2OSV: Crystal Structure Of Znua From E. Coli

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.
PDB ID: 2OSVDownload
MMDB ID: 45839
PDB Deposition Date: 2007/2/6
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 1.75  Å
Source Organism:
Similar Structures:
Biological Unit for 2OSV: monomeric; determined by author
Molecular Components in 2OSV
Label Count Molecule
Protein (1 molecule)
High-affinity Zinc Uptake System Protein Znua(Gene symbol: znuA)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB