Identification and characterization of a transcriptional regulator, SucR, that influences sucCD transcription in Corynebacterium glutamicum

We have identified and characterized a novel transcriptional regulator that binds to the promoter region of succinyl-CoA synthetase (sucCD) in Corynebacterium glutamicum. Using biotin-labeled DNA affinity beads, we identified a DeoR-type transcriptional regulator, SucR (Cg0146), which is a protein consisting of 282 amino acids with a mass of 31 kDa and RamB (Cg0444). The results of electrophoretic mobility shift assays verified that these regulators specifically bind to the sucCD promoter region. The putative SucR binding region extends from position −155 to −146 (a 10 bp sequence, ACTCTAGGGG) relative to the transcriptional start point of the sucCD operon. The expression level of sucCD in a sucR deletion mutant was seven times higher than that in wild-type cells grown on acetate. The increase in succinyl-CoA synthetase levels caused by inactivation of sucR. These assays revealed that SucR acts as a repressor of sucCD expression during acetate metabolism.

Research highlights► Identification of novel SucR regulator that bind to the sucCD promoter region. ► Expression of sucCD in the ΔsucR strain was 7-fold higher than in the wild-type strain at stationary phase when cells were grown on minimal medium with acetate as the sole carbon source. ► SucR is a negative transcriptional regulator of succinyl-CoA synthetase. ► The SucR binding sites in the sucCD promoter region was located from −155 to −146 (ACTCTAGGGG).