cyclic-gmp and 2-dodecenoic-acid

Quorum sensing (QS) signals are widely used by bacterial pathogens to control biological functions and virulence in response to changes in cell population densities.

Topics: Acyl-Butyrolactones; Bacterial Proteins; Biofilms; Burkholderia cenocepacia; Burkholderia Infections; Cyclic GMP; Fatty Acids, Monounsaturated; Gene Expression Regulation, Bacterial; Microbial Sensitivity Tests; Phenotype; Quorum Sensing; Signal Transduction; Virulence

The opportunistic human pathogen Burkholderia cenocepacia H111 uses two chemically distinct signal molecules for controlling gene expression in a cell density-dependent manner: N-acyl-homoserine lactones (AHLs) and cis-2-dodecenoic acid (BDSF). Binding of BDSF to its cognate receptor RpfR lowers the intracellular c-di-GMP level, which in turn leads to differential expression of target genes. In this study we analysed the transcriptional profile of B. cenocepacia H111 upon artificially altering the cellular c-di-GMP level. One hundred and eleven genes were shown to be differentially expressed, 96 of which were downregulated at a high c-di-GMP concentration. Our analysis revealed that the BDSF, AHL and c-di-GMP regulons overlap for the regulation of 24 genes and that a high c-di-GMP level suppresses expression of AHL-regulated genes. Phenotypic analyses confirmed changes in the expression of virulence factors, the production of AHL signal molecules and the biosynthesis of different biofilm matrix components upon altered c-di-GMP levels. We also demonstrate that the intracellular c-di-GMP level determines the virulence of B. cenocepacia to Caenorhabditis elegans and Galleria mellonella.

Topics: Acyl-Butyrolactones; Animals; Burkholderia cenocepacia; Caenorhabditis elegans; Cyclic GMP; Fatty Acids, Monounsaturated; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Moths; Quorum Sensing; Signal Transduction; Virulence; Virulence Factors

Quorum sensing (QS) signals are used by bacteria to regulate biological functions in response to cell population densities. Cyclic diguanosine monophosphate (c-di-GMP) regulates cell functions in response to diverse environmental chemical and physical signals that bacteria perceive. In

Topics: Animals; Bacterial Load; Bacterial Proteins; Biofilms; Burkholderia cenocepacia; Burkholderia Infections; Cyclic GMP; Fatty Acids, Monounsaturated; Gene Expression Regulation, Bacterial; Mice; Mutation; Phenotype; Quorum Sensing; Signal Transduction; Virulence

Burkholderia cenocepacia employs both N-Acyl homoserine lactone (AHL) and cis-2-dodecenoic acid (BDSF) quorum sensing (QS) systems in regulation of bacterial virulence. It was shown recently that disruption of BDSF synthase RpfFBc caused a reduction of AHL signal production in B. cenocepacia. However, how BDSF system influences AHL system is still not clear.. We show here that BDSF system controls AHL system through a novel signaling mechanism. Null mutation of either the BDSF synthase, RpfFBc, or the BDSF receptor, RpfR, caused a substantial down-regulation of AHL signal production in B. cenocepacia strain H111. Genetic and biochemical analyses showed that BDSF system controls AHL signal production through the transcriptional regulation of the AHL synthase gene cepI by modulating the intracellular level of second messenger cyclic di-GMP (c-di-GMP). Furthermore, we show that BDSF and AHL systems have a cumulative role in the regulation of various biological functions, including swarming motility, biofilm formation and virulence factor production, and exogenous addition of either BDSF or AHL signal molecules could only partially rescue the changed phenotypes of the double deletion mutant defective in BDSF and AHL signal production.. These results, together with our previous findings, thus depict a molecular mechanism with which BDSF regulates AHL signal production and bacterial virulence through modulating the phosphodiesterase activity of its receptor RpfR to influence the intracellular level of c-di-GMP.

Topics: 4-Butyrolactone; Bacterial Proteins; Burkholderia cenocepacia; Cyclic GMP; Down-Regulation; Fatty Acids, Monounsaturated; Gene Expression Regulation, Bacterial; Quorum Sensing; Signal Transduction

Many bacterial pathogens produce diffusible signal factor (DSF)-type quorum sensing (QS) signals in modulation of virulence and biofilm formation. Previous work on Xanthomonas campestris showed that the RpfC/RpfG two-component system is involved in sensing and responding to DSF signals, but little is known in other microorganisms. Here we show that in Burkholderia cenocepacia the DSF-family signal cis-2-dodecenoic acid (BDSF) negatively controls the intracellular cyclic dimeric guanosine monophosphate (c-di-GMP) level through a receptor protein RpfR, which contains Per/Arnt/Sim (PAS)-GGDEF-EAL domains. RpfR regulates the same phenotypes as BDSF including swarming motility, biofilm formation, and virulence. In addition, the BDSF(-) mutant phenotypes could be rescued by in trans expression of RpfR, or its EAL domain that functions as a c-di-GMP phosphodiesterase. BDSF is shown to bind to the PAS domain of RpfR with high affinity and stimulates its phosphodiesterase activity through induction of allosteric conformational changes. Our work presents a unique and widely conserved DSF-family signal receptor that directly links the signal perception to c-di-GMP turnover in regulation of bacterial physiology.

Topics: Bacterial Proteins; Burkholderia cenocepacia; Cell Communication; Cyclic GMP; Dimerization; Fatty Acids, Monounsaturated; Guanosine Monophosphate; Models, Genetic; Mutagenesis; Mutation; Phenotype; Protein Binding; Quorum Sensing; Receptors, Cell Surface; Signal Transduction; Virulence