PMID:15122898
| Citation |
Rothery, RA, Bertero, MG, Cammack, R, Palak, M, Blasco, F, Strynadka, NC and Weiner, JH (2004) The catalytic subunit of Escherichia coli nitrate reductase A contains a novel [4Fe-4S] cluster with a high-spin ground state. Biochemistry 43:5324-33 |
|---|---|
| Abstract |
We have used EPR spectroscopy, redox potentiometry, and protein crystallography to characterize the [4Fe-4S] cluster (FS0) of the Escherichia coli nitrate reductase A (NarGHI) catalytic subunit (NarG). FS0 is clearly visible in the crystal structure of NarGHI [Bertero, M. G., et al. (2003) Nat. Struct. Biol. 10, 681-687] but has novel coordination comprising one His residue and three Cys residues. At low temperatures (<15 K), reduced NarGHI exhibits a previously unobserved EPR signal comprising peaks at g = 5.023 and g = 5.556. We have assigned these features to a [4Fe-4S](+) cluster with an S = (3)/(2) ground state, with the g = 5.023 and g = 5.556 peaks corresponding to subpopulations exhibiting DeltaS = (1)/(2) and DeltaS = (3)/(2) transitions, respectively. Both peaks exhibit midpoint potentials of approximately -55 mV at pH 8.0 and are eliminated in the EPR spectrum of apomolybdo-NarGHI. The structure of apomolybdo-NarGHI reveals that FS0 is still present but that there is significant conformational disorder in a segment of residues that includes one of the Cys ligands. On the basis of these observations, we have assigned the high-spin EPR features of reduced NarGHI to FS0. |
| Links |
PubMed Online version:10.1021/bi049938l |
| Keywords |
Amino Acid Sequence; Apoproteins/chemistry; Catalytic Domain; Coenzymes/chemistry; Crystallography, X-Ray; Electron Spin Resonance Spectroscopy/methods; Escherichia coli Proteins/chemistry; Guanine Nucleotides/chemistry; Iron-Sulfur Proteins/chemistry; Molecular Sequence Data; Molybdenum/chemistry; Nitrate Reductase; Nitrate Reductases/chemistry; Oxidation-Reduction; Potentiometry; Protein Subunits/chemistry; Pterins/chemistry |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.