Copper I transfer between Enterococcus hirae CopA, CopZ and CopY in vitro

Binding and transfer of Cu(I) between three key proteins in the bacterium Enterococcus hirae has been studied. CopA, an ATPase protein, was truncated, and its metal binding domain (AMBD) was expressed as a fusion with maltose binding protein (abbreviated as AMBD-MBP). AMBD-MBP will bind and transfer 1 mol equivalent of Cu(I) to the repressor protein CopY in vitro. AMBD, which also has a higher relative affinity for Cu(I) than CopZ, can also perform the same Cu(I) transfer role in vitro that CopZ does. The ability of the metal binding domain of CopA to transfer Cu(I) to CopY suggest it may serve that role in E. hirae and possibly in those organisms that don't possess a CopZ type copper chaperone.