Structure of the cytochrome aa3 -600 heme-copper menaquinol oxidase bound to inhibitor HQNO shows TM0 is part of the quinol binding site.
Proc Natl Acad Sci U S A
; 117(2): 872-876, 2020 01 14.
Article
em En
| MEDLINE
| ID: mdl-31888984
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 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.
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MEDLINE
Assunto principal:
Bacillus subtilis
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Complexo IV da Cadeia de Transporte de Elétrons
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Cobre
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Heme
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Hidroquinonas
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article