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:ErfA is a transcription factor of Pseudomonas aeruginosa. We here define the genome-wide binding sites of ErfA by DAP-seq in Pseudomonas aeruginosa PAO1 and IHMA87, Pseudomonas chlororaphis PA23, Pseudomonas protegens CHA0 and Pseudomonas putida KT2440.
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 (Pa) is a ubiquitous bacterium that uses quorum sensing (QS), a cell-cell communication system that enables it to sense cell density and to alter gene expression. Pa has three complete QS circuits controlled by the transcriptional regulators LasR, RhlR, and PqsR (MvfR), that together control hundreds of genes, including virulence factors. In the well-described strain PAO1, QS is organized hierarchically, with PqsR and RhlR activity dependent on LasR. In PAO1, this hierarchy depends on the non-QS transcription factor MexT; by an unknown mechanism, deletion of mexT allows for RhlR activity in the absence of LasR. We aimed to identify how regulators such as MexT modulate the QS architecture in Pa. We compared the transcriptome of PAO1 to that of PAO1ΔmexT and identified 152 differentially expressed genes. MexT does not appear to regulate rhlR or pqsR directly; however, we identified two MexT-regulated operons that may affect the hierarchy in PAO1. These operons encode the drug efflux pump genes mexEF-oprN and the Pseudomonas quinolone signal (PQS) synthesis genes pqsABCDE. We performed genetic experiments to test whether the products of these genes affected the QS hierarchy. As with the mexT knockout mutant, we found that a PAO1 mexEF knockout mutant exhibited RhlR activity earlier, and to a higher magnitude, than wild-type PAO1. MexEF-OprN is known to export the PQS precursor HHQ, and we found that exogenous addition of PQS to PAO1 partially affects RhlR activity, resulting in earlier timing and higher magnitude compared to wild-type PAO1. We further elucidated that this is likely due to positive regulation by PqsE. These data link both the drug efflux pump MexEF-OprN and PQS QS to the regulation of the QS hierarchy in PAO1. We wondered if the same applied to QS architectures in Pa clinical isolates. We discovered that there are alternate QS architectures in clinical isolates, where RhlR activity is not fully dependent on LasR. In these isolates, surprisingly, MexT does not influence the relationship between LasR and RhlR, and this is indicative of a different QS architecture in the clinical isolates. Overall, we further elucidated the regulation of QS architecture in PAO1 and identified unique QS architectures in clinical isolates. Importantly, our work reveals a new suite of factors that regulate QS in Pa, with implications for a variety of Pa behaviors both in the laboratory and clinical settings.
Project description:Pseudomonas aeruginosa undergoes genetic change during chronic infection of the airways of cystic fibrosis (CF) patients. One common change is mutation of lasR. LasR is a transcriptional regulator that responds to one of the quorum sensing signals in P. aeruginosa, and regulates acute virulence factor expression as well as central metabolic functions. P. aeruginosa mutants in which lasR was inactivated emerged in the airways of CF patients early during chronic infection, and during growth in the laboratory on Luria-Bertani agar. Both environments are rich in amino acids. Inactivation of lasR in these isolates conferred a growth advantage with amino acids, a phenotype that could account for selection of lasR mutants both in vivo and in vitro. P. aeruginosa lasR mutants were identified by their distinctive colony morphology, including autolysis that correlated with an imbalance in 4-hydroxy-2-alkylquinolines (HAQs), and an iridescent metallic sheen likely caused by the accumulation of one such HAQ. The alterations in transcriptional profile due to inactivation of lasR were conserved in isolates from multiple young CF patients. P. aeruginosa lasR mutations may represent surrogate markers to delineate stages in the natural history of CF airway disease, each with different prognostic and therapeutic implications, analogous to the markers used to direct cancer treatment. Similar to cancer cell mutations that promote unrestricted growth, lasR mutations may promote unrestricted growth of P. aeruginosa in the CF airway by enabling more efficient utilization of available amino acids. Analyse the effects of mutation of the lasR gene in Pseudomonas aeruginosa isolates from cystic fibrosis patients by comparing the transcriptional profile of an isolate from a young patient with that of an isogenic engineered lasR mutant.
Project description:The role of the intracellular signaling molecule diadenosine tetraphosphate (Ap4A) has not so far been investigated in Pseudomonas aeruginosa. To fill this gap, we performed RNA sequencing (RNA-seq) analysis to compare the transcriptome of the reference strain P. aeruginosa PAO1 and an isogenic deletion mutant (ΔapaH) which is deficient in the Ap4A hydrolysing enzyme ApaH and accumulates high intracellular levels of Ap4A.
Project description:To better understand the role of QscR in P. aeruginosa gene regulation and to better understand the relationship between QscR, LasR and RhlR control of gene expression we used transcription profiling to identify a QscR-dependent regulon. Our analysis revealed that QscR activates some genes and represses others. Some of the repressed genes are not regulated by the LasR-I or RhlR-I systems while others are. The LasI-generated 3-oxododecanoyl-homoserine lactone serves as a signal molecule for QscR. Thus QscR appears to be an integral component of the P. aeruginosa quorum sensing circuitry. QscR uses the LasI-generated acyl-homoserine lactone signal and controls a specific regulon that overlaps with the already overlapping LasR and RhlR-dependent regulons. Experiment Overall Design: First comparisaon Experiment Overall Design: We first compared transcriptomes of the qscR mutant P. aeruginosa PAO-R3 and the parental strain PAO1 at several points during growth (OD600nm 0.5, 0.8, 1.4, 2.0 and 3.5). To identify those genes with expression significantly different between PAO1 and PAO-R3 at different culture densities we used CYBER-T. The Bayesian prior estimate was 10 and the sliding window size was 101. The p-value threshold was 0.001, the posterior probability of differential expression >0.95, and fold change was >2.5. Experiment Overall Design: Second comparison Experiment Overall Design: We selected genes that were at least 3-fold differentially expressed in the strain containing the L-arabinose promoter-driven qscR allele vs the strain containing L-arabinose promoter-driven qscR-Ddbd allele, and were also at least 3-fold differentially expressed in the parent strain PAO1 as compared to the strain containing the qscR null mutation. RNA were extracted from cultures at OD 0.5, 0.8, 1.4, 2.0 and 3.5
Project description:Analysis of Pseudomonas aeruginosa PAO1 (ATCC 15692) treated by Tanreqing. PAO1 cells are evaluated with RNA-seq to understand the genes affected by this antibacterial agent. Our results provide new vision on the mode of action by Tanreqing.
Project description:Analysis of Pseudomonas aeruginosa PAO1 (ATCC 15692) transcriptional response by disruption of oxyR. PAO1 cells are evaluated with RNA-seq to understand the genes affected by this mutation. Our results provide new vision on the regulation of oxyR in pathogens.