scholarly journals A NewN-Acyl Homoserine Lactone Synthase in an Uncultured Symbiont of the Red Sea Sponge Theonella swinhoei

2015 ◽  
Vol 82 (4) ◽  
pp. 1274-1285 ◽  
Author(s):  
Maya Britstein ◽  
Giulia Devescovi ◽  
Kim M. Handley ◽  
Assaf Malik ◽  
Markus Haber ◽  
...  
Keyword(s):  
Cell Communication ◽  
Homoserine Lactone ◽  
Marine Sponges ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Tetratricopeptide Repeats ◽  
Content Type ◽  
Theonella Swinhoei ◽  
Microbial Symbionts ◽  
Taxonomic Affiliation

ABSTRACTSponges harbor a remarkable diversity of microbial symbionts in which signal molecules can accumulate and enable cell-cell communication, such as quorum sensing (QS). Bacteria capable of QS were isolated from marine sponges; however, an extremely small fraction of the sponge microbiome is amenable to cultivation. We took advantage of community genome assembly and binning to investigate the uncultured majority of sponge symbionts. We identified a completeN-acyl-homoserine lactone (AHL)-QS system (designated TswIR) and seven partialluxIhomologues in the microbiome ofTheonella swinhoei. The TswIR system was novel and shown to be associated with an alphaproteobacterium of the orderRhodobacterales, here termedRhodobacteralesbacterium TS309. ThetswIgene, when expressed inEscherichia coli, produced three AHLs, two of which were also identified in aT. swinhoeisponge extract. The taxonomic affiliation of the 16S rRNA ofRhodobacteralesbacterium TS309 to a sponge-coral specific clade, its enrichment in sponge versus seawater and marine sediment samples, and the presence of sponge-specific features, such as ankyrin-like domains and tetratricopeptide repeats, indicate a likely symbiotic nature of this bacterium.

scholarly journals ThePseudomonas aeruginosaOrphan Quorum Sensing Signal Receptor QscR Regulates Global Quorum Sensing Gene Expression by Activating a Single Linked Operon

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Fengming Ding ◽  
Ken-Ichi Oinuma ◽  
Nicole E. Smalley ◽  
Amy L. Schaefer ◽  
Omar Hamwy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Null Mutant ◽  
Content Type ◽  
Single Operon

ABSTRACTPseudomonas aeruginosauses two acyl-homoserine lactone signals and two quorum sensing (QS) transcription factors, LasR and RhlR, to activate dozens of genes. LasR responds toN-3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and RhlR toN-butanoyl-homoserine lactone (C4-HSL). There is a thirdP. aeruginosaacyl-homoserine-lactone-responsive transcription factor, QscR, which acts to dampen or delay activation of genes by LasR and RhlR by an unknown mechanism. To better understand the role of QscR inP. aeruginosaQS, we performed a chromatin immunoprecipitation analysis, which showed this transcription factor bound the promoter of only a single operon of three genes linked toqscR, PA1895 to PA1897. Other genes that appear to be regulated by QscR in transcriptome studies were not direct targets of QscR. Deletion of PA1897 recapitulates the early QS activation phenotype of a QscR-null mutant, and the phenotype of a QscR-null mutant was complemented by PA1895-1897 but not by PA1897 alone. We conclude that QscR acts to modulate quorum sensing through regulation of a single operon, apparently raising the QS threshold of the population and providing a “brake” on QS autoinduction.IMPORTANCEQuorum sensing, a cell-cell communication system, is broadly distributed among bacteria and is commonly used to regulate the production of shared products. An important consequence of quorum sensing is a delay in production of certain products until the population density is high. The bacteriumPseudomonas aeruginosahas a particularly complicated quorum sensing system involving multiple signals and receptors. One of these receptors, QscR, downregulates gene expression, unlike the other receptors inP. aeruginosa. QscR does so by inducing the expression of a single operon whose function provides an element of resistance to a population reaching a quorum. This finding has importance for design of quorum sensing inhibitory strategies and can also inform design of synthetic biological circuits that use quorum sensing receptors to regulate gene expression.

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.

Biofilm Formation, Communication and Interactions of Mesophilic Leaching Bacteria during Pyrite Oxidation

2013 ◽  
Vol 825 ◽  
pp. 107-110
Author(s):  
Sören Bellenberg ◽  
Robert Barthen ◽  
Mario Vera ◽  
Nicolas Guiliani ◽  
Wolfgang Sand
Keyword(s):  
Quorum Sensing ◽  
Acidithiobacillus Ferrooxidans ◽  
Biofilm Formation ◽  
Pyrite Oxidation ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Mixed Cultures ◽  
Acyl Homoserine Lactone ◽  
Leaching Bacteria ◽  
Leaching Efficiency

A functional luxIR-type Quorum Sensing (QS) system is present in Acidithiobacillus ferrooxidans. However, cell-cell communication among various acidophilic chemolithoautotrophs growing on pyrite has not been studied in detail. These aspects are the scope of this study with emphasis on the effects exerted by the N-acyl-homoserine lactone (AHL) type signaling molecules which are produced by Acidithiobacillus ferrooxidans. Their effects on attachment and leaching efficiency by other leaching bacteria, such as Acidithiobacillus ferrivorans, Acidiferrobacter spp. SPIII/3 and Leptospirillum ferrooxidans in pure and mixed cultures growing on pyrite is shown.

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 LuxR- and LuxI-Type Quorum-Sensing Circuits Are Prevalent in Members of the Populus deltoides Microbiome

2013 ◽  
Vol 79 (18) ◽  
pp. 5745-5752 ◽  
Author(s):  
Amy L. Schaefer ◽  
Colin R. Lappala ◽  
Ryan P. Morlen ◽  
Dale A. Pelletier ◽  
Tse-Yuan S. Lu ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Populus Deltoides ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Bacterial Isolates ◽  
Content Type ◽  
Eastern Cottonwood ◽  
Bacterial Signaling ◽  
Signal Production ◽  
Plant Signals

ABSTRACTWe are interested in the root microbiome of the fast-growing Eastern cottonwood tree,Populus deltoides. There is a large bank of bacterial isolates fromP. deltoides, and there are 44 draft genomes of bacterial endophyte and rhizosphere isolates. As a first step in efforts to understand the roles of bacterial communication and plant-bacterial signaling inP. deltoides, we focused on the prevalence of acyl-homoserine lactone (AHL) quorum-sensing-signal production and reception in members of theP. deltoidesmicrobiome. We screened 129 bacterial isolates for AHL production using a broad-spectrum bioassay that responds to many but not all AHLs, and we queried the available genome sequences of microbiome isolates for homologs of AHL synthase and receptor genes. AHL signal production was detected in 40% of 129 strains tested. Positive isolates included members of theAlpha-,Beta-, andGammaproteobacteria. Members of theluxIfamily of AHL synthases were identified in 18 of 39 proteobacterial genomes, including genomes of some isolates that tested negative in the bioassay. Members of theluxRfamily of transcription factors, which includes AHL-responsive factors, were more abundant thanluxIhomologs. There were 72 in the 39 proteobacterial genomes. Some of theluxRhomologs appear to be members of a subfamily of LuxRs that respond to as-yet-unknown plant signals rather than bacterial AHLs. Apparently, there is a substantial capacity for AHL cell-to-cell communication in proteobacteria of theP. deltoidesmicrobiota, and there are alsoProteobacteriawith LuxR homologs of the type hypothesized to respond to plant signals or cues.

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 Complete Genome Sequence of Pseudomonas putida Strain TS312, Harboring an HdtS-Type N-Acyl-Homoserine Lactone Synthase, Isolated from a Paper Mill

2020 ◽  
Vol 9 (13) ◽  
Author(s):  
Ayaka Hosoe ◽  
Toshikazu Suenaga ◽  
Takumi Sugi ◽  
Taro Iizumi ◽  
Naohiro Nagai ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Paper Mill ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Gene Encoding ◽  
Content Type ◽  
Engineered Systems

We report the complete genome sequence of Pseudomonas putida strain TS312, in the class of Gammaproteobacteria. The strain, isolated from a paper mill, harbors the hdtS gene, encoding N-acyl-homoserine lactone synthase. Deciphering the genome contributes to revealing the mechanisms of quorum sensing and associated biofilm formation in engineered systems.

scholarly journals Disruption of Quorum Sensing and Virulence inBurkholderia cenocepaciaby a Structural Analogue of thecis-2-Dodecenoic Acid Signal

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Chaoyu Cui ◽  
Shihao Song ◽  
Chunxi Yang ◽  
Xiuyun Sun ◽  
Yutong Huang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Bacterial Infections ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Burkholderia Cenocepacia ◽  
Enoic Acid ◽  
Acyl Homoserine Lactone ◽  
Structural Analogue ◽  
Content Type ◽  
Signal Production

ABSTRACTQuorum sensing (QS) signals are widely used by bacterial pathogens to control biological functions and virulence in response to changes in cell population densities.Burkholderia cenocepaciaemploys a molecular mechanism in which thecis-2-dodecenoic acid (namedBurkholderiadiffusiblesignalfactor [BDSF]) QS system regulatesN-acyl homoserine lactone (AHL) signal production and virulence by modulating intracellular levels of cyclic diguanosine monophosphate (c-di-GMP). Thus, inhibition of BDSF signaling may offer a non-antibiotic-based therapeutic strategy against BDSF-regulated bacterial infections. In this study, we report the synthesis of small-molecule mimics of the BDSF signal and evaluate their ability to inhibit BDSF QS signaling inB. cenocepacia. A novel structural analogue of BDSF, 14-Me-C16:Δ2(cis-14-methylpentadec-2-enoic acid), was observed to inhibit BDSF production and impair BDSF-regulated phenotypes inB. cenocepacia, including motility, biofilm formation, and virulence, while it did not inhibit the growth rate of this pathogen. 14-Me-C16:Δ2also reduced AHL signal production. Genetic and biochemical analyses showed that 14-Me-C16:Δ2inhibited the production of the BDSF and AHL signals by decreasing the expression of their synthase-encoding genes. Notably, 14-Me-C16:Δ2attenuated BDSF-regulated phenotypes in variousBurkholderiaspecies. These findings suggest that 14-Me-C16:Δ2could potentially be developed as a new therapeutic agent against pathogenicBurkholderiaspecies by interfering with their QS signaling.IMPORTANCEBurkholderia cenocepaciais an important opportunistic pathogen which can cause life-threatening infections in susceptible individuals, particularly in cystic fibrosis and immunocompromised patients. It usually employs two types of quorum sensing (QS) systems, including thecis-2-dodecenoic acid (BDSF) system andN-acyl homoserine lactone (AHL) system, to regulate virulence. In this study, we have designed and identified an unsaturated fatty acid compound (cis-14-methylpentadec-2-enoic acid [14-Me-C16:Δ2]) that is capable of interfering withB. cenocepaciaQS signaling and virulence. We demonstrate that 14-Me-C16:Δ2reduced BDSF and AHL signal production inB. cenocepacia. It also impaired QS-regulated phenotypes in variousBurkholderiaspecies. These results suggest that 14-Me-C16:Δ2could interfere with QS signaling in manyBurkholderiaspecies and might be developed as a new antibacterial agent.

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