catechol + O2 = cis,cis-muconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Aromatic compound metabolism; beta-ketoadipate pathway; 5-oxo-4,5-dihydro-2-furylacetate from catechol: step 1/3. Belongs to the intradiol ring-cleavage dioxygenase family.