Ring-cleaving dioxygenase involved in oxoquinoline degradation and utilization. 3-hydroxy-1H-quinolin-4-one + O2 = CO + H(+) + N-formylanthranilate None. Contrary to most other dioxygenases, this enzyme does not require a cofactor for catalysis. Optimum pH is 8. Belongs to the AB hydrolase superfamily.