Reaction: androsta-1,4-diene-3,17-dione + NADH + H+ + O2 = 9α-hydroxyandrosta-1,4-diene-3,17-dione + NAD+ + H2O
Other name(s): KshAB; 3-ketosteroid 9α-hydroxylase
Systematic name: androsta-1,4-diene-3,17-dione,NADH:oxygen oxidoreductase (9α-hydroxylating)
Comments: The enzyme is involved in the cholesterol degradation pathway of several bacterial pathogens, such as Mycobacterium tuberculosis. It is a two-component system consisting of a terminal oxygenase (KshA) and a ferredoxin reductase (KshB). The oxygenase contains a Rieske-type iron-sulfur center and non-heme iron. The reductase component is a flavoprotein containing an NAD-binding domain and a plant-type iron-sulfur cluster. The product of the enzyme is unstable, and spontaneously converts to 3-hydroxy-9,10-seconandrost-1,3,5(10)-triene-9,17-dione.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, UM-BBD, CAS registry number:
1. Petrusma, M., Dijkhuizen, L. and van der Geize, R. Rhodococcus rhodochrous DSM 43269 3-ketosteroid 9α-hydroxylase, a two-component iron-sulfur-containing monooxygenase with subtle steroid substrate specificity. Appl. Environ. Microbiol. 75 (2009) 5300-5307. [PMID: 19561185]
2. Capyk, J.K., D'Angelo, I., Strynadka, N.C. and Eltis, L.D. Characterization of 3-ketosteroid 9α-hydroxylase, a Rieske oxygenase in the cholesterol degradation pathway of Mycobacterium tuberculosis. J. Biol. Chem. 284 (2009) 9937-9946. [PMID: 19234303]
3. Capyk, J.K., Casabon, I., Gruninger, R., Strynadka, N.C. and Eltis, L.D. Activity of 3-ketosteroid 9α-hydroxylase (KshAB) indicates cholesterol side chain and ring degradation occur simultaneously in Mycobacterium tuberculosis. J. Biol. Chem. (2011) . [PMID: 21987574]