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Structural characterization of a putative endogenous metal chelator in the periplasmic nickel transporter NikA.
- Source :
-
Biochemistry [Biochemistry] 2008 Sep 23; Vol. 47 (38), pp. 9937-43. Date of Electronic Publication: 2008 Aug 30. - Publication Year :
- 2008
-
Abstract
- Escherichia coli and related bacteria require nickel for the synthesis of hydrogenases, enzymes involved in hydrogen oxidation and proton reduction. Nickel transport to the cytoplasm depends on five proteins, NikA-E. We have previously reported the three-dimensional structure of the soluble periplasmic nickel transporter NikA in a complex with FeEDTA(H 2O) (-). We have now determined the structure of EDTA-free NikA and have found that it binds a small organic molecule that contributes three ligands to the coordination of a transition metal ion. Unexpectedly, His416, which was far from the metal-binding site in the FeEDTA(H 2O) (-)-NikA complex, becomes the fourth observed ligand to the metal. The best match to the omit map electron density is obtained for butane-1,2,4-tricarboxylate (BTC). Our attempts to obtain a BTC-Ni-NikA complex using apo protein and commercial reagents resulted in nickel-free BTC-NikA. Overall, our results suggest that nickel transport in vivo requires a specific metallophore that may be BTC.
Details
- Language :
- English
- ISSN :
- 1520-4995
- Volume :
- 47
- Issue :
- 38
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 18759453
- Full Text :
- https://doi.org/10.1021/bi801051y