Alpha-ketoglutarate protects Streptomyces coelicolor from visible light-induced phototoxicity.

It has been known that some Streptomyces species, including the model strain Streptomyces coelicolor, are vulnerable to visible light. Much evidence demonstrated that the phototoxicity induced by visible light is a consequence of the formation of intracellular reactive oxygen species (ROS), which are potentially harmful to cells. In this study, we found that α-ketoglutarate (α-KG) has a protective role against the phototoxicity in S. coelicolor. It could be because that α-KG can detoxify the ROS with the concomitant formation of succinate, which mediates the cells getting into anaerobiosis to produce more NADH and maintain intracellular redox homeostasis, a situation that was demonstrated by overexpressing gdhA in S. coelicolor. This finding, therefore, connects the central metabolites with the bacterial resistance against phototoxicity effect induced by visible light.