Project description:transcriptional profiling of L. monocytogenes ctsR mutant under pressure treatment SUBMITTER_CITATION: Liu, Y., Huang, L., Joerger, R.D., Gunther, N.W. 2012. Genes that are involved in high hydrostatic pressure treatments in a Listeria monocytogenes Scott A ctsR deletion mutant. Journal of Microbial and Biochemical Technology. 4:050-056.
Project description:High hydrostatic pressure processing (HPP) is currently being used as a treatment for certain foods to control the presence of food-borne pathogens, such as Listeria monocytogenes. Genomic microarray analysis was performed to determine the effects of HPP on L. monocytogenes in order to understand how it responds to mechanical stress injury. Reverse transcriptase PCR analysis of tufB and rpoC indicated that the reduction of mRNA expression in HPP treated cells was dependent on intensity and time of the treatment. Treatments of 400 and 600 MPa for 5 min. on cells in the exponential growth phase though leading to partial or complete cellular inactivation still resulted in measurable relative differential gene expression. Gene set enrichment analysis indicated HPP induced increased expression of genes associated with DNA repair mechanisms, transcription and translation protein complexes, the septal ring, the general protein translocase system, flagella assemblage and chemotaxis, and lipid and peptidoglycan biosynthetic pathways. HPP on the other hand appears to suppress a wide range of energy production and conversion, carbohydrate metabolism, and virulence associated genes accompanied by strong suppression of the SigB and PrfA regulons. HPP also induced repression of genes negatively controlled by pleotrophic regulator CodY. HPP-induced cellular damage appears to lead to increased expression of genes linked to sections of the cell previously shown in bacteria to be damaged or altered during HPP exposure and suppression of gene expression associated with cellular growth processes and virulence. Keywords: Stress response
Project description:The foodborne pathogen Listeria monocytogenes uses a number of transcriptional regulators, including the negative regulator CtsR, to control gene expression under different environmental conditions and in response to stress. Gene expression patterns of DctsR log phase cells were compared to both wt and ictsR-mcsA log phase cells grown with 0.5mM IPTG to identify CtsR-dependent genes.We identified 62 CtsR-dependent genes that showed significant expression ratios (adj. P < 0.05), with ≥ 1.5-fold differential expression either between ΔctsR and wt or between ΔctsR and ictsR-mcsA. Keywords: Listeria monocytogenes, CtsR regulon, log phase
Project description:The foodborne pathogen Listeria monocytogenes uses a number of transcriptional regulators, including the negative regulator HrcA, to control gene expression under different environmental conditions and in response to stress. Gene expression patterns of DhrcA stationary phase cells were compared to wt to identify hrcA-dependent genes. We identified 61 HrcA-dependent genes that showed significant expression ratios (adj. P < 0.05), with ≥ 1.5-fold differential expression between ΔhrcA and wt. Combined with microarray analysis, Hidden Markov Model searches show HrcA directly repress at least 8 genes. Keywords: Listeria monocytogenes, HrcA regulon, stationary phase
Project description:Listeria monocytogenes strain 10403S has been studied extensively for stress response activity toward multiple stressors (acid, osmotic, cold, high temperature, etc.) as well as multiple stress regulons (SigB, CtsR, HrcA, etc.). Here we aimed to determine the transcriptional response of Listeria monocytogenes in early log phase towards the strong oxidative stress imposed by ClO2. The elucidation of such a response allows for further a more completel understanding of the mechanism of inactivation by sanitizers, specifically ClO2.
Project description:These studies were designed to examine the transcription of Listeria monocytogenes strains 10403S and LO28 during intracellular replication in mammalian macrophages.
Project description:The stationary phase stress response transcriptome of the human bacterial pathogen Listeria monocytogenes was defined using RNA sequencing (RNA-Seq) with the Illumina Genome Analyzer. Specifically, bacterial transcriptomes were compared between stationary phase cells of L. monocytogenes 10403S and an otherwise isogenic DsigB mutant, which does not express the alternative sigma factor σB, a major regulator of genes contributing to stress response. Keywords: Transcriptome and differential expression analyses
Project description:A long-term-survival (LTS) phase in Listeria monocytogenes was recently discovered. Cells in this phase are coccoid in shape, survive for at least 30 d without any decrease in viable cell numbers, and are very resistant to heat and high pressure. However, how cells of L. monocytogenes transition to this long-term-survival phase is little understood. Therefore, a whole-genome expression analysis was conducted to study the transcription profile of L. monocytogenes as it enters the LTS phase. Transcription profiles at log, stationary and death phases were analyzed since differential gene expressions at these phases may contribute to the eventual transition to the LTS phase. Specifically, cells of L. monocytogenes F2365 at log, stationary, death and LTS phases were obtained by incubating cultures in TSBYE at 35°C for 13 h, 17 h, 24 h and 168-336 h, respectively. Also, to study cells transitioning from the LTS phase back to the log phase, 1 ml of the LTS-phase culture at 336 h was reinoculated into 100 ml of fresh TSBYE with incubation at 35°C for 8 h. Total RNAs of all samples were extracted, reverse transcribed into cDNAs and then hybridized to the L. monocytogenes expression microarray (Roche NimbleGen). During the transition from log phase to stationary phase, differential changes in gene expression involved genes associated with cell envelope, cell division, stress response, energy metabolism, protein synthesis and material transport. During the transition from stationary to death phase, differential changes were observed in genes related to cell envelope, detoxification, pathogenesis, energy metabolism, protein synthesis and material transport. When cultures transitioned from death phase to 168-h LTS phase, significant downregulation of genes associated with amino acid and protein biosynthesis, as well as stress responses, were observed (P < 0.05), while multiple genes related to cell envelope, energy production and material transportation were significantly upregulated (P < 0.05). High similarity of transcription profiles (r = 0.93) within LTS phase was observed when comparing transcriptomes at 168 h and 336 h. RNA quality measurement revealed a high level of degradation of ribosomal RNA during the LTS phase. The transcription profile at 8-h (log-phase) after re-inoculation of LTS cells also resembled that at 13 h (r = 0.94). We hypothesize that the upregulation of some compatible solute transporters during the LTS phase may result in accumulation of these solutes, which may lower intracellular water activity and thus enhance resistance of L. monocytogenes to heat and high pressure. Dormancy may be induced at the LTS phase which is suggested by the downregulation of genes associated with transcription and translation. Once fresh nutrients are provided, LTS cells may quickly exit dormancy and become metabolically active as they transition to the log phase.
Project description:Transcriptional profling of a Listeria monocytogenes under pressure comparing ctsR mutant and wild type one condition (pressure 450 Moa, 3min) experiment, mutant vs. wild type, 2 biological replicates, two technical replicates