The Pseudomonas Quinolone Signal Regulates rhl Quorum Sensing in Pseudomonas aeruginosa

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Barbara H. Iglewski (Creator)

Susan L. McKnight (Creator)

Everett C. Pesci (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: The opportunistic pathogen Pseudomonas aeruginosa uses intercellular signals to control the density-dependent expression of many virulence factors. The las and rhl quorum-sensing systems function respectively through the autoinducers N-(3-oxododecanoyl)-L-homoserine lactone and N-butyryl-L-homoserine lactone (C4- HSL) which are known to positively regulate the transcription of the elastase-encoding gene lasB. Recently we reported that a second type of intercellular signal is involved in lasB induction. This signal was identified as 2-heptyl-3-hydroxy-4-quinolone and designated the Pseudomonas quinolone signal (PQS). PQS was determined to be part of the quorum-sensing hierarchy since its production and bioactivity depended on the las and rhl quorum-sensing systems respectively. In order to define the role of PQS in the P. aeruginosa quorumsensing cascade lacZ gene fusions were used to determine the effect of PQS on the transcription of the quorum-sensing system genes lasR lasI rhlR and rhlI. We found that in P. aeruginosa PQS caused a major induction of rhlI*-lacZ and had lesser effects on the transcription of lasR*-lacZ and rhlR*-lacZ. We also observed that the transcription of both rhlI*-lacZ and lasB*-lacZ was cooperatively effected by C4-HSL and PQS. Additionally we present data indicating that PQS was not produced maximally until cultures reached the late stationary phase of growth. Taken together our results imply that PQS acts as a link between the las and rhl quorum-sensing systems and that this signal is not involved in sensing cell density. Originally published Journal of Bacteriology Vol. 182 No. 10 May 2000

Additional Information

Publication

Other

Journal of Bacteriology. 182:10(May 2000) p. 2702-2708.

Language: English

Date: 2011

Keywords

Pseudomonas aeruginosa, quinolone signal, las quorum sensing, rhl quorum sensing

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