IUBMB Enzyme Nomenclature


Accepted name: heme o synthase

Reaction: (2E,6E)-farnesyl diphosphate + protoheme IX + H2O = diphosphate + ferroheme o

For diagram of reaction click here

Other name(s): ctaB (gene name); COX10 (gene name)

Systematic name: (2E,6E)-farnesyl-diphosphate:protoheme IX farnesyltranstransferase

Comments: The enzyme, found in many archaea, bacteria, and eukaryotes, produces heme o, which in many cases is further modified into heme a. In organisms that produce heme a, the enzyme forms a complex with heme a synthase. In some archaeal species the enzyme transfers a geranylgeranyl group instead of a farnesyl group

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Saiki, K., Mogi, T. and Anraku, Y. Heme O biosynthesis in Escherichia coli: the cyoE gene in the cytochrome bo operon encodes a protoheme IX farnesyltransferase. Biochem. Biophys. Res. Commun. 189 (1992) 1491-1497. [PMID: 1336371]

2. Svensson, B., Lubben, M. and Hederstedt, L. Bacillus subtilis CtaA and CtaB function in haem A biosynthesis. Mol. Microbiol. 10 (1993) 193-201. [PMID: 7968515]

3. Glerum, D.M. and Tzagoloff, A. Isolation of a human cDNA for heme A:farnesyltransferase by functional complementation of a yeast cox10 mutant. Proc. Natl. Acad. Sci. USA 91 (1994) 8452-8456. [PMID: 8078902]

4. Lubben, M. and Morand, K. Novel prenylated hemes as cofactors of cytochrome oxidases. Archaea have modified hemes A and O. J. Biol. Chem 269 (1994) 21473-21479. [PMID: 8063781]

5. Brown, B.M., Wang, Z., Brown, K.R., Cricco, J.A. and Hegg, E.L. Heme O synthase and heme A synthase from Bacillus subtilis and Rhodobacter sphaeroides interact in Escherichia coli. Biochemistry 43 (2004) 13541-13548. [PMID: 15491161]

6. Mogi, T. Over-expression and characterization of Bacillus subtilis heme O synthase. J. Biochem. 145 (2009) 669-675. [PMID: 19204012]

[EC created 2017]

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