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

Molecular characterization of an operon, cueAR, encoding a putative P1-type ATPase and a MerR-type regulatory protein involved in copper homeostasis in Pseudomonas putida The GenBank accession number for the sequence reported in this paper is AF390440.

“…A cop box consisting of an 8 bp inverted repeat is found at the same location (between k10 and k35) as that described for the E. coli copA promoter, P copA ( Fig. 1c ; Outten et al, 2000 ;Stoyanov et al, 2001 copA transcriptional activator, CueR, are also present in P. putida P cueA . However, in comparison to E. coli P copA , the P. putida promoter carries additional inverted repeats both upstream and downstream of the cop box (Fig.…”

“…However, the threegene operon in Streptococcus, namely copYAZ, encodes a regulator similar to that encoded by the copYZAB copper-transport system of Enterococcus -this regulator is not of the MerR type. The copper-transport genes most similar to those of cueAR of P. putida are copA and cueR of Escherichia coli (Rensing et al, 2000 ;Outten et al, 2000 ;Stoyanov et al, 2001). However, the organization of these genes in E. coli is once again different as the two genes are separated by two unrelated genes.…”

“…The predicted CueR protein consists of 137 aa and shows a high degree of similarity to the MerR family of proteins, including the recently published Escherichia coli copper-transport regulator CueR ( Fig. 3a ; Outten et al, 2000 ;Stoyanov et al, 2001). …”

Interaction kinetics of the copper-responsive CopY repressor with the cop promoter of Enterococcus hirae

“…For the copperresponsive activator of E. coli, CueR, the free copper concentration to which it responded to was estimated to be in the zeptomolar range (10 -21 M [24]). This activator turns on copper homeostatic genes in response to copper, but the mechanism of this regulation does not resemble that of CopY of E. hirae [19,20].…”

“…This is supported by three observations: (1) the motif is conserved in all operons related to the E. hirae cop operon, (2) E. hirae [Zn(II)CopY] 2 exhibited the same affinity for these heterologous promoter regions which we tested, and (3) mutation of the conserved inverted-repeat completely abolishes repressor binding. The binding site of the copper-responsive repressor of E. coli, CueR, does not share sequence similarity to the cop box, which may thus be specific for Gram-positive bacteria [19,20].…”