Structure of the cytochrome aa 3 -600 heme-copper menaquinol oxidase bound to inhibitor HQNO shows TM0 is part of the quinol binding site
- Nanjing University of Chinese Medicine (China); Nanjing University of Chinese Medicine
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- Nanjing University of Chinese Medicine (China)
- PharmaBlock Sciences, Inc., Nanjing, China
- Shanghai Jiao Tong Univ. (China). School of Medicine
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 aa3-600 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.
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- FG02-87ER13716
- OSTI ID:
- 1800648
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 2 Vol. 117; ISSN 0027-8424
- Publisher:
- National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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