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Crystal structure of Zinc binding protein ZinT in complex with citrate from E. coli
Structural highlights
FunctionZINT_ECOLI May function as a periplasmic zinc chaperone or mediate direct transport of zinc from the periplasm to the cytoplasm under zinc-limited conditions. Binds zinc with high affinity, and can also bind cadmium, mercury or nickel. Preferentially binds Zn(2+) over Cd(2+). Contains one high affinity metal binding site, and can bind additional metal ions at other sites.[1] [2] Publication Abstract from PubMedThe ZnuABC ATP-binding cassette transporter found in gram-negative bacteria has been implicated in ensuring adequate zinc import into Zn(II)-poor environments. ZinT is an essential component of ZnuABC and contributes to metal transport by transferring metals to ZnuA, which delivers them to ZnuB in periplasmic zinc recruitment. Although several structures of E. coli ZinT have been reported, its zinc-binding sites and oligomeric state have not been clearly identified. Here, we report the crystal structure of E. coli ZinT at 1.76A resolution. This structure contains one zinc ion in its calycin-like domain, and this ion is coordinated by three highly conserved histidine residues (His167, His176 and His178). Moreover, three oxygen atoms (O1, O6 and O7) from the citrate molecule interact with zinc, giving the zinc ion stable octahedral coordination. Our EcZinT structure shows the fewest zinc ions bound of all reported EcZinT structures. Crystallographic packing and size exclusion chromatography suggest that EcZinT prefers to form monomers in solution. Our results provide insights into the molecular function of ZinT. Crystal structure of E. coli ZinT with one zinc-binding mode and complexed with citrate.,Chen J, Wang L, Shang F, Dong Y, Ha NC, Nam KH, Quan C, Xu Y Biochem Biophys Res Commun. 2018 Jun 2;500(2):139-144. doi:, 10.1016/j.bbrc.2018.03.192. Epub 2018 Apr 13. PMID:29596824[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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