Characterization of PlcRa, a new PlcR-like regulator involved in oxidative stress response and cysteine metabolism during early stationary phase in Bacillus cereus
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ABSTRACT:
ORGANISM(S): Bacillus cereus ATCC 14579
PROVIDER: GSE30514 | GEO | 2012/12/14
SECONDARY ACCESSION(S): PRJNA143285
REPOSITORIES: GEO
Similar Datasets
Project description:PlcR, the major virulence transcriptional regulator in the Bacillus cereus group belongs to the RNPP quorum sensor family and is activated through interaction with the secreted heptapeptide PapR7 used as a signalling molecule. We identified using modeling analysis a structural homologue of PlcR, PlcRa, in B. cereus. Whole-genome comparative microarrays identified 119 genes (threshold >3) differentially expressed at the onset of stationary phase in a plcRa mutant. phBC6A51 and phBC6A52 prophage genes were up-expressed in a plcRa mutant. Genes involved in oxidative stress response and in cysteine metabolism, including genes which belong to the CymR regulon, were down-regulated in a plcRa mutant. Accordingly, deletion of plcRa resulted in increased sensitivity to hydrogen peroxide and disulfide induced stresses. We also characterized a major target of PlcRa, the (BC2444) abrB2 gene, encoding a putative regulator belonging to AbrB family. PlcRa controlled CymR-regulated genes through AbrB2 and deletion of abrB2 gene resulted in increased sensitivity to hydrogen peroxide and disulfide induced stresses. In conclusion, we identified a new early stationary transcriptional regulator specific to B. cereus group members involved in oxidative stress response and CymR regulon activation. Two different comparisons were performed (both in biological duplo and Cy5-Cy3 dye-swapped) using 2 different time points: (1) B.cereus WT versus B. cereus plcRa overexpression strain at T1 (one hour after the onset of stationary phase) and T2 (two hours after the onset of stationary phase). (2) B.cereus WT versus B.cereus plcRa deletion strain at T1 and T2
2012-12-14 | E-GEOD-30514 | biostudies-arrayexpress
Project description:Acinetobacter baumannii is a Gram-negative opportunistic pathogen that causes multiple infections, including pneumonia, bacteremia, and wound infections. Due to multiple intrinsic and acquired drug-resistance mechanisms, A. baumannii isolates are commonly multi-drug resistant and infections are notoriously difficult to treat. Therefore, it is important to identify mechanisms used by A. baumannii to survive stresses encountered during infection as a means of identifying new drug targets. In this study, we determined the transcriptional response of A. baumannii to hydrogen peroxide stress using RNASequencing. Upon exposure to hydrogen peroxide, A. baumannii differentially transcribes several hundred genes. In this study, we also determined the transcriptional profile of A. baumannii strains with the transcriptional regulators mumR or oxyR genetically inactivated and identified transcriptional differences between these strains and wild-type A. baumannii in response to hydrogen peroxide stress. In doing this, the function of A. baumannii OxyR in hydrogen peroxide stress resistance and regulation of genes required for hydrogen peroxide detoxification was defined. Moreover, the contribution of the uncharacterized regulator MumR to hydrogen peroxide stress resistance was also explored. This work reveals the transcriptome of an important human pathogen in the presence of hydrogen peroxide stress.
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Project description:We explored genomic expression patterns in the yeast Saccharomyces cerevisiae responding to diverse environmental transitions. DNA microarrays were used to measure changes in transcript levels over time for almost every yeast gene, as cells responded to temperature shocks, hydrogen peroxide, the superoxide-generating drug menadione, the sulfhydryl-oxidizing agent diamide, the disulfide-reducing agent dithiothreitol, hyper- and hypo-osmotic shock, amino acid starvation, nitrogen source depletion, and progression into stationary phase. A large set of genes (approximately 900) showed a similar drastic response to almost all of these environmental changes. Additional features of the genomic responses were specialized for specific conditions. Promoter analysis and subsequent characterization of the responses of mutant strains implicated the transcription factors Yap1p, as well as Msn2p and Msn4p, in mediating specific features of the transcriptional response, while the identification of novel sequence elements provided clues to novel regulators. Physiological themes in the genomic responses to specific environmental stresses provided insights into the effects of those stresses on the cell. Study is described in more detail in Gasch AP et al.(2000) Mol Biol Cell 11:4241-57 Keywords: other
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Project description:Transcriptional profiling of S. mutans rpoE knockout mutant comparing to the wild type. The mutation of rpoE cause dramatic changes in phenotypes. The goal is to determine the genes affected by rpoE. The delta subunit of RNA polymerase, RpoE, is wide spread in low G+C Gram-positive bacteria and is thought to play a role in enhancing transcriptional specificity by blocking RNA polymerase binding at weak-promoter sites and stimulating RNA synthesis by accelerating core enzyme recycling. Despite the well-studied biochemical properties of RpoE, a role for this protein in vivo has not been defined in depth. In this study, we show that inactivation of rpoE in the human dental caries pathogen Streptococcus mutans causes impaired growth, and loss of important virulence traits, including biofilm formation, resistance to antibiotics, and tolerance to environmental stresses. Complementation of the mutant with rpoE expressed in trans restored its phenotype to wild type. The luciferase fusion reporter showed that rpoE was highly transcribed throughout growth, and that acid and hydrogen peroxide stresses repressed rpoE expression. Transcriptome profiling of wild type and ΔrpoE cells in the exponential and early stationary phase of growth, under acid and hydrogen peroxide stress and under both stresses combined revealed that genes involved in histidine synthesis, malolactic fermentation, biofilm formation, and antibiotic resistance were down-regulated in the ΔrpoE mutant in all conditions. Moreover, the loss of RpoE resulted in dramatic changes in transport and metabolism of carbohydrates and amino acids. Interestingly, differential expression, mostly up-regulation, of 330 non-coding regions was found. In conclusion, this study demonstrates that RpoE is an important global modulator of gene expression in S. mutans, which is required for optimal growth and environmental adaptation. 5 conditions, mutant vs wild type, biological replicates: 2, technical replicates: 2
2010-09-21 | E-GEOD-22333 | biostudies-arrayexpress
Project description:Antimicrobial chemicals are widely applied to clean and disinfect food-contacting surfaces. However, the cellular response of bacteria, such as Bacillus cereus, to various disinfectants is unclear. In this study, the physiological and genome-wide transcriptional responses of B. cereus ATCC 14579 exposed to four different disinfectants (i.e., benzalkonium chloride, sodium hypochlorite, hydrogen peroxide, and peracetic acid) were analyzed. The physiological response of B. cereus to different concentrations of the disinfectants used was investigated. For each disinfectant, concentrations leading to the attenuation of growth, growth arrest, and cell death were studied in more detail. The simultaneous analysis of the transcriptional responses of B. cereus upon exposure to the different concentrations of disinfectants revealed common responses induced by the four disinfectants. Notably, genes involved in the general and oxidative stress responses were commonly up-regulated. Furthermore, the obtained results indicate that all the disinfectants also induce specific responses. Exposure to benzalkonium chloride, a disinfectant known to induce membrane damage, specifically induced genes involved in the fatty acid metabolism. Benzalkonium chloride induced-membrane damage was confirmed by fluorescence microscopy and fatty acid analysis confirmed that fatty acid composition of cell membrane was affected upon exposure to benzalkonium chloride. Sodium hypochlorite induced genes involved in sulfur and sulfur-containing amino acids metabolism, which correlated with the observed sodium hypochlorite-specific induction of oxidation of sulphydryl groups. Hydrogen peroxide and peracetic acid exposures induced genes involved in DNA damage and the SOS response. Notably, hydrogen peroxide and peracetic acid-treated cells exhibited higher mutation rates corroborating with the induced SOS response. Understanding the mechanisms displayed by microorganisms coping with disinfectants-induced stress may allow for design of more efficient sequential and/or disinfectant combination treatments in food processing environments.
2010-03-31 | GSE18807 | GEO
Project description:Bacillus subtilis exhibits a complex adaptive response to low levels of peroxides. We used global transcriptional profiling to monitor the magnitude and kinetics of changes in the mRNA population after exposure to either hydrogen peroxide (H2O2) or tert-butyl peroxide (t-buOOH). The peroxide stimulons could be largely accounted for by three regulons controlled by the PerR, B, and OhrR transcription factors. Three members of the PerR regulon (katA, mrgA, and zosA) were strongly induced by H2O2 and weakly induced by t-buOOH. The remaining members of the PerR regulon were only modestly up-regulated by peroxide treatment. Overall, the magnitude of peroxide induction of PerR regulon genes corresponded well with the extent of derepression in a perR mutant strain. The B regulon was activated by 58 µM H2O2 but not by 8 µM H2O2 and was strongly activated by either t-buOOH or, in a control experiment, tert-butyl alcohol. Apart from the B regulon there was a single gene, ohrA, that was strongly and rapidly induced by t-buOOH exposure. This gene, controlled by the peroxide-sensing repressor OhrR, was not induced by any of the other conditions tested. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
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Project description:Salmonella enterica serovar Typhimurium is a Gram-negative bacterium, facultative anaerobe and intracellular pathogen that causes enteric fever in mice. Once orally ingested, Salmonella invades and traverse the mucosal intestinal epithelia, where it is phagocytized by specialized cells including macrophages, dendritic cells and neutrophils. Within these cells, the bacterium is kept in a compartment termed Salmonella containing vacuole where it is exposed to different adverse conditions including nutrient deprivation, acid pH, reactive oxygen (ROS) as well as nitrogen (RNS) species and low oxygen levels. Among the signals encountered by the bacteria, oxidative stress is one of the main challenges that it has to overcome in order to survive. In this context, the OxyR and SoxRS proteins are the most studied regulators involved in response to ROS. However, in the past years growing evidence suggests that the ArcAB two-component system might play a key role in modulating gene expression in response to ROS. Furthermore, the global regulator ArcA is required for the resistance of Escherichia coli, S. Enteritidis and Typhimurium to hydrogen peroxide (H2O2), however, the ArcA regulon under oxidative stress conditions remains elusive. Therefore, the aim of this work was to demonstrate that ArcAB regulates the expression of genes in response to hydrogen peroxide and determine the ArcA regulon under this condition. To achieve this, we evaluated transcriptomic changes in strain 14028s, ∆arcA in response to H2O2. Total RNA was harvested from three biological replicates of wt and arcA mutant cultures exposed or unexposed to 1.5 mM hydrogen peroxide for 20 min in LB medium.
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Project description:Bacillus subtilis exhibits a complex adaptive response to low levels of peroxides. We used global transcriptional profiling to monitor the magnitude and kinetics of changes in the mRNA population after exposure to either hydrogen peroxide (H2O2) or tert-butyl peroxide (t-buOOH). The peroxide stimulons could be largely accounted for by three regulons controlled by the PerR, B, and OhrR transcription factors. Three members of the PerR regulon (katA, mrgA, and zosA) were strongly induced by H2O2 and weakly induced by t-buOOH. The remaining members of the PerR regulon were only modestly up-regulated by peroxide treatment. Overall, the magnitude of peroxide induction of PerR regulon genes corresponded well with the extent of derepression in a perR mutant strain. The B regulon was activated by 58 µM H2O2 but not by 8 µM H2O2 and was strongly activated by either t-buOOH or, in a control experiment, tert-butyl alcohol. Apart from the B regulon there was a single gene, ohrA, that was strongly and rapidly induced by t-buOOH exposure. This gene, controlled by the peroxide-sensing repressor OhrR, was not induced by any of the other conditions tested. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Computed
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Project description:Transcriptional profiling of S. mutans rpoE knockout mutant comparing to the wild type. The mutation of rpoE cause dramatic changes in phenotypes. The goal is to determine the genes affected by rpoE. The delta subunit of RNA polymerase, RpoE, is wide spread in low G+C Gram-positive bacteria and is thought to play a role in enhancing transcriptional specificity by blocking RNA polymerase binding at weak-promoter sites and stimulating RNA synthesis by accelerating core enzyme recycling. Despite the well-studied biochemical properties of RpoE, a role for this protein in vivo has not been defined in depth. In this study, we show that inactivation of rpoE in the human dental caries pathogen Streptococcus mutans causes impaired growth, and loss of important virulence traits, including biofilm formation, resistance to antibiotics, and tolerance to environmental stresses. Complementation of the mutant with rpoE expressed in trans restored its phenotype to wild type. The luciferase fusion reporter showed that rpoE was highly transcribed throughout growth, and that acid and hydrogen peroxide stresses repressed rpoE expression. Transcriptome profiling of wild type and ΔrpoE cells in the exponential and early stationary phase of growth, under acid and hydrogen peroxide stress and under both stresses combined revealed that genes involved in histidine synthesis, malolactic fermentation, biofilm formation, and antibiotic resistance were down-regulated in the ΔrpoE mutant in all conditions. Moreover, the loss of RpoE resulted in dramatic changes in transport and metabolism of carbohydrates and amino acids. Interestingly, differential expression, mostly up-regulation, of 330 non-coding regions was found. In conclusion, this study demonstrates that RpoE is an important global modulator of gene expression in S. mutans, which is required for optimal growth and environmental adaptation.
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