137 results on '"Pignol D"'
Search Results
2. Transformation Cycle of Magnetosomes in Human Stem Cells: From Degradation to Biosynthesis of Magnetic Nanoparticles Anew
- Author
-
Curcio A., Van De Walle A., Serrano A., Preveral S., Péchoux C., Pignol D., Menguy N., Lefevre C.T., Espinosa A., Wilhelm C. and This work was supported by the European Union (ERC-2014-CoG project MaTissE #648779). The authors acknowledge the staff of the MPBT (physical properties - low temperature) platform of Sorbonne Université for their support. We thank Nathalie Luciani and Anouchka Plan Sangnier for help and fruitful discussions. We acknowledge the ESRF for beamtime and the CRG beamline BM25-SpLine personnel for technical support, and A.E. acknowledges support from Comunidad de Madrid (Talento project 2018-T1/IND-1005).
- Published
- 2020
3. Crystal structure of the essential repressor DdrO from radiation-resistant Deinococcus bacteria (Deinococcus deserti)
- Author
-
Arnoux, P., primary, Siponen, M.I., additional, Pignol, D., additional, De Groot, A., additional, and Blanchard, L., additional
- Published
- 2019
- Full Text
- View/download PDF
4. Crystal structure of a selenomethionine-substituted A70M I84M mutant of the essential repressor DdrO from radiation resistant-Deinococcus bacteria (Deinococcus deserti)
- Author
-
Arnoux, P., primary, Siponen, M.I., additional, Pignol, D., additional, De Groot, A., additional, and Blanchard, L., additional
- Published
- 2019
- Full Text
- View/download PDF
5. Crystal structure of the C-terminal dimerization domain of the essential repressor DdrO from radiation-resistant Deinococcus bacteria (Deinococcus deserti)
- Author
-
Pignol, D., primary, Arnoux, P., additional, Siponen, M.I., additional, Brandelet, G., additional, De Groot, A., additional, and Blanchard, L., additional
- Published
- 2019
- Full Text
- View/download PDF
6. Crystal structure of the N-terminal HTH DNA-binding domain of the essential repressor DdrO from radiation-resistant Deinococcus bacteria (Deinococcus deserti)
- Author
-
Arnoux, P., primary, Siponen, M.I., additional, Pignol, D., additional, Brandelet, G., additional, De Groot, A., additional, and Blanchard, L., additional
- Published
- 2019
- Full Text
- View/download PDF
7. Structure of Fatty acid Photodecarboxylase in complex with FAD and palmitic acid
- Author
-
Arnoux, P., primary, Sorigue, D., additional, Beisson, F., additional, and Pignol, D., additional
- Published
- 2017
- Full Text
- View/download PDF
8. Comparative genomic analysis provides insights into the evolution and niche adaptation of marine Magnetospira sp. QH-2 strain
- Author
-
Ji, B. Y., Zhang, S. D., Arnoux, P., Rouy, Z., Alberto, F., Philippe, N., Murat, D., Zhang, W. J., Rioux, J. B., Ginet, N., Sabaty, M., Mangenot, S., Pradel, Nathalie, Tian, J. S., Yang, J., Zhang, L. C., Zhang, W. Y., Pan, H. M., Henrissat, B., Coutinho, P. M., Li, Y., Xiao, T., Medigue, C., Barbe, V., Pignol, D., Talla, E., Wu, L. F., Laboratoire de chimie bactérienne (LCB), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB) (BIAM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-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), Microbiologie Environnementale et Moléculaire (MEM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Génomique métabolique (UMR 8030), Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Université Paris-Saclay-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 Paris-Saclay-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 d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Adaptation et pathogénie des micro-organismes [Grenoble] (LAPM), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Institut de Génomique d'Evry (IG), Université Paris-Saclay-Institut de Biologie François JACOB (JACOB), 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)), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institute of Computing Technology, Chinese Academy of Sciences,College of Hunan, Centre d'Immunologie de Marseille - Luminy (CIML), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Chinese Academy of Sciences [Qingdao], Architecture et fonction des macromolécules biologiques (AFMB), Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Shandong Agricultural University (SDAU), CAS Institute of Oceanology (IOCAS), Chinese Academy of Sciences [Beijing] (CAS), Institut des sciences biologiques (INSB-CNRS), This work was supported by Grands Projets de Séquençage, Agence Nationale de la Recherche (ANR‐2010‐BLAN‐1320‐01 to L.F.W.), National Science Fundation of China (NSFC40776094, 41276170 to T.X.), Centre National de la Recherche Scientifique (to LIA‐BioMNSL) and the Chinese Scholarship Council fellowship (to B.J., S.D.Z., W.J.Z and J.Y.)., ANR-10-BLAN-1320,MagneticFlAp,Mécanismes d'assemblage et de fonctionnement de l'appareillage flagellaire des bactéries magnétotactiques(2010), Institut de Biologie François JACOB (JACOB), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Institut des sciences biologiques (INSB), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-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)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-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 Paris-Saclay-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA)
- Subjects
DNA, Bacterial ,Genomic Islands ,[SDV]Life Sciences [q-bio] ,MESH: Symporters/genetics ,Adaptation, Biological ,MESH: Bacterial Proteins/genetics ,Synteny ,MESH: Quinone Reductases/genetics ,MESH: Biological Evolution ,MESH: Magnetospirillum/genetics ,Bacterial Proteins ,MESH: Magnetospirillum/physiology ,MESH: Genomic Islands ,Seawater ,MESH: Seawater/microbiology ,Magnetospirillum ,Quinone Reductases ,MESH: Phylogeny ,Ecosystem ,Phylogeny ,MESH: Adaptation, Biological/genetics ,Comparative Genomic Hybridization ,Symporters ,MESH: Magnetosomes/genetics ,MESH: Synteny ,MESH: Genome, Bacterial ,Biological Evolution ,MESH: Ecosystem ,MESH: DNA, Bacterial/genetics ,MESH: Comparative Genomic Hybridization ,MESH: DNA Transposable Elements ,Multigene Family ,DNA Transposable Elements ,MESH: Multigene Family ,Magnetosomes ,Genome, Bacterial - Abstract
International audience; Magnetotactic bacteria (MTB) are capable of synthesizing intracellular organelles, the magnetosomes, that are membrane-bounded magnetite or greigite crystals arranged in chains. Although MTB are widely spread in various ecosystems, few axenic cultures are available, and only freshwater Magnetospirillum spp. have been genetically analysed. Here, we present the complete genome sequence of a marine magnetotactic spirillum, Magnetospira sp. QH-2. The high number of repeats and transposable elements account for the differences in QH-2 genome structure compared with other relatives. Gene cluster synteny and gene correlation analyses indicate that the insertion of the magnetosome island in the QH-2 genome occurred after divergence between freshwater and marine magnetospirilla. The presence of a sodium-quinone reductase, sodium transporters and other functional genes are evidence of the adaptive evolution of Magnetospira sp. QH-2 to the marine ecosystem. Genes well conserved among freshwater magnetospirilla for nitrogen fixation and assimilatory nitrate respiration are absent from the QH-2 genome. Unlike freshwater Magnetospirillum spp., marine Magnetospira sp. QH-2 neither has TonB and TonB-dependent receptors nor does it grow on trace amounts of iron. Taken together, our results show a distinct, adaptive evolution of Magnetospira sp. QH-2 to marine sediments in comparison with its closely related freshwater counterparts.
- Published
- 2014
9. Crystal structure of FdhD in complex with GDP
- Author
-
Arnoux, P., primary, Walburger, A., additional, Magalon, A., additional, and Pignol, D., additional
- Published
- 2015
- Full Text
- View/download PDF
10. Bactéries environnementales accumulatrices de métaux
- Author
-
François, F., Molinier, A.-L., Peduzzi, J., Garcia, David, Pignol, D., Rebuffat, S., Laboratoire de chimie et biochimie des substances naturelles, Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Biologie cellulaire et moléculaire des plantes et des bactéries (BCMPB), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de la Méditerranée - Aix-Marseille 2, Université de la Méditerranée - Aix-Marseille 2-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)
- Subjects
[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology - Abstract
Les micro-organismes présents dans des milieux fortement pollués notamment par des métaux, sont capables de développer des systèmes de résistance variés. A partir de prélèvements environnementaux nous avons isolé des souches bactériennes accumulatrices d'arsenic et de mercure, métaux dont la toxicité est aiguë et pour lesquels les systèmes de biodépollution sont peu développés. Après mise au point d'un protocole d'isolement et la détermination des seuils de résistance, une première étape de culture des échantillons en présence de 5 mM d'As2O5, ou de 10 mM de Na2HAsO4 ou de 10 µM de HgCl2 a permis d'isoler environ 200 souches résistantes à ces métaux. Une seconde étape de détermination des niveaux de résistances à ces toxiques a été réalisée en milieu liquide ou gélosé, pauvre ou riche. Nous avons ainsi sélectionné plus de vingt souches présentant de fortes capacités de résistance à l'arsenic et au mercure, pouvant aller jusqu'à 10 mM d'As2O5, 250 mM de Na2HAsO4 et 0,12 mM de HgCl2. Certaines souches présentent une double résistance à ces deux métaux. Au sein de ces souches d'intérêt, identifiées par galerie API et/ou séquençage de l'ADNr 16s, des bactéries accumulatrices ont été recherchées par dosage de l'arsenic et du mercure total en spectrographie d'émission à plasma couplée à un spectromètre de masse (ICP-MS) dans les surnageants de culture et les culots bactériens. Des observations en microscopie électronique à transmission pourront confirmer ces accumulations par la présence de granules métalliques intracellulaires. Des observations de la répartition des éléments au niveau intracellulaire par imagerie en spectrométrie de masse avec ions secondaires (Nano-SIMS 50) sont en cours et permettront de confirmer la présence de granules d'arsenic et de mercure. Parallèlement, des essais de conservation des souches sélectionnées ont été réalisées par lyophilisation, sporulation et immobilisation en billes d'alginate, en vue d'une utilisation en biodépollution.
- Published
- 2007
11. Crystal structure of MamP soaked with iron(II)
- Author
-
Siponen, M., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2013
- Full Text
- View/download PDF
12. Crystal structure of MamP
- Author
-
Siponen, M., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2013
- Full Text
- View/download PDF
13. E81Q mutant of MtNAS in complex with a reaction intermediate
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2011
- Full Text
- View/download PDF
14. Crystal Structure of E81Q mutant of MtNAS in complex with L-Glutamate
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2009
- Full Text
- View/download PDF
15. Crystal Structure of MtNAS in complex with MTA and tNA
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2009
- Full Text
- View/download PDF
16. Crystal Structure of E81Q mutant of MtNAS in complex with S-ADENOSYLMETHIONINE
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2009
- Full Text
- View/download PDF
17. Crystal Structure of MtNAS in complex with thermonicotianamine
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2009
- Full Text
- View/download PDF
18. Crystal Structure of E81Q mutant of MtNAS
- Author
-
Dreyfus, C., primary, Pignol, D., additional, and Arnoux, P., additional
- Published
- 2009
- Full Text
- View/download PDF
19. Crystal Structure of the Lipocalin domain of Violaxanthin de-epoxidase (VDE) at pH5
- Author
-
Arnoux, P., primary, Morosinotto, T., additional, and Pignol, D., additional
- Published
- 2009
- Full Text
- View/download PDF
20. Crystal structures of a sodium-alpha-keto acid binding subunit from a TRAP transporter in its open form
- Author
-
Gonin, S., primary, Arnoux, P., additional, Pierru, B., additional, Alonso, B., additional, Sabaty, M., additional, and Pignol, D., additional
- Published
- 2007
- Full Text
- View/download PDF
21. Crystal structures of a sodium-alpha-keto acid binding subunit from a TRAP transporter in its closed forms
- Author
-
Gonin, S., primary, Arnoux, P., additional, Pierru, B., additional, Alonso, B., additional, Sabaty, M., additional, and Pignol, D., additional
- Published
- 2007
- Full Text
- View/download PDF
22. Crystal structure of Alr0975
- Author
-
Vivares, D., primary, Arnoux, P., additional, and Pignol, D., additional
- Published
- 2005
- Full Text
- View/download PDF
23. Crystal structure of the heterodimeric nitrate reductase from Rhodobacter sphaeroides
- Author
-
Arnoux, P., primary, Sabaty, M., additional, Alric, J., additional, Frangioni, B., additional, Guigliarelli, B., additional, Adriano, J.-M., additional, and Pignol, D., additional
- Published
- 2003
- Full Text
- View/download PDF
24. CRYSTAL STRUCTURE OF SIR-FP60
- Author
-
Gruez, A., primary, Pignol, D., additional, Zeghouf, M., additional, Coves, J., additional, Fontecave, M., additional, Ferrer, J.L., additional, and Fontecilla-Camps, J.C., additional
- Published
- 2000
- Full Text
- View/download PDF
25. CRYSTAL STRUCTURE OF HUMAN LITHOSTATHINE TO 1.3 A RESOLUTION
- Author
-
Gerbaud, V., primary, Pignol, D., additional, Loret, E., additional, Bertrand, J.A., additional, Berland, Y., additional, Fontecilla-Camps, J.C., additional, Canselier, J.P., additional, Gabas, N., additional, and Verdier, J.M., additional
- Published
- 1999
- Full Text
- View/download PDF
26. X-ray crystallographic analysis of the heterotrimeric globular heads of human C1q
- Author
-
Gruez, A., primary, Piras, C., additional, Pignol, D., additional, Lacroix, M., additional, Arlaud, G., additional, and Fontecilla-Camps, J.C., additional
- Published
- 1998
- Full Text
- View/download PDF
27. Pancreatic lipase-related protein type I: a specialized lipase or an inactive enzyme
- Author
-
Crenon, I., primary, Foglizzo, E., additional, Kerfelec, B., additional, Verine, A., additional, Pignol, D., additional, Hermoso, J., additional, Bonicel, J., additional, and Chapus, C., additional
- Published
- 1998
- Full Text
- View/download PDF
28. Crystal structure of human lithostathine, the pancreatic inhibitor of stone formation.
- Author
-
Bertrand, J. A., primary, Pignol, D., additional, Bernard, J. P., additional, Verdier, J. M., additional, Dagorn, J. C., additional, and Fontecilla-Camps, J. C., additional
- Published
- 1996
- Full Text
- View/download PDF
29. How to Escape from Model Bias with a High-Resolution Native Data Set – Structure Determination of the PcpA-S6 Subunit III
- Author
-
Pignol, D., primary, Gaboriaud, C., additional, Fontecilla-Camps, J. C., additional, Lamzin, V. S., additional, and Wilson, K. S., additional
- Published
- 1996
- Full Text
- View/download PDF
30. Crystal structure of bovine procarboxypeptidase A-S6 subunit III, a highly structured truncated zymogen E.
- Author
-
Pignol, D., primary, Gaboriaud, C., additional, Michon, T., additional, Kerfelec, B., additional, Chapus, C., additional, and Fontecilla-Camps, J.C., additional
- Published
- 1994
- Full Text
- View/download PDF
31. Dynamically adapted mesh refinement for combustion front tracking
- Author
-
Haldenwang, P. and Pignol, D.
- Published
- 2002
- Full Text
- View/download PDF
32. Critical role of micelles in pancreatic lipase activation revealed by small angle neutron scattering.
- Author
-
Pignol, D, Ayvazian, L, Kerfelec, B, Timmins, P, Crenon, I, Hermoso, J, Fontecilla-Camps, J C, and Chapus, C
- Abstract
In the duodenum, pancreatic lipase (PL) develops its activity on triglycerides by binding to the bile-emulsified oil droplets in the presence of its protein cofactor pancreatic colipase (PC). The neutron crystal structure of a PC-PL-micelle complex (Hermoso, J., Pignol, D., Penel, S., Roth, M., Chapus, C., and Fontecilla-Camps, J. C. (1997) EMBO J. 16, 5531-5536) has suggested that the stabilization of the enzyme in its active conformation and its adsorption to the emulsified oil droplets are mediated by a preformed lipase-colipase-micelle complex. Here, we correlate the ability of different amphypathic compounds to activate PL, with their association with PC-PL in solution. The method of small angle neutron scattering with D(2)O/H(2)O contrast variation was used to characterize a solution containing PC-PL complex and taurodeoxycholate micelles. The resulting radius of gyration (56 A) and the match point of the solution indicate the formation of a ternary complex that is similar to the one observed in the neutron crystal structure. In addition, we show that either bile salts, lysophospholipids, or nonionic detergents that form micelles with radii of gyration ranging from 13 to 26 A are able to bind to the PC-PL complex, whereas smaller micelles or nonmicellar compounds are not. This further supports the notion of a micelle size-dependent affinity process for lipase activation in vivo.
- Published
- 2000
33. Mechanism of calcite crystal growth inhibition by the N-terminal undecapeptide of lithostathine.
- Author
-
Gerbaud, V, Pignol, D, Loret, E, Bertrand, J A, Berland, Y, Fontecilla-Camps, J C, Canselier, J P, Gabas, N, and Verdier, J M
- Abstract
Pancreatic juice is supersaturated with calcium carbonate. Calcite crystals therefore may occur, obstruct pancreatic ducts, and finally cause a lithiasis. Human lithostathine, a protein synthesized by the pancreas, inhibits the growth of calcite crystals by inducing a habit modification: the rhombohedral (10 14) usual habit is transformed into a needle-like habit through the (11 0) crystal form. A similar observation was made with the N-terminal undecapeptide (pE(1)R(11)) of lithostathine. We therefore aimed at discovering how peptides inhibit calcium salt crystal growth. We solved the complete x-ray structure of lithostathine, including the flexible N-terminal domain, at 1.3 A. Docking studies of pE(1)R(11) with the (10 14) and (11 0) faces through molecular dynamics simulation resulted in three successive steps. First, the undecapeptide progressively unfolded as it approached the calcite surface. Second, mobile lateral chains of amino acids made hydrogen bonds with the calcite surface. Last, electrostatic bonds between calcium ions and peptide bonds stabilized and anchored pE(1)R(11) on the crystal surface. pE(1)R(11)-calcite interaction was stronger with the (11 0) face than with the (10 14) face, confirming earlier experimental observations. Energy contributions showed that the peptide backbone governed the binding more than did the lateral chains. The ability of peptides to inhibit crystal growth is therefore essentially based on backbone flexibility.
- Published
- 2000
34. Ion pairing between lipase and colipase plays a critical role in catalysis.
- Author
-
Ayvazian, L, Crenon, I, Hermoso, J, Pignol, D, Chapus, C, and Kerfelec, B
- Abstract
Among the polar interactions occurring in pancreatic lipase/colipase binding, only one ion pair involving lysine 400 on lipase and glutamic acid 45 on colipase has been described. These residues are strictly conserved among species, suggesting that the ion pair is likely to play an important role. Therefore, in order to prevent this interaction, mutations intended to neutralize or inverse the charge of these residues have been introduced in the cDNAs encoding horse lipase and colipase. The recombinant proteins have been expressed in insect cells, and their catalytic properties have been investigated. In all cases, preventing the formation of the correct ion pair Lys400/Glu45 leads to lipase-colipase complexes of reduced affinity unable to perform an efficient catalysis, notably in the presence of bile salt micelles. Diethyl p-nitrophenyl phosphate inhibition experiments with either mutant lipase or mutant colipase indicate a poor stabilization of the lipase flap. These results suggest that the ion pair plays a critical role in the active conformation of the lipase-colipase-micelle ternary complex by contributing to a correct orientation of colipase relative to lipase resulting in a proper opening of the flap.
- Published
- 1998
35. The lipase/colipase complex is activated by a micelle: neutron crystallographic evidence
- Author
-
Pignol, D., Hermoso, J., Kerfelec, B., Crenon, I., Chapus, C., Fontecilla-Camps, Carlos, and J.
- Published
- 1998
- Full Text
- View/download PDF
36. Lipase activation by nonionic detergents. The crystal structure of the porcine lipase-colipase-tetraethylene glycol monooctyl ether complex.
- Author
-
Hermoso, J, Pignol, D, Kerfelec, B, Crenon, I, Chapus, C, and Fontecilla-Camps, J C
- Abstract
The crystal structure of the ternary porcine lipase-colipase-tetra ethylene glycol monooctyl ether (TGME) complex has been determined at 2.8 A resolution. The crystals belong to the cubic space group F23 with a = 289.1 A and display a strong pseudo-symmetry corresponding to a P23 lattice. Unexpectedly, the crystalline two-domain lipase is found in its open configuration. This indicates that in the presence of colipase, pure micelles of the nonionic detergent TGME are able to activate the enzyme; a process that includes the movement of an N-terminal domain loop (the flap). The effects of TGME and colipase have been confirmed by chemical modification of the active site serine residue using diisopropyl p-nitrophenylphosphate (E600). In addition, the presence of a TGME molecule tightly bound to the active site pocket shows that TGME acts as a substrate analog, thus possibly explaining the inhibitory effect of this nonionic detergent on emulsified substrate hydrolysis at submicellar concentrations. A comparison of the lipase-colipase interactions between our porcine complex and the human-porcine complex (van Tilbeurgh, H., Egloff, M.-P., Martinez, C., Rugani, N., Verger, R., and Cambillau, C.(1993) Nature 362, 814-820) indicates that except for one salt bridge interaction, they are conserved. Analysis of the superimposed complexes shows a 5.4 degrees rotation on the relative position of the N-terminal domains excepting the flap that moves in a concerted fashion with the C-terminal domain. This flexibility may be important for the binding of the complex to the water-lipid interface.
- Published
- 1996
37. Reduction of Protein Bound Methionine Sulfoxide by a Periplasmic Dimethyl Sulfoxide Reductase.
- Author
-
Tarrago L, Grosse S, Lemaire D, Faure L, Tribout M, Siponen MI, Kojadinovic-Sirinelli M, Pignol D, Arnoux P, and Sabaty M
- Abstract
In proteins, methionine (Met) can be oxidized into Met sulfoxide (MetO). The ubiquitous methionine sulfoxide reductases (Msr) A and B are thiol-oxidoreductases reducing MetO. Reversible Met oxidation has a wide range of consequences, from protection against oxidative stress to fine-tuned regulation of protein functions. Bacteria distinguish themselves by the production of molybdenum-containing enzymes reducing MetO, such as the periplasmic MsrP which protects proteins during acute oxidative stress. The versatile dimethyl sulfoxide (DMSO) reductases were shown to reduce the free amino acid MetO, but their ability to reduce MetO within proteins was never evaluated. Here, using model oxidized proteins and peptides, enzymatic and mass spectrometry approaches, we showed that the Rhodobacter sphaeroides periplasmic DorA-type DMSO reductase reduces protein bound MetO as efficiently as the free amino acid L-MetO and with catalytic values in the range of those described for the canonical Msrs. The identification of this fourth type of enzyme able to reduce MetO in proteins, conserved across proteobacteria and actinobacteria, suggests that organisms employ enzymatic systems yet undiscovered to regulate protein oxidation states.
- Published
- 2020
- Full Text
- View/download PDF
38. A Sensitive Magnetic Arsenite-Specific Biosensor Hosted in Magnetotactic Bacteria.
- Author
-
Dieudonné A, Prévéral S, and Pignol D
- Subjects
- Arsenites metabolism, Bacterial Physiological Phenomena, Biosensing Techniques methods, Magnetic Phenomena, Taxis Response
- Abstract
According to the World Health Organization, arsenic is the water contaminant that affects the largest number of people worldwide. To limit its impact on the population, inexpensive, quick, and easy-to-use systems of detection are required. One promising solution could be the use of whole-cell biosensors, which have been extensively studied and could meet all these criteria even though they often lack sensitivity. Here, we investigated the benefit of using magnetotactic bacteria as cellular chassis to design and build sensitive magnetic bacterial biosensors. Promoters potentially inducible by arsenic were first identified in silico within the genomes of two magnetotactic bacteria strains, Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. The ArsR-dependent regulation was confirmed by reverse transcription-PCR experiments. Biosensors built by transcriptional fusion between the arsenic-inducible promoters and the bacterial luciferase luxCDABE operon gave an element-specific response in 30 min with an arsenite detection limit of 0.5 μM. After magnetic concentration, we improved the sensitivity of the biosensor by a factor of 50 to reach 10 nM, more than 1 order of magnitude below the recommended guidelines for arsenic in drinking water (0.13 μM). Finally, we demonstrated the successful preservation of the magnetic bacterium biosensors by freeze-drying. IMPORTANCE Whole-cell biosensors based on reporter genes can be designed for heavy metal detection but often require the optimization of their sensitivity and specific adaptations for practical use in the field. Magnetotactic bacteria as cellular hosts for biosensors are interesting models, as their intrinsic magnetism permits them to be easily concentrated and entrapped to increase the arsenic-response signal. This paves the way for the development of sensitive and immobilized whole-cell biosensors tailored for use in the field., (Copyright © 2020 American Society for Microbiology.)
- Published
- 2020
- Full Text
- View/download PDF
39. Repeated horizontal gene transfers triggered parallel evolution of magnetotaxis in two evolutionary divergent lineages of magnetotactic bacteria.
- Author
-
Monteil CL, Grouzdev DS, Perrière G, Alonso B, Rouy Z, Cruveiller S, Ginet N, Pignol D, and Lefevre CT
- Subjects
- Bacteria genetics, Gene Transfer, Horizontal, Gram-Negative Bacteria, Alphaproteobacteria, Magnetospirillum genetics
- Abstract
Under the same selection pressures, two genetically divergent populations may evolve in parallel toward the same adaptive solutions. Here, we hypothesized that magnetotaxis (i.e., magnetically guided chemotaxis) represents a key adaptation to micro-oxic habitats in aquatic sediments and that its parallel evolution homogenized the phenotypes of two evolutionary divergent clusters of freshwater spirilla. All magnetotactic bacteria affiliated to the Magnetospirillum genus (Alphaproteobacteria class) biomineralize the same magnetic particle chains and share highly similar physiological and ultrastructural features. We looked for the processes that could have contributed at shaping such an evolutionary pattern by reconciling species and gene trees using newly sequenced genomes of Magnetospirillum related bacteria. We showed that repeated horizontal gene transfers and homologous recombination of entire operons contributed to the parallel evolution of magnetotaxis. We propose that such processes could represent a more parsimonious and rapid solution for adaptation compared with independent and repeated de novo mutations, especially in the case of traits as complex as magnetotaxis involving tens of interacting proteins. Besides strengthening the idea about the importance of such a function in micro-oxic habitats, these results reinforce previous observations in experimental evolution suggesting that gene flow could alleviate clonal interference and speed up adaptation under some circumstances.
- Published
- 2020
- Full Text
- View/download PDF
40. Transformation Cycle of Magnetosomes in Human Stem Cells: From Degradation to Biosynthesis of Magnetic Nanoparticles Anew.
- Author
-
Curcio A, Van de Walle A, Serrano A, Preveral S, Péchoux C, Pignol D, Menguy N, Lefevre CT, Espinosa A, and Wilhelm C
- Subjects
- Cells, Cultured, Humans, Magnetosomes chemistry, Mesenchymal Stem Cells chemistry, Particle Size, Surface Properties, Magnetite Nanoparticles chemistry, Magnetosomes metabolism, Mesenchymal Stem Cells metabolism
- Abstract
The nanoparticles produced by magnetotactic bacteria, called magnetosomes, are made of a magnetite core with high levels of crystallinity surrounded by a lipid bilayer. This organized structure has been developed during the course of evolution of these organisms to adapt to their specific habitat and is assumed to resist degradation and to be able to withstand the demanding biological environment. Herein, we investigated magnetosomes' structural fate upon internalization in human stem cells using magnetic and photothermal measurements, electron microscopy, and X-ray absorption spectroscopy. All measurements first converge to the demonstration that intracellular magnetosomes can experience an important biodegradation, with up to 70% of their initial content degraded, which is associated with the progressive storage of the released iron in the ferritin protein. It correlates with an extensive magnetite to ferrihydrite phase transition. The ionic species delivered by this degradation could then be used by the cells to biosynthesize magnetic nanoparticles anew. In this case, cell magnetism first decreased with magnetosomes being dissolved, but then cells remagnetized entirely, evidencing the neo-synthesis of biogenic magnetic nanoparticles. Bacteria-made biogenic magnetosomes can thus be totally remodeled by human stem cells, into human cells-made magnetic nanoparticles.
- Published
- 2020
- Full Text
- View/download PDF
41. RGD-functionalized magnetosomes are efficient tumor radioenhancers for X-rays and protons.
- Author
-
Hafsi M, Preveral S, Hoog C, Hérault J, Perrier GA, Lefèvre CT, Michel H, Pignol D, Doyen J, Pourcher T, Humbert O, Thariat J, and Cambien B
- Subjects
- Animals, Cell Line, Tumor, Female, Humans, Mice, Mice, Inbred BALB C, Mice, Nude, Neoplasms, Experimental metabolism, Neoplasms, Experimental pathology, Proton Therapy, X-Ray Therapy, Magnetosomes chemistry, Magnetospirillum chemistry, Neoplasms, Experimental radiotherapy, Oligopeptides chemistry, Oligopeptides pharmacology, Radiation-Sensitizing Agents chemistry, Radiation-Sensitizing Agents pharmacology
- Abstract
Although chemically synthesized ferro/ferrimagnetic nanoparticles have attracted great attention in cancer theranostics, they lack radio-enhancement efficacy due to low targeting and internalization ability. Herein, we investigated the potential of RGD-tagged magnetosomes, bacterial biogenic magnetic nanoparticles naturally coated with a biological membrane and genetically engineered to express an RGD peptide, as tumor radioenhancers for conventional radiotherapy and proton therapy. Although native and RGD-magnetosomes similarly enhanced radiation-induced damage to plasmid DNA, RGD-magnetoprobes were able to boost the efficacy of radiotherapy to a much larger extent than native magnetosomes both on cancer cells and in tumors. Combined to magnetosomes@RGD, proton therapy exceeded the efficacy of X-rays at equivalent doses. Also, increased secondary emissions were measured after irradiation of magnetosomes with protons versus photons. Our results indicate the therapeutic advantage of using functionalized magnetoparticles to sensitize tumors to both X-rays and protons and strengthen the case for developing biogenic magnetoparticles for multimodal nanomedicine in cancer therapy., (Published by Elsevier Inc.)
- Published
- 2020
- Full Text
- View/download PDF
42. Crystal structure of the transcriptional repressor DdrO: insight into the metalloprotease/repressor-controlled radiation response in Deinococcus.
- Author
-
de Groot A, Siponen MI, Magerand R, Eugénie N, Martin-Arevalillo R, Doloy J, Lemaire D, Brandelet G, Parcy F, Dumas R, Roche P, Servant P, Confalonieri F, Arnoux P, Pignol D, and Blanchard L
- Subjects
- Amino Acid Sequence, Crystallography, X-Ray, DNA Damage, Gene Expression Regulation, Bacterial radiation effects, Metalloproteases chemistry, Metalloproteases genetics, Metalloproteases metabolism, Models, Molecular, Protein Structure, Secondary, Protein Structure, Tertiary, Repressor Proteins genetics, Transcription Factors genetics, Deinococcus enzymology, Deinococcus genetics, Deinococcus metabolism, Deinococcus radiation effects, Repressor Proteins chemistry, Stress, Physiological genetics, Stress, Physiological radiation effects, Transcription Factors chemistry
- Abstract
Exposure to harmful conditions such as radiation and desiccation induce oxidative stress and DNA damage. In radiation-resistant Deinococcus bacteria, the radiation/desiccation response is controlled by two proteins: the XRE family transcriptional repressor DdrO and the COG2856 metalloprotease IrrE. The latter cleaves and inactivates DdrO. Here, we report the biochemical characterization and crystal structure of DdrO, which is the first structure of a XRE protein targeted by a COG2856 protein. DdrO is composed of two domains that fold independently and are separated by a flexible linker. The N-terminal domain corresponds to the DNA-binding domain. The C-terminal domain, containing three alpha helices arranged in a novel fold, is required for DdrO dimerization. Cleavage by IrrE occurs in the loop between the last two helices of DdrO and abolishes dimerization and DNA binding. The cleavage site is hidden in the DdrO dimer structure, indicating that IrrE cleaves DdrO monomers or that the interaction with IrrE induces a structural change rendering accessible the cleavage site. Predicted COG2856/XRE regulatory protein pairs are found in many bacteria, and available data suggest two different molecular mechanisms for stress-induced gene expression: COG2856 protein-mediated cleavage or inhibition of oligomerization without cleavage of the XRE repressor., (© The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.)
- Published
- 2019
- Full Text
- View/download PDF
43. Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist.
- Author
-
Monteil CL, Vallenet D, Menguy N, Benzerara K, Barbe V, Fouteau S, Cruaud C, Floriani M, Viollier E, Adryanczyk G, Leonhardt N, Faivre D, Pignol D, López-García P, Weld RJ, and Lefevre CT
- Subjects
- Anaerobiosis, Biological Coevolution, Deltaproteobacteria classification, Deltaproteobacteria genetics, Deltaproteobacteria metabolism, Euglenozoa classification, Euglenozoa ultrastructure, Eukaryota, Ferrosoferric Oxide metabolism, Genome, Bacterial genetics, Geologic Sediments chemistry, Geologic Sediments microbiology, Hydrogen metabolism, Locomotion physiology, Magnetosomes genetics, Magnetosomes ultrastructure, Oceans and Seas, Phylogeny, RNA, Ribosomal genetics, Species Specificity, Deltaproteobacteria physiology, Euglenozoa microbiology, Euglenozoa physiology, Magnetic Fields, Symbiosis
- Abstract
Mutualistic symbioses are often a source of evolutionary innovation and drivers of biological diversification
1 . Widely distributed in the microbial world, particularly in anoxic settings2,3 , they often rely on metabolic exchanges and syntrophy2,4 . Here, we report a mutualistic symbiosis observed in marine anoxic sediments between excavate protists (Symbiontida, Euglenozoa)5 and ectosymbiotic Deltaproteobacteria biomineralizing ferrimagnetic nanoparticles. Light and electron microscopy observations as well as genomic data support a multi-layered mutualism based on collective magnetotactic motility with division of labour and interspecies hydrogen-transfer-based syntrophy6 . The guided motility of the consortia along the geomagnetic field is allowed by the magnetic moment of the non-motile ectosymbiotic bacteria combined with the protist motor activity, which is a unique example of eukaryotic magnetoreception7 acquired by symbiosis. The nearly complete deltaproteobacterial genome assembled from a single consortium contains a full magnetosome gene set8 , but shows signs of reduction, with the probable loss of flagellar genes. Based on the metabolic gene content, the ectosymbiotic bacteria are anaerobic sulfate-reducing chemolithoautotrophs that likely reduce sulfate with hydrogen produced by hydrogenosome-like organelles6 underlying the plasma membrane of the protist. In addition to being necessary hydrogen sinks, ectosymbionts may provide organics to the protist by diffusion and predation, as shown by magnetosome-containing digestive vacuoles. Phylogenetic analyses of 16S and 18S ribosomal RNA genes from magnetotactic consortia in marine sediments across the Northern and Southern hemispheres indicate a host-ectosymbiont specificity and co-evolution. This suggests a historical acquisition of magnetoreception by a euglenozoan ancestor from Deltaproteobacteria followed by subsequent diversification. It also supports the cosmopolitan nature of this type of symbiosis in marine anoxic sediments.- Published
- 2019
- Full Text
- View/download PDF
44. Magnetosomes: biogenic iron nanoparticles produced by environmental bacteria.
- Author
-
Dieudonné A, Pignol D, and Prévéral S
- Subjects
- Bacteria chemistry, Bacteria genetics, Bacteria isolation & purification, Environmental Microbiology, Magnetosomes chemistry, Magnetosomes genetics, Nanoparticles chemistry, Bacteria metabolism, Iron metabolism, Magnetosomes metabolism, Nanoparticles metabolism
- Abstract
The scientific community's interest in magnetotactic bacteria has increased substantially in recent decades. These prokaryotes have the particularity of synthesizing nanomagnets, called magnetosomes. The majority of research is based on several scientific questions. Where do magnetotactic bacteria live, what are their characteristics, and why are they magnetic? What are the molecular phenomena of magnetosome biomineralization and what are the physical characteristics of magnetosomes? In addition to scientific curiosity to better understand these stunning organisms, there are biotechnological opportunities to consider. Magnetotactic bacteria, as well as magnetosomes, are used in medical applications, for example cancer treatment, or in environmental ones, for example bioremediation. In this mini-review, we investigated all the aspects mentioned above and summarized the currently available knowledge.
- Published
- 2019
- Full Text
- View/download PDF
45. Tuning the redox properties of a [4Fe-4S] center to modulate the activity of Mo-bisPGD periplasmic nitrate reductase.
- Author
-
Zeamari K, Gerbaud G, Grosse S, Fourmond V, Chaspoul F, Biaso F, Arnoux P, Sabaty M, Pignol D, Guigliarelli B, and Burlat B
- Subjects
- Amino Acid Substitution, Catalytic Domain, Electron Transport, Iron-Sulfur Proteins genetics, Iron-Sulfur Proteins metabolism, Mutation, Missense, Nitrate Reductase genetics, Nitrate Reductase metabolism, Oxidation-Reduction, Periplasmic Proteins genetics, Periplasmic Proteins metabolism, Rhodobacter sphaeroides genetics, Iron-Sulfur Proteins chemistry, Nitrate Reductase chemistry, Periplasmic Proteins chemistry, Rhodobacter sphaeroides enzymology
- Abstract
Molybdoenzymes are ubiquitous in living organisms and catalyze, for most of them, oxidation-reduction reactions using a large range of substrates. Periplasmic nitrate reductase (NapAB) from Rhodobacter sphaeroides catalyzes the 2-electron reduction of nitrate into nitrite. Its active site is a Mo bis-(pyranopterin guanine dinucleotide), or Mo-bisPGD, found in most prokaryotic molybdoenzymes. A [4Fe-4S] cluster and two c-type hemes form an intramolecular electron transfer chain that deliver electrons to the active site. Lysine 56 is a highly conserved amino acid which connects, through hydrogen-bonds, the [4Fe-4S] center to one of the pyranopterin ligands of the Mo-cofactor. This residue was proposed to be involved in the intramolecular electron transfer, either defining an electron transfer pathway between the two redox cofactors, and/or modulating their redox properties. In this work, we investigated the role of this lysine by combining site-directed mutagenesis, activity assays, redox titrations, EPR and HYSCORE spectroscopies. Removal of a positively-charged residue at position 56 strongly decreased the redox potential of the [4Fe-4S] cluster at pH 8 by 230 mV to 400 mV in the K56H and K56M mutants, respectively, thus affecting the kinetics of electron transfer from the hemes to the [4Fe-4S] center up to 5 orders of magnitude. This effect was partly reversed at acidic pH in the K56H mutant likely due to protonation of the imidazole ring of the histidine. Overall, our study demonstrates the critical role of a charged residue from the second coordination sphere in tuning the reduction potential of the [4Fe-4S] cluster in RsNapAB and related molybdoenzymes., (Copyright © 2019. Published by Elsevier B.V.)
- Published
- 2019
- Full Text
- View/download PDF
46. Control by Metals of Staphylopine Dehydrogenase Activity during Metallophore Biosynthesis.
- Author
-
Hajjar C, Fanelli R, Laffont C, Brutesco C, Cullia G, Tribout M, Nurizzo D, Borezée-Durant E, Voulhoux R, Pignol D, Lavergne J, Cavelier F, and Arnoux P
- Subjects
- Metals, Heavy chemistry, Models, Molecular, Molecular Conformation, Staphylococcus aureus enzymology, Imidazoles metabolism, Metals, Heavy metabolism, Oxidoreductases metabolism
- Abstract
Enzymatic regulations are central processes for the adaptation to changing environments. In the particular case of metallophore-dependent metal uptake, there is a need to quickly adjust the production of these metallophores to the metal level outside the cell, to avoid metal shortage or overload, as well as waste of metallophores. In Staphylococcus aureus, CntM catalyzes the last biosynthetic step in the production of staphylopine, a broad-spectrum metallophore, through the reductive condensation of a pathway intermediate (xNA) with pyruvate. Here, we describe the chemical synthesis of this intermediate, which was instrumental in the structural and functional characterization of CntM and confirmed its opine synthase properties. The three-dimensional structure of CntM was obtained in an "open" form, in the apo state or as a complex with substrate or product. The xNA substrate appears mainly stabilized by its imidazole ring through a π-π interaction with the side chain of Tyr240. Intriguingly, we found that metals exerted various and sometime antagonistic effects on the reaction catalyzed by CntM: zinc and copper are moderate activators at low concentration and then total inhibitors at higher concentration, whereas manganese is only an activator and cobalt and nickel are only inhibitors. We propose a model in which the relative affinity of a metal toward xNA and an inhibitory binding site on the enzyme controls activation, inhibition, or both as a function of metal concentration. This metal-dependent regulation of a metallophore-producing enzyme might also take place in vivo, which could contribute to the adjustment of metallophore production to the internal metal level.
- Published
- 2019
- Full Text
- View/download PDF
47. Rhodobacter sphaeroides methionine sulfoxide reductase P reduces R - and S -diastereomers of methionine sulfoxide from a broad-spectrum of protein substrates.
- Author
-
Tarrago L, Grosse S, Siponen MI, Lemaire D, Alonso B, Miotello G, Armengaud J, Arnoux P, Pignol D, and Sabaty M
- Subjects
- Amino Acid Sequence, Bacterial Proteins genetics, Isoenzymes genetics, Isoenzymes metabolism, Methionine chemistry, Methionine metabolism, Methionine Sulfoxide Reductases genetics, Mutation, Oxidation-Reduction, Periplasmic Proteins genetics, Periplasmic Proteins metabolism, Rhodobacter sphaeroides genetics, Rhodobacter sphaeroides metabolism, Stereoisomerism, Substrate Specificity, Bacterial Proteins metabolism, Methionine analogs & derivatives, Methionine Sulfoxide Reductases metabolism, Rhodobacter sphaeroides enzymology
- Abstract
Methionine (Met) is prone to oxidation and can be converted to Met sulfoxide (MetO), which exists as R - and S -diastereomers. MetO can be reduced back to Met by the ubiquitous methionine sulfoxide reductase (Msr) enzymes. Canonical MsrA and MsrB were shown to be absolutely stereospecific for the reduction of S -diastereomer and R- diastereomer, respectively. Recently, a new enzymatic system, MsrQ/MsrP which is conserved in all gram-negative bacteria, was identified as a key actor for the reduction of oxidized periplasmic proteins. The haem-binding membrane protein MsrQ transmits reducing power from the electron transport chains to the molybdoenzyme MsrP, which acts as a protein-MetO reductase. The MsrQ/MsrP function was well established genetically, but the identity and biochemical properties of MsrP substrates remain unknown. In this work, using the purified MsrP enzyme from the photosynthetic bacteria Rhodobacter sphaeroides as a model, we show that it can reduce a broad spectrum of protein substrates. The most efficiently reduced MetO is found in clusters, in amino acid sequences devoid of threonine and proline on the C-terminal side. Moreover, R. sphaeroides MsrP lacks stereospecificity as it can reduce both R - and S -diastereomers of MetO, similarly to its Escherichia coli homolog, and preferentially acts on unfolded oxidized proteins. Overall, these results provide important insights into the function of a bacterial envelop protecting system, which should help understand how bacteria cope in harmful environments., (© 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)
- Published
- 2018
- Full Text
- View/download PDF
48. Genomic study of a novel magnetotactic Alphaproteobacteria uncovers the multiple ancestry of magnetotaxis.
- Author
-
Monteil CL, Perrière G, Menguy N, Ginet N, Alonso B, Waisbord N, Cruveiller S, Pignol D, and Lefèvre CT
- Subjects
- France, Gene Transfer, Horizontal, Genome, Bacterial, Magnetics, Mediterranean Sea, Water Microbiology, Alphaproteobacteria genetics, Evolution, Molecular, Magnetosomes genetics
- Abstract
Ecological and evolutionary processes involved in magnetotactic bacteria (MTB) adaptation to their environment have been a matter of debate for many years. Ongoing efforts for their characterization are progressively contributing to understand these processes, including the genetic and molecular mechanisms responsible for biomineralization. Despite numerous culture-independent MTB characterizations, essentially within the Proteobacteria phylum, only few species have been isolated in culture because of their complex growth conditions. Here, we report a newly cultivated magnetotactic, microaerophilic and chemoorganoheterotrophic bacterium isolated from the Mediterranean Sea in Marseille, France: Candidatus Terasakiella magnetica strain PR-1 that belongs to an Alphaproteobacteria genus with no magnetotactic relative. By comparing the morphology and the whole genome shotgun sequence of this MTB with those of closer relatives, we brought further evidence that the apparent vertical ancestry of magnetosome genes suggested by previous studies within Alphaproteobacteria hides a more complex evolutionary history involving horizontal gene transfers and/or duplication events before and after the emergence of Magnetospirillum, Magnetovibrio and Magnetospira genera. A genome-scale comparative genomics analysis identified several additional candidate functions and genes that could be specifically associated to MTB lifestyle in this class of bacteria., (© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.)
- Published
- 2018
- Full Text
- View/download PDF
49. Targeted thermal therapy with genetically engineered magnetite magnetosomes@RGD: Photothermia is far more efficient than magnetic hyperthermia.
- Author
-
Plan Sangnier A, Preveral S, Curcio A, K A Silva A, Lefèvre CT, Pignol D, Lalatonne Y, and Wilhelm C
- Subjects
- Animals, Antineoplastic Agents administration & dosage, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Female, HeLa Cells, Hot Temperature, Humans, Male, Mice, Mice, Nude, Oligopeptides chemistry, Oligopeptides pharmacology, PC-3 Cells, Prostatic Neoplasms drug therapy, Uterine Cervical Neoplasms drug therapy, Genetic Engineering methods, Magnetite Nanoparticles, Magnetosomes, Oligopeptides administration & dosage
- Abstract
Providing appropriate means for heat generation by low intratumoral nanoparticle concentrations is a major challenge for cancer nanotherapy. Here we propose RGD-tagged magnetosomes (magnetosomes@RGD) as a biogenic, genetically engineered, inorganic platform for multivalent thermal cancer treatment. Magnetosomes@RGD are biomagnetite nanoparticles synthesized by genetically modified magnetotactic bacteria thanks to a translational fusion of the RGD peptide with the magnetosomal protein MamC. Magnetosomes@RGD thus combine the high crystallinity of their magnetite core with efficient surface functionalization. The specific affinity of RGD was first quantified by single-cell magnetophoresis with a variety of cell types, including immune, muscle, endothelial, stem and cancer cells. The highest affinity and cellular uptake was observed with PC3 prostatic and HeLa uterine cancer cells. The efficiency of photothermia and magnetic hyperthermia was then compared on PC3 cells. Unexpectedly, photothermia was far more efficient than magnetic hyperthermia, which was almost totally inhibited by the cellular environment. RGD targeting was then assessed in vivo at tumor site, in mice bearing PC3 tumors. As a result, we demonstrate that targeted magnetic nanoparticles could generate heat on a therapeutic level after systemic administration, but only under laser excitation, and successfully inhibit tumor progression., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
50. Accumulation and Dissolution of Magnetite Crystals in a Magnetically Responsive Ciliate.
- Author
-
Monteil CL, Menguy N, Prévéral S, Warren A, Pignol D, and Lefèvre CT
- Subjects
- France, Oligohymenophorea physiology, Solubility, Bacteria chemistry, Ferrosoferric Oxide chemistry, Food Chain, Magnetosomes metabolism, Oligohymenophorea chemistry
- Abstract
Magnetotactic bacteria (MTB) represent a group of microorganisms that are widespread in aquatic habitats and thrive at oxic-anoxic interfaces. They are able to scavenge high concentrations of iron thanks to the biomineralization of magnetic crystals in their unique organelles, the so-called magnetosome chains. Although their biodiversity has been intensively studied, their ecology and impact on iron cycling remain largely unexplored. Predation by protozoa was suggested as one of the ecological processes that could be involved in the release of iron back into the ecosystem. Magnetic protozoa were previously observed in aquatic environments, but their diversity and the fate of particulate iron during grazing are poorly documented. In this study, we report the morphological and molecular characterizations of a magnetically responsive MTB-grazing protozoan able to ingest high quantities of MTB. This protozoan is tentatively identified as Uronema marinum , a ciliate known to be a predator of bacteria. Using light and electron microscopy, we investigated in detail the vacuoles in which the lysis of phagocytized prokaryotes occurs. We carried out high-resolution observations of aligned magnetosome chains and ongoing dissolution of crystals. Particulate iron in the ciliate represented approximately 0.01% of its total volume. We show the ubiquity of this interaction in other types of environments and describe different grazing strategies. These data contribute to the mounting evidence that the interactions between MTB and protozoa might play a significant role in iron turnover in microaerophilic habitats. IMPORTANCE Identifying participants of each biogeochemical cycle is a prerequisite to our understanding of ecosystem functioning. Magnetotactic bacteria (MTB) participate in iron cycling by concentrating large amounts of biomineralized iron minerals in their cells, which impacts their chemical environment at, or below, the oxic-anoxic transition zone in aquatic habitats. It was shown that some protozoa inhabiting this niche could become magnetic by the ingestion of magnetic crystals biomineralized by grazed MTB. In this study, we show that magnetic MTB grazers are commonly observed in marine and freshwater sediments and can sometimes accumulate very large amounts of particulate iron. We describe here different phagocytosis strategies, determined using magnetic particles from MTB as tracers after their ingestion by the protozoa. This study paves the way for potential scientific or medical applications using MTB grazers as magnetosome hyperaccumulators., (Copyright © 2018 American Society for Microbiology.)
- Published
- 2018
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.