Citrate Utilization by Corynebacterium glutamicum Is Controlled by the CitAB Two-Component System through Positive Regulation of the Citrate Transport Genes citH and tctCBA

摘要: ABSTRACT In this work, the molecular basis of aerobic citrate utilization by gram-positive bacterium Corynebacterium glutamicum was studied. Genome analysis revealed presence two putative transport systems. The permease encoded citH belongs to citrate-Mg2+:H+/citrate-Ca2+:H+ symporter family, whereas tctCBA operon is a member tripartite tricarboxylate transporter family. expression or in Escherichia coli enabled species utilize aerobically, indicating that both CitH and TctABC are functional transporters. Growth tests with recombinant E. strains indicated active Ca2+ Sr2+ but not Mg2+ Sr2+. We could subsequently show that, 50 mM as sole carbon energy source, C. wild type grew best when minimal medium supplemented CaCl2 MgCl2 SrCl2 also supported growth. Each transporters alone sufficient for growth on citrate. activated medium, independent absence glucose. This activation dependent two-component signal transduction system CitAB, composed sensor kinase CitA response regulator CitB. CitAB CitAB/DcuSR family systems, whose members control genes involved catabolism tricarboxylates dicarboxylates. first studied Actinobacteria.