The CarAc gene in Pseudomonas codes for the ferredoxin component of carbazole-1,9-dioxygenase. Together with CarAa and CarAd it forms the carbazole-1,9-dioxygenase (CARDO) enzyme which converts carbazole into 2'-aminobiphenyl-2,3-diol by cleaving one C-N bond in the original carbazole molecule.