Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen into the other donor
BRITE hierarchy

cholest-4-en-3-one,reduced [2Fe-2S] ferredoxin:oxygen oxidoreductase [(25R)-3-oxocholest-4-en-26-oate forming]

cholest-4-en-3-one + 6 reduced [2Fe-2S] ferredoxin + 3 O2 = (25R)-3-oxocholest-4-en-26-oate + 6 oxidized [2Fe-2S] ferredoxin + 4 H2O (overall reaction) [RN:R11361];
(1a) cholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-26-hydroxycholest-4-en-3-one + 2 oxidized [2Fe-2S] ferredoxin + H2O [RN:R11358];
(1b) (25R)-26-hydroxycholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-26-oxocholest-4-en-3-one + 2 oxidized [2Fe-2S] ferredoxin + 2 H2O [RN:R11359];
(1c) (25R)-26-oxocholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-3-oxocholest-4-en-26-oate + 2 oxidized [2Fe-2S] ferredoxin + H2O [RN:R11360]

R11358 R11359 R11360 R11361
Reaction

cholest-4-en-3-one [CPD:C00599];
reduced [2Fe-2S] ferredoxin [CPD:C22150];
O2 [CPD:C00007];
(25R)-26-hydroxycholest-4-en-3-one [CPD:C21303];
(25R)-26-oxocholest-4-en-3-one [CPD:C21305]

This cytochrome P-450 (heme-thiolate) enzyme, found in several bacterial pathogens, is involved in degradation of the host cholesterol. It catalyses the hydroxylation of the C-26 carbon, followed by oxidation of the alcohol to the carboxylic acid via the aldehyde intermediate, initiating the degradation of the alkyl side-chain of cholesterol. The products are exclusively in the (25R) conformation. The enzyme also accepts cholesterol as a substrate. cf. EC 1.14.15.29, cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]. The enzyme can receive electrons from ferredoxin reductase in vitro, its natural electron donor is not known yet.

EC 1.14.15.28 created 2016 as EC 1.14.13.221, transferred 2018 to EC 1.14.15.28

1  [PMID:20889498]

Driscoll MD, McLean KJ, Levy C, Mast N, Pikuleva IA, Lafite P, Rigby SE, Leys D, Munro AW

Structural and biochemical characterization of Mycobacterium tuberculosis CYP142: evidence for multiple cholesterol 27-hydroxylase activities in a human pathogen.

J Biol Chem 285:38270-82 (2010)
DOI:10.1074/jbc.M110.164293

[mtu:Rv3518c]

2  [PMID:20843794]

Johnston JB, Ouellet H, Ortiz de Montellano PR

Functional redundancy of steroid C26-monooxygenase activity in Mycobacterium tuberculosis revealed by biochemical and genetic analyses.

J Biol Chem 285:36352-60 (2010)
DOI:10.1074/jbc.M110.161117

[mtu:Rv3518c]