Regulation of expression of the tricarballylate utilization operon (tcuABC) of Salmonella enterica

Res Microbiol. 2009 Apr;160(3):179-86. doi: 10.1016/j.resmic.2009.01.001. Epub 2009 Jan 21.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / genetics
  • Adenylyl Cyclases / physiology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology
  • Cyclic AMP Receptor Protein / genetics
  • Cyclic AMP Receptor Protein / physiology
  • Gene Deletion
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Metabolic Networks and Pathways / genetics*
  • Operon*
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism
  • Salmonella typhimurium / physiology*
  • Tricarboxylic Acids / metabolism*


  • Bacterial Proteins
  • Cyclic AMP Receptor Protein
  • Tricarboxylic Acids
  • Adenylyl Cyclases
  • tricarballylic acid