Evidence for isofunctional enzymes used in m-cresol and 2,5-xylenol degradation via the gentisate pathway in Pseudomonas alcaligenes.

Study of the reaction sequence by which Pseudomonas alcaligenes (P25X1) and derived mutants degrade m-cresol, 2,5-xylenol, and their catabolites has provided indirect evidence for the existence of two or more isofunctional enzymes at three different steps. Maleylpyruvate hydrolase activity appears to reside in two different proteins with different specificity ranges, one of which (MPH1) is expressed constitutively; the other (MPH11) is strictly inducible. Two gentisate 1,2-dioxygenase activities were found, one of which is constitutively expressed and possesses a broader specificity range than the other, which is inducible.