Subunit II of Bacillus subtilis Cytochrome c Oxidase Is a Lipoprotein

Abstract

ABSTRACT The sequence of the N-terminal end of the deduced ctaC gene product of Bacillus species has the features of a bacterial lipoprotein. CtaC is the subunit II of cytochrome caa 3 , which is a cytochrome c oxidase. Using Bacillus subtilis mutants blocked in lipoprotein synthesis, we show that CtaC is a lipoprotein and that synthesis of the membrane-bound protein and covalent binding of heme to the cytochrome c domain is not dependent on processing at the N-terminal part of the protein. Mutants blocked in prolipoprotein diacylglyceryl transferase (Lgt) or signal peptidase type II (Lsp) are, however, deficient in cytochrome caa 3 enzyme activity. Removal of the signal peptide from the CtaC polypeptide, but not lipid modification, is seemingly required for formation of functional enzyme.