Project description:We examined whether the budding yeast Saccharomyces cerevisiae can sense chemical signals from prokaryotes, specifically a variety of quorum sensing molecules from different bacteria species and from Candida albicans. We found that only N-acyl-3-oxo-dodecanoyl homoserine lactone (C12) from the opportunistic human pathogen Pseudomonas aeruginosa induces a stress response in yeast. Microarray experiments were performed in order to continue investigating the stress response. We treated S. cerevesiae (WT strain W303) with N-(3-oxo-dodecanoyl) homoserine lactone (C12), a quorum sensing molecule of Pseudomonas aeruginosa, which we found causes a stress response using a GFP reporter for HSP-12. Treatment conditions: 100 uM C12, 100 uM C12-lactam (control: synthetic analogue of C12 that is inactive in P. aeruginosa), DMSO (control: solvent), and 0.3 mM H2O2 (for comparison to oxidative stress).
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:Pseudomonas aeruginosa is an opportunistic pathogen that can adapt to changing environments and can secrete an exopolysaccharide known as alginate as a protection response resulting in a colony morphology and phenotype referred to as mucoid. However how P. aeruginosa senses its environment and activates alginate overproduction is not fully understood. Previously, we showed that Pseudomonas isolation agar (PIA) supplemented with ammonium metavanadate (PIAAMV) induces P. aeruginosa to overproduce alginate. Vanadate is a phosphate mimic and causes protein misfolding by disruption of disulfide bonds. Here we used PIAAMV to characterize the pathways involved in inducible alginate production and tested the global effects of P. aeruginosa growth on PIAAMV by a mutant library screen, transcriptomics, and in a murine acute virulence model. The PA14 non-redundant mutant library was screened on PIAAMV to identify new genes that are required for the inducible alginate stress response. A functionally diverse set of genes encoding products involved in cell envelope biogenesis, peptidoglycan, uptake of phosphate and iron, phenazines biosynthesis, and other processes were identified as positive regulators of the mucoid phenotype on PIAAMV. Transcriptome analysis of P. aeruginosa growing in the presence of vanadate caused differential expression of genes involved in virulence, envelope biogenesis, and cell stress pathways. In this study, it was observed that growth on PIAAMV attenuates P. aeruginosa in a mouse pneumonia model. Induction of alginate overproduction occurs as a stress response to protect P. aeruginosa but it may be possible to modulate and inhibit these pathways based on the new genes identified in this study.
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:The Pseudomonas aeruginosa quorum-sensing (QS) systems contribute to bacterial homeostasis and pathogenicity. Although many regulators have been characterized to control the production of virulence factors and QS signaling molecules, its detailed regulatory mechanisms still remain elusive. Here, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) on 10 key QS regulators. The direct regulation of these genes by corresponding regulator has been confirmed by Electrophoretic mobility shift assays (EMSAs) and quantitative real-time polymerase chain reactions (qRT-PCR). Binding motifs are found by using MEME suite and verified by footprint assays in vitro. Collectively, this work provides new cues to better understand the detailed regulatory networks of QS systems. ChIP-seq of 10 QS regulators in Pseudomonas aeruginosa
Project description:Pseudomonas aeruginosa is an opportunistic pathogen that can adapt to changing environments and can secrete an exopolysaccharide known as alginate as a protection response resulting in a colony morphology and phenotype referred to as mucoid. However how P. aeruginosa senses its environment and activates alginate overproduction is not fully understood. Previously, we showed that Pseudomonas isolation agar (PIA) supplemented with ammonium metavanadate (PIAAMV) induces P. aeruginosa to overproduce alginate. Vanadate is a phosphate mimic and causes protein misfolding by disruption of disulfide bonds. Here we used PIAAMV to characterize the pathways involved in inducible alginate production and tested the global effects of P. aeruginosa growth on PIAAMV by a mutant library screen, transcriptomics, and in a murine acute virulence model. The PA14 non-redundant mutant library was screened on PIAAMV to identify new genes that are required for the inducible alginate stress response. A functionally diverse set of genes encoding products involved in cell envelope biogenesis, peptidoglycan, uptake of phosphate and iron, phenazines biosynthesis, and other processes were identified as positive regulators of the mucoid phenotype on PIAAMV. Transcriptome analysis of P. aeruginosa growing in the presence of vanadate caused differential expression of genes involved in virulence, envelope biogenesis, and cell stress pathways. In this study, it was observed that growth on PIAAMV attenuates P. aeruginosa in a mouse pneumonia model. Induction of alginate overproduction occurs as a stress response to protect P. aeruginosa but it may be possible to modulate and inhibit these pathways based on the new genes identified in this study. Strain PAO1 was cultured on both PIA and PIAAMV for 18 hr. Three separate plates were used for each media. The cells from each plate were scraped into 4 ml of RNA Protect (Qiagen) and stored immediately at -80°C. Cells were treated with RNAprotect (Qiagen) and total RNA was extracted using an RNeasy mini purification kit (Qiagen) per the manufacturer’s instructions. RNA quality and the presence of residual DNA were checked on an Agilent Bioanalyzer 2100 electrophoretic system pre- and post-DNase treatment. Ten micrograms of total RNA was used for cDNA synthesis, fragmentation, and labeling according to the Affymetrix GeneChip P. aeruginosa genome array expression analysis protocol. RNA isolation, cDNA preparation, labeling and microarray analysis were performed as previously described in reference: Damron, F. H., J. P. Owings, Y. Okkotsu, J. J. Varga, J. R. Schurr, J. B. Goldberg, M. J. Schurr, and H. D. Yu. 2012. Analysis of the Pseudomonas aeruginosa Regulon Controlled by the Sensor Kinase KinB and Sigma Factor RpoN. J Bacteriol 194:1317-30.
Project description:Purpose: The purpose of this study was to investigate the effect of quorum sensing on phage infection. Methods: We constructed the lasR gene knockout strain of Pseudomonas aeruginosa PAO1 and performed transcriptome sequencing.
Project description:To better understand the role of Neisseria gonorrhoeae CpxRA in controlling virulence determinants, here we defined genes potentially regulated by CpxRA by using RNA-Seq. We identified approximately 139 genes differentially expressed between cpxA (Cpx system active) and cpxR (Cpx system inactive) mutants. A large number of the differentially expressed genes encode envelope-localized proteins.
Project description:The Bae, Cpx, Psp, Rcs and ?E pathways constitute the Escherichia coli signaling systems that detect and respond to alterations of the bacterial envelope. Contributions of these systems to stress response have previously been examined individually; however, the possible interconnections between these pathways are unknown. Here we investigate the dynamics between the five stress response pathways by i) determining the specificities of each system with respect to signal inducing conditions, and ii) monitoring global transcriptional changes in response to transient over-expression of each of the effectors.
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.