Redox control of Hsp70-Co-chaperone interaction revealed by expression of a thioredoxin-like Arabidopsis protein.
By using a yeast functional complementation assay, we have identified AtTDX, a new Arabidopsis thaliana gene, encoding a two-domain 42-kDa protein. The amino-terminal domain of AtTDX is closely related to the co-chaperone Hsp70-interacting protein HIP, whereas its carboxyl-terminal part contains a thioredoxin domain. Both in vivo and in vitro assays showed that AtTDX is a protein-disulfide reductase. We next found that the HIP domain of AtTDX is capable of interacting with the ATPase domain of Ssb2, a yeast heat-shock protein 70 chaperone. Strikingly, the AtTDX-Ssb2 interaction can be released under oxidative stress, a redox-dependent regulation involving the thioredoxin activity of AtTDX. A mutation inactivating the cysteine 20 of the ATPase domain of Ssb2 was found to stabilize the AtTDX-Ssb2 interaction that becomes redox-insensitive. As cysteine 20 is conserved in virtually all the Hsp70 chaperones, our results suggest that this residue might be more generally the target of redox regulations of chaperone binding activity.
Vignols
Florence
F
Laboratoire Génome et Développement des Plantes, CNRS, UMR 5096, Université de Perpignan, 52 Avenue de Villeneuve, 66860 Perpignan, France. vignols@univ-perp.fr
Mouaheb
Nabil
N
Thomas
Dominique
D
Meyer
Yves
Y
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D013879:Thioredoxins / Q000096:biosynthesis* / Q000235:genetics
D029681:Arabidopsis Proteins; C504764:AtTDX protein, Arabidopsis; D018840:HSP70 Heat-Shock Proteins; C105426:Hip chaperone; D018832:Molecular Chaperones; D010940:Plant Proteins; D013879:Thioredoxins