The Enterococcus hirae copper chaperone CopZ delivers copper(I) to the CopY repressor

Expression of the cop operon which effects copper homeostasis in Enterococc us hirae is controlled by the copper responsive repressor CopY, Purified Zn (II)CopY binds to a synthetic cop promoter fragment in vitro. Here we show that the 8 kDa protein CopZ acts as a copper chaperone by specifically deli vering copper(I) to Zn(II)CopY and releasing CopY from the DNA. As shown by gel filtration and luminescence spectroscopy, two copper(I) are thereby qu antitatively transferred from Cu(I)CopZ to Zn(II)CopY, with displacement of the zinc(YI) and transfer of copper from a non-luminescent, exposed, bindi ng site in CopZ to a luminescent, solvent shielded, binding site in CopY, ( C) 1999 Federation of European Biochemical Societies.