Proteome analysis of extracellular proteins regulated by the las and rhl quorum sensing systems in Pseudomonas aeruginosa PAO1.
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 Deltalas mutants, although they were unaffected in Deltarhl 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.
Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Australia 2109.
Amanda S
AS
Nouwens
ARC Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, The University of Queensland, Australia 4072.
Scott A
SA
Beatson
ARC Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, The University of Queensland, Australia 4072.
Cynthia B
CB
Whitchurch
Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Australia 2109.
Bradley J
BJ
Walsh
Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523-1677, USA.
Herbert P
HP
Schweizer
ARC Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, The University of Queensland, Australia 4072.
John S
JS
Mattick
Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Australia 2109.
Stuart J
SJ
Cordwell
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008025:Ligases; D009154:Mutation; D020543:Proteome; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins; C081237:LasI protein, Pseudomonas aeruginosa; C080365:LasR protein, Pseudomonas aeruginosa; D020543:Proteome; C086515:RhlR protein, Pseudomonas aeruginosa; D015534:Trans-Activators; D014157:Transcription Factors; C091090:Vfr protein, Pseudomonas aeruginosa; D008025:Ligases; C096955:RHLI protein, Pseudomonas aeruginosa