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Lyngbyoic Acid, a "Tagged" Fatty Acid from a Marine Cyanobacterium, Disrupts Quorum Sensing in Pseudomonas aeruginosa

ABSTRACT: Quorum sensing (QS) is a mechanism of bacterial gene regulation in response to increases in population density. Production of small molecule QS signals, their accumulation within a diffusion-limited environment and their binding to the LuxR-type receptor trigger QS-controlled gene regulatory cascades. QS pathways mediated by acylhomoserine lactones (AHLs) in Gram-negative bacteria are the best studied. In Pseudomonas aeruginosa, for example, binding of AHLs to their cognate receptors (LasR, RhlR) controls production of virulence factors, pigments, antibiotics and other behaviors important for its interactions with eukaryotic hosts and other bacteria. We isolated a new small cyclopropane-containing fatty acid, lyngbyoic acid (1), as a major metabolite of the marine cyanobacterium, Lyngbya sp., collected off Fort Pierce, Florida. The structure of 1 was determined by NMR, MS and optical rotation. We screened 1 against four reporters based on AHL receptors from Vibrio fischeri (LuxR), Aeromonas hydrophila (AhyR), Agrobacterium tumefaciens (TraR) and P. aeruginosa (LasR) and found that 1 most strongly affected LasR. We show, by using a defined set of reporters, that compound 1 acts both through the AHL-binding site of LasR and independent of it. We also show that 1 reduces pyocyanin and LasB, both on the protein and transcript level, in wild-type P. aeruginosa, and that 1 directly inhibits LasB enzymatic activity. Conversely, dodecanoic acid (11) increased pyocanin and LasB, demonstrating that 1 is a “tagged” fatty acid potentially resistant to β-oxidation.

ORGANISM(S): Pseudomonas aeruginosa

PROVIDER: GSE22999 | GEO | 2011/01/24

SECONDARY ACCESSION(S): PRJNA127841

REPOSITORIES: GEO

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Lyngbyoic Acid, a "Tagged" Fatty Acid from a Marine Cyanobacterium, Disrupts Quorum Sensing in Pseudomonas aeruginosa

Project description:Quorum sensing (QS) is a mechanism of bacterial gene regulation in response to increases in population density. Production of small molecule QS signals, their accumulation within a diffusion-limited environment and their binding to the LuxR-type receptor trigger QS-controlled gene regulatory cascades. QS pathways mediated by acylhomoserine lactones (AHLs) in Gram-negative bacteria are the best studied. In Pseudomonas aeruginosa, for example, binding of AHLs to their cognate receptors (LasR, RhlR) controls production of virulence factors, pigments, antibiotics and other behaviors important for its interactions with eukaryotic hosts and other bacteria. We isolated a new small cyclopropane-containing fatty acid, lyngbyoic acid (1), as a major metabolite of the marine cyanobacterium, Lyngbya sp., collected off Fort Pierce, Florida. The structure of 1 was determined by NMR, MS and optical rotation. We screened 1 against four reporters based on AHL receptors from Vibrio fischeri (LuxR), Aeromonas hydrophila (AhyR), Agrobacterium tumefaciens (TraR) and P. aeruginosa (LasR) and found that 1 most strongly affected LasR. We show, by using a defined set of reporters, that compound 1 acts both through the AHL-binding site of LasR and independent of it. We also show that 1 reduces pyocyanin and LasB, both on the protein and transcript level, in wild-type P. aeruginosa, and that 1 directly inhibits LasB enzymatic activity. Conversely, dodecanoic acid (11) increased pyocanin and LasB, demonstrating that 1 is a “tagged” fatty acid potentially resistant to β-oxidation. 1 mL Cultures of P. aeruginosa PAO1 were grown for 6h at 37 °C with shaking either in the presence of lyngbyoic acid (1 mM) or EtOH alone (10 μL) as a control. RNA samples were obtained from one treated and one control culture, and were reverse transcribed, labeled and fragmented according to Affymetrix's protocol. The two samples were hybridized in duplicate.

2011-01-24 | E-GEOD-22999 | biostudies-arrayexpress

Evolution of the quorum sensing regulon in cooperating populations of Pseudomonas aeruginosa

Project description:We used the AHL-degrading enzyme AiiA-lactonase to interrogate the evolution of the LasR-dependent QS regulon of P. aeruginosa in conditions where QS is required to obtain carbon and energy, and show that populations of P. aeruginosa adaptively reduced the size of their QS regulon over ~1000 generations.

2021-06-09 | GSE176411 | GEO

Genome-wide map of Flagx3-DnaA bound to DNA in exponentially growing Sinorhizobium meliloti cultures

Project description:The genome of Sinorhizobium meliloti, a model for studying plant-bacteria symbiosis, contains the genes coding for eight LuxR-like proteins. Two of these, SinR and ExpR, are essential for quorum sensing (QS). Roles and regulation surrounding the others are mostly unknown. Here, we reveal the DNA recognition sequence and regulon of the LuxR-like protein SMc00877. Unlike ExpR, which uses the long chain acyl homoserine lactones (AHLs) as inducers, SMc00877 functioned independently of AHLs and was even functional in Escherichia coli. A target of SMc00877 is sinR, the major regulator of AHL production in S. meliloti. Disruption of SMc00877 decreased AHL production. A weaker production of AHLs resulted in smaller microcolonies, starting from single cells, and delayed AHL dependent regulation. SMc00877 was expressed only in growing cells in the presence of replete nutrients. Therefore, we renamed it NurR (nutrient sensitive LuxR-like regulator). We traced this nutrient-sensitive expression to transcription control by the DNA replication initiation factor, DnaA, which is essential for growth. These results indicate that NurR has a role in modulating the threshold of QS activation according to growth. We propose growth behavior as an additional prerequisite to population density for the activation of QS in S. meliloti.

2019-05-18 | GSE131423 | GEO

Influence of the pqs genes on Pseudomonas quorum sensing

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.

2024-03-17 | GSE261453 | GEO

Genetic and transcriptomic characteristics of RhlR-dependent quorum sensing in cystic fibrosis isolates of Pseudomonas aeruginosa: isolate E104

Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E104. In this strain, RhlR positively regulates 48 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.

2022-03-18 | GSE198534 | GEO

Genetic and transcriptomic characteristics of RhlR-dependent quorum sensing in cystic fibrosis isolates of Pseudomonas aeruginosa: isolate E113

Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E113. In this strain, RhlR positively regulates 186 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.

2022-03-18 | GSE198716 | GEO

Genetic and transcriptomic characteristics of RhlR-dependent quorum sensing in cystic fibrosis isolates of Pseudomonas aeruginosa: isolate E167

Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E167. In this strain, RhlR positively regulates 78 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.

2022-03-18 | GSE198719 | GEO

Genetic and transcriptomic characteristics of RhlR-dependent quorum sensing in cystic fibrosis isolates of Pseudomonas aeruginosa: isolate E131

Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E131. In this strain, RhlR positively regulates 105 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.

2022-03-18 | GSE198718 | GEO

Genetic and transcriptomic characteristics of RhlR-dependent quorum sensing in cystic fibrosis isolates of Pseudomonas aeruginosa: isolate E125

Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E125. In this strain, RhlR positively regulates 28 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.

2022-03-18 | GSE198717 | GEO

Effect of the LuxI/R gene on AHL-signaling Molecules and QS Regulatory Mechanism in Hafnia alvei H4

Project description:Hafnia alvei H4 is a bacteria subject to regulation by N-acyl-l-homoserine lactone (AHL)-mediated quorum sensing system and is closely related to the corruption of instant sea cucumber. Studying the effect of Hafnia alvei H4 quorum sensing regulatory genes on AHLs is necessary for the quality and preservation of instant sea cucumber. In this study, the draft genome of H. alvei H4, which comprises a single chromosome of 4,687,151 bp, was sequenced and analyzed and the types of AHLs were analyzed employing thin-layer chromatography (TLC) and LC-MS/MS. Then the wild-type strain of H. alvei H4 and the luxI/R double mutant (ΔluxIR) were compared by transcriptome sequencing (RNA-seq). The results indicate that the incomplete genome sequence revealed the presence of one quorum-sensing (QS) gene set, designated as lasI/expR. Three major AHLs, N-hexanoyl-L-homoserine lactone (C6-HSL), N-butyryl-L-homoserine lactone (C4-HSL), and N-(3-oxo-octanoyl)-L-homoserine lactone (3-oxo-C8-HSL) were found, with C6-HSL being the most abundant. C6-HSL was not detected in the culture of the luxI mutant (ΔluxI) and higher levels of C4-HSL was found in the culture of the luxR mutant (ΔluxR), which suggested that the luxR gene may have a positive effect on C4-HSL production. It was also found that AHL and QS genes are closely related in the absence of luxIR double deletion. The results of this study can further elucidate at the genetic level that luxI and luxR genes are involved in the regulation of AHL.

2019-10-10 | GSE137815 | GEO

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