Structure of Escherichia coli Succinate:Quinone Oxidoreductase with an Occupied and Empty Quinone-binding Site

Three new structures of Escherichia coli succinate-quinone oxidoreductase (SQR) have been solved. One with the specific quinone-binding site (Q-site) inhibitor carboxin present has been solved at 2.4 Å resolution and reveals how carboxin inhibits the Q-site. The other new structures are with the Q-s...

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Bibliographic Details
Published in:The Journal of biological chemistry 2009-10, Vol.284 (43), p.29836-29846
Main Authors: Ruprecht, Jonathan, Yankovskaya, Victoria, Maklashina, Elena, Iwata, So, Cecchini, Gary
Format: Article
Language:English
Subjects:
Animals
Binding Sites - physiology
Birds
Carboxin - chemistry
Electron Transport Complex II - chemistry
Escherichia coli
Escherichia coli - enzymology
Escherichia coli Proteins - chemistry
Metabolism and Bioenergetics
Protein Structure, Quaternary - physiology
Structural Homology, Protein
Ubiquinone - chemistry
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Summary:Three new structures of Escherichia coli succinate-quinone oxidoreductase (SQR) have been solved. One with the specific quinone-binding site (Q-site) inhibitor carboxin present has been solved at 2.4 Å resolution and reveals how carboxin inhibits the Q-site. The other new structures are with the Q-site inhibitor pentachlorophenol and with an empty Q-site. These structures reveal important details unresolved in earlier structures. Comparison of the new SQR structures shows how subtle rearrangements of the quinone-binding site accommodate the different inhibitors. The position of conserved water molecules near the quinone binding pocket leads to a reassessment of possible water-mediated proton uptake networks that complete reduction of ubiquinone. The dicarboxylate-binding site in the soluble domain of SQR is highly similar to that seen in high resolution structures of avian SQR (PDB 2H88) and soluble flavocytochrome c (PDB 1QJD) showing mechanistically significant structural features conserved across prokaryotic and eukaryotic SQRs.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M109.010058