CcmE is the product of one of a cluster of Ccm genes that are necessary for cytochrome c biosynthesis in eubacteria. Expression of these proteins is induced when the organisms are grown under anaerobic conditions with nitrate or nitrite as the final electron acceptor.

1: Escherichia coli genes required for cytochrome c maturation. Thony-Meyer L, Fischer F, Kunzler P, Ritz D, Hennecke H; J Bacteriol 1995;177:4321-4326. PMID:7635817

2: The cycHJKL gene cluser plays an essential role in the biogenesis of c-type cytochromes in Bradyrhizobium japonicum. Ritz D, Thony-Meyer L, Hennecke H; Mol Gen Genet 1995;247:27-38. PMID:7715601