In vitro, catalyzes the introduction of a 9alpha-hydroxyl moiety into the ring B of 3-ketosteroid substrates such as 1,4-androstadiene-3,17-dione (ADD), 4-androstene-3,17-dione (AD), 4-androstene-17beta-ol-3-one (testosterone), 4-pregnene-3,20-dione (progesterone), 23,24-bisnorcholesta-4-ene-22-oate and 23,24-bisnorcholesta-1,4-diene-22-oate. 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 [2Fe-2S] cluster per subunit. Binds 1 Fe cation. Homotrimer. The two-component system 3-ketosteroid-9-alpha-monooxygenase is composed of an oxygenase component KshA and a reductase component KshB. By 4-androstene-3,17-dione (AD).