLAN-1502-02], le Laboratoire d'Excellence Project [ANR-11-LABX-0057-MITOCROSS], and Danish Council for Independent Research in Natural Sciences
Subjects: Models, Molecular, Stereochemistry, Protein Conformation, RNA structure, RNA catalysis, GIR1, crystallography, SAXS, Homing endonuclease, Evolution, Molecular, ribozyme, arn, Protein structure, X-Ray Diffraction, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Scattering, Small Angle, Group I catalytic intron, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, RNA, Catalytic, Selection, Genetic, Genetics, Multidisciplinary, Crystallography, biology, GIR1 branching ribozyme, Ribozyme, Biological Sciences, Introns, biology.protein, Mammalian CPEB3 ribozyme, Hairpin ribozyme, VS ribozyme, Signal Transduction
Abstract: The lariat-capping (LC) ribozyme is a natural ribozyme isolated from eukaryotic microorganisms. Despite apparent structural similarity to group I introns, the LC ribozyme catalyzes cleavage by a 2',5' branching reaction, leaving the 3' product with a 3-nt lariat cap that functionally substitutes for a conventional mRNA cap in the downstream pre-mRNA encoding a homing endonuclease. We describe the crystal structures of the precleavage and postcleavage LC ribozymes, which suggest that structural features inherited from group I ribozymes have undergone speciation due to profound changes in molecular selection pressure, ultimately giving rise to an original branching ribozyme family. The structures elucidate the role of key elements that regulate the activity of the LC ribozyme by conformational switching and suggest a mechanism by which the signal for branching is transmitted to the catalytic core. The structures also show how conserved interactions twist residues, forming the lariat to join chemical groups involved in branching.
Published: 2014
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43. Involvement of protein IF2 N domain in ribosomal subunit joining revealed from architecture and function of the full-length initiation factor

Author: Angelita Simonetti, Daniel Eiler, Pierre Roblin, Albert Tsai, Bruno P. Klaholz, Isabelle Hazemann, Alexander G. Myasnikov, Stefano Marzi, Attilio Fabbretti, Isabelle M. L. Billas, Thomas A. Steitz, Claudio O. Gualerzi, Joseph D. Puglisi, Andrea C. Vaiana, Université de Strasbourg (UNISTRA), Stanford University, University of Camerino, Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Max Planck Institute for Biophysical Chemistry (MPI-BPC), Max-Planck-Gesellschaft, Yale University, Partenaires INRAE, Yale University [New Haven], Howard Hughes Medical Institute (HHMI), Dept Biol Struct, Flanders Institute for Biotechnology, European Research Council [243296], Centre National de la Recherche Scientifique (CNRS), Fondation pour la Recherche Medicale (FRM), French Infrastructure for Integrated Structural Biology [ANR-10-INSB-05-01], Instruct as part of European Strategy Forum on Research Infrastructures, and National Institutes of Health [GM51266, GM099587]
Subjects: Models, Molecular, BACTERIAL, TRANSLATION INITIATION, protein synthesis, Ribosome Subunits, Small, Bacterial, Ribosome Subunits, Large, Bacterial, integrated structural biology, Prokaryotic Initiation Factor-2, Biology, Ribosome, Structure-Activity Relationship, 03 medical and health sciences, X-Ray Diffraction, Eukaryotic initiation factor, Scattering, Small Angle, EF-G, BINDING, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Ribosome Subunits, Initiation factor, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, 30S, Peptide Chain Initiation, Translational, 030304 developmental biology, 50S, L12, 0303 health sciences, COMPLEX, Multidisciplinary, ELONGATION, Prokaryotic initiation factor-2, Thermus thermophilus, Cryoelectron Microscopy, 030302 biochemistry & molecular biology, SMALL-ANGLE SCATTERING, Biological Sciences, Protein Structure, Tertiary, Crystallography, ESCHERICHIA-COLI, Biophysics, Mutant Proteins, BACILLUS-STEAROTHERMOPHILUS, Eukaryotic Ribosome, Protein Binding
Abstract: International audience; Translation initiation factor 2 (IF2) promotes 30S initiation complex (IC) formation and 50S subunit joining, which produces the 70S IC. The architecture of full-length IF2, determined by small angle X-ray diffraction and cryo electron microscopy, reveals a more extended conformation of IF2 in solution and on the ribosome than in the crystal. The N-terminal domain is only partially visible in the 30S IC, but in the 70S IC, it stabilizes interactions between IF2 and the L7/L12 stalk of the 50S, and on its deletion, proper N-formyl-methionyl (fMet)-tRNA(fMet) positioning and efficient transpeptidation are affected. Accordingly, fast kinetics and single-molecule fluorescence data indicate that the N terminus promotes 70S IC formation by stabilizing the productive sampling of the 50S subunit during 30S IC joining. Together, our data highlight the dynamics of IF2-dependent ribosomal subunit joining and the role played by the N terminus of IF2 in this process.
Published: 2013
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44. Structure of glycoproteins from Acacia gum: an assembly of ring-like glycoproteins modules

Author: D. Renard, Michaël Nigen, Cyrille Garnier, Eléonore Lepvrier, Carmen Navarro Sanchez, Pierre Roblin, Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)
Subjects: food.ingredient, Polymers and Plastics, Size-exclusion chromatography, 02 engineering and technology, Galactans, Protein Structure, Secondary, 03 medical and health sciences, chemistry.chemical_compound, Gum Arabic, food, Microscopy, Electron, Transmission, X-Ray Diffraction, Arabinogalactan, Scattering, Small Angle, Materials Chemistry, Side chain, 030304 developmental biology, Polyproline helix, Glycoproteins, 0303 health sciences, [SDV.GEN]Life Sciences [q-bio]/Genetics, Acacia gum, Small-angle X-ray scattering, Chemistry, Hydrophilic interaction chromatography, Organic Chemistry, 021001 nanoscience & nanotechnology, Molecular Weight, Crystallography, Hydroxyproline, Monomer, HPSEC-MALLS, Chromatography, Gel, Gum arabic, Synchrotron radiation circular dichroism, Glycoprotein, 0210 nano-technology, Hydrophobic and Hydrophilic Interactions, Transmission electron microscopy
Abstract: International audience; The glycoprotein (GP) molecular fraction structure of the gum exudate of Acacia senegal (gum Arabic) isolated from hydrophobic interaction chromatography was investigated using high-performance size exclusion chromatography-multi angle laser light scattering (HPSEC-MALLS), small angle X-ray scattering (SAXS), synchrotron radiation circular dichroism (SRCD) and transmission electron microscopy (TEM) observations. In solution, GP would be a mixture of spheroidal monomers and more anisotropic oligomers as suggested by the two exponent values found in the R-g vs. M-w relationship and TEM observations. The GP conformation probed by SAXS was ascribed to a thin object with a triaxial ellipsoid morphology, certainly attributed to GP oligomers. A 9 nm diameter particle was also identified by SAXS in agreement with the dimensions identified by TEM on single isolated ring-like structures. The GP oligomerization process, as probed by TEM, would be the result of ring-like subunits self-association. This self-association would lead to more linear or, sometimes, cyclised assembly. At the molecular level, GP fraction was found to have secondary structures mainly made of beta-sheets and turns (64%) but also, to a lesser extent, made of polyproline II (PPII) and alpha-helices (19%). These features were characteristic of hydroxyprolin-rich glycoproteins with arabinosylated and arabinogalactan polysaccharide side chains grafted to the polypeptide backbone. The GP molecular fraction structure from Acacia gum would be an assembly of ring-like glycoproteins modules. These ring-like structures were certainly due to hydroxyproline (Hyp)-arabinogalactan (AG) subunits. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.
Published: 2013
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45. The asymmetric binding of PGC-1α to the ERRα and ERRγ nuclear receptor homodimers involves a similar recognition mechanism

Author: François Xavier Ogi, Yassmine Chebaro, Pierre Roblin, Dmitri I. Svergun, Mária Takács, Dino Moras, Isabelle M. L. Billas, Noelle Potier, Annick Dejaegere, Borries Demeler, Maxim V. Petoukhov, R. Andrew Atkinson, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), European Molecular Biology Laboratory (EMBL), King‘s College London, Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, NanoTemper Technologies GmbH [München], University of Texas Health Science Center, The University of Texas Health Science Center at Houston (UTHealth), Université de Strasbourg (UNISTRA), CNRS, INSERM, the Association pour la Recherche sur le Cancer (ARC), Karo Bio Research Foundation, French Infrastructure for Integrated Structural Biology (FRISBI) [ANR-10-INSB-05-01], Instruct as part of the European Strategy Forum on Research Infrastructures (ESFRI), WeNMR project [261572], BMBF research grant SYNC-LIFE [05K10YEA], ProdInra, Migration, Chimie de la matière complexe (CMC), and Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Models, Molecular, Macromolecular Assemblies, Protein Folding, Protein Conformation, Plasma protein binding, Biochemistry, Transactivation, 0302 clinical medicine, Protein structure, Endocrinology, X-Ray Diffraction, Molecular Cell Biology, Basic Cancer Research, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Macromolecular Structure Analysis, ComputingMilieux_MISCELLANEOUS, 0303 health sciences, Multidisciplinary, [SDV.IDA] Life Sciences [q-bio]/Food engineering, Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha, Cell biology, Receptors, Estrogen, Oncology, Medicine, ddc:500, Protein Binding, Research Article, Signal Transduction, Protein Structure, [SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering, Science, Molecular Sequence Data, Allosteric regulation, Biophysics, Biology, 03 medical and health sciences, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, Scattering, Small Angle, Humans, Protein Interaction Domains and Motifs, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Amino Acid Sequence, Protein Interactions, 030304 developmental biology, Hormone response element, Microscale thermophoresis, Cofactors, Cooperative binding, Computational Biology, Proteins, Hormones, Protein Subunits, Nuclear receptor, Protein Multimerization, Nuclear Receptor Signaling, 030217 neurology & neurosurgery, Transcription Factors
Abstract: International audience; Background: PGC-1 alpha is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERR alpha and ERR gamma) in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1 alpha and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al) that PGC-1 alpha binds in a strikingly different manner to ERR gamma ligand-binding domains (LBDs) compared to its mode of binding to ERR alpha and other nuclear receptors (NRs), where it interacts directly with the two ERR gamma homodimer subunits. Methods/Principal Findings: Here, we show that PGC-1 alpha receptor interacting domain (RID) binds in an almost identical manner to ERR alpha and ERR gamma homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1 alpha RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1 alpha RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1 alpha/ERRa LBDs and PGC-1 alpha/ERRc LBDs complexes share an identical architecture with an asymmetric binding of PGC-1 alpha to homodimeric ERR. Conclusions/Significance: These studies provide the molecular determinants for the specificity of interactions between PGC-1 alpha and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.
Published: 2013
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46. The structural organization of the N-terminus domain of SopB, a virulence factor of Salmonella, depends on the nature of its protein partners

Author: Vincent Villeret, Pierre Lebrun, Pierre Roblin, Prakash Rucktooa, Frédérique Dewitte, Zoé Lens, Coralie Bompard, Vincent Raussens, Véronique Receveur-Bréchot, Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Université Lille Nord de France (COMUE), Aix Marseille Université (AMU), Université libre de Bruxelles (ULB), CNRS (Centre National de la Recherche Scientifique, USR3078 CNRS/USTL, France), Region Nord Pas-de-Calais, CPER CIA, and Beam Allocation Groups 'Conformational properties of proteins in solution'
Subjects: Salmonella typhimurium, Type three secretion system, Biophysics, Virulence, Sigma Factor, Small angle X-ray scattering, Biochemistry, Protein Structure, Secondary, Virulence factor, Analytical Chemistry, Microbiology, 03 medical and health sciences, Bacterial Proteins, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Secretion, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Protein Structure, Quaternary, Molecular Biology, 030304 developmental biology, 0303 health sciences, biology, 030306 microbiology, Effector, Chaperone binding domain, Protein Structure, Tertiary, Cell biology, Bacterial virulence, Cytoplasm, Intrinsically disordered protein, Chaperone (protein), biology.protein, Chaperone binding, Molecular Chaperones
Abstract: International audience; The TTSS is used by Salmonella and many bacterial pathogens to inject virulence factors directly into the cytoplasm of target eukaryotic cells. Once translocated these so-called effector proteins hijack a vast array of crucial cellular functions to the benefit of the bacteria. In the bacterial cytoplasm, some effectors are stabilized and maintained in a secretion competent state by interaction with specific type III chaperones. In this work we studied the conformation of the Chaperone Binding Domain of the effector named Salmonella Outer protein B (SopB) alone and in complex with its cognate chaperone SigE by a combination of biochemical, biophysical and structural approaches. Our results show that the N-terminus part of SopB is mainly composed by alpha-helices and unfolded regions whose organization/stabilization depends on their interaction with the different partners. This suggests that the partially unfolded state of this N-terminal region, which confers the adaptability of the effector to bind very different partners during the infection cycle, allows the bacteria to modulate numerous host cells functions limiting the number of translocated effectors.
Published: 2013
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47. White wine proteins: how does the pH affect their conformation at room temperature?

Author: Aude Vernhet, Marie Dufrechou, Pierre Roblin, Céline Poncet-Legrand, Francois Xavier Sauvage, Sciences Pour l'Oenologie (SPO), Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), and Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)
Subjects: [SDV.SA]Life Sciences [q-bio]/Agricultural sciences, Circular dichroism, Protein Conformation, Wine, 01 natural sciences, Fluorescence spectroscopy, 0404 agricultural biotechnology, Electrochemistry, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, General Materials Science, Spectroscopy, biology, Small-angle X-ray scattering, Chemistry, Circular Dichroism, 010401 analytical chemistry, Temperature, Proteins, food and beverages, 04 agricultural and veterinary sciences, Surfaces and Interfaces, Hydrogen-Ion Concentration, Condensed Matter Physics, 040401 food science, Protein tertiary structure, 0104 chemical sciences, Crystallography, Invertase, Spectrometry, Fluorescence, White Wine, Chitinase, biology.protein
Abstract: Our studies focused on the determination of aggregation mechanisms of proteins occurring in wine at room temperature. Even if the wine pH range is narrow (2.8 to 3.7), some proteins are affected by this parameter. At low pH, the formation of aggregates and the development of a haze due to proteins sometimes occur. The objective of this work was to determine if the pH impacted the conformational stability of wine proteins. Different techniques were used: circular dichroism and fluorescence spectroscopy to investigate the modification of their secondary and tertiary structure and also SAXS to determine their global shape. Four pure proteins were used, two considered to be stable (invertase and thaumatin-like proteins) and two considered to be unstable (two chitinase isoforms). Two pH values were tested to emphasize their behavior (pH 2.5 and 4.0). The present work highlighted the fact that the conformational stability of some wine proteins (chitinases) was impacted by partial modifications, related to the exposure of some hydrophobic sites. These modifications were enough to destabilize the native state of the protein. These modifications were not observed on wine proteins determined to be stable (invertase and thaumatin-like proteins).
Published: 2013
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48. Structural insights into protein-only RNase P complexed with tRNA

Author: Anthony Gobert, Olivier Fuchsbauer, Philippe Giegé, Bernard Gutmann, René Boutin, Claude Sauter, Pierre Roblin, Franziska Pinker, Université de Strasbourg (UNISTRA), Centre National de la Recherche Scientifique (CNRS), Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, French 'Centre National de la Recherche Scientifique', University of Strasbourg, ANR Blanc research grant 'PRO-RNase P' [ANR 11 BSV8 008 01], LabEx consortium 'MitoCross', Institut de biologie moléculaire des plantes (IBMP), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), and Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Models, Molecular, RNA, Mitochondrial, General Physics and Astronomy, RNase PH, 0302 clinical medicine, RNA, Transfer, X-Ray Diffraction, X-RAY SOLUTION, [SDV.IDA]Life Sciences [q-bio]/Food engineering, RNA Precursors, CRYSTAL-STRUCTURE, RIBONUCLEASE-P, ComputingMilieux_MISCELLANEOUS, Ribonucleoprotein, chemistry.chemical_classification, Recombination, Genetic, 0303 health sciences, Multidisciplinary, SMALL-ANGLE SCATTERING, MIMICRY, ARABIDOPSIS, Solutions, Zinc, Biochemistry, Ribonucleoproteins, RNA, Plant, ESCHERICHIA-COLI, Transfer RNA, Protein Binding, RNase P, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Biology, Regulatory Sequences, Ribonucleic Acid, Models, Biological, General Biochemistry, Genetics and Molecular Biology, Ribonuclease P, Article, 03 medical and health sciences, Scattering, Small Angle, REVEALS, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, RNase H, PENTATRICOPEPTIDE REPEAT PROTEINS, 030304 developmental biology, Arabidopsis Proteins, Spectrophotometry, Atomic, RNA, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, General Chemistry, URACIL-DNA GLYCOSYLASE, RNase MRP, Enzyme, chemistry, biology.protein, 030217 neurology & neurosurgery
Abstract: RNase P is the essential activity removing 5′-leader sequences from transfer RNA precursors. RNase P was always associated with ribonucleoprotein complexes before the discovery of protein-only RNase P enzymes called PRORPs (PROteinaceous RNase P) in eukaryotes. Here we provide biophysical and functional data to understand the mode of action of PRORP enzymes. Activity assays and footprinting experiments show that the anticodon domain of transfer RNA is dispensable, whereas individual residues in D and TψC loops are essential for PRORP function. PRORP proteins are characterized in solution and a molecular envelope is derived from small-angle X-ray scattering. Conserved residues are shown to be involved in the binding of one zinc atom to PRORP. These results facilitate the elaboration of a model of the PRORP/transfer RNA interaction. The comparison with the ribonucleoprotein RNase P/transfer RNA complex suggests that transfer RNA recognition by PRORP proteins is similar to that by ribonucleoprotein RNase P., RNase P is a key enzyme implicated in transfer RNA maturation that removes the 5′-leader sequences from transfer RNA precursors. In this study, a biophysical characterization of a novel protein-only variant of RNase P, known as PRORP (PROteinaceous RNase P), reveals that transfer RNA recognition by PRORP is similar to that by ribonucleoprotein RNase P.
Published: 2013
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49. How a single residue in individual β-thymosin/WH2 domains controls their functions in actin assembly

Author: Dominique, Didry, Francois-Xavier, Cantrelle, Clotilde, Husson, Pierre, Roblin, Anna M Eswara, Moorthy, Javier, Perez, Christophe, Le Clainche, Maud, Hertzog, Eric, Guittet, Marie-France, Carlier, Carine, van Heijenoort, Louis, Renault, Institut de Chimie des Substances Naturelles (ICSN), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
Subjects: Thymosin, Sequence Homology, Amino Acid, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Molecular Sequence Data, Osmolar Concentration, Scattering, Small Angle, Amino Acid Sequence, macromolecular substances, Crystallography, X-Ray, Nuclear Magnetic Resonance, Biomolecular, Actins, Article
Abstract: International audience; β-Thymosin (βT) and WH2 domains are widespread, intrinsically disordered actin-binding peptides that display significant sequence variability and different regulations of actin self-assembly in motile and morphogenetic processes. Here, we reveal the structural mechanisms by which, in their 1:1 stoichiometric complexes with actin, they either inhibit assembly by sequestering actin monomers like Thymosin-β4, or enhance motility by directing polarized filament assembly like Ciboulot βT. We combined mutational, functional or structural analysis by X-ray crystallography, SAXS (small angle X-ray scattering) and NMR on Thymosin-β4, Ciboulot, TetraThymosinβ and the long WH2 domain of WASP-interacting protein. The latter sequesters G-actin with the same molecular mechanisms as Thymosin-β4. Functionally different βT/WH2 domains differ by distinct dynamics of their C-terminal half interactions with G-actin pointed face. These C-terminal interaction dynamics are controlled by the strength of electrostatic interactions with G-actin. At physiological ionic strength, a single salt bridge with actin located next to their central LKKT/V motif induces G-actin sequestration in both isolated long βT and WH2 domains. The results open perspectives for elucidating the functions of βT/WH2 domains in other modular proteins.
Published: 2012
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50. SAXS and X-ray crystallography suggest an unfolding model for the GDP/GTP conformational switch of the small GTPase Arf6

Author: Mahel Zeghouf, Valérie Biou, Kaheina Aizel, Carine van Heijenoort, Eric Jacquet, Javier Pérez, Sebastian Hansson, Pierre Roblin, Eric Guittet, Aurélien Thureau, Jacqueline Cherfils, Bernard Guibert, Institut de Chimie des Substances Naturelles (ICSN), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
Subjects: Protein Folding, Protein Conformation, Protein Data Bank (RCSB PDB), GTPase, Crystallography, X-Ray, Guanosine Diphosphate, 03 medical and health sciences, chemistry.chemical_compound, Protein structure, X-Ray Diffraction, Structural Biology, Scattering, Small Angle, Humans, Small GTPase, Molecular Biology, 030304 developmental biology, 0303 health sciences, ADP-Ribosylation Factors, [CHIM.ORGA]Chemical Sciences/Organic chemistry, 030302 biochemistry & molecular biology, Crystallography, chemistry, ADP-Ribosylation Factor 6, Guanosine diphosphate, Thermodynamics, Protein folding, Guanosine Triphosphate, Guanine nucleotide exchange factor, Heteronuclear single quantum coherence spectroscopy
Abstract: International audience; The small GTPases Arf1 and Arf6 have nonoverlapping functions in cellular traffic despite their very high sequence and structural resemblance. Notably, the exquisite isoform specificity of their guanine nucleotide exchange factors and their distinctive sensitivity to the drug brefeldin A cannot be explained by any straightforward structural model. Here we integrated structural and spectroscopic methods to address this issue using Δ13Arf6-GDP, a truncated mutant that mimics membrane-bound Arf6-GDP. The crystal structure of Δ13Arf6-GDP reveals an unprecedented unfolding of the GTPase core β-strands, which is fully accounted for by small-angle X-ray scattering data in solution and by ab initio three-dimensional envelope calculation. NMR chemical shifts identify this structural disorder in Δ13Arf6-GDP, but not in the closely related Δ17Arf1-GDP, which is consistent with their comparative thermodynamic and hydrodynamic analyses. Taken together, these experiments suggest an unfolding model for the nucleotide switch of Arf6 and shed new light on its biochemical differences with Arf1.
Published: 2010
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