he overarching goal of our research is to better understand the mechanisms by which metalloproteins obtain and transport their target metal ions. We have characterized the maturation of a copper-containing subunit of cytochrome c oxidase (CuA) in T. thermophilus, as well as the metal ion transport mechanism of a tripartite Cu/Ag ion efflux pump and metallochaperone in E. coli (CusF(CBA)) These characterizations are vital to understanding the basic and applied biochemistry of metal ion homeostasis in living cells, and will inform future research of detrimental mutations and metal ion related diseases in humans as well as possible antimicrobial targets.