Glutathionylation of chloroplast thioredoxin f is a redox signaling mechanism in plants.
Thioredoxin f (TRXf) is a key factor in the redox regulation of chloroplastic carbon fixation enzymes, whereas glutathione is an important thiol buffer whose status is modulated by stress conditions. Here, we report specific glutathionylation of TRXf. A conserved cysteine is present in the TRXf primary sequence, in addition to its two active-site cysteines. The additional cysteine becomes glutathionylated when TRXf is exposed to oxidized glutathione or to reduced glutathione plus oxidants. No other chloroplastic TRX, from either Arabidopsis or Chlamydomonas, is glutathionylated under these conditions. Glutathionylation decreases the ability of TRXf to be reduced by ferredoxin-thioredoxin reductase and results in impaired light activation of target enzymes in a reconstituted thylakoid system. Although several mammalian proteins undergoing glutathionylation have already been identified, TRXf is among the first plant proteins found to undergo this posttranslational modification. This report suggests that a crosstalk between the TRX and glutathione systems mediates a previously uncharacterized form of redox signaling in plants in stress conditions.
Michelet
Laure
L
Institut de Biotechnologie des Plantes, Unité Mixte de Recherche 8618, Unité Mixte de Recherche 8619, Centre National de la Recherche Scientifique/Université Paris-Sud, 91405 Orsay Cedex, France.
Zaffagnini
Mirko
M
Marchand
Christophe
C
Collin
Valérie
V
Decottignies
Paulette
P
Tsan
Pascale
P
Lancelin
Jean-Marc
JM
Trost
Paolo
P
Miginiac-Maslow
Myroslawa
M
Noctor
Graham
G
Lemaire
Stéphane D
SD
D000818:Animals; D017360:Arabidopsis / Q000378:metabolism; D002696:Chlamydomonas / Q000378:metabolism; D054479:Chloroplast Thioredoxins; D002736:Chloroplasts / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000378:metabolism; D008958:Models, Molecular; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010944:Plants / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013879:Thioredoxins / Q000737:chemistry / Q000378:metabolism*
D054479:Chloroplast Thioredoxins; D013879:Thioredoxins; D009249:NADP; D008291:Malate Dehydrogenase; D005978:Glutathione