ABSTRACT: The protein Aldehyde responsive quorum-sensing Inhibitor (ARQL) was exposed to increasing levels of glyoxal, to identify the glycation modifications.
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: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: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: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:Coumarin has been reported as a quorum sensing inhibitor for Pseudomonas aeruginosa. The goal of this transcriptomic analysis is to elucidate the effect of coumarin on gene expression of P. aeruginosa. Therefore, planktonic cells of P. aeruginosa were treated by coumarin for 1h and biofilms were formed in the presence of coumarin for 24h. Unreated controls (with dimethyl sulfoxide ) for both planktonic and biofilm samples were also included. Three biological replicates per treatment were performed with RNA sequencing.
Project description:We show that ZS1 in the medium supplemented with YE (YE-medium) produces more cell biomass but less rhamnolipid than it does in Glc-medium. To elucidate the transcriptional regulation of genes that are involved in biosynthesis of rhamnolipids and its precursors, RNA-seq-based transcriptional profiling of ZS1 cells in response to reciprocal change of YEand Glc-media is performed. Based on the assembly of ZS1 transcriptome using the reference PAO1 genome, we show that genes involved in energy metabolic pathways in ZS1 strain are highly transcribed in YE medium but not in Glc-medium, in agreement with their cell mass production. Similarly, transcription of quorum sensing systems genes lasI-lasR, rhlI-rhlR, and pqsH-mvfR are downregulated in Glc-medium. On the other hand, we show that two of the three enzymes RhlB and RhlC essential for rhamnolipid biosynthesis are transcriptionally upregulated, independent of quorum sensing signals. Notably, three of the four enzymes involved in dTDP-L-rhamnose, a precursor for the rhamnolipid biosynthesis, are downregulated in Glc except for RmlD that catalyzes the last reaction in the pathway. Together, our results indicate that increased rhamnolipid production in ZS1 cells is independent of quorum sensing signals. We propose that quorum sensing-independent rhamnolipid production in ZS1 Glc-culture is achieved by transcriptional re-programming of the minimum number of genes involved in rhamnolipid biosynthesis.
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.