Project description:The ParS/ParR two component regulatory system plays important roles for multidrug resistance in Pseudomonas aeruginosa. In this study we report RNA-seq analyses of the transcriptomes of P. aeruginosa PAO1 wild type and par mutants growing in a minimal medium containing 2% casamino acids. This has allowed the quantification of PAO1 transcriptome, and further defines the regulon that is dependent on the ParS/ParR system for expression. Our RNA-seq analysis produced the first estimates of absolute transcript abundance for the 5570 coding genes in P. aeruginosa PAO1. Comparative transcriptomics of P. aeruginosa PAO1 and par mutants identified a total of 464 genes regulated by ParS and ParR. Results also showed that mutations in the parS/parR system abolished the expression of the mexEF-oprN operon by down-regulating the regulatory gene mexS. In addition to affecting drug resistance genes, transcripts of quorum sensing genes (rhlIR and pqsABCDE-phnAB), were significantly up-regulated in both parS and parR mutants. Consistent with these results, a significant portion of the ParS/ParR regulated genes belonged to the MexEF-OprN and quorum sensing regulons. Deletion of par genes also lead to overproduction of phenazines and increased swarming motility, consistent with the up-regulation of quorum sensing genes. Our results established a link among ParS/ParR, MexEF-OprN and quorum sensing in Pseudomonas aeruginosa. Based on these results, we propose a model to illustrate the relationship among these regulatory systems in P. aeruginosa. A total of 9 samples were analyzed in AB medium + 2% casamino acids, Pseudomonas aeruginosa PAO1 wild type strain (3 replicates); Pseudomonas aeruginosa parS mutant (3 replicates); Pseudomonas aeruginosa parR mutant (3 replicates).
Project description:The ParS/ParR two component regulatory system plays important roles for multidrug resistance in Pseudomonas aeruginosa. In this study we report RNA-seq analyses of the transcriptomes of P. aeruginosa PAO1 wild type and par mutants growing in a minimal medium containing 2% casamino acids. This has allowed the quantification of PAO1 transcriptome, and further defines the regulon that is dependent on the ParS/ParR system for expression. Our RNA-seq analysis produced the first estimates of absolute transcript abundance for the 5570 coding genes in P. aeruginosa PAO1. Comparative transcriptomics of P. aeruginosa PAO1 and par mutants identified a total of 464 genes regulated by ParS and ParR. Results also showed that mutations in the parS/parR system abolished the expression of the mexEF-oprN operon by down-regulating the regulatory gene mexS. In addition to affecting drug resistance genes, transcripts of quorum sensing genes (rhlIR and pqsABCDE-phnAB), were significantly up-regulated in both parS and parR mutants. Consistent with these results, a significant portion of the ParS/ParR regulated genes belonged to the MexEF-OprN and quorum sensing regulons. Deletion of par genes also lead to overproduction of phenazines and increased swarming motility, consistent with the up-regulation of quorum sensing genes. Our results established a link among ParS/ParR, MexEF-OprN and quorum sensing in Pseudomonas aeruginosa. Based on these results, we propose a model to illustrate the relationship among these regulatory systems in P. aeruginosa.
Project description:Pseudomonas aeruginosa is a common pathogen in the lungs of the cystic fibrosis patients. As infection develops the organism progressively adapts to its environment and its mode of pathogenesis alters, frequently including the loss of quorum sensing (QS) regulated virulence factors. We used microarrays to determine genomic differences by comparative genome hybridisation between two P. aeruginosa isolates from CF patients, one of which exhibited an active quorum sensing (QS) system (UUPA38) typical of early acute infection while the other was QS-compromised (UUPA85) typical of chronic CF-adapted infection.
Project description:Many Gram-negative bacteria employ cell-to-cell communication mediated by N-acyl homoserine lactones (quorum sensing) to control expression of a wide range of genes including, but not limited to, genes encoding virulence factors. Outside the laboratory, the bacteria live in complex communities where signals may be perceived across species. We here present a newly found natural quorum sensing inhibitor, produced by the pseudomonads Pseudomonas sp. B13 and Pseudomonas reinekei MT1 as a blind end in the biodegradation of organochloride xenobiotics, which inhibits quorum sensing in P. aeruginosa in naturally occurring concentrations. This catabolite, 4-methylenebut-2-en-4-olide, also known as protoanemonin, has been reported to possess antibacterial properties, but seems to have dual functions. Using transcriptomics and proteomics, we found that protoanemonin significantly reduced expression of genes and secretion of proteins known to be under control of quorum sensing in P. aeruginosa. Moreover, we found activation of genes and gene products involved in iron starvation response. It is thus likely that inhibition of quorum sensing, as the production of antibiotics, is a phenomenon found in complex bacterial communities.
Project description:Pseudomonas aeruginosa is a common pathogen in the lungs of the cystic fibrosis patients. As infection develops the organism progressively adapts to its environment and its mode of pathogenesis alters, frequently including the loss of quorum sensing regulated virulence factors. We used microarrays to detail differences between two P. aeruginosa isolates from CF patients, one of which (UUPA38) exhibited an active quorum sensing system (QS+) typical of early acute infection while the other (UUPA85) was QS-compromised (QS-) typical of chronic CF-adapted infection.
Project description:Quorum signal uptake is an indispensable part of quorum sensing regulations. The coperative regulation of uptake repressor and kinase precisely signale the cells for quorum sensing uptake and terminate the quorum sensing signal production. We use the DNA microarray to detail the E. coli quorum sensing uptake reuglations and related gene regulations. Experiment Overall Design: W3110 wild type and its isogenic mutants lsrR, lsrK's RNA samples were extracted and hybridized for Affymetrix array.
Project description:Quorum sensing, a cell-to-cell communication system based on small signal molecules, is employed by the human pathogen Pseudomonas aeruginosa to regulate virulence and biofilm development. Moreover, regulation by small trans-encoded RNAs has become a focal issue in virulence gene expression of bacterial pathogens. In this study, we have identified the small RNA PhrS as an activator of PqsR synthesis, one of the key quorum sensing regulators in P. aeruginosa. Genetic studies revealed a novel mode of regulation by a sRNA, whereby PhrS uses a base-pairing mechanism to activate a short upstream open reading frame to which the pqsR gene is translationally coupled. Expression of phrS is induced by the oxygen-responsive regulator ANR when the oxygen supply decreases. Thus, PhrS is the first bacterial sRNA that provides a regulatory link between oxygen availability and quorum sensing, which may impact on oxygen-limited growth in P. aeruginosa biofilms. Keywords: genetic modification
Project description:The PqsE enzyme plays a vital role in quorum sensing and virulence in Pseudomonas aeruginosa, yet its enzymatic function is unknown. Here, we identify the protein interaction network of PqsE as well as that of a catalytically dead variant, PqsE(D73A) in P. aeruginosa PA14. Our analyses identify proteins that interact with PqsE that are independent of and that depend on PqsE catalytic function. One such catalysis-independent interaction is with the quorum-sensing regulator, RhlR, consistent with our previous work. We also characterize the PqsE interaction network in a delta rhlR P. aeruginosa PA14 strain and identify additional proteins as PqsE-interactors.
Project description:Quorum sensing, a cell-to-cell communication system based on small signal molecules, is employed by the human pathogen Pseudomonas aeruginosa to regulate virulence and biofilm development. Moreover, regulation by small trans-encoded RNAs has become a focal issue in virulence gene expression of bacterial pathogens. In this study, we have identified the small RNA PhrS as an activator of PqsR synthesis, one of the key quorum sensing regulators in P. aeruginosa. Genetic studies revealed a novel mode of regulation by a sRNA, whereby PhrS uses a base-pairing mechanism to activate a short upstream open reading frame to which the pqsR gene is translationally coupled. Expression of phrS is induced by the oxygen-responsive regulator ANR when the oxygen supply decreases. Thus, PhrS is the first bacterial sRNA that provides a regulatory link between oxygen availability and quorum sensing, which may impact on oxygen-limited growth in P. aeruginosa biofilms. Keywords: genetic modification Comparative transcriptome analysis with the delta-phrS strains PAO6671(pJT19) and PAO6671(pJTphrS), whereby the first strain harboured the parental vector and the latter a plasmid-borne inducible phrS gene
Project description:Pseudomonas aeruginosa is a common pathogen in the lungs of the cystic fibrosis patients. As infection develops the organism progressively adapts to its environment and its mode of pathogenesis alters, frequently including the loss of quorum sensing regulated virulence factors. We used microarrays to detail differences between two P. aeruginosa isolates from CF patients, one of which (UUPA38) exhibited an active quorum sensing system (QS+) typical of early acute infection while the other (UUPA85) was QS-compromised (QS-) typical of chronic CF-adapted infection. Bacterial cell biomass was harvested from triplicate biofilm and planktonic cultures of each of 2 strains of P. aeruginosa. RNA was extracted, converted to cDNA and hybridized to Affymetrix microarrays. We aimed to identify genes which were differentially transcribed between the 2 isolates during both modes of growth.