Regulation of las and rhl quorum sensing in Pseudomonas aeruginosa.


Journal Article

The production of several virulence factors by Pseudomonas aeruginosa is controlled according to cell density through two quorum-sensing systems, las and rhl. The las system is comprised of the transcriptional activator protein LasR and of LasI, which directs the synthesis of the autoinducer PAI-1. Similarly, the rhl system consists of the transcriptional activator protein RhlR and of RhlI, which directs synthesis of the autoinducer PAI-2 (formerly referred to as factor 2). To study the interrelation between the two P. aeruginosa quorum-sensing systems, we fused a lacZ reporter gene to lasR, rhlR, and rhlA and monitored expression of these three genes under various conditions. Our data indicate that lasR and rhlR are expressed in a growth-dependent manner, with activation of each gene occurring during the last half of log-phase growth. We also show that the las quorum-sensing system controls the rhl quorum-sensing system in two ways. First, we found that LasR and PAI-1 activated rhlR transcription. Second, we showed that PAI-1 blocked PAI-2 from binding to RhlR, thereby inhibiting the expression of rhlA. Our data thus indicate that the las system exerts two levels of control on RhlR, transcriptional and posttranslational.

Full Text

Cited Authors

  • Pesci, EC; Pearson, JP; Seed, PC; Iglewski, BH

Published Date

  • May 1997

Published In

Volume / Issue

  • 179 / 10

Start / End Page

  • 3127 - 3132

PubMed ID

  • 9150205

Pubmed Central ID

  • 9150205

International Standard Serial Number (ISSN)

  • 0021-9193

Digital Object Identifier (DOI)

  • 10.1128/jb.179.10.3127-3132.1997


  • eng

Conference Location

  • United States