National Center for
4I8C: X-ray Structure of Nika in Complex With Ni-(l-his)2
J. Inorg. Biochem. (2012) 121C p.16-18
The ABC-type importer NikABCDE mediates nickel acquisition in Escherichia coli. The periplasmic nickel-binding component NikA has a folding similar to that of the peptide transporter OppA and does not bind free nickel. Instead, we showed that the metal is tetra-coordinated by an organic tri-dentate molecule and His416. Conversely, it has been recently reported that NikA binds Ni-((L)-His)(2) and that addition of histidine increases the rate of nickel uptake in vivo. Here, we report the structure of NikA/Ni-((L)-His)(2) and show that histidine binding differs from peptide binding in OppA. The structure also confirms the central role of His416 in nickel binding.