title: beta-Ketoadipate pathway in Trichosporon cutaneum modified for methyl-substituted metabolites.
abstract: Trichosporon cutaneum, when grown with p-cresol, catalyzed intradiol fission of the benzene nucleus of 4-methylcatechol before the complete catabolism of these two substrates. Steps in their conversion to pyruvate and acetyl coenzyme A were investigated by using cell extracts, and some properties of various new microbial catabolites are also described. These included (-)-2,5-dihydro-3-methyl-5-oxofuran-2-acetic acid (beta-methylmuconolactone) and (-)-3-keto-4-methyladipic acid and its coenzyme A ester; the latter was degraded by an enzymatic reaction sequence that included the coenzyme A esters of methylsuccinic, itaconic, and citramalic acids. A notable feature of this sequence is the formation of beta-methylmuconolactone which can be readily metabolized, in contrast to the analogous reaction in bacteria that gives the "dead-end" compound gamma-methylmuconolactone; this compound cannot be enzymatically degraded and so renders the beta-ketoadipate pathway unavailable for methyl-substituted bacterial sources of carbon that are catabolized by way of 4-methylcatechol.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000272:Adipates / Q000138:chemical synthesis / Q000378:metabolism*; D007700:Kinetics; D003904:Mitosporic Fungi / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013869:Thiolester Hydrolases / Q000378:metabolism
chemical_list: D000272:Adipates; C027316:3-oxoadipic acid; D000255:Adenosine Triphosphate; D006899:Mixed Function Oxygenases; D013869:Thiolester Hydrolases; C046584:succinyl-CoA hydrolase