Regulatory interaction of the Corynebacterium glutamicum whc genes in oxidative stress responses

In this study, we analyzed the regulatory interaction of the Corynebacterium glutamicum whc genes that play roles in oxidative stress responses. We found that whcE and whcA transcription was minimal in the whcB-deleted mutant (ΔwhcB). However, whcB and whcA transcription increased in the ΔwhcE mutant during the log phase, whereas their transcription decreased during the stationary phase. In addition, cells carrying the P180-whcB vector, which showed retarded growth due to uncontrolled whcB overexpression, recovered when whcA was deleted from the cells. Furthermore, introducing a ΔwhcE mutation into cells carrying the P180-whcB vector also resulted in improved growth and decreased whcA transcription during the log phase, suggesting that the action of whcB on whcA is mediated by whcE. Collectively, these findings show that, although the whc genes are paralogues, they play distinctive regulatory roles during cellular responses to oxidative stress. Notably, the whcE gene played a dual role of repressing and activating the whcB gene depending on the growth phase.