Regulation of quorum sensing by RpoS in Pseudomonas aeruginosa.
The LasR-LasI and RhlR-RhlI quorum-sensing systems are global regulators of gene expression in the opportunistic pathogen Pseudomonas aeruginosa. Previous studies suggest that the RhlR-RhlI system activates expression of rpoS. We constructed merodiploid strains of P. aeruginosa containing the native rpoS gene and an rpoS-lacZ fusion. Studies of lacZ transcription in these strains indicated that rpoS was not regulated by RhlR-RhlI. We also generated an rpoS null mutant. This rpoS mutant showed elevated levels of rhlI (but not rhlR) transcription, elevated levels of the RhlI-generated acylhomoserine lactone quorum-sensing signal, and elevated levels of RhlR-RhlI-regulated gene transcription. These findings indicate that there is a relationship between RpoS and quorum sensing, but rather than the RhlR-RhlI system influencing the expression of rpoS, it appears that RpoS regulates rhlI.
Whiteley
M
M
Department of Microbiology, University of Iowa, Iowa City, Iowa 52242, USA.
Parsek
M R
MR
Greenberg
E P
EP
D001426:Bacterial Proteins / Q000502:physiology*; D015169:Colony Count, Microbial; D008025:Ligases; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity; D011710:Pyocyanine / Q000378:metabolism; D012808:Sigma Factor / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C086515:RhlR protein, Pseudomonas aeruginosa; D012808:Sigma Factor; D014157:Transcription Factors; C069567:sigma factor KatF protein, Bacteria; D011710:Pyocyanine; D008025:Ligases; C096955:RHLI protein, Pseudomonas aeruginosa