Part of the multicomponent carbazole 1,9a-dioxygenase (CARDO), that converts carbazole (CAR) into 2-aminobiphenyl-2,3-diol. It can use both NAD and NADP as electron donors, but NAD is supposed to be the physiological electron donor. H(+) + NAD(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADH + 2 oxidized [2Fe-2S]-[ferredoxin] H(+) + NADP(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADPH + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 1 [2Fe-2S] cluster per subunit. Binds 1 FAD per subunit. Optimum pH is between 7 and 7.5. Optimum temperature is 30 degrees Celsius. Monomer. Carbazole 1,9a-dioxygenase complex consists of a terminal oxygenase component CarAa, a ferredoxin reductase component CarAd and a ferredoxin component CarAc.