Project description:LuxS is an enzyme involved in the activated methyl cycle. The by-product of this cycle, autoinducer 2 (AI-2), could be an important quorum sensing signal. LuxS was conserved and regulated many behaviors in different bacteria, but in most species, whether the regulations are related to AI-2 mediated quorum sensing is still unknown. In our previous study, Actinobacillus pleuropneumoniae, the etiologic agent of porcine contagious pleuropneumonia, was found to possess the functional LuxS affecting biofilm formation and virulence. In this study, microarray was used to compare the transcriptional profiles of the A. pleuropneumoniae wildtype strain 4074, luxS mutant and its AI-2 supplemented strain in four different growth phases. The results demonstrated that both LuxS and AI-2 played important roles in metabolism of this bacterium. AI-2 did not recover the gene expression changes caused by luxS deletion but caused more extensive metabolic alterations in the luxS mutant in a concentration dependent manner. Regulations of the genes involved in iron metabolism, carbonhydrate transport and host cell adhesion were validated by real-time RT-PCR and phenotypic investigations under different conditions. The results demonstrated that sugar uptake was repressed by LuxS independent of AI-2. However, iron metabolism, an important process of infection for A. pleuropneumoniae, could be controlled by LuxS through AI-2. Adhesion to host cells was also affected by LuxS and AI-2, but exogenous AI-2 displayed more obvious effects. Our results indicated that both LuxS and AI-2 are essential in the metabolism of A. pleuropneumoniae. The function of LuxS/AI-2 displayed pleiotropic roles in different conditions. AI-2 may not serve as a quorum sensing autoinducer but a metabolite or an environmental cue to affect the metabolism and virulence traits of this important pathogen. A. pleuropneumoniae strains were cultured in TSB medium supplemented with 10 M-NM-<g/ml of nicotinamide adenine dinucleotide (NAD) and 10% (v/v) filtered cattle serum at 37M-BM-0C. For samples from the mutant supplemented with AI-2, 100M-NM-<M and 25M-NM-<M AI-2 precursor (DPD) were added into the medium before early exponential phase as well as one hour before late exponential phase to cover the whole growth phase respectively. The samples were collected from early, middle, late exponential phase and stationary phase respectively and the total RNA were extracted using RNA-Solv Reagent (Omega) according to the manufacturerM-bM-^@M-^Ys instructions. For each time point, four biological replicates were combined into two samples. The intensities were normalized and transformed into log2 value. The values for each time point were averaged and the genes with log2 ratio >=1 or <=-1 were selected as differentially expressed genes.
Project description:Ms1 RNA is ~300 nt sRNA that is highly expressed in stationary phase of growth and binds to the RNA polymerase (RNAP) core. We assume that by binding to RNAP, Ms1 could regulate transcription. Our aim was to reveal the most prominent changes in the transcriptome upon entry into stationary phase that might be dependent on Ms1. We performed RNA-seq data to characterize exponential (Ms_WT_exp) and stationary phase (Ms_WT_stat) transcriptome in M. smegmatis in wild type cells. In addition, we compared the transcriptome of the Ms1 knockout cells (Ms_KO_stat) with wild type cells in stationary phase and in exponential phase (Ms_KO_exp).
Project description:We report the application of RNA-Seq to assess transcriptional profiles of S. aureus CC30 strains with allelic replacements (knockouts) of two genes in the LFR genomic islet: 1) fatty acid desaturase (fad) and 2) a MocR regulator. The overall results of our study suggest that the LFR islet enhances metabolic plasticity of the CC30 lineage which contributes to increased colonization, survival and persistence in the host. The background strain used for these experiments was UAMS-1. Allelic replacements of fad and MocR were made in UAMS-1. The RNA-Seq experiments compared the transcriptional profiles of UAMS-1 vs. delta fad, and UAMS-1 vs. delta MocR. Two biological replicates were used for each RNA-Seq analysis.
Project description:LuxS is an enzyme involved in the activated methyl cycle and the by-product autoinducer 2 (AI-2) was a quorum sensing signal in some species. In our previous study, the functional LuxS in AI-2 production was verified in the porcine respiratory pathogen Actinobacillus pleuropneumoniae. Enhanced biofilm formation and reduced virulence were observed in the luxS mutant. To comprehensively understand the luxS function, in this study, the transcriptional profiles were compared between the A. pleuropneumoniae luxS mutant and its parental strain in four different growth phases using microarray. Many genes associated with infection were differentially expressed. The biofilm formation genes pgaABC in the luxS mutant were up-regulated in early exponential phase, while 8 genes associated with adhesion were down-regulated in late exponential phase. A group of genes involved in iron acquisition and metabolism were regulated in four growth phases. Further investigations on these virulence traits demonstrated that the luxS mutant showed enhanced biofilm formation and reduced adhesion ability and these effects were not due to lack of AI-2. But AI-2 could increase biofilm formation and adhesion of A. pleuropneumoniae independent of LuxS. Growth under iron restricted condition could be controlled by LuxS through AI-2 production. These results revealed pleiotropic roles of LuxS and AI-2 on A. pleuropneumoniae virulence traits. A. pleuropneumoniae strains were cultured in TSB medium supplemented with 10 M-NM-<g/ml of nicotinamide adenine dinucleotide (NAD) and 10% (v/v)filtered cattle serum at 37M-BM-0C. The samples were collected from early exponential phase, middle exponential phase, late exponential phase and stationary phase respectively and the total RNA were extracted using RNA-Solv Reagent (Omega) according to the manufacturerM-bM-^@M-^Ys instructions. For each time point, four biological replicates were combined into two samples. The intensities were normalized and transformed into log2 value.The fold changes >=1.5 or <=-1.5 were selected as differentially expressed genes.
Project description:We analyze the transcriptomic response of the phytopathogenic enterobacterium Dickeya dadantii to an increase of DNA supercoiling induced by seconeolitsine, a topoisomerase I inhibitor. The shock was applied to Dickeya cells grown in minimal medium supplemented with sucrose, in exponential or transition to stationary phase.
Project description:We analyze the transcriptomic response of the phytopathogenic enterobacterium Dickeya dadantii to a DNA supercoiling relaxation shock using the gyrase inhibitor novobiocin. The shock was applied to Dickeya cells grown in minimal medium supplemented with sucrose, in exponential or transition to stationary phase, and in minimal medium with sucrose + PGA (a pectin derivative) in transition to stationary phase.
Project description:We analyze the transcriptomic response of the phytopathogenic enterobacterium Dickeya dadantii ihfA mutant to a DNA supercoiling relaxation shock using the gyrase inhibitor novobiocin. The shock was applied to Dickeya cells grown in minimal medium supplemented with sucrose, in exponential or transition to stationary phase, and in minimal medium with sucrose + PGA (a pectin derivative) in transition to stationary phase.