Effects of Promoter Mutations on the in Vivo Regulation of the cop Operon of Enterococcus hirae by Copper(I) and Copper(II)

Characterization of a copper-transport operon, copYAZ, from Streptococcus mutans The GenBank accession number for the cop operon sequence reported in this paper is AF296446.

“…hirae), and the hypothetical protein encoded by orfY of L. sake. These regulatory proteins have been shown to repress transcription when the effector molecules (β-lactam antibiotics) or ions (Cu# + ) are absent or at physiological levels by binding to inverted repeat sequences overlapping the promoter (Hiramatsu et al, 1992 ;Smith & Murray, 1992 ;Strausak & Solioz, 1997 ;Wittman et al, 1993 ;Wunderli-Ye & Solioz, 1999b). Our studies on the CAT reporter gene suggest that Strep.…”

“…The C-terminal motif may play an important role in derepressing transcription of the cop operon. In the enterococcal system, the binding of copper to CopY, presumably at the CXCX % CXC motif, at high copper concentrations induced disassociation of the protein-DNA complex, thereby allowing transcription (Odermatt & Solioz, 1995 ;Strausak & Solioz, 1997 ;Wunderli-Ye & Solioz, 1999b).…”

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

“…From previous in vivo and in vitro studies, it was clear that copper releases zinc from [Zn(II)CopY] 2 , thereby releasing the repressor from the DNA and allowing transcription of the cop operon to proceed [5,6,7]. Thus, the effect of Cu(I) on the release of [Zn(II)-CopY] 2 bound to a sensor chip with immobilized hirae1 DNA was investigated.…”

“…The two CopY binding sites feature an inverted repeat and flank the start of transcription ( Fig. 1 [6,7]). The N-terminal half of CopY shows 30% sequence similarity to the bacterial repressors of ß-lactamases, PenI, of Bacillus licheniformis [8] and related proteins and probably corresponds to the domain that recognizes the DNA promoter sequences [9].…”

Stalking metal-linked dimers

“…A diglutamine motif (QQ) of the cro repressor, also found in CopY, has been shown to specifically interact with the ACA sequence within the TACAnnTGTA DNA motif [26]. While it has been suggested that CopY may be binding to DNA in the same fashion [27], the QQ residues are not at all conserved across bacterial homologs.…”