title: Regulation of expression of the tricarballylate utilization operon (tcuABC) of Salmonella enterica.
abstract: The tricarballylate utilization locus (tcuRABC) of Salmonella enterica serovar Typhimurium is comprised of a 3-gene operon (tcuABC) that encodes functions that allow this bacterium to use tricarballylate as a source of carbon and energy, and the tcuR gene, which encodes a putative LysR-type transcriptional regulator. In our studies, transcription of the tcuABC operon peaked at mid-log phase, and declined moderately during stationary phase. This pattern was not due to a change in the amount of TcuR in the cell, as tcuR expression did not change under the conditions tested, and TcuR did not control tcuR expression. Tricarballylate was the co-inducer. tcuABC expression was negatively affected by the cAMP receptor protein (Crp). Expression of tcuABC was one order of magnitude higher in a crp mutant strain than in the crp(+) strain; derepression of tcuABC expression was also observed in a strain lacking adenylate cyclase (Cya). At present, it is unclear whether the effect of Crp is direct or indirect. Studies with molecular mimics of tricarballylate showed that the co-inducer site restricts binding of structural mimics that contain a hydroxyl group. Two classes of TcuR constitutive variants were isolated. Class I variants responded to tricarballylate, while Class II did not.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Lewis
authors.forename: Lisa W
authors.initials: LW
authors.lastname: Stamper
authors.forename: Jorge C
authors.initials: JC
authors.lastname: Escalante-Semerena
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D009876:Operon; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014233:Tricarboxylic Acids / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D014233:Tricarboxylic Acids; D000262:Adenylyl Cyclases; C028021:tricarballylic acid