FIG. 1.

Present status of knowledge on ortho cleavage pathway for catechol (top) or 4-methylcatechol (bottom) degradation. Metabolic routes for 4-methylcatechol have been proposed for C. necator JMP134 (lower branch) and R. rhodochrous N75 (upper branch). Enzyme names are as follows: 1, catechol 1,2-dioxygenase; 2, muconate cycloisomerase; 3, 4-methylmuconolactone methylisomerase; 4, muconolactone or methylmuconolactone isomerase; 5, 3-oxoadipate enol-lactone hydrolase; 6, 3-oxoadipate:succinyl-CoA transferase; 7, 3-oxoadipyl-CoA thiolase; 8, 3-methylmuconolactone-CoA synthetase; ?, unknown enzymes.