2osv
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Crystal Structure of ZnuA from E. coli
OverviewOverview
Bacterial ATP-binding cassette transport systems for high-affinity uptake, of zinc and manganese use a cluster 9 solute-binding protein. Structures, of four cluster 9 transport proteins have been determined previously., However, the structural determinants for discrimination between zinc and, manganese remain under discussion. To further investigate the variability, of metal binding sites in bacterial transporters, we have determined the, structure of the zinc-bound transport protein ZnuA from Escherichia coli, to 1.75 A resolution. The overall structure of ZnuA is similar to other, solute-binding transporters. A scaffolding alpha-helix forms the backbone, for two structurally related globular domains. The metal-binding site is, located at the domain interface. The bound zinc ion is coordinated by, three histidine residues (His78, His161 and His225) and one glutamate, residue (Glu77). The functional role of Glu77 for metal binding is, unexpected, because this residue is not conserved in previously determined, structures of zinc and manganese-specific transport proteins. The observed, metal coordination by four protein residues differs significantly from the, zinc-binding site in the ZnuA transporter from Synechocystis 6803, which, binds zinc via three histidine residues. In addition, the E. coli ZnuA, structure reveals the presence of a disulfide bond in the C-terminal, globular domain that is not present in previously determined cluster 9, transport protein structures.
About this StructureAbout this Structure
2OSV is a Single protein structure of sequence from Escherichia coli with ZN as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Crystal Structure of the Zinc-binding Transport Protein ZnuA from Escherichia coli Reveals an Unexpected Variation in Metal Coordination., Li H, Jogl G, J Mol Biol. 2007 Mar 15;. PMID:17399739
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