title: NTR/NRX define a new thioredoxin system in the nucleus of Arabidopsis thaliana cells.
abstract: Thioredoxins (TRX) are key components of cellular redox balance, regulating many target proteins through thiol/disulfide exchange reactions. In higher plants, TRX constitute a complex multigenic family whose members have been found in almost all cellular compartments. Although chloroplastic and cytosolic TRX systems have been largely studied, the presence of a nuclear TRX system has been elusive for a long time. Nucleoredoxins (NRX) are potential nuclear TRX found in most eukaryotic organisms. In contrast to mammals, which harbor a unique NRX, angiosperms generally possess multiple NRX organized in three subfamilies. Here, we show that Arabidopsis thaliana has two NRX genes (AtNRX1 and AtNRX2), respectively, belonging to subgroups I and III. While NRX1 harbors typical TRX active sites (WCG/PPC), NRX2 has atypical active sites (WCRPC and WCPPF). Nevertheless, both NRX1 and NRX2 have disulfide reduction capacities, although NRX1 alone can be reduced by the thioredoxin reductase NTRA. We also show that both NRX1 and NRX2 have a dual nuclear/cytosolic localization. Interestingly, we found that NTRA, previously identified as a cytosolic protein, is also partially localized in the nucleus, suggesting that a complete TRX system is functional in the nucleus. We show that NRX1 is mainly found as a dimer in vivo. nrx1 and nrx2 knockout mutant plants exhibit no phenotypic perturbations under standard growth conditions. However, the nrx1 mutant shows a reduced pollen fertility phenotype, suggesting a specific role of NRX1 at the haploid phase.
authors.affiliation: Université Perpignan Via Domitia, CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 58 Avenue Paul Alduy-Bat T, F-66860, Perpignan, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Marchal
authors.forename: Valérie
authors.initials: V
authors.lastname: Delorme-Hinoux
authors.forename: Laetitia
authors.initials: L
authors.lastname: Bariat
authors.forename: Wafi
authors.initials: W
authors.lastname: Siala
authors.forename: Christophe
authors.initials: C
authors.lastname: Belin
authors.forename: Julio
authors.initials: J
authors.lastname: Saez-Vasquez
authors.forename: Christophe
authors.initials: C
authors.lastname: Riondet
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Reichheld
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054464:Peroxiredoxins / Q000235:genetics; D010802:Phylogeny; D011058:Pollen / Q000502:physiology; D055503:Protein Multimerization; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004220:Disulfides; D008565:Membrane Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C103243:TRX1 protein, S cerevisiae; C516110:TRX2 protein, S cerevisiae; D013879:Thioredoxins; D010088:Oxidoreductases; C105231:nucleoredoxin; D054464:Peroxiredoxins; C497521:NTRA protein, Arabidopsis; D013880:Thioredoxin-Disulfide Reductase
keywords: Arabidopsis.; nucleoredoxin; nucleus; thioredoxin