scholarly journals Posttranscriptional Control of Quorum-Sensing-Dependent Virulence Genes by DksA in Pseudomonas aeruginosa

2003 ◽  
Vol 185 (12) ◽  
pp. 3558-3566 ◽  
Author(s):  
Florence Jude ◽  
Thilo Köhler ◽  
Pavel Branny ◽  
Karl Perron ◽  
Matthias P. Mayer ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Genes ◽  
Wild Type Strain ◽  
Wild Type ◽  
Posttranscriptional Control ◽  
E Coli ◽  
Sensing Systems ◽  
Regulator Genes ◽  
Virulence Factor Production

ABSTRACT Pseudomonas aeruginosa controls the secretion of extracellular virulence factors, including rhamnolipids and LasB elastase, by the las and rhl quorum-sensing systems. Here, we mutated the dksA gene of P. aeruginosa by insertion of an Ω-Hg cassette. The mutant displayed growth rates similar to that of the wild type in rich medium but was impaired in growth in defined minimal medium. Production of rhamnolipids and LasB elastase by the dksA mutant was only 4 and 10%, respectively, of wild-type levels. These defects could be partially complemented by introduction of the plasmid-encoded dksA genes from P. aeruginosa or Escherichia coli. In the dksA mutant, the expression of rhlI was increased early during exponential growth, but expression of other quorum-sensing regulator genes—lasR, lasI, and rhlR—was not affected. Although the transcription of the lasB and rhlAB genes was comparable between the dksA mutant and the wild-type strain in peptone tryptic soy broth medium, we observed reduced translation of both genes in the dksA mutant. Similarly, we found that full translation of lasB and rhlAB genes in E. coli also requires the dksA gene. DksA is therefore a novel regulator involved in the posttranscriptional control of extracellular virulence factor production in P. aeruginosa.

scholarly journals Pseudomonas aeruginosa Cell-to-Cell Signaling Is Required for Virulence in a Model of Acute Pulmonary Infection

2000 ◽  
Vol 68 (7) ◽  
pp. 4331-4334 ◽  
Author(s):  
James P. Pearson ◽  
Matthew Feldman ◽  
Barbara H. Iglewski ◽  
Alice Prince
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Cell Signaling ◽  
Type Strain ◽  
Pulmonary Infection ◽  
Virulence Genes ◽  
Wild Type Strain ◽  
Wild Type ◽  
Neonatal Mice ◽  
Mutant Strains

ABSTRACT Cell-to-cell signaling controls many virulence genes inPseudomonas aeruginosa. We tested the virulence oflas and rhl quorum-sensing mutants in neonatal mice. A lasI rhlI double mutant was nearly avirulent, and the respective single mutant strains were reduced in virulence compared with the wild-type strain. Quorum sensing plays a role in P. aeruginosa pneumonia in neonatal mice.

scholarly journals Quorum Sensing Is a Global Regulatory Mechanism in Enterohemorrhagic Escherichia coli O157:H7

2001 ◽  
Vol 183 (17) ◽  
pp. 5187-5197 ◽  
Author(s):  
Vanessa Sperandio ◽  
Alfredo G. Torres ◽  
Jorge A. Girón ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Type Strain ◽  
Wild Type Strain ◽  
Regulatory Mechanism ◽  
Sos Response ◽  
Enterohemorrhagic Escherichia Coli ◽  
Trna Genes ◽  
Wild Type ◽  
E Coli

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for outbreaks of bloody diarrhea and hemolytic-uremic syndrome in many countries. EHEC virulence mechanisms include the production of Shiga toxins (Stx) and formation of attaching and effacing (AE) lesions on intestinal epithelial cells. We recently reported that genes involved in the formation of the AE lesion were regulated by quorum sensing through autoinducer-2, which is synthesized by the product of the luxS gene. In this study we hybridized an E. coli gene array with cDNA synthesized from RNA that was extracted from EHEC strain 86-24 and its isogenicluxS mutant. We observed that 404 genes were regulated by luxS at least fivefold, which comprises approximately 10% of the array genes; 235 of these genes were up-regulated and 169 were down-regulated in the wild-type strain compared to in theluxS mutant. Down-regulated genes included several involved in cell division, as well as ribosomal and tRNA genes. Consistent with this pattern of gene expression, theluxS mutant grows faster than the wild-type strain (generation times of 37.5 and 60 min, respectively, in Dulbecco modified Eagle medium). Up-regulated genes included several involved in the expression and assembly of flagella, motility, and chemotaxis. Using operon::lacZ fusions to class I, II, and III flagellar genes, we were able to confirm this transcriptional regulation. We also observed fewer flagella by Western blotting and electron microscopy and decreased motility halos in semisolid agar in the luxS mutant. The average swimming speeds for the wild-type strain and the luxS mutant are 12.5 and 6.6 μm/s, respectively. We also observed an increase in the production of Stx due to quorum sensing. Genes encoding Stx, which are transcribed along with λ-like phage genes, are induced by an SOS response, and genes involved in the SOS response were also regulated by quorum sensing. These results indicate that quorum sensing is a global regulatory mechanism for basic physiological functions of E. coli as well as for virulence factors.

scholarly journals Quorum-Sensing Systems in the Plant Growth-Promoting Bacterium Paraburkholderia phytofirmans PsJN Exhibit Cross-Regulation and Are Involved in Biofilm Formation

2017 ◽  
Vol 30 (7) ◽  
pp. 557-565 ◽  
Author(s):  
Ana Zúñiga ◽  
Raúl A. Donoso ◽  
Daniela Ruiz ◽  
Gonzalo A. Ruz ◽  
Bernardo González
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Transcript Levels ◽  
Sensing Systems ◽  
Plant Growth Promoting ◽  
Growth Promoting

Quorum-sensing systems play important roles in host colonization and host establishment of Burkholderiales species. Beneficial Paraburkholderia species share a conserved quorum-sensing (QS) system, designated BraI/R, that controls different phenotypes. In this context, the plant growth-promoting bacterium Paraburkholderia phytofirmans PsJN possesses two different homoserine lactone QS systems BpI.1/R.1 and BpI.2/R.2 (BraI/R-like QS system). The BpI.1/R.1 QS system was previously reported to be important to colonize and produce beneficial effects in Arabidopsis thaliana plants. Here, we analyzed the temporal variations of the QS gene transcript levels in the wild-type strain colonizing plant roots. The gene expression patterns showed relevant differences in both QS systems compared with the wild-type strain in the unplanted control treatment. The gene expression data were used to reconstruct a regulatory network model of QS systems in P. phytofirmans PsJN, using a Boolean network model. Also, we examined the phenotypic traits and transcript levels of genes involved in QS systems, using P. phytofirmans mutants in homoserine lactone synthases genes. We observed that the BpI.1/R.1 QS system regulates biofilm formation production in strain PsJN and this phenotype was associated with the lower expression of a specific extracytoplasmic function sigma factor ecf26.1 gene (implicated in biofilm formation) in the bpI.1 mutant strain.

scholarly journals Overexpression of the MexEF-OprN Multidrug Efflux System Affects Cell-to-Cell Signaling in Pseudomonas aeruginosa

2001 ◽  
Vol 183 (18) ◽  
pp. 5213-5222 ◽  
Author(s):  
Thilo Köhler ◽  
Christian van Delden ◽  
Lasta Kocjancic Curty ◽  
Mehri Michea Hamzehpour ◽  
Jean-Claude Pechere
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Efflux System ◽  
Sensing Systems ◽  
In The Wild ◽  
Type Mutant ◽  
Regulator Genes

ABSTRACT Intrinsic and acquired antibiotic resistance of the nosocomial pathogen Pseudomonas aeruginosa is mediated mainly by the expression of several efflux pumps of broad substrate specificity. Here we report that nfxC type mutants, overexpressing the MexEF-OprN efflux system, produce lower levels of extracellular virulence factors than the susceptible wild type. These include pyocyanin, elastase, and rhamnolipids, three factors controlled by the las and rhl quorum-sensing systems of P. aeruginosa. In agreement with these observations are the decreased transcription of the elastase genelasB and the rhamnosyltransferase genesrhlAB measured in nfxC type mutants. Expression of the lasR and rhlR regulator genes was not affected in the nfxC type mutant. In contrast, transcription of the C4-homoserine lactone (C4-HSL) autoinducer synthase gene rhlI was reduced by 50% in the nfxC type mutant relative to that in the wild type. This correlates with a similar decrease in C4-HSL levels detected in supernatants of the nfxC type mutant. Transcription of an rhlAB-lacZ fusion could be partially restored by the addition of synthetic C4-HSL andPseudomonas quinolone signal (PQS). It is proposed that the MexEF-OprN efflux pump affects intracellular PQS levels.

scholarly journals Inhibition of Quorum Sensing by a Pseudomonas aeruginosa dksA Homologue

2001 ◽  
Vol 183 (5) ◽  
pp. 1531-1539 ◽  
Author(s):  
Pavel Branny ◽  
James P. Pearson ◽  
Everett C. Pesci ◽  
Thilo Köhler ◽  
Barbara H. Iglewski ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Northern Blot ◽  
Blot Analysis ◽  
Northern Blot Analysis ◽  
Homoserine Lactone ◽  
Suppressor Gene ◽  
Multicopy Plasmid ◽  
Sensing Systems ◽  
Virulence Factor Production

ABSTRACT The Pseudomonas aeruginosa las (lasR-lasI) andrhl (rhlR-rhlI) quorum-sensing systems regulate the expression of several virulence factors, including elastase and rhamnolipid. P. aeruginosa strain PR1-E4 is alasR deletion mutant that contains a second, undefined mutation which allows production of elastase and rhamnolipid despite a nonfunctional las system. We have previously shown that this strain accomplishes this by increasing the expression of the autoinducer synthase gene rhlI. In this report, we show that the elastolytic phenotype of mutant PR1-E4 can be complemented with a P. aeruginosa homologue of the Escherichia coli dnaK mutation suppressor gene dksA. When supplied in trans on a multicopy plasmid, this gene completely suppressed elastase production by mutant PR1-E4. Cloning and Northern blot analysis revealed that dksA was neither mutated nor less transcribed in mutant PR1-E4. When overexpressed,dksA also reduced rhamnolipid production by both mutant PR1-E4 and the wild type, PAO1. Using Northern blot analysis andlacZ reporter fusions, we show that dksAinhibits rhlI, rhlAB, and lasB transcription. Exogenous N-butyryl–l-homoserine lactone overcame the reduced expression of rhlI and restoredrhlAB and lasB expression, as well as elastase production. Our results suggest that the overproduction of the P. aeruginosa DksA homologue inhibits quorum-sensing-dependent virulence factor production by downregulating the transcription of the autoinducer synthase gene rhlI.

Allicin inhibits Pseudomonas aeruginosa virulence by suppressing the rhl and pqs quorum-sensing systems

2019 ◽  
Vol 65 (8) ◽  
pp. 563-574 ◽  
Author(s):  
Zhimin Xu ◽  
Hong Zhang ◽  
Hua Yu ◽  
Qian Dai ◽  
Junzhi Xiong ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Associated Factors ◽  
Therapeutic Agent ◽  
Virulence Regulation ◽  
Sensing Systems ◽  
Potential Use ◽  
Virulence Factor Production

Pseudomonas aeruginosa is a virulent bacterium that secretes a variety of virulence factors that aid in establishing infections in individuals. Allicin, derived from garlic, has been shown to inhibit virulence factor production and biofilm formation in P. aeruginosa. However, the mechanisms underlying the allicin-mediated regulation of P. aeruginosa virulence remain unclear. In this study, we investigated the possible mechanisms underlying allicin-mediated virulence regulation in P. aeruginosa. The results showed that allicin attenuates the production of P. aeruginosa virulence-associated factors, such as elastase, pyocyanin, pyoverdine, and rhamnolipids, by inhibiting the rhl and pqs quorum-sensing systems. Further analysis revealed that the rhl and pqs systems play different roles during the allicin-mediated regulation process. Taken together, these results support the potential use of allicin as a therapeutic agent in controlling P. aeruginosa infection and associated mechanisms.

scholarly journals Intra-species signaling between Pseudomonas aeruginosa genotypes increases production of quorum sensing controlled virulence factors

2020 ◽  
Author(s):  
Dallas L. Mould ◽  
Nico J. Botelho ◽  
Deborah A. Hogan
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Diverse Population ◽  
Loss Of Function ◽  
Wild Type ◽  
Natural Settings ◽  
Citrate Release ◽  
Virulence Factor Production

AbstractThe opportunistic pathogen Pseudomonas aeruginosa damages hosts through the production of diverse secreted products, many of which are regulated by quorum sensing. The lasR gene, which encodes a central quorum-sensing regulator, is frequently mutated, and loss of LasR function impairs the activity of downstream regulators RhlR and PqsR. We found that in diverse models, the presence of P. aeruginosa wild type causes LasR loss-of-function strains to hyperproduce RhlR/I-regulated antagonistic factors, and autoinducer production by the wild type is not required for this effect. We uncovered a reciprocal interaction between isogenic wild type and lasR mutant pairs wherein the iron-scavenging siderophore pyochelin, specifically produced by the lasR mutant, induces citrate release and cross-feeding from wild type. Citrate stimulates RhlR signaling and RhlI levels in LasR-but not in LasR+ strains, and the interactions occur in diverse media. Co-culture interactions between strains that differ by the function of a single transcription factor may explain worse outcomes associated with mixtures of LasR+ and LasR loss-of-function strains. More broadly, this report illustrates how interactions within a genotypically diverse population, similar to those that frequently develop in natural settings, can promote net virulence factor production.

scholarly journals Interdependence of multi-drug efflux pumps and quorum sensing systems in Pseudomonas aeruginosa

2014 ◽  
Vol 21 ◽  
pp. 92
Author(s):  
K. Ganguly ◽  
J.L. Phillips ◽  
M.S. Wren ◽  
P.E. Pardington ◽  
S. Gnanakaran ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Efflux Pumps ◽  
Drug Efflux ◽  
Sensing Systems ◽  
Drug Efflux Pumps

scholarly journals The YebC Family Protein PA0964 Negatively Regulates the Pseudomonas aeruginosa Quinolone Signal System and Pyocyanin Production

2008 ◽  
Vol 190 (18) ◽  
pp. 6217-6227 ◽  
Author(s):  
Haihua Liang ◽  
Lingling Li ◽  
Zhaolin Dong ◽  
Michael G. Surette ◽  
Kangmin Duan
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Response Regulator ◽  
Initial Study ◽  
Pfam Family ◽  
Swarming Motility ◽  
Sensing Systems ◽  
Family Protein ◽  
Pyocyanin Production

ABSTRACT Bacterial pathogenicity is often manifested by the expression of various cell-associated and secreted virulence factors, such as exoenzymes, protease, and toxins. In Pseudomonas aeruginosa, the expression of virulence genes is coordinately controlled by the global regulatory quorum-sensing systems, which includes the las and rhl systems as well as the Pseudomonas quinolone signal (PQS) system. Phenazine compounds are among the virulence factors under the control of both the rhl and PQS systems. In this study, regulation of the phzA1B1C1D1E1 (phzA1) operon, which is involved in phenazine synthesis, was investigated. In an initial study of inducing conditions, we observed that phzA1 was induced by subinhibitory concentrations of tetracycline. Screening of 13,000 mutants revealed 32 genes that altered phzA1 expression in the presence of subinhibitory tetracycline concentrations. Among them, the gene PA0964, designated pmpR ( p qsR-mediated P QS r egulator), has been identified as a novel regulator of the PQS system. It belongs to a large group of widespread conserved hypothetical proteins with unknown function, the YebC protein family (Pfam family DUF28). It negatively regulates the quorum-sensing response regulator pqsR of the PQS system by binding at its promoter region. Alongside phzA1 expression and phenazine and pyocyanin production, a set of virulence factors genes controlled by both rhl and the PQS were shown to be modulated by PmpR. Swarming motility and biofilm formation were also significantly affected. The results added another layer of regulation in the rather complex quorum-sensing systems in P. aeruginosa and demonstrated a clear functional clue for the YebC family proteins.

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