Component of anthranilate dioxygenase multicomponent enzyme system which catalyzes the incorporation of both atoms of molecular oxygen into anthranilate to form catechol. anthranilate + 3 H(+) + NADH + O2 = catechol + CO2 + NAD(+) + NH4(+) anthranilate + 3 H(+) + NADPH + O2 = catechol + CO2 + NADP(+) + NH4(+) KM values measured using the AntAB complex. Optimum pH is 6.3 for the reverse reaction. Aromatic compound metabolism; anthranilate degradation via hydroxylation; catechol from anthranilate: step 1/1. The anthranilate dioxygenase (AntDO) multicomponent enzyme system is composed of an oxygenase component and a NADH:acceptor reductase component (AntC). The oxygenase component is a heterohexamer of 3 large (AntA) and 3 small (AntB) subunits. Belongs to the bacterial ring-hydroxylating dioxygenase beta subunit family.