Multiple homologues of LuxR and LuxI control expression of virulence determinants and secondary metabolites through quorum sensing in Pseudomonas aeruginosa PAO1

Authors

  • Amel Latifi,

    1. Laboratoire d'Ingenierie et Dynamique des Systémes Membranaires, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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  • Michael K. Winson,

    1. Department of Applied Biochemistry and Food Science, University of Nottingham, Faculty of Agricultural and Food Sciences, Sutton Bonington Campus, Leicestershire LE12 5RD, UK
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  • Maryline Foglino,

    1. Laboratoire d'Ingenierie et Dynamique des Systémes Membranaires, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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  • Barrie W. Bycroft,

    1. Department of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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  • Gordon S. A. B. Stewart,

    1. Department of Applied Biochemistry and Food Science, University of Nottingham, Faculty of Agricultural and Food Sciences, Sutton Bonington Campus, Leicestershire LE12 5RD, UK
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  • Andrée Lazdunski,

    1. Laboratoire d'Ingenierie et Dynamique des Systémes Membranaires, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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  • Paul Williams

    Corresponding author
    1. Department of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
    • *For correspondence. E-mail pazpw@pan1.pharm.nottingham.ac.uk; Tel. (0115) 951 5047; Fax (0115) 951 5102.

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Abstract

In Pseudomonas aeruginosa PAO1, expression of elastase is dependent upon an interaction between the positive transcriptional activator LasR and the autoinducer molecule N(3-oxododecanoyl)-l-homoserine lactone (OdDHL), the synthesis of which is directed by LasI. Previously we have shown that in PAN067, an elastase-negative mutant of PAO1, elastase production can be restored to some extent by addition of exogenous N(3-oxohexanoyl)-l-homoserine lactone (OHHL). Here we report that PAN067 is also defective in the production of alkaline protease, haemolysin, cyanide, pyocyanin and autoinducer(s). As neither addition of exogenous OdDHL nor introduction of IasR restored PAN067 to the parental phenotype, we sought to complement PAN067 with PAO1 DNA. From a cosmid library, a 2 kb DNA fragment was identified which re-established production of autoinducer(s) and exoproducts in PAN067. From the nucleotide sequence of this fragment, two genes termed rhIR and rhII were identified. RhII is responsible for autoinducer synthesis and shares 31% homology with LasI; RhIR has been previously identified in P. aeruginosa strain DSM2659 as a regulator of rhamnolipid biosynthesis and shares 28% identity with LasR. These data provide clear evidence that multiple families of quorum-sensing modulons interactively regulate gene expression in P. aeruginosa.

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