Graded Response of the Multifunctional 2-Cysteine Peroxiredoxin, CgPrx, to Increasing Levels of Hydrogen Peroxide in Corynebacterium glutamicum

Aims: Eukaryotic typical 2-cysteine (Cys) peroxiredoxins (Prxs) are multifunctional proteins subjected to complex regulation and play important roles in oxidative stress resistance, hydrogen peroxide (H2O2) signaling modulation, aging, and cancer, but the information on the biochemical functions and regulation mechanisms of prokaryotic atypical 2-Cys Prxs is largely lacking. Results: In this study, we show that at low peroxide concentrations, the atypical 2-Cys Prx in Corynebacterium glutamicum (CgPrx) mainly exists as monomers and displays thioredoxin (Trx)-dependent peroxidase activity. Moderate oxidative stress causes reversible S-mycothiolation of the H2O2-sensing Cys63 residue, which keeps CgPrx exclusively in dimer form with neither peroxidase nor chaperone activity. Then, the increased levels of H2O2 could act as a messenger to oxidize the redox-sensitive regulator hydrogen peroxide-inducible gene activator, leading to activation of expression of the more efficient mycothiol peroxidase and...