Involved in the degradation of cholesterol. Catalyzes the introduction of a 9a-hydroxyl moiety into 1,4-androstadiene-3,17-dione (ADD) to yield the 9alpha-hydroxy-1,4-androstadiene-3,17-dione (9OHADD) intermediate which spontaneously form 3-hydroxy-9,10-seconandrost-1,3,5(10)-triene-9,17-dione (HSA) via the meta-cleavage of ring B with concomitant aromatization of ring A. KSH is also able to use 4-androstene-3,17-dione (AD), 3-oxo-23,24-bisnorcholesta-4-en-22-oate (4-BNC), 3-oxo-23,24-bisnorcholesta-1,4-dien-22-oate (1,4-BNC), 3-oxo-23,24-bisnorcholesta-4-en-22-oyl-coenzyme A thioester (4-BNC-CoA) and 3-oxo-23,24-bisnorcholesta-1,4-dien-22-oyl-coenzyme A thioester (1,4-BNC-CoA) as substrates. androsta-1,4-diene-3,17-dione + 2 H(+) + O2 + 2 reduced [2Fe-2S]-[ferredoxin] = 9alpha-hydroxyandrosta-1,4-diene-3,17-dione + H2O + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 1 FAD per subunit. Binds 1 2Fe-2S cluster. kcat is 2.7 sec(-1) for 1,4-BNC-CoA as substrate (at pH 7 and at 22 degrees Celsius) (PubMed:21987574). kcat is 0.8 sec(-1) for ADD as substrate (at pH 7 and at 25 degrees Celsius) (PubMed:19234303). kcat is 0.61 sec(-1) for 4-BNC-CoA as substrate (at pH 7 and at 22 degrees Celsius) (PubMed:21987574). kcat is 0.25 sec(-1) for 1,4-BNC as substrate (at pH 7 and at 22 degrees Celsius) (PubMed:21987574). kcat is 0.08 sec(-1) for 4-BNC as substrate (at pH 7 and at 22 degrees Celsius) (PubMed:21987574). kcat is 0.07 sec(-1) for AD as substrate (at pH 7 and at 25 degrees Celsius) (PubMed:19234303). Lipid metabolism; steroid biosynthesis. Monomer. The two-component system 3-ketosteroid-9-alpha-monooxygenase is composed of an oxygenase component KshA and a reductase component KshB. Induced by KstR.