title: Catabolism of L-tyrosine by the homoprotocatechuate pathway in gram-positive bacteria.
abstract: A metabolic pathway for L-tyrosine catabolism involves 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid) as substrate for fission of the benzene nucleus. Cell extracts of an organism tentatively identified as a Micrococcus possessed the enzymes required for degrading homoprotocatechuate to succinate and pyruvate, and stoichiometry was established for several of these reactions. When the required coenzymes were added, cell extracts degraded L-tyrosine to the ring-fission product of homoprotocatechuate 2,3-dioxygenase and also converted 4-hydroxyphenylpyruvic acid into 4-hydroxyphenylacetic acid. This compound, in turn, gave stoichiometric amounts of the ring-fission product of homoprotocatechuate by the action of a nicotinamide adenine dinucleotide phosphate-dependent 3-hydroxylase coupled with homoprotocatechuate 2,3-dioxygenase. Evidence is presented that this route for L-tyrosine catabolism is taken by five other gram-positive strains, including Micrococcus lysodeikticus and a species of Bacillus. Five other gram-positive bacteria from other genera employed the alternative homogentisate pathway.
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D002474:Cell-Free System; D003352:Corynebacterium / Q000201:enzymology / Q000378:metabolism; D008837:Micrococcus / Q000201:enzymology / Q000378:metabolism; D009161:Mycobacterium / Q000201:enzymology / Q000378:metabolism; D009615:Nocardia / Q000201:enzymology / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D010648:Phenylacetates / Q000378:metabolism*; D011773:Pyruvates / Q000096:biosynthesis; D013237:Stereoisomerism; D013386:Succinates / Q000096:biosynthesis; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D010648:Phenylacetates; D011773:Pyruvates; D013386:Succinates; D015102:3,4-Dihydroxyphenylacetic Acid; D014443:Tyrosine; D010105:Oxygenases