Expression data from Pseudomonas aeruginosa (wild type and lasRrhlR mutant strains) exposed to human neutrophils
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ABSTRACT:
ORGANISM(S): Pseudomonas aeruginosa PAO1 Pseudomonas aeruginosa
PROVIDER: GSE6769 | GEO | 2009/08/04
SECONDARY ACCESSION(S): PRJNA98929
REPOSITORIES: GEO
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Project description:In the present in vitro study, interactions between P. aeruginosa (sessile biofilms as well as planktonic cells) and PMNs were analyzed by means of DNA microarray based transcriptomics. We found that the P. aeruginosa wild type biofilms, in contrast to planktonic cultures and quorum sensing (QS) deficient strains, respond to PMN exposure in a rather aggressive manner. The response does not involve protective mechanisms such as those involved in oxidative stress. Rather it is dominated by QS controlled virulence determinants such as those encoded by pqs, phz, rhlAB, all of which are designed to cripple Eukaryotic cells including PMNs and macrophages. Our comparative analysis supports the view that QS plays a major role in mechanisms by which P. aeruginosa evades host defense systems. Keywords: Stress response The biofilms were allowed to grow and develop in the biofilm flow chambers for 3 days before challenge with PMNs. Fresh PMNs from human volunteers were isolated and resuspended in RPMI-1640 medium (BIOCHROM AG) as previously described by Bjarnsholt et al. 2005 (Bjarnsholt et al., 2005). Prior to PMN injection the flow was halted. Ten million PMNs were resuspended in 6 ml of RPMI media and injected into the flow chamber. The concentration of PMNs was found by microscopy to be approximately 1 PMN per 1000 bacterial cells. PMNs and biofilm were incubated for 2 hours. The flow chambers were rolled every 15 minutes to ensure that the entire biofilm was exposed to the PMNs. After incubation the fluid inside the chamber was discarded and the attached biofilm cells were loosened by rolling. The cells were then mechanically removed and collected in 6 ml of RNAlater®
2009-08-04 | E-GEOD-6769 | biostudies-arrayexpress
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: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 pathogenicity mainly relies on its ability to finely control the expression of virulence determinants via multiple quorum sensing (QS) systems. Despite the relevant role of the pqs QS system in controlling the expression of key virulence factors and biofilm formation in P. aeruginosa, our understanding of the molecular mechanisms governing this QS circuit, which employs 2-alkyl-4-quinolones (AQs) as signal molecules, is still preliminary, probably due to its complexity. Multiple genes are required for the synthesis of the primary AQs, 2-heptyl-4-hydroxyquinoline (HHQ), 2-heptyl-3-hydroxy-4-quinolone (PQS), and 2-heptyl-4-hydroxyquinoline N-oxide (HQNO). These include the pqsABCDE operon, required for the synthesis of HHQ, which in turn is oxidized to PQS via the action of the monooxygenase PqsH. The monooxygenase PqsL is required for HQNO synthesis together with the pqsABCD genes. The fifth gene of the pqsABCDE operon, pqsE, is also required for the production of major virulence factors and for biofilm formation, and exerts a homeostatic effect on AQs synthesis by repressing the transcription of the pqsABCDE operon. The pqs system is subject to positive autoregulation, with the PqsR regulator promoting pqsABCDE transcription upon binding to HHQ or PQS. However, the individual contributions and relative importance of HHQ, PQS, HQNO and PqsE to AQ-dependent signalling is not fully apparent, because of the overlapping and interdependent nature of the factors involved in this complex QS network. We used microarrays to detail the global response of a P. aeruginosa mutant strain unable to synthesise or convert AQs, and to express PqsE to exogenously provided AQs or IPTG (to induce pqsE expression).
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Project description:The Pseudomonas aeruginosa MvfR-dependent QS regulatory pathway controls the expression of key virulence genes; and is activated via the extracellular signals 4-hydroxy-2-heptylquinoline (HHQ) and 3,4-dihydroxy-2-heptylquinoline (PQS). Our findings reveal a multi-layered homeostatic regulation of PQS and HHQ and the MvfR regulon component PqsE which is a key mediator in orchestrating this homeostatic regulation.
2009-07-17 | GSE17116 | GEO
Project description:Pseudomonas aeruginosa is a versatile opportunistic pathogen requiring iron for its survival and virulence within the host. The ability to switch to heme as an iron source provides an advantage in chronic infection. We have recently shown the extracellular heme metabolites biliverdin IX (BVIX) and/or BVIX positively regulate the heme dependent cell surface signaling cascade. We further investigated the role of BVIX and BVIX in cell signaling utilizing allelic strains lacking a functional HemO (hemOin), or one reengineered to produce BVIX (hemO). Compared to PAO1 both strains show a heme dependent growth defect, decreased swarming and twitching and less robust biofilm formation. Interestingly, the motility and biofilm defects were partially rescued on addition of exogenous BVIX and BVIX. Utilizing LC-MS/MS we performed a comparative proteomics and metabolomics analysis of PAO1 versus the allelic strains in shaking and static conditions. In shaking conditions, the hemO allelic strains showed a significant increase in proteins involved in quorum sensing (QS), phenazine production and chemotaxis.Metabolite profiling further revealed increased levels of PQS and phenazine metabolites. In static conditions we observed a significant repression of chemosensory pathways and Type IV pili (TFP) biogenesis proteins as well as several phosphodiesterases associated with biofilm dispersal. We propose BVIX metabolites function as signaling and chemotactic molecules integrating heme utilization as an iron source into the adaptation of P. aeruginosa from a planktonic to sessile lifestyle.
2024-01-19 | PXD045835 | Pride
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.
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