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First published online October 27, 2006; 10.1104/pp.106.089458 Plant Physiology 142:1364-1379 (2006) © 2006 American Society of Plant Biologists Plant Glutathione Peroxidases Are Functional Peroxiredoxins Distributed in Several Subcellular Compartments and Regulated during Biotic and Abiotic Stresses1,[W]Unité Mixte de Recherche Institut National de la Recherche Agronomique-Université Henri Poincaré 1136, Interactions Arbres/Micro-organismes, Institut de Formation et de Recherche 110 Génomique, Ecophysiologie et Ecologie Fonctionnelles, Université Henri Poincaré, Faculté des Sciences, 54506 Vandoeuvre cedex, France (N.N., E.G., J.-P.J., N.R.); Commissariat à l'Energie Atomique/Cadarache, Direction des Sciences du Vivant, Département d'Ecophysiologie Végétale et de Microbiologie, Laboratoire d'Ecophysiologie Moléculaire des Plantes, 13108 Saint-Paul-lez-Durance cedex, France (V.C., P.R.); Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, 67084 Strasbourg cedex, France (J.G.); Department of Chemistryand Biochemistry, and Center for Biotechnology and Genomics, Texas Tech University, Lubbock, Texas 794091061 (M.H., D.B.K.); and Institut de Biotechnologie des Plantes, Unité Mixte de Recherche 8618, Université de Paris Sud, 91405 Orsay cedex, France (E.I.)
We provide here an exhaustive overview of the glutathione (GSH) peroxidase (Gpx) family of poplar (Populus trichocarpa). Although these proteins were initially defined as GSH dependent, in fact they use only reduced thioredoxin (Trx) for their regeneration and do not react with GSH or glutaredoxin, constituting a fifth class of peroxiredoxins. The two chloroplastic Gpxs display a marked selectivity toward their electron donors, being exclusively specific for Trxs of the y type for their reduction. In contrast, poplar Gpxs are much less specific with regard to their electron-accepting substrates, reducing hydrogen peroxide and more complex hydroperoxides equally well. Site-directed mutagenesis indicates that the catalytic mechanism and the Trx-mediated recycling process involve only two (cysteine [Cys]-107 and Cys-155) of the three conserved Cys, which form a disulfide bridge with an oxidation-redox midpoint potential of 295 mV. The reduction/formation of this disulfide is detected both by a shift on sodium dodecyl sulfate-polyacrylamide gel electrophoresis or by measuring the intrinsic tryptophan fluorescence of the protein. The six genes identified coding for Gpxs are expressed in various poplar organs, and two of them are localized in the chloroplast, with one colocalizing in mitochondria, suggesting a broad distribution of Gpxs in plant cells. The abundance of some Gpxs is modified in plants subjected to environmental constraints, generally increasing during fungal infection, water deficit, and metal stress, and decreasing during photooxidative stress, showing that Gpx proteins are involved in the response to both biotic and abiotic stress conditions.
1 This work supported by the Robert A. Welch Foundation (work carried out at Texas Tech University; grant no. D0710 to D.B.K.), by Commissariat à l'Energie Atomique (program Toxicologie Nucléaire Environnementale), by MENRT (grant to N.N.), and by BQR Région Lorraine (to N.R., J.P.J., and E.G.). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Nicolas Rouhier (nrouhier{at}scbiol.uhp-nancy.fr). [W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.106.089458 * Corresponding author; e-mail nrouhier{at}scbiol.uhp-nancy.fr. Received September 4, 2006; accepted October 11, 2006; published October 27, 2006. This article has been cited by other articles:
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