Ring-cleaving dioxygenase involved in quinaldine degradation and utilization. 3-hydroxy-2-methyl-1H-quinolin-4-one + O2 = CO + H(+) + N-acetylanthranilate None. Contrary to most other dioxygenases, this enzyme does not require a cofactor for catalysis. Optimum pH is 8-11. Expressed from a large linear plasmid that contains the operon for quinaldine degradation. Belongs to the AB hydrolase superfamily.