Listeria monocytogenes strain F2365 has reduced ability to survive stress while maintaining virulence characteristics
Ontology highlight
ABSTRACT:
ORGANISM(S): Listeria monocytogenes
SUBMITTER: Haley Oliver
PROVIDER: E-GEOD-42730 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Listeria monocytogenes is well known to have the ability to survive and grow under a variety of stress conditions. The ability to survive and grow under osmotic stress conditions in particular appears to be important for both growth in certain foods and food associated environments as well as for host infection. To characterize the contributions of transcriptional regulators important for stress response and virulence (i.e., Sigma B - M-OM-^CB and PrfA), we initially analyzed three L. monocytogenes parent strains and isogenic mutants ( delta sigB, delta prfA, and delta sigB delta prfA), representing different serotypes and lineages, for their ability to grow in BHI with 11% NaCl (1.9M) at 25M-BM-0C. No significant differences were observed in terms of growth between the parent strains and their respective mutants lacking prfA (i.e. delta prfA, and delta sigB delta prfA mutant strains). While for all strains, the delta sigB mutant showed a prolonged lag phase as compared to the parent strains, maximum growth rates were only reduced for the delta sigB mutant of lineage I and IV strains. Interestingly, for the serotype 1/2b strain, the delta sigB mutant reached a higher maximum cell density than the parent strain or the delta prfA mutant. Caco-2 intestinal epithelial cells invasion assays and hemolytic activity assays showed a significant role for M-OM-^CB in the former and for PrfA in the latter. To initially explore the mechanism that may contribute to the extended lag phase in the delta sigB mutant, microarray was performed to compare transcript levels between the lineage I, serotype 1/2b, parent strain and its isogenic delta sigB mutant in lag phase at 25M-BM-0C in the presence of 11% NaCl. Microarray data showed significant lower and higher transcript levels for 135 and 173 genes, respectively, in the parent strain as compared to the delta sigB strains. Overall, 51 of the 173 M-OM-^CB up-regulated genes had previously been found among the 249 M-OM-^CB-dependent genes identified in a microarray study conducted in stationary phase cells, indicating that up to 122 genes may be transcribed in a M-OM-^CB-dependent manner during lag phase under salt stress. Notable genes that showed higher transcript levels in the parent strain include inlD (encoding an internalin protein that may be involved in virulence), sigH (encoding an alternative M-OM-^C factor), glpK (encoding a glycerol kinase) and resD (encoding a two-component response regulator ResD); while, genes that showed lower transcript levels in the parent strain include dnaK (encoding a dihydroxyacetone kinase), groES (encoding a class I heat-shock protein GroES), grpE (encoding a co-chaperone GrpE) and fri (encoding a non-heme iron-binding ferritin). These data showed that although PrfA does not contribute to growth under osmotic stress at 25M-BM-0C, M-OM-^CB does contribute to survival of L. monocytogenes under high salt conditions. Moreover, the M-OM-^CB-dependent transcriptome of L. monocytogenes lag phase cells under salt stress was characterized and includes previously identified as well as novel M-OM-^CB-dependent genes, including a number of stress response and virulence-associated genes. Independent RNA isolations were performed for one wildtype (lineage I) and M-NM-^TsigB strains from cells grown to lag phase. Three biological replicates were used in competitive whole-genome microarray experiments. For each set of hybridizations, RNA from a L. monocytogenes wildtype strain was hybridized with RNA from its isogenic M-NM-^TsigB null mutant.
2013-07-20 | E-GEOD-49056 | biostudies-arrayexpress
Project description:Listeria monocytogenes strains classify into at least three distinct phylogenetic lineages. Correlations exist between lineage classification and source of bacterial isolation, e.g., human clinical and food isolates usually classify into either lineage I or II, however, human clinical isolates are over-represented in lineage I while food isolates are over-represented in lineage II. σB, a transcriptional regulator previously demonstrated to contribute to environmental stress response and virulence in L. monocytogenes lineage II strains, was hypothesized to provide differential capabilities for L. monocytogenes survival in various niches (e.g., food vs. human clinical). To determine if σB contributions to stress response and virulence differ across diverse L. monocytogenes strains, ΔsigB mutations were created in strains from lineages I, II, IIIA, and IIIB. Paired parent and ΔsigB mutant strains were tested for acid and oxidative stress survival, Caco-2 cell invasion efficiency, and virulence using the guinea pig listeriosis infection model. Parent and ΔsigB mutant strain transcriptomes were compared using whole-genome expression microarrays. σB contributed to virulence in each strain. However, while σB contributed significantly to acid and oxidative stress survival and Caco-2 cell invasion in lineage I, II, and IIIB strains, σB contributions were not significant for these phenotypes in the lineage IIIA strain. A core set of 63 genes was positively regulated by σB in all four strains; different total numbers of genes were positively regulated by σB in each strain. Our results suggest that σB universally contributes to L. monocytogenes virulence, but specific σB-regulated stress response phenotypes vary among strains.
2010-06-01 | E-GEOD-21427 | biostudies-arrayexpress
Project description:The formation of Listeria monocytogenes biofilms contributes to persistent contamination in food processing facilities. A microarray comparison of L. monocytogenes between the transcriptome of the strong biofilm forming strain (Bfms) Scott A and the weak biofilm forming (Bfmw) strain F2365 was conducted to identify genes potentially involved in biofilm formation. Among 951 genes with significant difference in expression between the two strains, a GntR-family response regulator encoding gene (LMOf2365_0414), designated lbrA, was found to be highly expressed in Scott A relative to F2365. A Scott A lbrA-deletion mutant, designated AW3, formed biofilm to a much lesser extent as compared to the parent strain by a rapid attachment assay and scanning electron microscopy. Complementation with lbrA from Scott A restored the Bfms phenotype in the AW3 derivative. A second microarray assessment using the lbrA deletion mutant AW3 and the wild type Scott A revealed a total of 304 genes with expression significantly different between the two strains, indicating the potential regulatory role of LbrA in L. monocytogenes. A cloned copy of Scott A lbrA was unable to confer enhanced biofilm forming potential in F2365, suggesting that additional factors contributed to weak biofilm formation by F2365. Findings from the study may lead to new strategies to modulate biofilm formation. Two comparisons were performed between 1) strong biofilm former Listeria monocytogenes strain ScottA versus weak biofilm former Listeria monocytogenes strain F2365; 2) Listeria monocytogenes ScottA LbrA deletion mutant strain versus Listeria monocytogenes ScottA. Four replicates were loaded for the first comparison and two replicates were loaded for the second comparison.
2012-09-06 | E-GEOD-40598 | biostudies-arrayexpress
Project description:Listeria monocytogenes strain F2365 was the first strain representative of serotype 4b (lineage I) to be sequenced in 2004, suggesting it could become the model organism for this serotype, which is associated with most human outbreaks of listeriosis worldwide to date. F2365 itself is an outbreak strain involved in the Mexican-style soft cheese outbreak in California in 1985. In this study we show through phenotypic and transcriptomic analysis that L. monocytogenes strain F2365 has reduced ability to respond to stress due to the absence of a functional σB-dependent stress response system. F2365 shows no B-dependent ability to survive acid or oxidative stress nor B-dependent ability to infect Caco-2 epithelial cell in vitro or guinea pigs in vivo. Therefore, there is substantial evidence that F2365 is an atypical strain and is not a suitable representative of outbreak-associated serotype 4b strains.
2013-06-01 | GSE42730 | GEO
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. Independent RNA isolations were performed for strain 10403S with and without exposure to ClO2 from cells grown to early log phase. Four biological replicates were used in competitive whole-genome microarray experiments. For each set of hybridizations, RNA from a control sample of Listeria monocytogenes was hybridized with RNA from a culture of L. monocytogenes following exposure to ClO2. Dye swapping was performed for the four replicates to mitigate any concerns of dye bias.
2014-03-07 | E-GEOD-48187 | biostudies-arrayexpress
Project description:Iron is an essential cofactor for a wide range of cellular processes. Previous studies have shown that siderophore-mediated uptake and intracellular handling of iron are crucial for virulence of Aspergillus fumigatus. Here we show that the bzip-type transcription factor HapX plays a crucial role in the transcriptional remodeling required for adaption to iron starvation in this opportunistic fungal pathogen. HapX was found to be interconnected in a negative feed-back loop with the previously identified iron regulator SreA: SreA repressed expression of hapX during iron sufficiency and HapX repressed sreA during iron starvation. Genome-wide transcriptional profiling and analysis of selected metabolites (protophorphyrine IX, siderophores and amino acids) indicated extensive metabolic remodeling in response to iron starvation. HapX was found to participate in both, repression and activation of genes during iron starvation. HapX was in particular required for repression of iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino acid metabolism, iron-sulfur-cluster biosynthesis and heme biosynthesis. Pathways positively affected by HapX included production of siderophores and the ribotoxin and major allergen AspF1. Analysis of the free amino acid pool revealed HapX-dependent coordination of the production of siderophores with the supply of its precursor ornithine. Consistent with the hapX expression pattern, HapX-deficiency was deleterious with respect to growth rate and conidiation during iron depleted but not iron-replete conditions. HapX-deficiency caused significant attenuation of virulence in a murine model aspergillosis underlining that A. fumigatus faces iron starvation in the host and that the HapX-dependent metabolic reprogramming is therefore crucial for virulence. A. fumigatus 293 and hapX mutants were grown in the presence and absence of iron and in cultures shifted from no iron to iron-containing conditions after 1 h incubation. Hybridizations were performed with biological replicates for wt vs hapX +/- iron. For the iron-shift experiments, there were biological replicates for wt in both conditions and for hapX in -iron but there was only a single biological sample for hapX iron-shift sample. All hybs were performed with flip-dye pairs.
2010-07-01 | E-GEOD-22052 | biostudies-arrayexpress
Project description:Dendritic cells (DC) play an important role in host immunity by acting as a bridge between the innate and adaptive immune systems. They are antigen presenting cells that obtain microbial antigens by direct phagocytosis of the microbe or by cross presentation of antigens taken up from the surrounding environment. Monocyte derived DC were co-cultured with resting conidia of Aspergillus fumigatus at an MOI of 5 for 12 hours, cells were sampled every three hours. RNA was extracted from both organisms at each time point and hybridised to micro-arrays, whole genome Aspergillus fumigatus array (JCVI) and a custom immune array for DC. The genes up-regulated by DC in the presence of A. fumigatus indicated that the cells were producing a pro-inflammatory response. There was an increase in IL8 expression over time confirming its association with germ tube emergence. Over the course of the experiment there was increased expression of 210 genes by A. fumigatus, GO analysis indicated significant up-regulation of the following biological processes: fermentation, drug transport, pathogenesis, transport, tyrosine catabolism and response to oxidative stress. There were two clusters of temporally regulated genes showing up regulation before 6hr and after 6 hrs. This may be related to the increased mortality exhibited in DC at 6h. The initial analysis of A. fumigatus gene expression in response to DC shows similarity to its response to neutrophils with an up-regulation in catabolism and response to oxidative stress. A. fumigatus AF293 cells were grown in the presence and absence of human dendritic cells for 0h - 12h. Hybridizations were performed with biological replicates and flip-dye pairs.
2010-07-01 | E-GEOD-22053 | biostudies-arrayexpress
Project description:Deletion of AcuM caused attenuated virulence in mouse models of Aspergillosis, we carried out the microarry to figure out pathways have been changed to affect the virulence. Transcriptional profiling of Aspergillus fumigatus mycelium comparing mutant ?acuM with wild type Af293, and complemented strain ?acuM ::acuM with mutant ?acuM . Three time points comparison under RPMI: 8 hour, 18 hour, 24 hour. Biological replicates: 2, independently grown and harvest. One replicate per array.
2010-10-11 | E-GEOD-24466 | biostudies-arrayexpress
Project description:PrfA activity was studied in L. monocytogenes strain EGD and in an isogenic prfA deletion mutant (EGDΔprfA) carrying multiple copies of the wild-type prfA or the mutant prfA* gene (strains EGDΔprfApPrfA and EGDΔprfApPrfA*) after growth in brain heart infusion (BHI), Luria-Bertani broth (LB) or a defined minimal medium (MM) supplemented either with one of the three PTS-carbohydrates, glucose, mannose and cellobiose, or the non-PTS carbon source glycerol. Low PrfA activity was observed in the wild-type EGD strain in BHI and LB with either of these carbon sources, while PrfA activity was high in minimal medium in presence of glycerol but significantly reduced in presence of cellobiose. The strains expressing the prfA and prfA* gene under the prfA promoters, P1 and P2, produced equally large amounts of PrfA protein and high PrfA activity was observed in strain EGDΔprfApPrfA* under all growth conditions. In contrast, high PrfA activity in strain EGDΔprfApPrfA was only observed when this strain was cultured in BHI but not in LB or MM (in presence of either carbon source). A ptsH mutant (lacking a functional HPr) was able to grow in BHI suggesting that growth of L. monocytogenes in this culture medium is supported by carbon sources whose uptake and metabolism are independent of the PTS pathway. However, this mutant was unable to grow in LB and MM regardless which of the four carbon sources was added, suggesting that uptake of the used carbohydrates and the catabolism of glycerol depend fully on the functional common PTS pathway. Furthermore, the growth rates of L. monocytogenes are strongly reduced in presence of large amounts of PrfA protein when growing MM but less in LB and only slightly in BHI. The expression profiles of the genes encoding PTS permeases were determined in the three strains under various growth conditions. The data suggest that PrfA activity correlates with the expression level and the phosphorylation state of specific PTS permeases. This SuperSeries is composed of the following subset Series: GSE12143: Listeria monocytogenes EGD after growth BHI vs. LB vs. MM GSE12145: Listeria monocytogenes EGDΔprfApPrfA and EGDΔprfApPrfA* compared to the wild type strain EGD GSE12146: Listeria monocytogenes EGD and EGD-e
2008-11-30 | E-GEOD-12151 | biostudies-arrayexpress
Project description:Transcriptional profile after growth in MM (minimal medium (Premaratne et al. 2001) supplemented with 50 mM Glucose. Note: strain "EGD" has not been deposited at ATCC/NCTC. It is a derivative of the original Murray strain (Murray et al. 1926), obtained from S.H.E. Kaufmann. Strain "EGD-e" has been obtained from H. Hahn (Berlin) via T. Chakraborty (Gießen) and is deposited under ATTC BAA-679 and in the Pasteur culture collection. Keywords: strain comparison A total of three independently isolated RNA samples from each strain were used for the analysis.
2008-11-30 | E-GEOD-12146 | biostudies-arrayexpress