The Paracoccus denitrificans cytochrome aa3 has a third subunit

Abstract

The presence of a third polypeptide subunit in Paracoccus cytochrome c oxidase is demonstrated. This protein (apparent molecular mass 23 kDa) binds dicyclohexylcarbodiimide in membranes of aerobically grown bacteria and in the purified enzyme. The N‐terminal amino‐acid sequence of this dicyclohexylcarbodiimide‐binding protein is identical to the deduced sequence of the COIII gene product [Raitio et al. (1987)EMBO J. 6, 2825–2833]. We conclude that the aa3‐type oxidase in Paracoccus is composed of at least three subunits, which correspond to the three mitochondrially coded polypeptides in the eukaryotic enzyme. Copyright © 1988, Wiley Blackwell. All rights reserved