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Cryo-EM structures of intermediates suggest an alternative catalytic reaction cycle for cytochrome c oxidase.

ABSTRACT: Cytochrome c oxidases are among the most important and fundamental enzymes of life. Integrated into membranes they use four electrons from cytochrome c molecules to reduce molecular oxygen (dioxygen) to water. Their catalytic cycle has been considered to start with the oxidized form. Subsequent electron transfers lead to the E-state, the R-state (which binds oxygen), the P-state (with an already split dioxygen bond), the F-state and the O-state again. Here, we determined structures of up to 1.9 Å resolution of these intermediates by single particle cryo-EM. Our results suggest that in the O-state the active site contains a peroxide dianion and in the P-state possibly an intact dioxygen molecule, the F-state may contain a superoxide anion. Thus, the enzyme's catalytic cycle may have to be turned by 180 degrees.

SUBMITTER: Kolbe F

PROVIDER: S-EPMC8617209 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Cryo-EM structures of intermediates suggest an alternative catalytic reaction cycle for cytochrome c oxidase.

Kolbe F F Safarian S S Piórek Ż Ż Welsch S S Müller H H Michel H H

Nature communications 20211125 1

Cytochrome c oxidases are among the most important and fundamental enzymes of life. Integrated into membranes they use four electrons from cytochrome c molecules to reduce molecular oxygen (dioxygen) to water. Their catalytic cycle has been considered to start with the oxidized form. Subsequent electron transfers lead to the E-state, the R-state (which binds oxygen), the P-state (with an already split dioxygen bond), the F-state and the O-state again. Here, we determined structures of up to 1.9 ...[more]

PMID: 34824221

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