EC - Heme o synthase

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IntEnz Enzyme Nomenclature


Accepted name:
heme o synthase
Other names:
ctaB (gene name)
COX10 (gene name)
Systematic name:
(2E,6E)-farnesyl-diphosphate:protoheme IX farnesyltranstransferase



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

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
UniProtKB/Swiss-Prot: (536) [show] [UniProt]


  1. Saiki, K., Mogi, T., 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: 1491-1497 (1992). [PMID: 1336371]
  2. Svensson, B., Lubben, M., Hederstedt, L.
    Bacillus subtilis CtaA and CtaB function in haem A biosynthesis.
    Mol. Microbiol. 10: 193-201 (1993). [PMID: 7968515]
  3. Glerum, D. M., Tzagoloff, A.
    Isolation of a human cDNA for heme A:farnesyltransferase by functional complementation of a yeast cox10 mutant.
    Proc. Natl. Acad. Sci. U.S.A. 91: 8452-8456 (1994). [PMID: 8078902]
  4. Brown, B. M., Wang, Z., Brown, K. R., Cricco, J. A., Hegg, E. L.
    Heme O synthase and heme A synthase from Bacillus subtilis and Rhodobacter sphaeroides interact in Escherichia coli.
    Biochemistry 43: 13541-13548 (2004). [PMID: 15491161]
  5. Mogi, T.
    Over-expression and characterization of Bacillus subtilis heme O synthase.
    J. Biochem. 145: 669-675 (2009). [PMID: 19204012]
  6. Lubben, M., Morand, K.
    Novel prenylated hemes as cofactors of cytochrome oxidases. Archaea have modified hemes A and O.
    J. Biol. Chem. 269: 21473-21479 (1994). [PMID: 8063781]

[EC created 2017]