Identification of Plant Glutaredoxin Targets

Glutaredoxins (Grxs) are small ubiquitous proteins of the thioredoxin (Trx) family, which catalyze dithiol–disulfide exchange reactions or reduce protein-mixed glutathione disulfides. In plants, several Trx-interacting proteins have been isolated from different compartments, whereas very few Grx-interacting proteins are known. We describe here the determination of Grx target proteins using a mutated poplar Grx, various tissular and subcellular plant extracts, and liquid chromatography coupled to tandem mass spectrometry detection. We have identified 94 putative targets, involved in many processes, including oxidative stress response [peroxiredoxins (Prxs), ascorbate peroxidase, catalase], nitrogen, sulfur, and carbon metabolisms (methionine synthase, alanine aminotransferase, phosphoglycerate kinase), translation (elongation factors E and Tu), or protein folding (heat shock protein 70). Some of these proteins were previously found to interact with Trx or to be glutathiolated in other organisms, but others...