MetaCyc EC 1.14.15.20 -- heme oxygenase (biliverdin-producing, ferredoxin)

Parent Class: EC-Numbers → 1 -- Oxidoreductases → 1.14 -- Acting on paired donors, with incorporation or reduction of molecular oxygen → 1.14.15 -- With a reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen into the other donor

Synonyms: HO1 (gene name), HY1 (gene name), HO3 (gene name), HO4 (gene name), pbsA1 (gene name)

Systematic Name: protoheme,reduced ferredoxin:oxygen oxidoreductase (α-methene-oxidizing, hydroxylating)

Unification Links: BRENDA:1.14.15.20, ENZYME:1.14.15.20, IUBMB-ExplorEnz:1.14.15.20

Reaction:
6 reduced ferredoxin [iron-sulfur] cluster + protoheme + 3 dioxygen + 8 H+ → (Z,Z)-biliverdin-IX α + Fe2+ + carbon monoxide + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O

Enzymes and Genes:
heme oxygenase: hemO ( Neisseria meningitidis )
heme oxygenase (biliverdin-producing, ferredoxin): hmuO ( Corynebacterium diphtheriae )
heme oxygenase: bphO ( Pseudomonas aeruginosa )
heme oxygenase: ho1 ( Gloeobacter violaceus )
heme oxygenase 1: pbsA1 ( Synechocystis sp. PCC 6803 )
heme oxygenase: ho1 ( Parasynechococcus marenigrum WH 8102 )
heme oxygenase: ho1 ( Prochlorococcus phage P-SSM2 )
heme oxygenase 1: pbsA1 ( Nostoc sp. PCC 7120 = FACHB-418 )
heme oxygenase: HO3 ( Arabidopsis thaliana col )
heme oxygenase: HO4 ( Arabidopsis thaliana col )
heme oxygenase: HO1 ( Arabidopsis thaliana col )

Summary:
The enzyme, found in plants, algae, and cyanobacteria, participates in the biosynthesis of phytochromobilin and phytobilins. The terminal oxygen atoms that are incorporated into the carbonyl groups of pyrrole rings A and B of biliverdin are derived from two separate oxygen molecules. The third oxygen molecule provides the oxygen atom that converts the α-carbon to carbon monoxide. Unlike this enzyme, which uses ferredoxin as its electron donor, the electron source for the related mammalian enzyme ( EC 1.14.14.18) is EC 1.6.2.4, NADPH—hemoprotein reductase.

Citations: [Montgomery02, Sugishima04, Dammeyer08]

References

Dammeyer08: Dammeyer T, Frankenberg-Dinkel N (2008). "Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms." Photochem Photobiol Sci 7(10);1121-30. PMID: 18846276

Montgomery02: Montgomery BL, Lagarias JC (2002). "Phytochrome ancestry: sensors of bilins and light." Trends Plant Sci 7(8);357-66. PMID: 12167331

Sugishima04: Sugishima M, Migita CT, Zhang X, Yoshida T, Fukuyama K (2004). "Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme." Eur J Biochem 271(22);4517-25. PMID: 15560792

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 46(D1):D633-D639 2018
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