A Pseudomonas aeruginosa LysR-type transcriptional regulator, PA1290, essential for productive biofilm and influences virulence and pathogenesis
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ABSTRACT:
ORGANISM(S): Pseudomonas aeruginosa
PROVIDER: GSE336336 | GEO | 2026/06/27
REPOSITORIES: GEO
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Project description:The transposon insertion mutation of regulator PA3321 (PA3321∷Tn) significantly reduced biofilm formation, while enhancing virulence in Drosophila melanogaster fruit fly and BALB/C mouse infection models. This regulator influenced bacterial motility, c-di-GMP signaling, and the RhlI-RhlR and Pseudomonas quinolone signal (PQS) quorum-sensing (QS) systems. We used RNA-seq assays to identify the regulatory mechanisms of PA3321. We observed that 391 genes were up-regulated and 114 genes were down-regulated in the absence of PA3321, many of which are involved in rhamnolipid synthesis, type II, type III, and type VI secretion systems, and QS systems.
2026-06-16 | GSE335556 | GEO
Project description:The transposon insertion mutation of regulator PA1290 (PA1290∷Tn) significantly reduced biofilm formation, while enhancing virulence in Drosophila melanogaster fruit fly and BALB/C mouse infection models. This regulator influenced bacterial motility, c-di-GMP signaling, and the RhlI-RhlR and Pseudomonas quinolone signal (PQS) quorum-sensing (QS) systems. We used RNA-seq assays to identify the regulatory mechanisms of PA1290. We observed that 391 genes were up-regulated and 114 genes were down-regulated in the absence of PA1290, many of which are involved in rhamnolipid synthesis, type II, type III, and type VI secretion systems, and QS systems.
2026-06-27 | GSE336337 | GEO
Project description:The transposon insertion mutation of regulator PA3321 (PA3321∷Tn) significantly reduced biofilm formation, while enhancing virulence in Drosophila melanogaster fruit fly and BALB/C mouse infection models. This regulator influenced bacterial motility, c-di-GMP signaling, and the RhlI-RhlR and Pseudomonas quinolone signal (PQS) quorum-sensing (QS) systems. We used RNA-seq assays to identify the regulatory mechanisms of PA3321. We observed that 391 genes were up-regulated and 114 genes were down-regulated in the absence of PA3321, many of which are involved in rhamnolipid synthesis, type II, type III, and type VI secretion systems, and QS systems.
2026-06-17 | GSE335729 | GEO
Project description:The opportunistic pathogen Pseudomonas aeruginosa has complex quorum sensing (QS) circuitry, which involves two acylhomoserine lactone (AHL) systems, the LasI AHL synthase and LasR AHL-dependent transcriptional activator system and the RhlI AHL synthase-RhlR AHL-responsive transcriptional activator. There is also a quinoline signaling system (the Pseudomonas quinolone signal, PQS, system). Although there is a core set of genes regulated by the AHL circuits, there is substantial strain-to-strain variation in the non-core QS regulated genes. Reductive evolution of the QS regulon, and variation in specific genes activated by QS occurs in laboratory evolution experiments with the model strain PAO1. We used a transcriptomics approach to test the hypothesis that reductive evolution in the PAO1 QS regulon can in large part be explained by a simple null mutation in pqsR, the gene encoding the transcriptional activator of the pqs operon. We found that PqsR had very little influence on the AHL QS regulon. This was a surprising finding because the last gene in the PqsR-dependent pqs operon, pqsE, codes for a protein, which physically interacts with RhlR and this interaction is required for full RhlR-dependent activation of some genes. We used comparative transcriptomics to examine the influence of a pqsE mutation on the QS regulon and identified only three transcripts, which were strictly dependent on PqsE. By using reporter constructs we showed that the PqsE influence on other genes was dependent on experimental conditions and we have gained some insight about those conditions. This work adds to our understanding of the plasticity of the P. aeruginosa QS regulon and to the role PqsE plays in RhlR-dependent gene activation.
2024-03-17 | GSE261453 | GEO
Project description:Virulence factor production and the development of biofilms in Pseudomonas aeruginosa have been shown to be regulated by two hierarchically organised quorum sensing (QS) systems via small acyl-homoserine lactone (AHL) signal molecules. Recently, a third bacterial signal molecule, the Pseudomonas quinolone signal (PQS), has been identified, which positively regulates a subset of genes dependent on the QS systems. To further dissect the various independent regulation levels for many QS induced genes and to evaluate the impact of PQS on the QS circuitry, we performed a transcriptome analysis of PAO1 cultures supplemented with PQS. The global transcriptional profile in response to PQS revealed a marked up-regulation of genes belonging to the tightly interdependent functional groups of iron acquisition and oxidative stress response. Remarkably, not only most of the differentially regulated genes but also the induction of a lacZ transcriptional fusion of rhlR could be traced back to a iron chelating effect of PQS. Nevertheless, although iron deficiency per se induced rhlR, there seems to be PQS specific effects that are independent of the PQS effect on P. aeruginosa iron homeostasis Keywords: PQS response
2006-12-12 | GSE3836 | GEO
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.
2025-04-09 | GSE291609 | GEO
Project description:Virulence factor production and the development of biofilms in Pseudomonas aeruginosa have been shown to be regulated by two hierarchically organised quorum sensing (QS) systems via small acyl-homoserine lactone (AHL) signal molecules. Recently, a third bacterial signal molecule, the Pseudomonas quinolone signal (PQS), has been identified, which positively regulates a subset of genes dependent on the QS systems. To further dissect the various independent regulation levels for many QS induced genes and to evaluate the impact of PQS on the QS circuitry, we performed a transcriptome analysis of PAO1 cultures supplemented with PQS. The global transcriptional profile in response to PQS revealed a marked up-regulation of genes belonging to the tightly interdependent functional groups of iron acquisition and oxidative stress response. Remarkably, not only most of the differentially regulated genes but also the induction of a lacZ transcriptional fusion of rhlR could be traced back to a iron chelating effect of PQS. Nevertheless, although iron deficiency per se induced rhlR, there seems to be PQS specific effects that are independent of the PQS effect on P. aeruginosa iron homeostasis Experiment Overall Design: For RNA extraction bacteria were harvested at early logarithmic, late logarithmic and stationary phase of growth. Three independent cultures of PQS-treated and untreated PAO1 each were pooled and the RNA was immediately stabilized with RNAprotect Bacteria Reagent (Qiagen, Valencia, CA). RNA was isolated using the RNeasy kit (Qiagen), treated with DNaseI (Roche) for 30 min at 37M-BM-0C and re-purified with the RNeasy spin column. The subsequent steps of cDNA generation and Biotin-ddUTP terminal labelling were performed as described in the manufacturerM-bM-^@M-^Ys instructions for the P. aeruginosa GeneChipM-CM-^R. Fragmented and labelled cDNA was hybridised to a GeneChip at 50 M-BM-0C for 16 h. The washing steps, staining and scanning of the microarrays were performed using the Affymetrix GeneChip system. Data analysis was performed using the Affymetrix Microarray Suite Software 5.0 with Affymetrix default parameters. As expression analysis was performed in duplicate, a total of two GeneChips per culture condition was scanned at 570 nm, 3 M-BM-5m resolution in an Affymetrix GeneChip scanner. The signals were multiplied by a scaling factor to make the average signal for all the arrays equivalent. The data were imported into a Microsoft Access database capable of searching for genes, which were found in all four pairings defined by the Affymetrix Microarray Suite Software as having significant changes in their signal intensities. Data were combined with the latest annotation from the website of the P. aeruginosa PAO1 sequence and the community annotation project provided at www.pseudomonas.com.
2008-11-07 | E-GEOD-3836 | biostudies-arrayexpress
Project description:Pseudomonas aeruginosa is a major cause of nosocomial infections and also leads to severe exacerbations in cystic fibrosis or chronic obstructive pulmonary disease. Three intertwined quorum sensing systems control virulence of P. aeruginosa, with the rhl circuit playing the leading role in late and chronic infections. The majority of traits controlled by rhl transcription factor RhlR depend on PqsE, a dispensable thioesterase in Pseudomonas Quinolone Signal (PQS) biosynthesis that interferes with RhlR through an enigmatic mechanism likely involving direct interaction of both proteins. Here we show that PqsE and RhlR form a 2:2 protein complex that, together with RhlR agonist N-butanoyl-L-homoserine lactone (C4-HSL), solubilizes RhlR and thereby renders the otherwise insoluble transcription factor active. We determined crystal structures of the complex and identified residues essential for the interaction. To corroborate the chaperone like activity of PqsE, we designed stability-optimized variants of RhlR that bypass the need for C4-HSL and PqsE in activating PqsE/RhlR-controlled processes of P. aeruginosa. Together, our data provide insight into the unique regulatory role of PqsE and lay groundwork for developing new P. aeruginosa-specific pharmaceuticals.
2023-03-11 | PXD038000 | Pride
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E167. In this strain, RhlR positively regulates 78 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
2022-03-18 | GSE198719 | GEO
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E104. In this strain, RhlR positively regulates 48 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
2022-03-18 | GSE198534 | GEO