1. Structure of the cytochrome aa(3)-600 heme-copper menaquinol oxidase bound to inhibitor HQNO shows TM0 is part of the quinol binding site
- Author
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Zhengguang Zhang, Bing Liu, Jingjing Xu, Aiwu Zhou, Jiao Li, Yuchen Liu, Liu Liu, Sophia M. Yi, Robert B. Gennis, Jin Li, Ziqiao Ding, and Jiapeng Zhu
- Subjects
Models, Molecular ,Ubiquinol ,Semiquinone ,Cytochrome ,Stereochemistry ,Protein Conformation ,macromolecular substances ,Heme ,Naphthols ,Crystallography, X-Ray ,Electron Transport ,Electron Transport Complex IV ,03 medical and health sciences ,chemistry.chemical_compound ,Oxidoreductase ,Amino Acid Sequence ,030304 developmental biology ,chemistry.chemical_classification ,0303 health sciences ,Multidisciplinary ,Binding Sites ,biology ,Terpenes ,Cytochrome c ,030302 biochemistry & molecular biology ,Hydrogen Bonding ,Vitamin K 2 ,Proton Pumps ,Cytochrome b Group ,Hydroquinones ,Protein Subunits ,chemistry ,Menaquinol oxidase ,Physical Sciences ,biology.protein ,Cytochrome aa3 ,Oxidoreductases ,Copper ,Bacillus subtilis - Abstract
Virtually all proton-pumping terminal respiratory oxygen reductases are members of the heme-copper oxidoreductase superfamily. Most of these enzymes use reduced cytochrome c as a source of electrons, but a group of enzymes have evolved to directly oxidize membrane-bound quinols, usually menaquinol or ubiquinol. All of the quinol oxidases have an additional transmembrane helix (TM0) in subunit I that is not present in the related cytochrome c oxidases. The current work reports the 3.6-Å-resolution X-ray structure of the cytochrome aa 3 -600 menaquinol oxidase from Bacillus subtilis containing 1 equivalent of menaquinone. The structure shows that TM0 forms part of a cleft to accommodate the menaquinol-7 substrate. Crystals which have been soaked with the quinol-analog inhibitor HQNO ( N -oxo-2-heptyl-4-hydroxyquinoline) or 3-iodo-HQNO reveal a single binding site where the inhibitor forms hydrogen bonds to amino acid residues shown previously by spectroscopic methods to interact with the semiquinone state of menaquinone, a catalytic intermediate.
- Published
- 2019