Project description:In this study, RNA-seq was used to compare the transcriptomes of L. monocytogenes strain H7858 grown on cold smoked salmon (CSS) and in modified brain heart infusion broth (MBHIB, water-phase salt 4.65%, pH 6.1) at 7oC. RNA-seq was performed on H7858 RNA samples representing four independent biological replicates of growth experiments that involved growth of H7858 on CSS or in MBHIB. Samples for RNA preparation were collected when H7858 was grown to late log phase on these two matrices. Indexed and purified cDNA libraries (8 libraries including 4 replicates for each CSS and MBHIB) were loaded together onto an independent flow cell without any other samples; sequencing was carried out by running Hiseq 2000 (single-end, 100-bp per read). Reads alignment was carried out using the Burrows-Wheeler Aligner (BWA). Differential expression of genes in different strains was statistically assessed using the BaySeq method. Significant differential transcription of 149 genes in H7858 was observed between these two treatments including 88 genes and 61 genes up- and downregulated, respectively, in H7858 grown on CSS compared to in MBHIB. Our results show that genes involved in cobalamin biosynthesis, ethanolamine and 1,2-propanediol utilization, and specific carbohydrate transport systems have significantly higher transcript level in H7858 grown on CSS compared to in MBHIB. PrfA-dependent gene enrichment analysis showed that, genes regulated by PrfA were overrepresented among L. monocytogenes genes with higher transcript level on CSS than in MBHIB. Transcriptome profiles of L. monocytogenes grown on cold smoked salmon and in modified BHI broth at 7oC were generated by deep sequencing, in quadruplicate, using Illumina Hiseq 2000 (100 bp per read, single-end).
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: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: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:Several Toll-like receptors are activated by Listeria monocytogenes infection, resulting in the activation of MyD88 dependent signaling pathway. However, the negative role of MyD88 in gene expresson is unclear. To address this, we performed microarray analysis of mRNAs from WT or MyD88-/- peritoneal macrophages infected with Listeria monocytogenes.
Project description:Listeria monocytogenes cells (strain LI0521) were digested with trypsin for the identification of surface proteins. The supernatant was filter-sterilized and subjected to identification by LC-MS/MS. Concurrently secreted or shed proteins were identified by isolating filter-sterilized supernatants following incubation of L. monocytogenes cells in buffer without trypsin. This was followed by trypsin digest of the sterilized supernatant and identification by LC-MS/MS.
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:These studies were designed to examine the acute Listeria monocytogenes transcriptional response to mammalian (porcine) bile. Triplicate WT Listeria monocytogenes (strain 10403S) were grown to mid-log in BHI at 37 °C. Samples were divided, and either treated or not treated by addition of porcine bile (Sigma, to 1% final) for 30 minutes.