The paa cluster of Escherichia coli W involved in the aerobic catabolism of phenylacetic acid (PA) has been cloned and sequenced. It was shown to map at min 31.0 of the chromosome at the right end of the mao region responsible for the transformation of 2-phenylethylamine into PA. The 14 paa genes are organized in three transcription units:paaZ and paaABCDEFGHIJK, encoding catabolic genes; and paaXY, containing thepaaX regulatory gene. The paaK gene codes for a phenylacetyl-CoA ligase that catalyzes the activation of PA to phenylacetyl-CoA (PA-CoA). The paaABCDE gene products, which may constitute a multicomponent oxygenase, are involved in PA-CoA hydroxylation. The PaaZ protein appears to catalyze the third enzymatic step, with the paaFGHIJ gene products, which show significant similarity to fatty acid β-oxidation enzymes, likely involved in further mineralization to Krebs cycle intermediates. Three promoters, Pz, Pa, and Px, driven the expression of genes paaZ, paaABCDEFGHIJK, and paaX, respectively, have been identified. ThePa promoter is negatively controlled by thepaaX gene product. As PA-CoA is the true inducer, PaaX becomes the first regulator of an aromatic catabolic pathway that responds to a CoA derivative. The aerobic catabolism of PA in E. coli represents a novel hybrid pathway that could be a widespread way of PA catabolism in bacteria.
Catabolism of Phenylacetic Acid in Escherichia coli
A. Ferrández,B. Miñambres,B. Garcı́a,E. R. Olivera,J. Luengo,J. L. García,E. Díaz
Published 1998 in Journal of Biological Chemistry
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- Publication year
1998
- Venue
Journal of Biological Chemistry
- Publication date
1998-10-02
- Fields of study
Biology, Medicine, Chemistry
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Semantic Scholar, PubMed
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