title: Strain-dependent diversity in the Pseudomonas aeruginosa quorum-sensing regulon.
abstract: Quorum sensing allows bacteria to sense and respond to changes in population density. Acyl-homoserine lactones serve as quorum-sensing signals for many Proteobacteria, and acyl-homoserine lactone signaling is known to control cooperative activities. Quorum-controlled activities vary from one species to another. Quorum-sensing controls a constellation of genes in the opportunistic pathogen Pseudomonas aeruginosa, which thrives in a number of habitats ranging from soil and water to animal hosts. We hypothesized that there would be significant variation in quorum-sensing regulons among strains of P. aeruginosa isolated from different habitats and that differences in the quorum-sensing regulons might reveal insights about the ecology of P. aeruginosa. As a test of our hypothesis we used RNA-seq to identify quorum-controlled genes in seven P. aeruginosa isolates of diverse origins. Although our approach certainly overlooks some quorum-sensing-regulated genes we found a shared set of genes, i.e., a core quorum-controlled gene set, and we identified distinct, strain-variable sets of quorum-controlled genes, i.e., accessory genes. Some quorum-controlled genes in some strains were not present in the genomes of other strains. We detected a correlation between traits encoded by some genes in the strain-variable subsets of the quorum regulons and the ecology of the isolates. These findings indicate a role for quorum sensing in extension of the range of habitats in which a species can thrive. This study also provides a framework for understanding the molecular mechanisms by which quorum-sensing systems operate, the evolutionary pressures by which they are maintained, and their importance in disparate ecological contexts.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Sudha
authors.initials: S
authors.lastname: Chugani
authors.forename: Byoung Sik
authors.initials: BS
authors.lastname: Kim
authors.forename: Somsak
authors.initials: S
authors.lastname: Phattarasukol
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Brittnacher
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Harwood
authors.forename: E Peter
authors.initials: EP
authors.lastname: Greenberg
mesh_terms: D016000:Cluster Analysis; D003550:Cystic Fibrosis / Q000382:microbiology; D004783:Environmental Microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics; D006801:Humans; D018551:Solanum lycopersicum / Q000382:microbiology; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D053038:Quorum Sensing / Q000235:genetics*; D018085:Regulon; D017422:Sequence Analysis, DNA; D013045:Species Specificity