title: Phenylacetate catabolism in Rhodococcus sp. strain RHA1: a central pathway for degradation of aromatic compounds.
abstract: In gram-negative bacteria, a pathway for aerobic degradation of phenylacetic acid (PAA) that proceeds via phenylacetyl-coenzyme A (CoA) and hydrolytic ring fission plays a central role in the degradation of a range of aromatic compounds. In contrast, the PAA pathway and its role are not well characterized in gram-positive bacteria. A cluster including 13 paa genes encoding enzymes orthologous to those of gram-negative bacteria was identified on the chromosome of Rhodococcus sp. strain RHA1. These genes were transcribed during growth on PAA, with 11 of the genes apparently in an operon yielding a single transcript. Quantitative proteomic analyses revealed that at least 146 proteins were more than twice as abundant in PAA-grown cells of RHA1 than in pyruvate-grown cells. Of these proteins, 29 were identified, including 8 encoded by the paa genes. Knockout mutagenesis indicated that paaN, encoding a putative ring-opening enzyme, was essential for growth on PAA. However, paaF, encoding phenylacetyl-CoA ligase, and paaR, encoding a putative regulator, were not essential. paaN was also essential for growth of RHA1 on phenylacetaldehyde, phenylpyruvate, 4-phenylbutyrate, 2-phenylethanol, 2-phenylethylamine, and l-phenylalanine. In contrast, growth on 3-hydroxyphenylacetate, ethylbenzene, and styrene was unaffected. These results suggest that the range of substrates degraded via the PAA pathway in RHA1 is somewhat limited relative to the range in previously characterized gram-negative bacteria.
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Juana María
authors.initials: JM
authors.lastname: Navarro-Llorens
authors.forename: Marianna A
authors.initials: MA
authors.lastname: Patrauchan
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Stewart
authors.forename: Julian E
authors.initials: JE
authors.lastname: Davies
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Eltis
authors.forename: William W
authors.initials: WW
authors.lastname: Mohn
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000378:metabolism; D002876:Chromosomes, Bacterial; D015180:Electrophoresis, Gel, Two-Dimensional; D006136:GTP Cyclohydrolase / Q000235:genetics; D005798:Genes, Bacterial; D005810:Multigene Family; D010627:Phenethylamines / Q000378:metabolism; D010648:Phenylacetates / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D010654:Phenylbutyrates / Q000378:metabolism; D010626:Phenylethyl Alcohol / Q000378:metabolism; D010667:Phenylpyruvic Acids / Q000378:metabolism; D020543:Proteome / Q000032:analysis / Q000378:metabolism; D012240:Rhodococcus / Q000235:genetics / Q000378:metabolism*
chemical_list: D010627:Phenethylamines; D010648:Phenylacetates; D010654:Phenylbutyrates; D010667:Phenylpyruvic Acids; D020543:Proteome; C029261:phenethylamine; D010649:Phenylalanine; C075773:4-phenylbutyric acid; D006136:GTP Cyclohydrolase; C025136:phenylacetic acid; D000079:Acetaldehyde; D010626:Phenylethyl Alcohol; C013192:phenylacetaldehyde; C031606:phenylpyruvic acid