Identification of a Copper-Responsive Two-Component System on the Chromosome of Escherichia coli K-12

Abstract

Using a genetic screen we have identified two chromosomal genes, cusRS (ylcA ybcZ), from Escherichia coli K-12 that encode a two-component, signal transduction system that is responsive to copper ions. This regulatory system is required for copper-induced expression of pcoE, a plasmid-borne gene from the E. coli copper resistance operon pco. The closest homologs of CusR and CusS are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: PcoR and PcoS from the pco operon of E. coli; CopR and CopS from the cop operon, which provides copper resistance to Pseudomonas syringae; and SilR and SilS from the sil locus, which provides silver ion resistance to Salmonella enterica serovar Typhimurium. The genes cusRS are also required for the copper-dependent expression of at least one chromosomal gene, designated cusC (ylcB), which is allelic to the recently identified virulence gene ibeB in E. coli K1. The cus locus may comprise a copper ion efflux system, because the expression of cusC is induced by high concentrations of copper ions. Furthermore, the translation products of cusC and additional downstream genes are homologous to known metal ion antiporters.

Dissecting the Salmonella response to copper

“…The CusR/CusS system is predicted to monitor the periplasmic concentration of the metal ion, to modulate the expression of an RND-type copper efflux pump, encoded by the cusCFBA operon (Franke et al, 2003;Munson et al, 2000). Recently, it was shown that transcription of a second, uncharacterized, two-component system, encoded by the yedWV operon, is activated by copper ions in a CusR-dependent manner (Yamamoto & Ishihama, 2005), although its role in copper tolerance remains unclear.…”

Transcriptional Activation of an Escherichia coliCopper Efflux Regulon by the Chromosomal MerR Homologue, CueR

“…Recently, the first copper-responsive regulatory system in the E. coli chromosome, a two-component signal transduction system designated Cu-sensing or cus locus, was identified (9). The cusRS genes form a sensor/regulator pair that activates the adjacent but divergently transcribed gene, cusC, and possibly two adjacent downstream genes, cusBA, in response to increasing copper.…”

The Escherichia coli Copper-responsivecopA Promoter Is Activated by Gold

“…Mammalian systems require copper for many enzymes (4). Recently, new elements of copper homeostasis in bacteria have been identified, including transporters, multicopper oxidases, and two-component and MerR-like regulators (5)(6)(7)(8)(9).…”