PMID:16011372
| Citation |
Cherrier, MV, Martin, L, Cavazza, C, Jacquamet, L, Lemaire, D, Gaillard, J and Fontecilla-Camps, JC (2005) Crystallographic and spectroscopic evidence for high affinity binding of FeEDTA(H2O)- to the periplasmic nickel transporter NikA. J. Am. Chem. Soc. 127:10075-82 |
|---|---|
| Abstract |
Because nickel is both essential and toxic to a great variety of organisms, its detection and transport is highly regulated. In Escherichia coli and other related Gram-negative bacteria, high affinity nickel transport depends on proteins expressed by the nik operon. A central actor of this process is the periplasmic NikA transport protein. A previous structural report has proposed that nickel binds to NikA as a pentahydrate species. However, both stereochemical considerations and X-ray absorption spectroscopic results are incompatible with that interpretation. Here, we report the 1.8 A resolution structure of NikA and show that it binds FeEDTA(H2O)- with very high affinity. In addition, we provide crystallographic evidence that a metal-EDTA complex was also bound to the previously reported NikA structure. Our observations strongly suggest that nickel transport in E. coli requires the binding of this metal ion to a metallophore that bears significant resemblance to EDTA. They also provide a basis for the potential use of NikA in the bioremediation of toxic transition metals and the design of artificial metalloenzymes. |
| Links |
PubMed Online version:10.1021/ja0518530 |
| Keywords |
ATP-Binding Cassette Transporters/chemistry; ATP-Binding Cassette Transporters/metabolism; Binding Sites; Crystallography, X-Ray; Edetic Acid/chemistry; Edetic Acid/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/metabolism; Ferrous Compounds/chemistry; Ferrous Compounds/metabolism; Iron/chemistry; Iron/metabolism; Mass Spectrometry; Nickel/chemistry; Nickel/metabolism; Periplasm/chemistry; Protein Structure, Tertiary |
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