Glutathionylation in photosynthetic organisms

Protein glutathionylation is a reversible posttranslational modification promoted by oxidative and nitrosative stresses and consisting of the formation of a mixed disulfide between glutathione and a protein cysteine residue. This modification can protect specific cysteines from irreversible oxidation but can also modulate protein activities, either positively or negatively, and thereby play a role in many cellular processes including signaling. While the mechanism of glutathionylation prevailing in vivo remains unclear, the reverse reaction, called deglutathionylation, is mainly catalyzed by small disulfide oxidoreductases of the thioredoxin family named glutaredoxins (GRXs). This chapter will provide an overview of our current knowledge of the underlying molecular mechanisms, and especially the functions of GRXs, but will also review the targets and the possible physiological functions of protein glutathionylation.