Anaerobic Regulation of Citrate Fermentation by CitAB in Escherichia coli

In Escherichia coli, CitB, a cognate response regulator of CitA, specifically bound to the promoter regions for mdh, citA, citC, and exuT. Transcription of these genes was induced by citrate under anaerobic conditions in a CitAB-dependent manner. Taking this together, we conclude that CitAB is the master regulatory system that activates the set of genes involved in citrate fermentation in E. coli.