1SIW

Crystal structure of the apomolybdo-NarGHI

Summary for 1SIW

• Entry DOI: 10.2210/pdb1siw/pdb
• Related: 1Q16
• Descriptor: Respiratory nitrate reductase 1 alpha chain, Respiratory nitrate reductase 1 beta chain, Respiratory nitrate reductase 1 gamma chain, ... (9 entities in total)
• Functional Keywords: apomolybdo-narghi; electron-transfer; membrane protein, oxidoreductase
• Biological source: Escherichia coli; More
• Cellular location: Cell membrane; Peripheral membrane protein: P09152 P11349; Cell inner membrane; Multi-pass membrane protein: P11350
• Total number of polymer chains: 3
• Total formula weight: 229007.97

Authors

Rothery, R.A.,Bertero, M.G.,Cammack, R.,Palak, M.,Blasco, F.,Strynadka, N.C.,Weiner, J.H. (deposition date: 2004-03-01, release date: 2004-06-08, Last modification date: 2024-11-20)

Primary citation

Rothery, R.A.,Bertero, M.G.,Cammack, R.,Palak, M.,Blasco, F.,Strynadka, N.C.,Weiner, J.H.
The catalytic subunit of Escherichia coli nitrate reductase A contains a novel [4Fe-4S] cluster with a high-spin ground state
Biochemistry, 43:5324-5333, 2004

PubMed 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.

PubMed: 15122898
DOI: 10.1021/bi049938l

Experimental method

X-RAY DIFFRACTION (2.2 Å)