1NTM
Crystal Structure of Mitochondrial Cytochrome bc1 Complex at 2.4 Angstrom
Summary for 1NTM
| Entry DOI | 10.2210/pdb1ntm/pdb |
| Descriptor | Ubiquinol-cytochrome C reductase complex core protein I, mitochondrial, Ubiquinol-cytochrome C reductase complex 7.2 kDa protein, Ubiquinol-cytochrome C reductase complex 6.4 kDa protein, ... (14 entities in total) |
| Functional Keywords | bc1, qcr, membrane protein, proton translocation, electron transfer, protease, mpp, mitochondrial processing peptidase, cytochrome c1, cytochrome b, rieske, iron sulfur protein, oxidoreductase |
| Biological source | Bos taurus (cattle) More |
| Cellular location | Mitochondrion inner membrane; Peripheral membrane protein; Matrix side: P31800 P23004 Mitochondrion inner membrane: P00130 P07552 P13272 P00129 P13271 P00126 P13272 Mitochondrion inner membrane; Multi-pass membrane protein (By similarity): P00157 Mitochondrion inner membrane; Single-pass membrane protein; Intermembrane side: P00125 |
| Total number of polymer chains | 11 |
| Total formula weight | 241220.30 |
| Authors | |
| Primary citation | Gao, X.,Wen, X.,Esser, L.,Quinn, B.,Yu, L.,Yu, C.-A.,Xia, D. Structural basis for the quinone reduction in the bc(1) complex: a comparative analysis of crystal structures of mitochondrial cytochrome bc(1) with bound substrate and inhibitors at the Q(i) site Biochemistry, 42:9067-9080, 2003 Cited by PubMed Abstract: Cytochrome bc(1) is an integral membrane protein complex essential to cellular respiration and photosynthesis. The Q cycle reaction mechanism of bc(1) postulates a separated quinone reduction (Q(i)) and quinol oxidation (Q(o)) site. In a complete catalytic cycle, a quinone molecule at the Q(i) site receives two electrons from the b(H) heme and two protons from the negative side of the membrane; this process is specifically inhibited by antimycin A and NQNO. The structures of bovine mitochondrial bc(1) in the presence or absence of bound substrate ubiquinone and with either the bound antimycin A(1) or NQNO were determined and refined. A ubiquinone with its first two isoprenoid repeats and an antimycin A(1) were identified in the Q(i) pocket of the substrate and inhibitor bound structures, respectively; the NQNO, on the other hand, was identified in both Q(i) and Q(o) pockets in the inhibitor complex. The two inhibitors occupied different portions of the Q(i) pocket and competed with substrate for binding. In the Q(o) pocket, the NQNO behaves similarly to stigmatellin, inducing an iron-sulfur protein conformational arrest. Extensive binding interactions and conformational adjustments of residues lining the Q(i) pocket provide a structural basis for the high affinity binding of antimycin A and for phenotypes of inhibitor resistance. A two-water-mediated ubiquinone protonation mechanism is proposed involving three Q(i) site residues His(201), Lys(227), and Asp(228). PubMed: 12885240DOI: 10.1021/bi0341814 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.4 Å) |
Structure validation
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