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Les glutathion peroxydases et protéine disulfure isomérases de peuplier : potentialités du repliement thiorédoxine pour la catalyse des réactions redox

Abstract : Protein activity and folding can be regulated by post-translational modifications that can impact on their physiological functions. One of these is the formation/reduction of disulfide bridges. The aim of the present work is to study the structure-function relationship of protein members of the thioredoxin superfamily, the protein disulfide isomerases (PDI) and the glutathione peroxidases (Gpx). A precise biochemical study has allowed us to demonstrate that this enzyme is an efficient peroxynitrite scavenger, a new finding for this type of protein and allowed investigating several steps of the Gpx5 catalytic mechanism (i.e. sulfenic acid formation, structural changes between reduce dand oxidized forms, Trx-mediated recycling). We also demonstrate that the dimer form of Gpx5 is not absolutely required for peroxide reduction but probably involved in peroxide specificity. Finally, the capability of the peroxidatic cysteine to be overoxidized brings some new clues in favor of an additional signaling function for Gpx5. Concerning PDIs, a detailed phylogenetic analysis of photosynthetic organisms allowed us to identify 9 classes of PDIs and to propose a new nomenclature that fits all these organisms. The biochemical characterization of isoforms of interest has allowed us to highlight some specificity of PDI-L1a and PDI-M in terms of reduction or oxidation reactions catalyzed. A detailed analysis of PDI-M isoform also indicates that the two Trx modules of this protein show differential oxidation or reduction capacities. We could not detect any activity for PDI-A isoforms, leaving us to wonder whether this enzyme is simply active or possesses highly specific protein partners.
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https://hal.univ-lorraine.fr/tel-01746183
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Submitted on : Thursday, March 29, 2018 - 10:26:20 AM
Last modification on : Wednesday, September 8, 2021 - 4:02:07 PM
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Benjamin Selles. Les glutathion peroxydases et protéine disulfure isomérases de peuplier : potentialités du repliement thiorédoxine pour la catalyse des réactions redox. Biologie végétale. Université Henri Poincaré - Nancy 1, 2011. Français. ⟨NNT : 2011NAN10028⟩. ⟨tel-01746183⟩

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