8 results on '"Auguin, Daniel"'
Search Results
2. Deciphering Molecular Mechanisms Involved in the Modulation of Human Aquaporins' Water Permeability by Zinc Cations: A Molecular Dynamics Approach.
- Author
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Mom, Robin, Réty, Stéphane, Mocquet, Vincent, and Auguin, Daniel
- Subjects
MOLECULAR dynamics ,ZINC ,ZINC proteins ,AQUAPORINS ,PERMEABILITY ,IN vitro studies - Abstract
Aquaporins (AQPs) constitute a wide family of water channels implicated in all kind of physiological processes. Zinc is the second most abundant trace element in the human body and a few studies have highlighted regulation of AQP0 and AQP4 by zinc. In the present work, we addressed the putative regulation of AQPs by zinc cations in silico through molecular dynamics simulations of human AQP0, AQP2, AQP4, and AQP5. Our results align with other scales of study and several in vitro techniques, hence strengthening the reliability of this regulation by zinc. We also described two distinct putative molecular mechanisms associated with the increase or decrease in AQPs' water permeability after zinc binding. In association with other studies, our work will help deciphering the interaction networks existing between zinc and channel proteins. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Plant Aquaporin Gating Is Reversed by Phosphorylation on Intracellular Loop D—Evidence from Molecular Dynamics Simulations.
- Author
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Mom, Robin, Réty, Stéphane, Mocquet, Vincent, and Auguin, Daniel
- Subjects
MOLECULAR dynamics ,AQUAPORINS ,GATES ,BIOLOGICAL membranes ,PHOSPHORYLATION ,MEMBRANE proteins ,CELL membranes - Abstract
Aquaporins (AQPs) constitute a wide and ancient protein family of transmembrane channels dedicated to the regulation of water exchange across biological membranes. In plants, higher numbers of AQP homologues have been conserved compared to other kingdoms of life such as in animals or in bacteria. As an illustration of this plant-specific functional diversity, plasma membrane intrinsic proteins (PIPs, i.e., a subfamily of plant AQPs) possess a long intracellular loop D, which can gate the channel by changing conformation as a function of the cellular environment. However, even though the closure of the AQP by loop D conformational changes is well described, the opening of the channel, on the other hand, is still misunderstood. Several studies have pointed to phosphorylation events as the trigger for the transition from closed- to open-channel states. Nonetheless, no clear answer has been obtained yet. Hence, in order to gain a more complete grasp of plant AQP regulation through this intracellular loop D gating, we investigated the opening of the channel in silico through molecular dynamics simulations of the crystallographic structure of Spinacia oleracea PIP2;1 (SoPIP2;1). Through this technique, we addressed the mechanistic details of these conformational changes, which eventually allowed us to propose a molecular mechanism for PIP functional regulation by loop D phosphorylation. More precisely, our results highlight the phosphorylation of loop D serine 188 as a trigger of SoPIP2;1 water channel opening. Finally, we discuss the significance of this result for the study of plant AQP functional diversity. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Cortisol Interaction with Aquaporin-2 Modulates Its Water Permeability: Perspectives for Non-Genomic Effects of Corticosteroids.
- Author
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Mom, Robin, Réty, Stéphane, and Auguin, Daniel
- Subjects
PERMEABILITY ,AQUAPORINS ,MOLECULAR dynamics ,HYDROCORTISONE ,GLUCOCORTICOID receptors - Abstract
Aquaporins (AQPs) are water channels widely distributed in living organisms and involved in many pathophysiologies as well as in cell volume regulations (CVR). In the present study, based on the structural homology existing between mineralocorticoid receptors (MRs), glucocorticoid receptors (GRs), cholesterol consensus motif (CCM) and the extra-cellular vestibules of AQPs, we investigated the binding of corticosteroids on the AQP family through in silico molecular dynamics simulations of AQP2 interactions with cortisol. We propose, for the first time, a putative AQPs corticosteroid binding site (ACBS) and discussed its conservation through structural alignment. Corticosteroids can mediate non-genomic effects; nonetheless, the transduction pathways involved are still misunderstood. Moreover, a growing body of evidence is pointing toward the existence of a novel membrane receptor mediating part of these rapid corticosteroids' effects. Our results suggest that the naturally produced glucocorticoid cortisol inhibits channel water permeability. Based on these results, we propose a detailed description of a putative underlying molecular mechanism. In this process, we also bring new insights on the regulatory function of AQPs extra-cellular loops and on the role of ions in tuning the water permeability. Altogether, this work brings new insights into the non-genomic effects of corticosteroids through the proposition of AQPs as the membrane receptor of this family of regulatory molecules. This original result is the starting point for future investigations to define more in-depth and in vivo the validity of this functional model. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Fungal X-Intrinsic Protein Aquaporin from Trichoderma atroviride: Structural and Functional Considerations
- Author
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Ben Amira, Maroua, Faize, Mohamed, Karlsson, Magnus, Dubey, Mukesh, Frac, Magdalena, Panek, Jacek, Fumanal, Boris, Gousset-Dupont, Aurelie, Julien, Jean-Louis, Chaar, Hatem, Auguin, Daniel, Mom, Robin, Label, Philippe, Venisse, Jean-Stephane, Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Faculté des Sciences de Bizerte [Université de Carthage], Université de Carthage - University of Carthage, Université Chouaib Doukkali (UCD), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Swedish University of Agricultural Sciences (SLU), Polish Academy of Sciences (PAN), Institut National de la Recherche Agronomique de Tunisie (INRAT), Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), Université d'Orléans (UO)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), and Technical University of Denmark [Lyngby] (DTU)
- Subjects
Protein Conformation ,[SDV]Life Sciences [q-bio] ,lcsh:QR1-502 ,Hyphae ,pentose phosphate pathway ,Aquaporins ,Models, Biological ,lcsh:Microbiology ,Article ,stress responses ,3D modeling ,Fungal Proteins ,Gene Expression Regulation, Fungal ,Computer Simulation ,Biomass ,Phylogeny ,Oligonucleotide Array Sequence Analysis ,uncharacterized X-Intrinsic proteins ,chlamydospores ,Biochemistry and Molecular Biology ,Water ,Carbon ,aquaporin ,Kinetics ,Phenotype ,Trichoderma atroviride ,Hypocreales ,Mutation ,Gene Deletion - Abstract
International audience; The major intrinsic protein (MIP) superfamily is a key part of the fungal transmembrane transport network. It facilitates the transport of water and low molecular weight solutes across biomembranes. The fungal uncharacterized X-Intrinsic Protein (XIP) subfamily includes the full protein diversity of MIP. Their biological functions still remain fully hypothetical. The aim of this study is still to deepen the diversity and the structure of the XIP subfamily in light of the MIP counterparts—the aquaporins (AQPs) and aquaglyceroporins (AQGPs)—and to describe for the first time their function in the development, biomass accumulation, and mycoparasitic aptitudes of the fungal bioagent Trichoderma atroviride. The fungus-XIP clade, with one member (TriatXIP), is one of the three clades of MIPs that make up the diversity of T. atroviride MIPs, along with the AQPs (three members) and the AQGPs (three members). TriatXIP resembles those of strict aquaporins, predicting water diffusion and possibly other small polar solutes due to particularly wider ar/R constriction with a Lysine substitution at the LE2 position. The XIP loss of function in ΔTriatXIP mutants slightly delays biomass accumulation but does not impact mycoparasitic activities. ΔTriatMIP forms colonies similar to wild type; however, the hyphae are slightly thinner and colonies produce rare chlamydospores in PDA and specific media, most of which are relatively small and exhibit abnormal morphologies. To better understand the molecular causes of these deviant phenotypes, a wide-metabolic survey of the ΔTriatXIPs demonstrates that the delayed growth kinetic, correlated to a decrease in respiration rate, is caused by perturbations in the pentose phosphate pathway. Furthermore, the null expression of the XIP gene strongly impacts the expression of four expressed MIPencoding genes of T. atroviride, a plausible compensating effect which safeguards the physiological integrity and life cycle of the fungus. This paper offers an overview of the fungal XIP family in the biocontrol agent T. atroviride which will be useful for further functional analysis of this particular MIP subfamily in vegetative growth and the environmental stress response in fungi. Ultimately, these findings have implications for the ecophysiology of Trichoderma spp. in natural, agronomic, and industrial systems.
- Published
- 2021
6. A Perspective for Ménière's Disease: In Silico Investigations of Dexamethasone as a Direct Modulator of AQP2.
- Author
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Mom, Robin, Robert-Paganin, Julien, Mom, Thierry, Chabbert, Christian, Réty, Stéphane, and Auguin, Daniel
- Subjects
MENIERE'S disease ,DEXAMETHASONE ,AQUAPORINS ,SENSORINEURAL hearing loss ,MOLECULAR dynamics ,POTASSIUM ions - Abstract
Ménière's disease is a chronic illness characterized by intermittent episodes of vertigo associated with fluctuating sensorineural hearing loss, tinnitus and aural pressure. This pathology strongly correlates with a dilatation of the fluid compartment of the endolymph, so-called hydrops. Dexamethasone is one of the therapeutic approaches recommended when conventional antivertigo treatments have failed. Several mechanisms of actions have been hypothesized for the mode of action of dexamethasone, such as the anti-inflammatory effect or as a regulator of inner ear water homeostasis. However, none of them have been experimentally confirmed so far. Aquaporins (AQPs) are transmembrane water channels and are hence central in the regulation of transcellular water fluxes. In the present study, we investigated the hypothesis that dexamethasone could impact water fluxes in the inner ear by targeting AQP2. We addressed this question through molecular dynamics simulations approaches and managed to demonstrate a direct interaction between AQP2 and dexamethasone and its significant impact on the channel water permeability. Through compartmentalization of sodium and potassium ions, a significant effect of Na+ upon AQP2 water permeability was highlighted as well. The molecular mechanisms involved in dexamethasone binding and in its regulatory action upon AQP2 function are described. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
7. Functional Divergence of Poplar Histidine-Aspartate Kinase HK1 Paralogs in Response to Osmotic Stress.
- Author
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Héricourt, François, Chefdor, Françoise, Djeghdir, Inès, Larcher, Mélanie, Lafontaine, Florent, Courdavault, Vincent, Auguin, Daniel, Coste, Franck, Depierreux, Christiane, Tanigawa, Mirai, Maeda, Tatsuya, Glévarec, Gaëlle, and Carpin, Sabine
- Subjects
HISTIDINE ,PHOSPHORYLATION ,ASPARTATES ,AMINO acids ,PHOSPHOTRANSFERASES - Abstract
Previous works have shown the existence of protein partnerships belonging to a MultiStep Phosphorelay (MSP) in Populus putatively involved in osmosensing. This study is focused on the identification of a histidine-aspartate kinase, HK1b, paralog of HK1a. The characterization of HK1b showed its ability to homo- and hetero-dimerize and to interact with a few Histidine-containing Phosphotransfer (HPt) proteins, suggesting a preferential partnership in poplar MSP linked to drought perception. Furthermore, determinants for interaction specificity between HK1a/1b and HPts were studied by mutagenesis analysis, identifying amino acids involved in this specificity. The HK1b expression analysis in different poplar organs revealed its co-expression with three HPts, reinforcing the hypothesis of partnership participation in the MSP in planta. Moreover, HK1b was shown to act as an osmosensor with kinase activity in a functional complementation assay of an osmosensor deficient yeast strain. These results revealed that HK1b showed a different behaviour for canonical phosphorylation of histidine and aspartate residues. These phosphorylation modularities of canonical amino acids could explain the improved osmosensor performances observed in yeast. As conserved duplicates reflect the selective pressures imposed by the environmental requirements on the species, our results emphasize the importance of HK1 gene duplication in poplar adaptation to drought stress. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
8. Fungal X -Intrinsic Protein Aquaporin from Trichoderma atroviride : Structural and Functional Considerations.
- Author
-
Amira, Maroua Ben, Faize, Mohamed, Karlsson, Magnus, Dubey, Mukesh, Frąc, Magdalena, Panek, Jacek, Fumanal, Boris, Gousset-Dupont, Aurélie, Julien, Jean-Louis, Chaar, Hatem, Auguin, Daniel, Mom, Robin, Label, Philippe, and Venisse, Jean-Stéphane
- Subjects
PENTOSE phosphate pathway ,TRICHODERMA ,MOLECULAR weights ,PROTEINS ,BIOLOGICAL pest control agents - Abstract
The major intrinsic protein (MIP) superfamily is a key part of the fungal transmembrane transport network. It facilitates the transport of water and low molecular weight solutes across biomembranes. The fungal uncharacterized X-Intrinsic Protein (XIP) subfamily includes the full protein diversity of MIP. Their biological functions still remain fully hypothetical. The aim of this study is still to deepen the diversity and the structure of the XIP subfamily in light of the MIP counterparts—the aquaporins (AQPs) and aquaglyceroporins (AQGPs)—and to describe for the first time their function in the development, biomass accumulation, and mycoparasitic aptitudes of the fungal bioagent Trichoderma atroviride. The fungus-XIP clade, with one member (TriatXIP), is one of the three clades of MIPs that make up the diversity of T. atroviride MIPs, along with the AQPs (three members) and the AQGPs (three members). TriatXIP resembles those of strict aquaporins, predicting water diffusion and possibly other small polar solutes due to particularly wider ar/R constriction with a Lysine substitution at the LE2 position. The XIP loss of function in ∆TriatXIP mutants slightly delays biomass accumulation but does not impact mycoparasitic activities. ∆TriatMIP forms colonies similar to wild type; however, the hyphae are slightly thinner and colonies produce rare chlamydospores in PDA and specific media, most of which are relatively small and exhibit abnormal morphologies. To better understand the molecular causes of these deviant phenotypes, a wide-metabolic survey of the ∆TriatXIPs demonstrates that the delayed growth kinetic, correlated to a decrease in respiration rate, is caused by perturbations in the pentose phosphate pathway. Furthermore, the null expression of the XIP gene strongly impacts the expression of four expressed MIP-encoding genes of T. atroviride, a plausible compensating effect which safeguards the physiological integrity and life cycle of the fungus. This paper offers an overview of the fungal XIP family in the biocontrol agent T. atroviride which will be useful for further functional analysis of this particular MIP subfamily in vegetative growth and the environmental stress response in fungi. Ultimately, these findings have implications for the ecophysiology of Trichoderma spp. in natural, agronomic, and industrial systems. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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