scholarly journals Quorum Quenching by an N-Acyl-Homoserine Lactone Acylase from Pseudomonas aeruginosa PAO1

2006 ◽  
Vol 74 (3) ◽  
pp. 1673-1682 ◽  
Author(s):  
Charles F. Sio ◽  
Linda G. Otten ◽  
Robbert H. Cool ◽  
Stephen P. Diggle ◽  
Peter G. Braun ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Side Chain ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Beta Lactam ◽  
Signal Molecule ◽  
Pathogenic Potential

ABSTRACT The virulence of the opportunistic human pathogen Pseudomonas aeruginosa PAO1 is controlled by an N-acyl-homoserine lactone (AHL)-dependent quorum-sensing system. During functional analysis of putative acylase genes in the P. aeruginosa PAO1 genome, the PA2385 gene was found to encode an acylase that removes the fatty acid side chain from the homoserine lactone (HSL) nucleus of AHL-dependent quorum-sensing signal molecules. Analysis showed that the posttranslational processing of the acylase and the hydrolysis reaction type are similar to those of the beta-lactam acylases, strongly suggesting that the PA2385 protein is a member of the N-terminal nucleophile hydrolase superfamily. In a bioassay, the purified acylase was shown to degrade AHLs with side chains ranging in length from 11 to 14 carbons at physiologically relevant low concentrations. The substituent at the 3′ position of the side chain did not affect activity, indicating broad-range AHL quorum-quenching activity. Of the two main AHL signal molecules of P. aeruginosa PAO1, N-butanoyl-l-homoserine lactone (C4-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL), only 3-oxo-C12-HSL is degraded by the enzyme. Addition of the purified protein to P. aeruginosa PAO1 cultures completely inhibited accumulation of 3-oxo-C12-HSL and production of the signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone and reduced production of the virulence factors elastase and pyocyanin. Similar results were obtained when the PA2385 gene was overexpressed in P. aeruginosa. These results demonstrate that the protein has in situ quorum-quenching activity. The quorum-quenching AHL acylase may enable P. aeruginosa PAO1 to modulate its own quorum-sensing-dependent pathogenic potential and, moreover, offers possibilities for novel antipseudomonal therapies.

scholarly journals Efficacy of Liposomal Bismuth-Ethanedithiol-Loaded Tobramycin after Intratracheal Administration in Rats with Pulmonary Pseudomonas aeruginosa Infection

2012 ◽  
Vol 57 (1) ◽  
pp. 569-578 ◽  
Author(s):  
Moayad Alhariri ◽  
Abdelwahab Omri
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Homoserine Lactone ◽  
Protease Production ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Signal Molecule ◽  
Intratracheal Administration ◽  
Content Type

ABSTRACTWe sought to investigate alterations in quorum-sensing signal moleculeN-acyl homoserine lactone secretion and in the release ofPseudomonas aeruginosavirulence factors, as well as thein vivoantimicrobial activity of bismuth-ethanedithiol incorporated into a liposome-loaded tobramycin formulation (LipoBiEDT-TOB) administered to rats chronically infected withP. aeruginosa. The quorum-sensing signal moleculeN-acyl homoserine lactone was monitored by using a biosensor organism.P. aeruginosavirulence factors were assessed spectrophotometrically. An agar beads model of chronicPseudomonaslung infection in rats was used to evaluate the efficacy of the liposomal formulation in the reduction of bacterial count. The levels of active tobramycin in the lungs and the kidneys were evaluated by microbiological assay. LipoBiEDT-TOB was effective in disrupting both quorum-sensing signal moleculesN-3-oxo-dodeccanoylhomoserine lactone andN-butanoylhomoserine lactone, as well as significantly (P< 0.05) reducing lipase, chitinase, and protease production. At 24 h after 3 treatments, the CFU counts in lungs of animals treated with LipoBiEDT-TOB were of 3 log10CFU/lung, comparated to 7.4 and 4.7 log10CFU/lung, respectively, in untreated lungs and in lungs treated with free antibiotic. The antibiotic concentration after the last dose of LipoBiEDT-TOB was 25.1 μg/lung, while no tobramycin was detected in the kidneys. As for the free antibiotic, we found 6.5 μg/kidney but could not detect any tobramycin in the lungs. Taken together, LipoBiEDT-TOB reduced the production of quorum-sensing molecules and virulence factors and could highly improve the management of chronic pulmonary infection in cystic fibrosis patients.

scholarly journals A Distinct QscR Regulon in the Pseudomonas aeruginosa Quorum-Sensing Circuit

2006 ◽  
Vol 188 (9) ◽  
pp. 3365-3370 ◽  
Author(s):  
Yannick Lequette ◽  
Joon-Hee Lee ◽  
Fouzia Ledgham ◽  
Andrée Lazdunski ◽  
E. Peter Greenberg
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Signal Molecule ◽  
Control Of Gene Expression ◽  
Signaling Systems ◽  
Sensing Systems

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa possesses two complete acyl-homoserine lactone (acyl-HSL) signaling systems. One system consists of LasI and LasR, which generate a 3-oxododecanoyl-homoserine lactone signal and respond to that signal, respectively. The other system is RhlI and RhlR, which generate butanoyl-homoserine lactone and respond to butanoyl-homoserine lactone, respectively. These quorum-sensing systems control hundreds of genes. There is also an orphan LasR-RhlR homolog, QscR, for which there is no cognate acyl-HSL synthetic enzyme. We previously reported that a qscR mutant is hypervirulent and showed that QscR transiently represses a few quorum-sensing-controlled genes. 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.

Inhibitive Effect of Eugenol and Its Nanoemulsion on Quorum Sensing–Mediated Virulence Factors and Biofilm Formation by Pseudomonas aeruginosa

2019 ◽  
Vol 82 (3) ◽  
pp. 379-389 ◽  
Author(s):  
ZAIXIANG LOU ◽  
KEKGABILE S. LETSIDIDI ◽  
FUHAO YU ◽  
ZEJUN PEI ◽  
HONGXIN WANG ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Expression Level ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Swarming Motility ◽  
Violacein Production ◽  
Virulence Factor Production

ABSTRACT The aim of the present study was to evaluate the quorum sensing (QS) inhibition potential of eugenol and eugenol nanoemulsion against QS-dependent virulence factor production and gene expression, as well as biofilm formation in Pseudomonas aeruginosa. In the current study, eugenol nanoemulsion at a sub-MIC of 0.2 mg/mL specifically inhibited about 50% of the QS-mediated violacein production in Chromobacterium violaceum, as well as the production of N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) and C4-HSL N-acyl homoserine lactone signal molecules, pyocyanin, and swarming motility in P. aeruginosa. The inhibitive effect of eugenol and its nanoemulsion on the expression of the QS synthase genes was concentration dependent, displaying 65 and 52% expression level for lasI, respectively, and 61 and 45% expression level for rhlI, respectively, at a concentration of 0.2 mg/mL. In addition, the inhibitive effect of eugenol and its nanoemulsion on the expression of the rhlA gene responsible for the production of rhamnolipid was also concentration dependent, displaying 65 and 51% expression level for the rhlA gene, respectively, at a concentration of 0.2 mg/mL. Eugenol and its nanoemulsion also displayed 36 and 63% respective inhibition of biofilm formation by P. aeruginosa at the 0.2 mg/mL concentration. Therefore, the nanoemulsion could be used as a novel QS-based antibacterial and antibiofilm agent for the control of harmful bacteria.

scholarly journals Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Rita S. Valente ◽  
Pol Nadal-Jimenez ◽  
André F. P. Carvalho ◽  
Filipe J. D. Vieira ◽  
Karina B. Xavier
Keyword(s):  
Signal Transduction ◽  
Quorum Sensing ◽  
Plant Pathogen ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Interspecies Interactions ◽  
Major Factors

ABSTRACT Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora), two signaling networks—the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway—control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants. We show that the AHL system controls the Gac/Rsm system by affecting the expression of the regulatory RNA RsmB. This regulation is mediated by ExpR2, the quorum-sensing receptor that responds to the P. wasabiae cognate AHL but also to AHLs produced by other bacterial species. As a consequence, this level of regulation allows P. wasabiae to bypass the Gac-dependent regulation of RsmB in the presence of exogenous AHLs or AHL-producing bacteria. We provide in vivo evidence that this pivotal role of RsmB in signal transduction is important for the ability of P. wasabiae to induce virulence in response to other AHL-producing bacteria in multispecies plant lesions. Our results suggest that the signaling architecture in P. wasabiae was coopted to prime the bacteria to eavesdrop on other bacteria and quickly join the efforts of other species, which are already exploiting host resources. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways.

scholarly journals Cross-Species GacA-Controlled Induction of Antibiosis in Pseudomonads

2006 ◽  
Vol 73 (2) ◽  
pp. 650-654 ◽  
Author(s):  
Christophe Dubuis ◽  
Dieter Haas
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Fluorescens ◽  
Small Rnas ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Pseudomonas Corrugata ◽  
Interspecies Communication ◽  
Antibiotic Compounds ◽  
Culture Supernatants

ABSTRACT Signal extracts prepared from culture supernatants of Pseudomonas fluorescens CHA0 and Pseudomonas aeruginosa PAO stimulated GacA-dependent expression of small RNAs and hence of antibiotic compounds in both hosts. Pseudomonas corrugata LMG2172 and P. fluorescens SBW25 also produced signal molecules stimulating GacA-controlled antibiotic synthesis in strain CHA0, illustrating a novel, N-acyl-homoserine lactone-independent type of interspecies communication.

Occurrence of Proteolytic Activity and N-Acyl-Homoserine Lactone Signals in the Spoilage of Aerobically Chill-Stored Proteinaceous Raw Foods

2006 ◽  
Vol 69 (11) ◽  
pp. 2729-2737 ◽  
Author(s):  
M. LIU ◽  
J. M. GRAY ◽  
M. W. GRIFFITHS
Keyword(s):  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Food Systems ◽  
Bacterial Flora ◽  
Homoserine Lactone ◽  
Food Samples ◽  
Clear Correlation ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Raw Foods

Proteolytic pseudomonads dominate the spoilage flora of aerobically chill-stored proteinaceous raw foods. Proteolysis during spoilage of these food systems affects both food quality and the dynamics of the bacterial community because it increases the availability of nutrients to the community as a whole. Quorum sensing, or cell-cell signaling, is associated closely with ecological interactions among bacteria in mixed communities. The potential role of quorum sensing in proteolytic food spoilage was examined, based on the evaluation of N-acyl-homoserine lactone (AHL) signal molecules. The occurrence of proteolytic activity and AHL signals was studied during spoilage of aerobically chill-stored ground beef, fish, chicken, and raw milk. Pseudomonads dominated the psychrotrophic flora, followed distantly by members of the Enterobacteriaceae. The growth of pseudomonads was correlated with the occurrence of proteolytic activity in all food systems. AHL concentration began increasing significantly only after the onset of proteolytic activity. Widely divergent AHL profiles were revealed by thin-layer chromatography analysis of the different food samples, and these profiles were likely determined by the undefined bacterial flora in these systems and by the characterized pseudomonads and Enterobacteriaceae. Although Hafnia alvei was a major component of the Enterobacteriaceae flora in all foods tested and a strong AHL producer, the signal molecules produced by H. alvei strain EB1 did not influence protease production by Pseudomonas fluorescens strain 395 in vitro. These results do not indicate any clear correlation between the overall detectable AHL signal molecules accumulated in the food samples and proteolytic activity.

scholarly journals Interference with Pseudomonas aeruginosa Quorum Sensing and Virulence by the Mycobacterial Pseudomonas Quinolone Signal Dioxygenase AqdC in Combination with the N-Acylhomoserine Lactone Lactonase QsdA

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Franziska S. Birmes ◽  
Ruth Säring ◽  
Miriam C. Hauke ◽  
Niklas H. Ritzmann ◽  
Steffen L. Drees ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Rhodococcus Erythropolis ◽  
Quorum Quenching ◽  
Signal Molecules ◽  
Content Type ◽  
Acylhomoserine Lactone ◽  
Regulatory Effects ◽  
Epithelial Lung Cells

ABSTRACT The nosocomial pathogen Pseudomonas aeruginosa regulates its virulence via a complex quorum sensing network, which, besides N-acylhomoserine lactones, includes the alkylquinolone signal molecules 2-heptyl-3-hydroxy-4(1H)-quinolone (Pseudomonas quinolone signal [PQS]) and 2-heptyl-4(1H)-quinolone (HHQ). Mycobacteroides abscessus subsp. abscessus, an emerging pathogen, is capable of degrading the PQS and also HHQ. Here, we show that although M. abscessus subsp. abscessus reduced PQS levels in coculture with P. aeruginosa PAO1, this did not suffice for quenching the production of the virulence factors pyocyanin, pyoverdine, and rhamnolipids. However, the levels of these virulence factors were reduced in cocultures of P. aeruginosa PAO1 with recombinant M. abscessus subsp. massiliense overexpressing the PQS dioxygenase gene aqdC of M. abscessus subsp. abscessus, corroborating the potential of AqdC as a quorum quenching enzyme. When added extracellularly to P. aeruginosa cultures, AqdC quenched alkylquinolone and pyocyanin production but induced an increase in elastase levels. When supplementing P. aeruginosa cultures with QsdA, an enzyme from Rhodococcus erythropolis which inactivates N-acylhomoserine lactone signals, rhamnolipid and elastase levels were quenched, but HHQ and pyocyanin synthesis was promoted. Thus, single quorum quenching enzymes, targeting individual circuits within a complex quorum sensing network, may also elicit undesirable regulatory effects. Supernatants of P. aeruginosa cultures grown in the presence of AqdC, QsdA, or both enzymes were less cytotoxic to human epithelial lung cells than supernatants of untreated cultures. Furthermore, the combination of both aqdC and qsdA in P. aeruginosa resulted in a decline of Caenorhabditis elegans mortality under P. aeruginosa exposure.

scholarly journals Endophytic Actinomycetes: A Novel Source of Potential Acyl Homoserine Lactone Degrading Enzymes

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Surang Chankhamhaengdecha ◽  
Suphatra Hongvijit ◽  
Akkaraphol Srichaisupakit ◽  
Pattra Charnchai ◽  
Watanalai Panbangred
Keyword(s):  
Pathogenic Bacteria ◽  
Sequence Similarity ◽  
Soft Rot ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Amide Bond ◽  
Side Chain ◽  
Signal Molecules ◽  
Endophytic Actinomycetes

Several Gram-negative pathogenic bacteria employN-acyl-L-homoserine lactone (HSL) quorum sensing (QS) system to control their virulence traits. Degradation of acyl-HSL signal molecules by quorum quenching enzyme (QQE) results in a loss of pathogenicity in QS-dependent organisms. The QQE activity of actinomycetes in rhizospheric soil and inside plant tissue was explored in order to obtain novel strains with high HSL-degrading activity. Among 344 rhizospheric and 132 endophytic isolates, 127 (36.9%) and 68 (51.5%) of them, respectively, possessed the QQE activity. The highest HSL-degrading activity was at151.30±3.1 nmole/h/mL from an endophytic actinomycetes isolate, LPC029. The isolate was identified asStreptomycesbased on16S  rRNAgene sequence similarity. The QQE from LPC029 revealed HSL-acylase activity that was able to cleave an amide bond of acyl-side chain in HSL substrate as determined by HPLC. LPC029 HSL-acylase showed broad substrate specificity from C6- to C12-HSL in which C10HSL is the most favorable substrate for this enzyme. In anin vitropathogenicity assay, the partially purified HSL-acylase efficiently suppressed soft rot of potato caused byPectobacterium carotovorumssp.carotovorumas demonstrated. To our knowledge, this is the first report of HSL-acylase activity derived from an endophyticStreptomyces.

Novel bacteria degrading N-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria

Microbiology ◽  
2003 ◽  
Vol 149 (8) ◽  
pp. 1981-1989 ◽  
Author(s):  
Stéphane Uroz ◽  
Cathy D'Angelo-Picard ◽  
Aurélien Carlier ◽  
Miena Elasri ◽  
Carine Sicot ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Rhodococcus Erythropolis ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
In Planta ◽  
Signal Molecule ◽  
Violacein Production ◽  
Regulated Functions

Bacteria degrading the quorum-sensing (QS) signal molecule N-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. Twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic REP-PCR and rrs PCR-RFLP profiles. Representative strains from each group were identified as members of the genera Pseudomonas, Comamonas, Variovorax and Rhodococcus. All these isolates degraded N-acylhomoserine lactones other than the hexanoic acid derivative, albeit with different specificity and kinetics. One of these isolates, Rhodococcus erythropolis strain W2, was used to quench QS-regulated functions of other microbes. In vitro, W2 strongly interfered with violacein production by Chromobacterium violaceum, and transfer of pathogenicity in Agrobacterium tumefaciens. In planta, R. erythropolis W2 markedly reduced the pathogenicity of Pectobacterium carotovorum subsp. carotovorum in potato tubers. These series of results reveal the diversity of the QS-interfering bacteria in the rhizosphere and demonstrate the validity of targeting QS signal molecules to control pathogens with natural bacterial isolates.

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