Uncovering the dynamic mechanisms of the Pseudomonas aeruginosa quorum sensing and virulence networks using Boolean modelling

AbstractIntroductionPseudomonas aeruginosa is an opportunistic pathogen with an extraordinary metabolic adaptability and a large repertoire of virulence factors that allow it to cause acute and chronic infections. Treatment of P. aeruginosa infections often fail due to its antibiotic resistance mechanisms, thus novel strategies aim at targeting virulence factors instead of growth-related features. However, there is currently not a clear understanding of the dynamic nature inherent to the wiring of its virulence networks.ResultsIn this study, we manually reconstructed the signalling and transcriptional regulatory networks of 12 acute (incl. pyocin and elastase) and 8 chronic virulence factors (incl. biofilm), and the 4 quorum sensing (QS) systems of P. aeruginosa. Using Boolean modelling (BM), we unveiled the important roles that stochasticity and node connectivity play in the networks’ inherent dynamicity and robustness. We showed that both the static interactions, as well as the time when the interactions take place, are important features in the QS network. In addition, we found that the virulence factors of the acute networks are under strict repression, or under an activation that is non-strict or oscillatory, while the chronic networks favour the repression of the virulence factor, with only moderate activation under certain conditions.ConclusionIn conclusion, our in silico-modelling framework provided us with a system-level view of the P. aeruginosa virulence and QS networks to gain new insights into the various mechanisms that support its pathogenicity and response to stressors targeting these networks. Thus, we suggest that BM provides an invaluable tool to guide the design of new treatments against P. aeruginosa.

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Pseudomonas aeruginosa las and rhl quorum-sensing systems are important for infection and inflammation in a rat prostatitis model

Microbiology ◽

10.1099/mic.0.028464-0 ◽

2009 ◽

Vol 155 (8) ◽

pp. 2612-2619 ◽

Cited By ~ 21

Author(s):

Lisa K. Nelson ◽

Genevieve H. D'Amours ◽

Kimberley M. Sproule-Willoughby ◽

Douglas W. Morck ◽

Howard Ceri

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Tissue Damage ◽

Inflammatory Markers ◽

Bacterial Colonization ◽

Opportunistic Pathogen ◽

Infection Model ◽

Chronic Infections ◽

Strain Pao1 ◽

Rat Prostate

Pseudomonas aeruginosa frequently acts as an opportunistic pathogen of mucosal surfaces; yet, despite causing aggressive prostatitis in some men, its role as a pathogen in the prostate has not been investigated. Consequently, we developed a Ps. aeruginosa infection model in the rat prostate by instilling wild-type (WT) Ps. aeruginosa strain PAO1 into the rat prostate. It was found that Ps. aeruginosa produced acute and chronic infections in this mucosal tissue as determined by bacterial colonization, gross morphology, tissue damage and inflammatory markers. WT strain PAO1 and its isogenic mutant PAO-JP2, in which both the lasI and rhlI quorum-sensing signal systems have been silenced, were compared during both acute and chronic prostate infections. In acute infections, bacterial numbers and inflammatory markers were comparable between WT PA01 and PAO-JP2; however, considerably less tissue damage occurred in infections with PAO-JP2. Chronic infections with PAO-JP2 resulted in reduced bacterial colonization, tissue damage and inflammation as compared to WT PAO1 infections. Therefore, the quorum-sensing lasI and rhlI genes in Ps. aeruginosa affect acute prostate infections, but play a considerably more important role in maintaining chronic infections. We have thus developed a highly reproducible model for the study of Ps. aeruginosa virulence in the prostate.

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Plantain Herb Extracts significantly attenuate the quorum sensing-controlled virulence factors and inhibit biofilm formation in Pseudomonas aeruginosa PAO1

E3S Web of Conferences ◽

10.1051/e3sconf/20197801004 ◽

2019 ◽

Vol 78 ◽

pp. 01004

Author(s):

Shan Li ◽

Jiangning Yao ◽

Haoming Li

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Biofilm Formation ◽

Opportunistic Pathogen ◽

Significant Inhibition ◽

Control Group ◽

Produce Cell ◽

Group B ◽

Herb Extracts

Pseudomonas aeruginosa is a Gram-negative organism that can survive under harsh conditions, and it is also an opportunistic pathogen that can produce cell-associated extracellular virulence factors. Several of these virulence factors have been demonstrated to be regulated by quorum sensing (QS). Plantain Herb has been used as antibacterial agents for many centuries in China. In this study, we analyzed Plantain Herb Extracts (PHE) at the concentration of 16 μg/mL (Group A, MIC), 8 μg/mL (Group B, 1/2 MIC) and 4 μg/mL (Group C, 1/4 MIC) for inhibition of the virulence factors production and biofilm formation in P. aeruginosa PAO1. The virulence factors included pyocyanin, rhamnolipids, protease and alginate. PHE showed significant inhibition of virulence factors as compared to the control group without interfering its growth. Thus, PHE might be a potent QS inhibitor and anti-biofilm agent in the treatment of Pseudomonas aeruginosa infections.

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PqsE Functions Independently of PqsR-Pseudomonas Quinolone Signal and Enhances the rhl Quorum-Sensing System

Journal of Bacteriology ◽

10.1128/jb.00753-08 ◽

2008 ◽

Vol 190 (21) ◽

pp. 7043-7051 ◽

Cited By ~ 105

Author(s):

John M. Farrow ◽

Zoe M. Sund ◽

Matthew L. Ellison ◽

Dana S. Wade ◽

James P. Coleman ◽

...

Keyword(s):

Quorum Sensing ◽

Virulence Factors ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Chronic Infections ◽

Signaling Systems ◽

Sensing System ◽

Pseudomonas Quinolone Signal ◽

Quorum Sensing System ◽

Hostile Environments

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute and chronic infections in immunocompromised individuals. This gram-negative bacterium produces a battery of virulence factors that allow it to infect and survive in many different hostile environments. The control of many of these virulence factors falls under the influence of one of three P. aeruginosa cell-to-cell signaling systems. The focus of this study, the quinolone signaling system, functions through the Pseudomonas quinolone signal (PQS), previously identified as 2-heptyl-3-hydroxy-4-quinolone. This signal binds to and activates the LysR-type transcriptional regulator PqsR (also known as MvfR), which in turn induces the expression of the pqsABCDE operon. The first four genes of this operon are required for PQS synthesis, but the fifth gene, pqsE, is not. The function of the pqsE gene is not known, but it is required for the production of multiple PQS-controlled virulence factors and for virulence in multiple models of infection. In this report, we show that PqsE can activate PQS-controlled genes in the absence of PqsR and PQS. Our data also suggest that the regulatory activity of PqsE requires RhlR and indicate that a pqsE mutant can be complemented for pyocyanin production by a large excess of exogenous N-butyryl homoserine lactone (C4-HSL). Finally, we show that PqsE enhances the ability of Escherichia coli expressing RhlR to respond to C4-HSL. Overall, our data lead us to conclude that PqsE functions as a regulator that is independent of PqsR and PQS but dependent on the rhl quorum-sensing system.

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Cladodionen Is a Potential Quorum Sensing Inhibitor Against Pseudomonas aeruginosa

Marine Drugs ◽

10.3390/md18040205 ◽

2020 ◽

Vol 18 (4) ◽

pp. 205 ◽

Cited By ~ 1

Author(s):

Mengjia Wang ◽

Lu Zhao ◽

Hao Wu ◽

Chaoyue Zhao ◽

Qianhong Gong ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Binding Affinity ◽

Virulence Factors ◽

Jiaozhou Bay ◽

Opportunistic Pathogen ◽

Inhibitory Effect ◽

Marine Fungus ◽

Docking Analysis ◽

Novel Approach

Pseudomonas aeruginosa is an opportunistic pathogen using virulence factors and biofilm regulated by quorum sensing (QS) systems to infect patients and protect itself from environmental stress and antibiotics. Interfering with QS systems is a novel approach to combat P. aeruginosa infections without killing the bacteria, meaning that it is much harder for bacteria to develop drug resistance. A marine fungus Cladosporium sp. Z148 with anti-QS activity was obtained from Jiaozhou Bay, China. Cladodionen, a novel QS inhibitor, was isolated from the extracts of this fungus. Cladodionen had a better inhibitory effect than pyocyanin on the production of elastase and rhamnolipid. It also inhibited biofilm formation and motilities. The mRNA expressions of QS-related genes, including receptor proteins (lasR, rhlR and pqsR), autoinducer synthases (lasI, rhlI and pqsA) and virulence factors (lasB and rhlA) were down-regulated by cladodionen. Molecular docking analysis showed that cladodionen had better binding affinity to LasR and PqsR than natural ligands. Moreover, the binding affinity of cladodionen to LasR was higher than to PqsR. Cladodionen exhibits potential as a QS inhibitor against P. aeruginosa, and its structure–activity relationships should be further studied to illustrate the mode of action, optimize its structure and improve anti-QS activity.

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The flavanone naringenin reduces the production of quorum sensing-controlled virulence factors in Pseudomonas aeruginosa PAO1

Microbiology ◽

10.1099/mic.0.049338-0 ◽

2011 ◽

Vol 157 (7) ◽

pp. 2120-2132 ◽

Cited By ~ 123

Author(s):

Olivier M. Vandeputte ◽

Martin Kiendrebeogo ◽

Tsiry Rasamiravaka ◽

Caroline Stévigny ◽

Pierre Duez ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Pathogenic Bacteria ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Gene Products ◽

Strain Pao1 ◽

Preliminary Screening ◽

Mutant Strains

Preliminary screening of the Malagasy plant Combretum albiflorum for compounds attenuating the production of quorum sensing (QS)-controlled virulence factors in bacteria led to the identification of active fractions containing flavonoids. In the present study, several flavonoids belonging to the flavone, flavanone, flavonol and chalcone structural groups were screened for their capacity to reduce the production of QS-controlled factors in the opportunistic pathogen Pseudomonas aeruginosa (strain PAO1). Flavanones (i.e. naringenin, eriodictyol and taxifolin) significantly reduced the production of pyocyanin and elastase in P. aeruginosa without affecting bacterial growth. Consistently, naringenin and taxifolin reduced the expression of several QS-controlled genes (i.e. lasI, lasR, rhlI, rhlR, lasA, lasB, phzA1 and rhlA) in P. aeruginosa PAO1. Naringenin also dramatically reduced the production of the acylhomoserine lactones N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) and N-butanoyl-l-homoserine lactone (C4-HSL), which is driven by the lasI and rhlI gene products, respectively. In addition, using mutant strains deficient for autoinduction (ΔlasI and ΔrhlI) and LasR- and RhlR-based biosensors, it was shown that QS inhibition by naringenin not only is the consequence of a reduced production of autoinduction compounds but also results from a defect in the proper functioning of the RlhR–C4-HSL complex. Widely distributed in the plant kingdom, flavonoids are known for their numerous and determinant roles in plant physiology, plant development and in the success of plant–rhizobia interactions, but, as shown here, some of them also have a role as inhibitors of the virulence of pathogenic bacteria by interfering with QS mechanisms.

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Roles of Two-Component Systems in Pseudomonas aeruginosa Virulence

International Journal of Molecular Sciences ◽

10.3390/ijms222212152 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12152

Author(s):

Maria Sultan ◽

Rekha Arya ◽

Kyeong Kyu Kim

Keyword(s):

Pseudomonas Aeruginosa ◽

Virulence Factors ◽

Opportunistic Pathogen ◽

Secretion Systems ◽

Chronic Infections ◽

Potential Threat ◽

Wide Range ◽

Component Systems ◽

Two Component ◽

Two Component Systems

Pseudomonas aeruginosa is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. P. aeruginosa poses a potential threat to human health worldwide due to its omnipresent nature, robust host accumulation, high virulence, and significant resistance to multiple antibiotics. The pathogenicity of P. aeruginosa, which is associated with acute and chronic infections, is linked with multiple virulence factors and associated secretion systems, such as the ability to form and utilize a biofilm, pili, flagella, alginate, pyocyanin, proteases, and toxins. Two-component systems (TCSs) of P. aeruginosa perform an essential role in controlling virulence factors in response to internal and external stimuli. Therefore, understanding the mechanism of TCSs to perceive and respond to signals from the environment and control the production of virulence factors during infection is essential to understanding the diseases caused by P. aeruginosa infection and further develop new antibiotics to treat this pathogen. This review discusses the important virulence factors of P. aeruginosa and the understanding of their regulation through TCSs by focusing on biofilm, motility, pyocyanin, and cytotoxins.

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Characterization of Pseudomonas aeruginosa Quorum Sensing Inhibitors from the Endophyte Lasiodiplodia venezuelensis and Evaluation of Their Antivirulence Effects by Metabolomics

Microorganisms ◽

10.3390/microorganisms9091807 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1807

Author(s):

Léonie Pellissier ◽

Sara Leoni ◽

Laurence Marcourt ◽

Emerson Ferreira Queiroz ◽

Nicole Lecoultre ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Antimicrobial Agents ◽

Fungal Endophytes ◽

Opportunistic Pathogen ◽

Single Step ◽

Bioactive Natural Products ◽

Quorum Sensing Inhibitors ◽

Wide Range

The opportunistic pathogen Pseudomonas aeruginosa is one of the “critical priority pathogens” due to its multidrug resistance to a wide range of antibiotics. Its ability to invade and damage host tissues is due to the use of quorum sensing (QS) to collectively produce a plethora of virulence factors. Inhibition of QS is an attractive strategy for new antimicrobial agents because it disrupts the initial events of infection without killing the pathogen. Highly diverse microorganisms as endophytes represent an under-explored source of bioactive natural products, offering opportunities for the discovery of novel QS inhibitors (QSI). In the present work, the objective was to explore selective QSIs within a unique collection of fungal endophytes isolated from the tropical palm Astrocaryum sciophilum. The fungi were cultured, extracted, and screened for their antibacterial and specific anti-QS activities against P. aeruginosa. The endophytic strain Lasiodiplodia venezuelensis was prioritized for scaled-up fractionation for its selective activity, leading to the isolation of eight compounds in a single step. Among them, two pyran-derivatives were found to be responsible for the QSI activity, with an effect on some QS-regulated virulence factors. Additional non-targeted metabolomic studies on P. aeruginosa documented their effects on the production of various virulence-related metabolites.

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SuhB Is a Regulator of Multiple Virulence Genes and Essential for Pathogenesis of Pseudomonas aeruginosa

mBio ◽

10.1128/mbio.00419-13 ◽

2013 ◽

Vol 4 (6) ◽

Cited By ~ 38

Author(s):

Kewei Li ◽

Chang Xu ◽

Yongxin Jin ◽

Ziyu Sun ◽

Chang Liu ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Virulence Factors ◽

Biofilm Formation ◽

Regulatory Networks ◽

Virulence Genes ◽

Chronic Infections ◽

Content Type ◽

Factors Associated ◽

Acute Infections

ABSTRACTDuring initial colonization and chronic infection, pathogenic bacteria encounter distinct host environments. Adjusting gene expression accordingly is essential for the pathogenesis.Pseudomonas aeruginosahas evolved complicated regulatory networks to regulate different sets of virulence factors to facilitate colonization and persistence. The type III secretion system (T3SS) and motility are associated with acute infections, while biofilm formation and the type VI secretion system (T6SS) are associated with chronic persistence. To identify novel regulatory genes required for pathogenesis, we screened aP. aeruginosatransposon (Tn) insertion library and foundsuhBto be an essential gene for the T3SS gene expression. The expression ofsuhBwas upregulated in a mouse acute lung infection model, and loss ofsuhBresulted in avirulence. Suppression of T3SS gene expression in thesuhBmutant is linked to a defective translation of the T3SS master regulator, ExsA. Further studies demonstrated thatsuhBmutation led to the upregulation of GacA and its downstream small RNAs, RsmY and RsmZ, triggering T6SS expression and biofilm formation while inhibiting the T3SS. Our results demonstrate that anin vivo-inducible gene,suhB, reciprocally regulates genes associated with acute and chronic infections and plays an essential role in the pathogenesis ofP. aeruginosa.IMPORTANCEA variety of bacterial pathogens, such asPseudomonas aeruginosa, cause acute and chronic infections in humans. During infections, pathogens produce different sets of virulence genes for colonization, tissue damage, and dissemination and for countering host immune responses. Complex regulatory networks control the delicate tuning of gene expression in response to host environments to enable the survival and growth of invading pathogens. Here we identifiedsuhBas a critical gene for the regulation of virulence factors inP. aeruginosa. The expression ofsuhBwas upregulated during acute infection in an animal model, and mutation ofsuhBrenderedP. aeruginosaavirulent. Moreover, we demonstrate that SuhB is required for the activation of virulence factors associated with acute infections while suppressing virulence factors associated with chronic infections. Our report provides new insights into the multilayered regulatory network of virulence genes inP. aeruginosa.

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Traditional Chinese Medicine Tanreqing Inhibits Quorum Sensing Systems in Pseudomonas aeruginosa

Frontiers in Microbiology ◽

10.3389/fmicb.2020.517462 ◽

2020 ◽

Vol 11 ◽

Author(s):

Weifeng Yang ◽

Qing Wei ◽

Qian Tong ◽

Kaiyu Cui ◽

Gaiying He ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Chinese Medicine ◽

Traditional Chinese Medicine ◽

Quorum Sensing ◽

Virulence Factors ◽

Bacterial Infections ◽

Cell Communication ◽

Opportunistic Pathogen ◽

Communication Process ◽

Phenotypic Analysis

Pseudomonas aeruginosa is an opportunistic pathogen that can infect a wide variety of hosts including humans, plants, and animals. The production of virulence factors is the determinant of the infection paradigm and is under orchestrated regulation via cell-to-cell communication process called quorum sensing (QS). To disable QS circuits and prevent bacterial infections, a large battery of anti-QS agents, particularly from traditional Chinese medicine have been developed. Here, we used P. aeruginosa as a model microorganism to investigate the effect of traditional Chinese medicine Tanreqing (TRQ) formula on bacterial pathogenicity. Phenotypic analysis showed that TRQ treatment could completely inhibit the production of phenazine pyocyanin and moderately inhibit the production of virulence factors such as rhamnolipids, elastase, and alkaline protease. Further transcriptomic analyses revealed that TRQ treatment could significantly attenuate the expression of QS-regulated genes in P. aeruginosa and TRQ-treated P. aeruginosa regulon shared a large overlap with QS regulon. Component contribution to QS inhibition shed light on the indispensable role of all five components in TRQ formula. Further genetic analysis indicated that upstream regulators of QS systems, including two-component systems GacS/GacA and PprA/PprB, were both inhibited by TRQ treatment. Finally, our TRQ formula could efficiently protect Caenorhabditis elegans from killing by P. aeruginosa. Altogether, we have proved TRQ formula as an effective and specific agent to attenuate bacterial virulence and combat bacterial infections.

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Intraspecies Signaling between Common Variants of Pseudomonas aeruginosa Increases Production of Quorum-Sensing-Controlled Virulence Factors

mBio ◽

10.1128/mbio.01865-20 ◽

2020 ◽

Vol 11 (4) ◽

Cited By ~ 2

Author(s):

Dallas L. Mould ◽

Nico J. Botelho ◽

Deborah A. Hogan

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Opportunistic Pathogen ◽

Loss Of Function ◽

Wild Type ◽

Chronic Infections ◽

Content Type ◽

Complex Interactions ◽

Natural Settings ◽

Citrate Release

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa damages hosts through the production of diverse secreted products, many of which are regulated by quorum sensing (QS). The lasR gene, which encodes a central QS regulator, is frequently mutated in clinical isolates from chronic infections, and loss of LasR function (LasR−) generally impairs the activity of downstream QS regulators RhlR and PqsR. We found that in cocultures containing LasR+ and LasR− strains, LasR− strains hyperproduce the RhlR/RhlI-regulated antagonistic factors pyocyanin and rhamnolipids in diverse models and media and in different strain backgrounds. Diffusible QS autoinducers produced by the wild type were not required for this effect. Using transcriptomics, genetics, and biochemical approaches, we uncovered a reciprocal interaction between wild-type and lasR mutant pairs wherein the iron-scavenging siderophore pyochelin produced by the lasR mutant induced citrate release and cross-feeding from the wild type. Citrate, a metabolite often secreted in low iron environments, stimulated RhlR signaling and RhlI levels in LasR−but not in LasR+ strains. These studies reveal the potential for complex interactions between recently diverged, genetically distinct isolates within populations from single chronic infections. IMPORTANCE Coculture interactions between lasR loss-of-function and LasR+ Pseudomonas aeruginosa strains may explain the worse outcomes associated with the presence of LasR− strains. More broadly, this report illustrates how interactions within a genotypically diverse population, similar to those that frequently develop in natural settings, can promote unpredictably high virulence factor production.

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