Regulation of Quinone Oxidoreductase by the Redox-sensing Transcriptional Regulator QorR in Corynebacterium glutamicum

Corynebacterium glutamicum cgR_1435 (cg1552) encodes a protein of the DUF24 protein family, which is a novel family of transcriptional regulators. CgR1435 (QorR) is a negative regulator of cgR 1436 (qor2), which is located upstream of cgR 1435 (qorR) in the opposite orientation, and its structural gene. QorR binds to the intergenic region between qor2 and qorR to repress their expression, which is induced by the thiol-specific oxidant diamide. The DNA-binding activity of QorR is impaired by oxidants such as diamide, H2O2, and cumene hydroperoxide in vitro, and its lone cysteine residue (Cys-17) is essential for redox-responsive regulation of QorR activity both in vivo and in vitro. Moreover, a disruptant of qor2, which is a homologue of the ytfG gene of Escherichia coli encoding quinone oxidoreductase, shows increased sensitivity to diamide. It is concluded that the redox-sensing transcriptional regulator QorR is involved in disulfide stress response of C. glutamicum by regulating qor2 expression.