Physiological roles of mycothiol in detoxification and tolerance to multiple poisonous chemicals in Corynebacterium glutamicum.

Mycothiol (MSH) plays important roles in maintaining cytosolic redox homeostasis and in adapting to reactive oxygen species in the high-(G + C)-content Gram-positive Actinobacteria. However, its physiological roles are ill defined compared to glutathione, the functional analog of MSH in Gram-negative bacteria and most eukaryotes. In this research, we explored the impact of intracellular MSH on cellular physiology by using MSH-deficient mutants in the model organism Corynebacterium glutamicum. We found that intracellular MSH contributes significantly to resistance to alkylating agents, glyphosate, ethanol, antibiotics, heavy metals and aromatic compounds. In addition, intracellular MSH is beneficial for withstanding oxidative stress induced by various oxidants in C. glutamicum. This study greatly expanded our current knowledge on the physiological functions of mycothiol in C. glutamicum and could be applied to improve the robustness of this scientifically and commercially important species in the future.