Transcriptional control of the succinate dehydrogenase operon sdhCAB of Corynebacterium glutamicum by the cAMP-dependent regulator GlxR and the LuxR-type regulator RamA

In experiments performed to identify transcriptional regulators of the tricarboxylic acid cycle of Corynebacterium glutamicum, the cAMP-dependent regulator GlxR and the regulators of acetate metabolism RamA and RamB were enriched by DNA affinity chromatography with the promoter region of the sdhCAB operon encoding succinate dehydrogenase. The binding of purified GlxR, RamA and RamB was verified by electrophoretic mobility shift assays and the regulatory effects of these proteins on sdhCAB gene expression were tested by promoter activity assays and SDH activity measurements. Evidence was obtained that GlxR functions as a repressor and RamA as an activator of sdhCAB expression, whereas RamB had no obvious influence under the conditions tested.