Catabolism of tryptophan, anthranilate, and 2,3-dihydroxybenzoate in Trichosporon cutaneum

Abstract

T. cutaneum degraded L-tryptophan by a reaction sequence that included L-kynurenine, anthranilate, 2,3-dihydroxybenzoate, catechol and β-ketoadipate as catabolites. All of the enzymes of the sequence were induced by both L-tryptophan and salicylate, and those for oxidizing kynurenine and its catabolites were induced by anthranilate but not by benzoate; induction was not coordinate. Molecular weights of 66,100 and 36,500 were determined, respectively, for purified 2,3-dihydroxybenzoate decarboxylase and its single subunit. Substrates for this enzyme were restricted to benzoic acids substituted with hydroxyl groups at C-2 and C-3; no added coenzyme was required for activity. Partially purified anthranilate hydroxylase (deaminating) catalyzed the incorporation of one atom of 18O, derived from either 18O2 or H218O, into 2,3-dihydroxybenzoic acid.