title: Integration of chemotaxis, transport and catabolism in Pseudomonas putida and identification of the aromatic acid chemoreceptor PcaY.
abstract: Aromatic and hydroaromatic compounds that are metabolized through the β-ketoadipate catabolic pathway serve as chemoattractants for Pseudomonas putida F1. A screen of P. putida F1 mutants, each lacking one of the genes encoding the 18 putative methyl-accepting chemotaxis proteins (MCPs), revealed that pcaY encodes the MCP required for metabolism-independent chemotaxis to vanillate, vanillin, 4-hydroxybenzoate, benzoate, protocatechuate, quinate, shikimate, as well as 10 substituted benzoates that do not serve as growth substrates for P. putida F1. Chemotaxis was induced during growth on aromatic compounds, and an analysis of a pcaY-lacZ fusion revealed that pcaY is expressed in the presence of β-ketoadipate, a common intermediate in the pathway. pcaY expression also required the transcriptional activator PcaR, indicating that pcaY is a member of the pca regulon, which includes three unlinked gene clusters that encode five enzymes required for the conversion of 4-hydroxybenzoate to tricarboxylic acid cycle intermediates as well as the major facilitator superfamily transport protein PcaK. The 4-hydroxybenzoate permease PcaK was shown to modulate the chemotactic response by facilitating the uptake of 4-hydroxybenzoate, which leads to the accumulation of β-ketoadipate, thereby increasing pcaY expression. The results show that chemotaxis, transport and metabolism of aromatic compounds are intimately linked in P. putida.
authors.affiliation: Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, CA, USA.
authors.forename: Rita A
authors.initials: RA
authors.lastname: Luu
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Kootstra
authors.forename: Vasyl
authors.initials: V
authors.lastname: Nesteryuk
authors.forename: Ceanne N
authors.initials: CN
authors.lastname: Brunton
authors.forename: Juanito V
authors.initials: JV
authors.lastname: Parales
authors.forename: Jayna L
authors.initials: JL
authors.lastname: Ditty
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Parales
mesh_terms: D000272:Adipates / Q000378:metabolism; D000595:Amino Acid Sequence; D000975:Antioxidants / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001547:Benzaldehydes / Q000378:metabolism; D001565:Benzoates / Q000378:metabolism*; D001692:Biological Transport; D002633:Chemotaxis; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D005810:Multigene Family; D009154:Mutation; D010226:Parabens / Q000378:metabolism; D016958:Pseudomonas putida / Q000235:genetics / Q000502:physiology*; D018085:Regulon
chemical_list: D000272:Adipates; D000975:Antioxidants; D001426:Bacterial Proteins; D001547:Benzaldehydes; D001565:Benzoates; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D010226:Parabens; C027316:3-oxoadipic acid; C100058:vanillin; C038193:4-hydroxybenzoic acid