A transcriptome analysis of the Vibrio fischeri LuxR-LuxI regulon
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ABSTRACT: Acyl-homoserine lactone (acyl-HSL) quorum sensing was first discovered in Vibrio fischeri where it serves as a key control element of the seven-gene luminescence (lux) operon. Since this initial discovery, other bacteria have been shown to control hundreds of genes by acyl-HSL quorum sensing. Until recently, it has been difficult to examine the global nature of quorum sensing in V. fischeri. However, the complete genome sequence of V. fischeri is now available and this has enabled us to use transcriptomics to identify quorum-sensing regulated genes and to study the quorum-controlled regulon of this bacterium. In this study, we used DNA microarray technology to identify over two-dozen V. fischeri genes regulated by the quorum sensing signal N-3-oxohexanoyl-L-homoserine lactone (3OC6-HSL). Keywords: Comparison of transcriptome profiles
Project description:Quorum sensing is a term used to describe cell-to-cell communication that allows cell density-dependent gene expression. Many Gram-negative bacteria use acyl-homoserine lactone (acyl-HSL) synthases to generate fatty acyl-HSL quorum sensing signals, which function with signal receptors to control expression of specific genes. The fatty acyl group is derived from fatty acid biosynthesis and provides signal specificity, but the variety of signals is limited. We have discovered that the photosynthetic bacterium Rhodopseudomonas palustris uses an acyl-HSL synthase to produce p-coumaroyl-HSL by using environmental p-coumaric acid rather than fatty acids from cellular pools. The bacterium has a signal receptor with homology to fatty acyl-HSL receptors that responds to p-coumaroyl-HSL to regulate global gene expression. We also found that p-coumaroyl-HSL is made by other bacteria including Bradyrhizobium BTAi1 and Silicibacter pomeroyi DSS-3. This discovery extends the range of possibilities for acyl-HSL quorum sensing and raises fundamental questions about quorum sensing within the context of environmental signaling. Keywords: Comparison of transcriptome profiles Transcriptome profiles between Rhodopseudomonas palustris cells grown in the in the presence or absence of pC-HSL were compared.
Project description:Quorum sensing is a term used to describe cell-to-cell communication that allows cell density-dependent gene expression. Many Gram-negative bacteria use acyl-homoserine lactone (acyl-HSL) synthases to generate fatty acyl-HSL quorum sensing signals, which function with signal receptors to control expression of specific genes. The fatty acyl group is derived from fatty acid biosynthesis and provides signal specificity, but the variety of signals is limited. We have discovered that the photosynthetic bacterium Rhodopseudomonas palustris uses an acyl-HSL synthase to produce p-coumaroyl-HSL by using environmental p-coumaric acid rather than fatty acids from cellular pools. The bacterium has a signal receptor with homology to fatty acyl-HSL receptors that responds to p-coumaroyl-HSL to regulate global gene expression. We also found that p-coumaroyl-HSL is made by other bacteria including Bradyrhizobium BTAi1 and Silicibacter pomeroyi DSS-3. This discovery extends the range of possibilities for acyl-HSL quorum sensing and raises fundamental questions about quorum sensing within the context of environmental signaling. Keywords: Comparison of transcriptome profiles
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.
Project description:Transcriptional profiling of Arabidopsis comparing 1μM 3OC6-HSL-treated Arabidopsis wild-type Col-0 with control untreated Col-0. A transcriptomic analysis for Arabidopsis responses to bacterial quorum sensing molecule N-3oxo-hexanoyl-homoserine lactone (3OC6-HSL).
Project description:Transcriptional profiling of Arabidopsis comparing 10 μM 3OC8-HSL-treated Arabidopsis wild-type Col-0 with control untreated Col-0. A transcriptomic analysis for Arabidopsis responses to bacterial quorum sensing molecule N-3oxo-octanoyl-homoserine lactone (3OC8-HSL).
Project description:Aerobic methanotrophic bacteria use methane as their sole source of carbon and energy and serve as a major sink for the potent greenhouse gas methane in freshwater ecosystems. Despite this important environmental role, little is known about the molecular details of how these organisms interact in the environment. Many bacterial species use quorum sensing systems to regulate gene expression in a density-dependent manner. We have identified a quorum sensing system in the genome of Methylobacter tundripaludum, a dominant methane-oxidizer in methane enrichments of sediment from Lake Washington (Seattle, WA, USA). We determined that M. tundripaludum primarily produces N-3-hydroxydecanoyl-L-homoserine lactone (3-OH-CÂ10-HSL) and that production is governed by a positive feedback loop. We then further characterized this system by determining which genes are regulated by quorum sensing in this methane-oxidizer using RNA-seq, and discovered this system regulates the expression of a novel nonribosomal peptide synthetase biosynthetic gene cluster. These results identify and characterize a mode of cellular communication in an aerobic methane-oxidizing bacterium. Samples are 2 sets of biological replicates of a Methylobacter tundripaludum strain 21/22 mutant where the acyl-homoserine lactone (AHL) synthase gene mbaI (T451DRAFT_0796) has been deleted. The mutant strain was grown to log (48 hours) or stationary (68 hours) phase in the absence or presence of the AHL 3-OH-C10-HSL.
Project description:The etiologic agent of bubonic plague, Yersinia pestis, senses cell density-dependent chemical signals to synchronize transcription between cells of the population in a process named quorum sensing. Though the closely related enteric pathogen Y. pseudotuberculosis uses quorum sensing system to regulate motility, the role of quorum sensing in Y. pestis has been unclear. In this study we performed transcriptional profiling experiments to identify Y. pestis quorum sensing regulated functions. Our analysis revealed that acyl-homoserine lactone based quorum sensing controls the expression of several metabolic functions. Maltose fermentation and the glyoxylate bypass are induced by acyl-homoserine lactone signaling. This effect was seen to be temperature conditional. Metabolism is unresponsive to quorum sensing regulation at mammalian body temperature, indicating a potential role for quorum sensing regulation of metabolism specifically during colonization of the flea vector. It is proposed that utilization of alternative carbon sources may enhance growth and/or survival during prolonged flea colonization, contributing to maintenance of plague in nature.
Project description:To address the question of how quorum sensing controls biofilm formation in Acidithiobacillus ferrooxidans ATCC23270, the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic acyl homoserine lactone (AHL) analogue has been studied. Tetrazole 9c was used in DNA microarray experiments that allowed the identification of genes regulated by quorum sensing signalling, and more particularly those involved in early biofilm formation.
Project description:The common opportunistic human pathogen Pseudomonas aeruginosa employs quorum sensing QS to regulate a large set of genes involved in virulence and host-pathogen interactions. The Las circuit positioned on the top of the QS hierarchy in P. aeruginosa, makes use of N-acyl-L-homoserine lactones (AHL) as signal molecules, like N-3-oxo-dodecanoyl-L-homoserine lactone (3O-C12-HSL). Here, a quantitative proteomic approach was used to study the effect of natural 3O-C12-HSL and four AHL analogues on the expression and excretion of QS-regulated extracellular proteins. Treatment with AHL compounds resulted in significant difference in appearance of the 3O-C12-HSL-responsive reference proteins related to QS communication and virulence, i.e., a distinct activity as QS modulators. In summary, 3O-C12-HSL has a profound effect on extracellular proteome involved in the pathogenicity of P. aeruginosa, and the four AHL analogues have achieved a distinct inhibitory effect on the extracellular proteome.
Project description:In order to gain coherent insights into plant responses we performed transcriptional analysis of Arabidopsis seedling after treatment with three different AHLs: N-hexanoyl-L-homoserine lactone (C6-HSL), N-3-oxo-decanoyl-L-homoserine lactone (oxo-C10-HSL), and N-3-oxo-tetradecanoyl-L-homoserine lactone (oxo-C14-HSL). Furthermore, we analyzed the transcriptome of oxo-C14-HSL pretreated plants after a secondary challenge with 100 nM flg22 for 2 and 24 hours after treatment. Gene expression in Arabidopsis thaliana seedlings were measured after a 3-days-pretreatment with 6 µM of three different N-acyl homoserine lactones in comparison to plants treated with the coresponding volume of acetone (solvent control). Plants pretreated with oxo-C14-HSL were in addition treated with 100nM of flg22 to induced defense response. Three independent experiments were performed (replicates).