cytochrome o ubiquinol oxidase complex

GO:0009319 · Energy complex · Multiprotein complex · Proposed

A four-polypeptide respiratory-chain protein complex that possesses cytochrome o ubiquinol oxidase activity and contains associated prosthetic groups. [GO:0009319]

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Cytochrome o ubiquinol oxidase, subunit I	Protein	part of	`InterPro:IPR014207`	cyoB	UNKNOWN	Large membrane-embedded subunit of cytochrome bo3 terminal oxidase. `InterPro:IPR014207` InterPro IPR014207 is the source-neutral family for CyoB, subunit I of cytochrome o ubiquinol oxidase. `PDB:1FFT` The PDB:1FFT deposition maps polymer entity 1 of the E. coli ubiquinol oxidase structure to UniProtKB:P0ABI8/CYOB_ECOLI.
Cytochrome o ubiquinol oxidase subunit II	Protein	part of	`InterPro:IPR006333`	cyoA	UNKNOWN	Quinol-side subunit of the cytochrome o ubiquinol oxidase terminal oxidase. `InterPro:IPR006333` InterPro IPR006333 is the source-neutral family for cytochrome o ubiquinol oxidase subunit II. `PDB:1FFT` The PDB:1FFT deposition maps polymer entity 2 of the E. coli ubiquinol oxidase structure to UniProtKB:P0ABJ1/CYOA_ECOLI.
Cytochrome o ubiquinol oxidase, subunit III	Protein	part of	`InterPro:IPR014206`	cyoC	UNKNOWN	Membrane subunit of the cytochrome o ubiquinol oxidase terminal oxidase. `InterPro:IPR014206` InterPro IPR014206 is the source-neutral family for CyoC, subunit III of cytochrome o ubiquinol oxidase. `PDB:1FFT` The PDB:1FFT deposition maps polymer entity 3 of the E. coli ubiquinol oxidase structure to UniProtKB:P0ABJ3/CYOC_ECOLI.
Cytochrome o ubiquinol oxidase subunit IV	Protein	part of	`InterPro:IPR014210`	cyoD	UNKNOWN	Small fourth membrane subunit of the cytochrome o ubiquinol oxidase terminal oxidase. `InterPro:IPR014210` InterPro IPR014210 is the source-neutral family for CyoD, subunit IV of cytochrome o ubiquinol oxidase. `UniProtKB:P0ABJ6` Reviewed UniProtKB entry P0ABJ6 records E. coli cyoD as cytochrome bo3 ubiquinol oxidase subunit 4.

Canonical examples

NCBITaxon:562 Escherichia coli — Bacterial source of the four-polypeptide cytochrome bo3 ubiquinol oxidase structure deposited as PDB:1FFT. [PDB:1FFT]

Functions

cytochrome bo3 ubiquinol oxidase activity GO:0009486 — Cytochrome bo3 ubiquinol oxidase oxidizes ubiquinol, reduces molecular oxygen to water, and moves protons to the periplasmic side of the respiratory membrane.
- GO:0009486 GO:0009486 defines the cytochrome bo3 ubiquinol oxidase reaction with ubiquinol as donor, oxygen as acceptor, and proton release on the periplasmic side.
- DOI:10.1038/82824 Abramson et al. 2000 solved the E. coli ubiquinol oxidase structure and its ubiquinone binding site.

Mechanism graphs

Cytochrome bo3 oxidizes ubiquinol with oxygen (FUNCTION)

Cytochrome o ubiquinol oxidase is a terminal respiratory oxidase that converts ubiquinol and oxygen to ubiquinone and water while contributing to the proton motive force.

Subject	Predicate	Object	Evidence
cytochrome o ubiquinol oxidase complex	enables	cytochrome bo3 ubiquinol oxidase activity	`GO:0009319` GO:0009319 defines the complex by possession of cytochrome o ubiquinol oxidase activity.
ubiquinol	donates electrons to	cytochrome bo3 ubiquinol oxidase activity	`GO:0009486` GO:0009486 records ubiquinol as the electron donor in this terminal oxidase reaction.
molecular oxygen	accepts electrons in	cytochrome bo3 ubiquinol oxidase activity	`GO:0009486` GO:0009486 records molecular oxygen as the acceptor that is reduced to water.
cytochrome bo3 ubiquinol oxidase activity	produces	ubiquinone	`GO:0009486` GO:0009486 records ubiquinone as a product of the cytochrome bo3 ubiquinol oxidase reaction.
cytochrome bo3 ubiquinol oxidase activity	produces	water	`GO:0009486` GO:0009486 records water as a product of oxygen reduction by cytochrome bo3 ubiquinol oxidase.
cytochrome bo3 ubiquinol oxidase activity	contributes to	transmembrane proton motive force	`GO:0009486` The GO:0009486 reaction accounts for protons moved to the periplasmic side during cytochrome bo3 ubiquinol oxidase activity.

Evidence

GO:0009319 Gene Ontology cellular-component term for cytochrome o ubiquinol oxidase complex.
GO:0098803 Gene Ontology cellular-component term for respiratory chain complexes.
GO:0009486 Gene Ontology molecular-function term for cytochrome bo3 ubiquinol oxidase activity.
DOI:10.1038/82824 Abramson et al. 2000, The structure of the ubiquinol oxidase from Escherichia coli and its ubiquinone binding site, Nature Structural Biology.
PMID:11017202 PubMed identifier for Abramson et al. 2000 as reported by the RCSB PDB:1FFT primary citation.
PDB:1FFT RCSB Protein Data Bank entry for the E. coli cytochrome bo3 ubiquinol oxidase structure from Abramson et al. 2000.

Curation history

2026-09-24T04:18:51Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-24T04:21:10Z codex · EXPANDED_RECORD — Added GO respiratory-chain parentage, four InterPro-grounded Cyo subunits, the E. coli PDB:1FFT canonical example, cytochrome bo3 ubiquinol oxidase activity, primary Abramson et al. literature/PDB evidence, and a compact terminal-oxidase function graph.

Source: data/structures/energy_complex/cytochrome_o_ubiquinol_oxidase_complex.yaml