|PROSITE documentation PDOC00075|
Cytochrome c oxidase (EC 18.104.22.168) [1,2] is an oligomeric enzymatic complex which is a component of the respiratory chain and is involved in the transfer of electrons from cytochrome c to oxygen. In eukaryotes this enzyme complex is located in the mitochondrial inner membrane; in aerobic prokaryotes it is found in the plasma membrane. The enzyme complex consists of 3-4 subunits (prokaryotes) to up to 13 polypeptides (mammals).
Subunit 2 (CO II) transfers the electrons from cytochrome c to the catalytic subunit 1. It contains two adjacent transmembrane regions in its N-terminus and the major part of the protein is exposed to the periplasmic or to the mitochondrial intermembrane space, respectively. CO II provides the substrate-binding site and contains a copper center called Cu(A), located in the extramembrane domain (see <PDB:1OCZ; B>), probably the primary acceptor in cytochrome c oxidase. An exception is the corresponding subunit of the cbb3-type oxidase which lacks the copper A redox-center. Several bacterial CO II have a C-terminal extension that contains a covalently bound heme c.
It has been shown [3,4] that nitrous oxide reductase (EC 22.214.171.124) (gene nosZ) of Pseudomonas has sequence similarity in its C-terminus to CO II. This enzyme is part of the bacterial respiratory system which is activated under anaerobic conditions in the presence of nitrate or nitrous oxide. NosZ is a periplasmic homodimer that contains a dinuclear copper center, probably located in a 3-dimensional fold similar to the cupredoxin-like fold that has been suggested for the copper-binding site of CO II .
The dinuclear purple copper center is formed by 2 histidines and 2 cysteines . We used this region as a signature pattern. The conserved valine and the conserved methionine are said to be involved in stabilizing the copper-binding fold by interacting with each other. We also developed two profiles, one directed against the transmembrane region and one against the copper center.Note:
Cytochrome cbb(3) subunit 2 does not belong to this family.Last update:
June 2004 / Text revised; profiles added.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Capaldi R.A., Malatesta F., Darley-Usmar V.M.|
|Title||Structure of cytochrome c oxidase.|
|Source||Biochim. Biophys. Acta 726:135-148(1983).|
|2||Authors||Garcia-Horsman J.A., Barquera B., Rumbley J., Ma J., Gennis R.B.|
|Source||J. Bacteriol. 176:5587-5600(1994).|
|3||Authors||van der Oost J., Lappalainen P., Musacchio A., Warne A., Lemieux L., Rumbley J., Gennis R.B., Aasa R., Pascher T., Malmstrom B.G., Saraste M.|
|Source||EMBO J. 11:3209-3217(1992).|
|4||Authors||Zumft W.G., Dreusch A., Lochelt S., Cuypers H., Friedrich B., Schneider B.|
|Title||Derived amino acid sequences of the nosZ gene (respiratory N2O reductase) from Alcaligenes eutrophus, Pseudomonas aeruginosa and Pseudomonas stutzeri reveal potential copper-binding residues. Implications for the CuA site of N2O reductase and cytochrome-c oxidase.|
|Source||Eur. J. Biochem. 208:31-40(1992).|
|Source||Unpublished observations (1994).|