Intradiol ring-cleavage dioxygenase; part of the benzoic acid degradation pathway also known as the protocatechuic acid pathway (PubMed:25479309). Benzoic acid debradation begins with the conversion of benzoic acid into 4-hydroxybenzoic acid through hydroxylation by the benzoate-4-monooxygenase bphA, and its partner NADPH-cytochrome P450 reductase cprA which act as a mediator in electron donation from NADPH (By similarity). 4-Hydroxybenzoic acid is then converted into 3,4-dihydroxybenzoic acid (also called protocatechuic acid) by the p-hydroxybenzoate-m-hydroxylase phhA (Probable). Protocatechuic acid is converted into 3-carboxy-cis,cis-muconic acid by the intradiol ring-cleavage dioxygenase prcA, which is further metabolized through the 3-oxoadipate pathway to finally enter the tricarboxylic acid cycle (TCA) (Probable). 3,4-dihydroxybenzoate + O2 = 3-carboxy-cis,cis-muconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Homodimer. Expression is up-regulated in the presence of benzoate. Belongs to the intradiol ring-cleavage dioxygenase family.