1siw
From Proteopedia
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| , resolution 2.20Å | |||||||
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| Ligands: | , , , , , | ||||||
| Gene: | Operon narGHJI: NARG, NARC, BISD, B1224 (Escherichia coli), Operon narGHJI: NARH, B1225 (Escherichia coli), Operon narGHJI: NARI, CHLI, B1227 (Escherichia coli) | ||||||
| Activity: | Nitrate reductase, with EC number 1.7.99.4 | ||||||
| Related: | 1Q16
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of the apomolybdo-NarGHI
Overview
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.
About this Structure
1SIW is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
The catalytic subunit of Escherichia coli nitrate reductase A contains a novel [4Fe-4S] cluster with a high-spin ground state., Rothery RA, Bertero MG, Cammack R, Palak M, Blasco F, Strynadka NC, Weiner JH, Biochemistry. 2004 May 11;43(18):5324-33. PMID:15122898
Page seeded by OCA on Sun Mar 30 23:42:38 2008
