Chlorocatechol 1,2-dioxygenase involved in the degradation of chlorinated benzenes, that occurs via chlorocatechol intermediates. Displays broad substrate specificity. Preferentially cleaves 3-chlorocatechol and 3,4-dichlorocatechol, and shows lower activity on 3,5-dichlorocatechol, 3,6-dichlorocatechol and 3,4,6-trichlorocatechol in vitro. Is not able to convert 3,4,5-trichlorocatechol and 3,4,5,6-tetrachlorocatechol. Thus, probably functions in the degradation pathways of 1,2-dichlorobenzene, 1,4-dichlorobenzene and 1,2,4-trichlorobenzene (via 3,4-dichlorocatechol, 3,6-dichlorocatechol and 3,4,6-trichlorocatechol intermediates, respectively), which allow Pseudomonas sp. strain P51 to grow on these substrates as the sole carbon and energy source. 3-chlorocatechol + O2 = (2E,4Z)-2-chloromuconate + 2 H(+) 3,4-dichlorocatechol + O2 = (2Z,4Z)-2,3-dichloromuconate + 2 H(+) 3,5-dichlorocatechol + O2 = (2E,4E)-2,4-dichloromuconate + 2 H(+) 3,6-dichlorocatechol + O2 = (2E,4E)-2,5-dichloromuconate + H(+) 3,4,6-trichlorocatechol + O2 = (2Z,4E)-2,3,5-trichloromuconate + H(+) Binds 1 Fe(3+) ion per subunit. Xenobiotic degradation. Belongs to the intradiol ring-cleavage dioxygenase family.