title: Multiple N-acyl-L-homoserine lactone signal molecules regulate production of virulence determinants and secondary metabolites in Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa produces a spectrum of exoproducts many of which have been implicated in the pathogenesis of human infection. Expression of some of these factors requires cell-cell communication involving the interaction of a small diffusible molecule, an "autoinducer," with a positive transcriptional activator. In P. aeruginosa PAO1, LasI directs the synthesis of the autoinducer N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), which activates the positive transcriptional activator, LasR. Recently, we have discovered a second signaling molecule-based modulon in PAO1, termed vsm, which contains the genes vsmR and vsmI. Using HPLC, mass spectrometry, and NMR spectroscopy we now establish that in Escherichia coli, VsmI directs the synthesis of N-butanoyl-L-homoserine lactone (BHL) and N-hexanoyl-L-homoserine lactone (HHL). These compounds are present in the spent culture supernatants of P. aeruginosa in a molar ratio of approximately 15:1 and their structures were unequivocally confirmed by chemical synthesis. Addition of either BHL or HHL to PAN067, a pleiotropic P. aeruginosa mutant unable to synthesize either of these autoinducers, restored elastase, chitinase, and cyanide production. In E. coli carrying a vsmR/vsmI'::lux transcriptional fusion, BHL and HHL activated VsmR to a similar extent. Analogues of these N-acyl-L-homoserine lactones in which the N-acyl side chain has been extended and/or oxidized at the C-3 position exhibit substantially lower activity (e.g., OdDHL) or no activity (e.g., dDHL) in this lux reporter assay. These data indicate that multiple families of quorum sensing modulons interactively regulate gene expression in P. aeruginosa.
authors.affiliation: Department of Applied Biochemistry and Food Science, University of Nottingham, Leicestershire, United Kingdom.
authors.forename: M K
authors.initials: MK
authors.lastname: Winson
authors.forename: M
authors.initials: M
authors.lastname: Camara
authors.forename: A
authors.initials: A
authors.lastname: Latifi
authors.forename: M
authors.initials: M
authors.lastname: Foglino
authors.forename: S R
authors.initials: SR
authors.lastname: Chhabra
authors.forename: M
authors.initials: M
authors.lastname: Daykin
authors.forename: M
authors.initials: M
authors.lastname: Bally
authors.forename: V
authors.initials: V
authors.lastname: Chapon
authors.forename: G P
authors.initials: GP
authors.lastname: Salmond
authors.forename: B W
authors.initials: BW
authors.lastname: Bycroft
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D002450:Cell Communication; D002851:Chromatography, High Pressure Liquid; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000378:metabolism; D005798:Genes, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D007783:Lactones / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D015398:Signal Transduction; D015534:Trans-Activators / Q000096:biosynthesis*; D014774:Virulence / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D007783:Lactones; C081237:LasI protein, Pseudomonas aeruginosa; C080365:LasR protein, Pseudomonas aeruginosa; D015534:Trans-Activators; D006714:Homoserine