title: Evidence for isofunctional enzymes in the degradation of phenol, m- and p-toluate, and p-cresol via catechol meta-cleavage pathways in Alcaligenes eutrophus.
abstract: A study of the degradation of phenol, p-cresol, and m- and p-toluate by Alcaligenes eutrophus 345 has provided evidence that these compounds are metabolized via separate catechol meta-cleavage pathways. Analysis of the enzymes synthesized by wild-type and mutant strains and by strains cured of the plasmid pRA1000, which encodes m- and p-toluate degradation, indicated that two or more isofunctional enzymes mediated several steps in the pathway. The formation of three catechol 2,3-oxygenases and two 2-hydroxymuconic semialdehyde hydrolases was indicated from an examination of the ratio of the specific activities of these enzymes against various substrates. Evidence for two 2-hydroxymuconic semialdehyde dehydrogenases, two 4-oxalocrotonate isomerases and decarboxylases, and three 2-ketopent-4-enoate hydratases was derived from the induction of these enzymes under different growth conditions. Each activity was detected when the wild type was grown in the presence of m-toluate, but not when grown with phenol (except for a hydratase) or p-cresol, whereas in strains cured of pRA1000, growth with phenol or p-cresol, but not with m-toluate, induced these enzymes. Hydroxylation of phenol and p-cresol appears to be mediated by the same enzyme.
mesh_terms: D000421:Alcaligenes / Q000201:enzymology* / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000445:Aldehyde Oxidoreductases; D001565:Benzoates / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism; D050557:Catechol 2,3-Dioxygenase; D002396:Catechols / Q000378:metabolism; D003408:Cresols / Q000378:metabolism*; D003437:Crotonates / Q000378:metabolism; D049308:Dioxygenases; D006836:Hydro-Lyases / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism; D006900:Hydroxylation; D007535:Isomerases / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D019800:Phenol; D010636:Phenols / Q000378:metabolism*; D011506:Proteins
chemical_list: D001565:Benzoates; D002396:Catechols; D003408:Cresols; D003437:Crotonates; D010636:Phenols; D011506:Proteins; C032538:4-cresol; C009503:3-toluic acid; C002788:oxalocrotonate; D019800:Phenol; C009504:4-toluic acid; D000429:Alcohol Oxidoreductases; D010105:Oxygenases; D049308:Dioxygenases; D050557:Catechol 2,3-Dioxygenase; D000445:Aldehyde Oxidoreductases; C023320:2-hydroxymuconic semialdehyde dehydrogenase; D006867:Hydrolases; C092541:2-hydroxymuconate-semialdehyde hydrolase; C021917:4-oxalocrotonate decarboxylase; D002262:Carboxy-Lyases; D006836:Hydro-Lyases; C061677:2-oxopent-4-enoate hydratase; C021918:4-oxalocrotonate tautomerase; D007535:Isomerases; C034221:catechol