A hierarchical quorum‐sensing cascade in Pseudomonas aeruginosa links the transcriptional activators LasR and RhIR (VsmR) to expression of the stationary‐phase sigma factor RpoS
- 1 September 1996
- journal article
- research article
- Published by Wiley in Molecular Microbiology
- Vol. 21 (6), 1137-1146
- https://doi.org/10.1046/j.1365-2958.1996.00063.x
Abstract
In Pseudomonas aeruginosa, the production of many virulence factors and secondary metabolites is regulated in concert with cell density through quorum sensing. Two quorum-sensing regulons have been identified in which the LuxR homologues LasR and RhIR are activated by N-(3-oxododecanoyl)-l-homo-serine lactone (OdDHL) and N-butanoyl-l-homoserine lactone (BHL) respectively. The lasR and rhIR genes are linked to the luxl homologues last and rhll, which are responsible for synthesis of OdDHL and BHL, respectively. As lasRI and rhlRI are both involved in regulating synthesis of exoenzymes such as elastase, we sought to determine the nature of their interrelationship. By using lacZ transcriptional fusions in both homologous (P. aeruginosa) and heterologous (Escherichia coli) genetic backgrounds we provide evidence that (i) lasR is expressed constitutively throughout the growth cycle, (ii) rhIR expression is regulated by LasR/OdDHL, and (iii) that RhIR/BHL regulates rhll. We also show that expression of the stationary-phase sigma factor gene rpoS is abolished in a P. aeruginosa lasR mutant and in the pleiotropic BHL-negative mutant PAN067. Furthermore, our data reveal that in E. coli, an rpoS-lacZ fusion is regulated directly by RhIR/BHL. Taken together, these results indicate that P. aeruginosa employs a multilayered hierarchical quorum-sensing cascade involving RhIR/BHL and LasR/OdDHL, interlinked via RpoS, to integrate the regulation of virulence determinants and secondary metabolites with adaptation and survival in the stationary phase.Keywords
This publication has 39 references indexed in Scilit:
- Characterisation of the yenI/yenR locus from Yersinia enterocolitica mediating the synthesis of two N‐acylhomoserine lactone signal moleculesMolecular Microbiology, 1995
- Multiple homologues of LuxR and LuxI control expression of virulence determinants and secondary metabolites through quorum sensing in Pseudomonas aeruginosa PAO1Molecular Microbiology, 1995
- The bacterial ‘enigma’: cracking the code of cell–cell communicationMolecular Microbiology, 1995
- Cloning, analysis and expression of an rpoS homologue gene from Pseudomonas aeruginosa PAO1Gene, 1994
- Transcription of the principal sigma‐factor genes, rpoD and rpoS, in Pseudomonas aeruginosa is controlled according to the growth phaseMolecular Microbiology, 1994
- Agrobacterium conjugation and gene regulation by N-acyl-L-homoserine lactonesNature, 1993
- Survival of hunger and stress: The role of rpoS in early stationary phase gene regulation in E. coliCell, 1993
- Small molecule-mediated density-dependent control of gene expression in prokaryotes: Bioluminescence and the biosynthesis of carbapenem antibioticsFEMS Microbiology Letters, 1992
- Nucleotide sequence of the luxR and luxI genes and structure of the primary regulatory region of the lux regulon of Vibrio fischeri ATCC 7744Biochemistry, 1988
- Structural identification of autoinducer of Photobacterium fischeri luciferaseBiochemistry, 1981