title: A distinct QscR regulon in the Pseudomonas aeruginosa quorum-sensing circuit.
abstract: The opportunistic pathogen Pseudomonas aeruginosa possesses two complete acyl-homoserine lactone (acyl-HSL) signaling systems. One system consists of LasI and LasR, which generate a 3-oxododecanoyl-homoserine lactone signal and respond to that signal, respectively. The other system is RhlI and RhlR, which generate butanoyl-homoserine lactone and respond to butanoyl-homoserine lactone, respectively. These quorum-sensing systems control hundreds of genes. There is also an orphan LasR-RhlR homolog, QscR, for which there is no cognate acyl-HSL synthetic enzyme. We previously reported that a qscR mutant is hypervirulent and showed that QscR transiently represses a few quorum-sensing-controlled genes. To better understand the role of QscR in P. aeruginosa gene regulation and to better understand the relationship between QscR, LasR, and RhlR control of gene expression, we used transcription profiling to identify a QscR-dependent regulon. Our analysis revealed that QscR activates some genes and represses others. Some of the repressed genes are not regulated by the LasR-I or RhlR-I systems, while others are. The LasI-generated 3-oxododecanoyl-homoserine lactone serves as a signal molecule for QscR. Thus, QscR appears to be an integral component of the P. aeruginosa quorum-sensing circuitry. QscR uses the LasI-generated acyl-homoserine lactone signal and controls a specific regulon that overlaps with the already overlapping LasR- and RhlR-dependent regulons.
authors.affiliation: Department of Microbiology, University of Washington, Seattle 98195-7242, USA.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Lequette
authors.forename: Joon-Hee
authors.initials: JH
authors.lastname: Lee
authors.forename: Fouzia
authors.initials: F
authors.lastname: Ledgham
authors.forename: Andrée
authors.initials: A
authors.lastname: Lazdunski
authors.forename: E Peter
authors.initials: EP
authors.lastname: Greenberg
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D005798:Genes, Bacterial / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C080365:LasR protein, Pseudomonas aeruginosa; C434259:QscR protein, Pseudomonas aeruginosa; D012097:Repressor Proteins; C086515:RhlR protein, Pseudomonas aeruginosa; D015534:Trans-Activators