PDBsum entry 1q16

Go to PDB code: 
Top Page protein ligands metals Protein-protein interface(s) links
Oxidoreductase PDB id
Protein chains
1244 a.a. *
509 a.a. *
224 a.a. *
MD1 ×2
SF4 ×4
HEM ×2
Waters ×1213
* Residue conservation analysis

References listed in PDB file
Key reference
Title Insights into the respiratory electron transfer pathway from the structure of nitrate reductase a.
Authors M.G.Bertero, R.A.Rothery, M.Palak, C.Hou, D.Lim, F.Blasco, J.H.Weiner, N.C.Strynadka.
Ref. Nat Struct Biol, 2003, 10, 681-687. [DOI no: 10.1038/nsb969]
PubMed id 12910261
The facultative anaerobe Escherichia coli is able to assemble specific respiratory chains by synthesis of appropriate dehydrogenases and reductases in response to the availability of specific substrates. Under anaerobic conditions in the presence of nitrate, E. coli synthesizes the cytoplasmic membrane-bound quinol-nitrate oxidoreductase (nitrate reductase A; NarGHI), which reduces nitrate to nitrite and forms part of a redox loop generating a proton-motive force. We present here the crystal structure of NarGHI at a resolution of 1.9 A. The NarGHI structure identifies the number, coordination scheme and environment of the redox-active prosthetic groups, a unique coordination of the molybdenum atom, the first structural evidence for the role of an open bicyclic form of the molybdo-bis(molybdopterin guanine dinucleotide) (Mo-bisMGD) cofactor in the catalytic mechanism and a novel fold of the membrane anchor subunit. Our findings provide fundamental molecular details for understanding the mechanism of proton-motive force generation by a redox loop.
Figure 1.
Figure 1. Proposed mechanism for the proton-motive force generating redox loop by NarGHI and FdnGHI. MQ and MQH2, menoquinone and menaquinol, respectively; b[D] and b[P], distal and proximal heme, respectively; FS, [Fe-S] clusters; Mo-bisMGD, molybdenum cofactor.
Figure 5.
Figure 5. Structure of the integral membrane NarI subunit. (a) Ribbon representation of NarI viewed parallel to the membrane. NarI transmembrane helices are numbered from I to V. Hemes b[P] and b[D] are shown in magenta stick rendering with the Fe atoms in orange. (b) GRASP37 surface representation of NarI viewed from the same direction as in a. Polar and hydrophobic areas are in gray and green, respectively. The region above the dotted line is involved in interactions with NarGH.
The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2003, 10, 681-687) copyright 2003.
Go to PROCHECK summary