Intradiol ring-cleavage dioxygenase involved in an alternative pathway to the protocatechuic acid pathway since it is active on hydroxyquinol and catechol but not on protocatechuic acid. catechol + O2 = cis,cis-muconate + 2 H(+) benzene-1,2,4-triol + O2 = 3-hydroxy-cis,cis-muconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Homodimer. Expression is slightly induced in the presence of caffeic acid, p-hydroxybenzoic acid and protocatechuic acid. Leads to reduced growth on protocatechuic acid and the accumulation of hydroxyquinol, when prcA is also deleted. Belongs to the intradiol ring-cleavage dioxygenase family.