Structure and metal binding properties of ZnuA, a periplasmic zinc transporter from Escherichia coli.

ZnuA is the periplasmic Zn(2+)-binding protein associated with the high-affinity ATP-binding cassette ZnuABC transporter from Escherichia coli. Although several structures of ZnuA and its homologs have been determined, details regarding metal ion stoichiometry, affinity, and specificity as well as the mechanism of metal uptake and transfer remain unclear. The crystal structures of E.