Quorum sensing (QS)-based transcriptional responses in Pseudomonas aeruginosa have been defined on the basis of increases in transcript levels of QS-controlled genes such as lasB and aprA following the hierarchical transcriptional increases of central controllers such as the lasR gene. These increases occur at high bacterial concentrations such as early-stationary-phase growth in vitro. However...

Cystic fibrosis lung disease is characterized by chronic airway infections with the opportunistic pathogen Pseudomonas aeruginosa and severe neutrophilic pulmonary inflammation. P. aeruginosa undergoes extensive genetic adaptation to the cystic fibrosis (CF) lung environment, and adaptive mutations in the quorum sensing regulator gene lasR commonly arise. We sought to define how mutations in la...

Survival of Pseudomonas aeruginosa in cystic fibrosis (CF) chronic infections is based on a genetic adaptation process consisting of mutations in specific genes, which can produce advantageous phenotypic switches and ensure its persistence in the lung. Among these, mutations inactivating the regulators MucA (alginate biosynthesis), LasR (quorum sensing) and MexZ (multidrug-efflux pump MexXY) ar...

Pseudomonas aeruginosa LasB elastase gene (lasB) transcription is controlled by the two-component quorum-sensing system of LasR, and the autoinducer, 3OC(12)-HSL (N-3-[oxododecanoyl]homoserine lactone). LasR and 3OC(12)-HSL-mediated lasB activation requires a functional operator sequence (OP1) in the lasB promoter region. Optimal activation of lasB, however, requires a second sequence of 70% id...

We have cloned and sequenced the lasR gene, which is involved in the transcriptional activation of several pathogenic factors, from Pseudomonas aeruginosa IFO3455 and PA103. These clones were predicted to be an open reading frame of 239 amino acids as reported for the PAO1 strain. There is only a single base change resulting in an amino acid exchange from M145 (PAO1) to I (IFO3455). PA103 DNA d...

In Pseudomonas aeruginosa, quorum sensing constitutes a highly complex cell-to-cell communication system that, along with the cognate acylhomoserine lactone signals and regulators LasR and RhlR, modulates the production of virulence factors and a wide range of metabolic functions. In a previous paper, the authors reported that mismatch repair disruption in P. aeruginosa results in the spontaneo...

The LasR/LasI quorum-sensing system in Pseudomonas aeruginosa influences global gene expression and mediates pathogenesis. In this study, we show that the quorum-sensing system activates, via the transcriptional regulator PA4778, a copper resistance system composed of 11 genes. The quorum-sensing global regulator LasR was recently shown to directly activate transcription of PA4778, a cueR homol...

In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL). Functional acti...

Chronic Pseudomonas aeruginosa infections cause significant morbidity in patients with cystic fibrosis (CF). Over years to decades, P. aeruginosa adapts genetically as it establishes chronic lung infections. Nonsynonymous mutations in lasR, the quorum-sensing (QS) master regulator, are common in CF. In laboratory strains of P. aeruginosa, LasR activates transcription of dozens of genes, includi...

In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) via acyl-homoserine lactone (AHL) signals coordinates virulence gene expression. AHL signals must reach a critical threshold before enough is bound by cognate regulators LasR and RhlR to drive transcription of target genes. In addition, three anti-activator proteins, QteE, QscR, and QslA, sequester QS regulators to increa...