Proteome analysis of extracellular proteins regulated by the las and rhl quorum sensing systems in Pseudomonas aeruginosa PAO1

Amanda S. Nouwens, Scott A. Beatson, Cynthia B. Whitchurch, Bradley J. Walsh, Herbert P. Schweizer, John S. Mattick, Stuart J. Cordwell*

*Corresponding author for this work

    Research output: Contribution to journalReview articlepeer-review

    108 Citations (Scopus)

    Abstract

    The las and rhl quorum sensing (QS) systems regulate the expression of several genes in response to cell density changes in Pseudomonas aeruginosa. Many of these genes encode surface-associated or secreted virulence factors. Proteins from stationary phase culture supernatants were collected from wild-type and P. aeruginosa PAO1 mutants deficient in one or more of the lasRI, rhlRI and vfr genes and analysed using two-dimensional gel electrophoresis. All mutants released significantly lower amounts of protein than the wild-type. Protein spot patterns from each strain were compared using image analysis and visible spot differences were identified using mass spectrometry. Several previously unknown QS-regulated proteins were characterized, including an aminopeptidase (PA2939), an endoproteinase (PrpL) and a unique 'hypothetical' protein (PA0572), which could not be detected in the culture supernatants of Δlas mutants, although they were unaffected in Δrhl mutants. Chitin-binding protein (CbpD) and a hypothetical protein (PA4944) with similarity to host factor I (HF-I) could not be detected when any of the lasRI or rhlRI genes were disrupted. Fourteen proteins were present at significantly greater levels in the culture supernatants of QS mutants, suggesting that QS may also negatively control the expression of some genes. Increased levels of two-partner secretion exoproteins (PA0041 and PA4625) were observed and may be linked to increased stability of their cognate transporters in a QS-defective background. Known QS-regulated extracellular proteins, including elastase (lasB), LasA protease lasA) and alkaline metalloproteinase (aprA) were also detected.

    Original languageEnglish
    Pages (from-to)1311-1322
    Number of pages12
    JournalMicrobiology
    Volume149
    Issue number5
    DOIs
    Publication statusPublished - 1 May 2003

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