CYP125A

PMID:19846551

PMID:19843222

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 ferredoxin]:oxygen oxidoreductase [(25S)-3-oxocholest-4-en-26-oate-forming]

cholest-4-en-3-one + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+ + 3 O2 = (25S)-3-oxocholest-4-en-26-oate + 6 oxidized ferredoxin [iron-sulfur] cluster + 4 H2O (overall reaction) [RN:R11357];
(1a) cholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-26-hydroxycholest-4-en-3-one + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O [RN:R09859];
(1b) (25S)-26-hydroxycholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-26-oxocholest-4-en-3-one + 2 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O [RN:R11355];
(1c) (25S)-26-oxocholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-3-oxocholest-4-en-26-oate + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O [RN:R11356]

R09859 R11355 R11356 R11357
Reaction

cholest-4-en-3-one [CPD:C00599];
reduced ferredoxin [iron-sulfur] cluster [CPD:C00138];
H+ [CPD:C00080];
O2 [CPD:C00007];
(25S)-26-hydroxycholest-4-en-3-one [CPD:C20143];
(25S)-26-oxocholest-4-en-3-one [CPD:C21304]

A cytochrome P-450 (heme-thiolate) protein found in several bacterial pathogens. The enzyme is involved in degradation of the host's 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 [4]. The products are exclusively in the (25S) configuration. The enzyme is part of a two-component system that also includes a ferredoxin reductase (most likely KshB, which also interacts with EC 1.14.15.30, 3-ketosteroid 9alpha-monooxygenase). The enzyme also accepts cholesterol as a substrate. cf. EC 1.14.15.28, cholest-4-en-3-one 27-monooxygenase.

EC 1.14.15.29 created 2012 as EC 1.14.13.141, modified 2016, transferred 2018 to EC 1.14.15.29