D
IPR033945

Cytochrome c oxidase subunit III domain

InterPro entry
Short nameCyt_c_oxase_su3_dom
Overlapping
homologous
superfamilies
 
domain relationships

Description

Cytochrome c oxidase (
7.1.1.9
) is the terminal enzyme of the respiratory chain of mitochondria and many aerobic bacteria. It catalyses the transfer of electrons from reduced cytochrome c to molecular oxygen:

4 cytochrome c+2 + 4 H+ + O2 --> 4 cytochrome c+3 + 2 H2O

This reaction is coupled to the pumping of four additional protons across the mitochondrial or bacterial membrane
[2, 6]
.

Cytochrome c oxidase is an oligomeric enzymatic complex that is located in the mitochondrial inner membrane of eukaryotes and in the plasma membrane of aerobic prokaryotes. The core structure of prokaryotic and eukaryotic cytochrome c oxidase contains three common subunits, I, II and III. In prokaryotes, subunits I and III can be fused and a fourth subunit is sometimes found, whereas in eukaryotes there are a variable number of additional small polypeptidic subunits
[5]
. The functional role of subunit III is not yet understood.

As the bacterial respiratory systems are branched, they have a number of distinct terminal oxidases, rather than the single cytochrome c oxidase present in the eukaryotic mitochondrial systems. Even though the cytochrome o complex oxidises quinol (ubiquinol) and does not catalyse the oxidation of reduced cytochrome c, they belong to the same haem-copper oxidase superfamily as cytochrome c oxidases. Members of this family share sequence similarities in all three core subunits: subunit I is the most conserved subunit, whereas subunit II is the least conserved
[4, 3, 1]
.

This entry represents a structural domain found in subunit III of cytochrome c oxidase specifically.

References

1.The superfamily of heme-copper respiratory oxidases. Garcia-Horsman JA, Barquera B, Rumbley J, Ma J, Gennis RB. J. Bacteriol. 176, 5587-600, (1994). View articlePMID: 8083153

2.Cytochrome c oxidase: catalytic cycle and mechanisms of proton pumping--a discussion. Michel H. Biochemistry 38, 15129-40, (1999). View articlePMID: 10563795

3.The sequence of the cyo operon indicates substantial structural similarities between the cytochrome o ubiquinol oxidase of Escherichia coli and the aa3-type family of cytochrome c oxidases. Chepuri V, Lemieux L, Au DC, Gennis RB. J. Biol. Chem. 265, 11185-92, (1990). View articlePMID: 2162835

4.Molecular cloning, sequencing, and physiological characterization of the qox operon from Bacillus subtilis encoding the aa3-600 quinol oxidase. Santana M, Kunst F, Hullo MF, Rapoport G, Danchin A, Glaser P. J. Biol. Chem. 267, 10225-31, (1992). View articlePMID: 1316894

5.Cytochrome oxidase genes from Thermus thermophilus. Nucleotide sequence of the fused gene and analysis of the deduced primary structures for subunits I and III of cytochrome caa3. Mather MW, Springer P, Hensel S, Buse G, Fee JA. J. Biol. Chem. 268, 5395-408, (1993). View articlePMID: 8383670

6.Proton-coupled electron transfer drives the proton pump of cytochrome c oxidase. Belevich I, Verkhovsky MI, Wikstrom M. Nature 440, 829-32, (2006). View articlePMID: 16598262

GO terms

biological process

  • None

cellular component

  • None

Cross References

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