Interaction of the CopZ copper chaperone with the CopA copper ATPase of Enterococcus hirae assessed by surface plasmon resonance

Intracellular copper routing in Enterococcus hirae can be accomplished by t he CopZ metallochaperone. Using surface plasmon resonance analysis, we show here that CopZ interacts with the CopA copper ATPase. The binding affinity of CopZ for CopA was increased in the presence of copper, due to a 15-fold lower dissociation rate constant. Mutating the N-terminal copper binding m otif of CopA from CxxC to SxxS abolished this copper-induced effect. Moreov er, CopZ failed to show an interaction with an unrelated copper binding pro tein used as a control. These results show that (i) the CopA copper ATPase specifically interacts with the CopZ chaperone, (ii) this interaction is ba sed on protein-protein interaction, and (iii) surface plasmon resonance is a novel tool for quantitative analysis of metallochaperone-target interacti ons. (C) 2001 Academic Press.