A novel hybrid kinase is essential for regulating the σB-mediated stress response of Bacillus cereus.
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ABSTRACT:
ORGANISM(S): Bacillus cereus ATCC 14579
PROVIDER: GSE14589 | GEO | 2009/12/17
SECONDARY ACCESSION(S): PRJNA111709
REPOSITORIES: GEO
Similar Datasets
Project description:A common bacterial strategy for monitoring environmental challenges is to use two-component systems, which consist of a sensor histidine kinase (HK) and a response regulator (RR). In the food-borne pathogen Bacillus cereus, the alternative sigma factor ÏB is activated by the RR RsbY. Here we present strong indications that the PP2C-type phosphatase RsbY receives its input from the multi-sensor hybrid kinase BC1008 (renamed RsbK). Genome analyses revealed that, across bacilli, rsbY and rsbK are located in a conserved gene cluster. A B. cereus rsbK deletion strain was shown to be incapable of inducing ÏB upon stress conditions and was impaired in its heat adaptive response. Comparison of the wild-type and rsbK mutant transcriptomes upon heat shock revealed that RsbK was primarily involved in the activation of the ÏB-mediated stress response. Truncation of the RsbK RR receiver domain demonstrated the importance of this domain for ÏB induction upon stress. The domain architecture of RsbK suggests that in the B. cereus group and in other bacilli, environmental and intracellular stress signalling routes are combined into one single protein. This strategy is markedly different from the ÏB activation pathway in other low-GC Grampositives. Two different comparisons were performed (both in duplo and Cy5-Cy3 dye-swapped): (1) B. cereus WT 30°C versus B. cereus WT 42°C (10 min heat shock) (2) B. cereus WT 42°C versus B. cereus FM1404 42°C Data from comparisons (2) were subsequently compared with transcriptome data obtained previously by Van Schaik et al., 2007
2010-06-24 | E-GEOD-14589 | biostudies-arrayexpress
Project description:The alternative sigma factor sigmaB has an important role in the acquisition of stress-resistance in many gram-positive bacteria. In the foodborne pathogen Bacillus cereus sigmaB is activated strongly upon a heat shock and other stress conditions. Here we describe the identification of the set of sigmaB-regulated genes in B. cereus by DNA microarray analysis of the transcriptome upon a mild heat shock. A total of 24 genes could be identified as being sigmaB-dependent as witnessed by (i) significantly lower expression-levels of these genes in mutants deleted for sigB and rsbY (encoding the alternative sigma factor sigmaB and a PP2C phosphatase that acts as a crucial positive regulator of sigmaB-activity, respectively) than in the parental strain B. cereus ATCC 14579, and (ii) increased expression of these genes upon a heat shock. Newly identified members of the sigmaB-regulon of B. cereus include an ECF-sigma factor (sigmaZ), a histidine kinase and two genes that have predicted functions in spore germination. Our data indicate that the sigmaB-regulon of B. cereus is considerably smaller than that of other gram-positive bacteria. This appears to be in line with phylogenetic analyses of sigmaB in which sigmaB in the B. cereus group was suggested to be close to the ancestral form of sigmaB in gram-positive bacteria. Keywords: stress response, comparative genomics
2007-04-10 | GSE6005 | GEO
Project description:The alternative sigma factor sigmaB has an important role in the acquisition of stress-resistance in many gram-positive bacteria. In the foodborne pathogen Bacillus cereus sigmaB is activated strongly upon a heat shock and other stress conditions. Here we describe the identification of the set of sigmaB-regulated genes in B. cereus by DNA microarray analysis of the transcriptome upon a mild heat shock. A total of 24 genes could be identified as being sigmaB-dependent as witnessed by (i) significantly lower expression-levels of these genes in mutants deleted for sigB and rsbY (encoding the alternative sigma factor sigmaB and a PP2C phosphatase that acts as a crucial positive regulator of sigmaB-activity, respectively) than in the parental strain B. cereus ATCC 14579, and (ii) increased expression of these genes upon a heat shock. Newly identified members of the sigmaB-regulon of B. cereus include an ECF-sigma factor (sigmaZ), a histidine kinase and two genes that have predicted functions in spore germination. Our data indicate that the sigmaB-regulon of B. cereus is considerably smaller than that of other gram-positive bacteria. This appears to be in line with phylogenetic analyses of sigmaB in which sigmaB in the B. cereus group was suggested to be close to the ancestral form of sigmaB in gram-positive bacteria. Three comparisons were performed: WT-DsigB, WT-DrsbY and WT30degrees-WT42degrees
2010-07-01 | E-GEOD-6005 | 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 extensively studied intracellular pathogen, L. monocytogenes, is an ideal model for identifying small-molecule agents for treating bacterial infections. By selecting specific biological targets in L. monocytogenes, which are common to Gram-positive pathogens, we could extrapolate drug discovery information derived from this well-studied bacterium. Attenuating the pathogen’s virulence and stress response attributes without killing it, eliminates selective pressure caused by disruption of essential gene functions (as done by current antibiotics) and reduces the likelihood of developing microbes that are impervious to the effects of antibiotics. To this end, we have assessed multiple libraries of small organic compounds to identify inhibitors of L. monocytogenes σB, the alternative sigma factor common to several clinically relevant Gram-positive pathogens, such as Staphylococcus aureus, Bacillus cereus, and Bacillus anthracis. The role of σB as a transcriptional regulator of stress response and virulence makes it an ideal, well conserved target for chemotherapeutic development.
2011-12-06 | GSE16887 | GEO
Project description:In several gram-positive bacterial genera including Bacillus, Staphylococcus, and Listeria, sigma B (σB) has been identified as a stress-responsive alternative sigma factor responsible for initiating transcription of genes (the σB regulon) involved in response to stress-inducing environmental conditions. In L. monocytogenes, a foodborne pathogen of considerable threat to public health and the food industry, σB is involved in regulation of stress response and virulence gene expression. We have defined the σB regulon in L. monocytogenes during early stationary phase and under salt stress (0.3M NaCl) conditions using whole-genome microarrays, identifying 168 genes that generated ≥2.0-fold higher signals in the parental strain 10403S than in an isogenic sigB null mutant (ΔsigB), categorized into nine functional groups including stress-response genes (12), virulence genes (5), and genes related to transport (26) and metabolism (45). To gain a broader biological perspective of the σB stress response system, we applied these microarrays to Listeria innocua under the same environmental conditions. Our studies revealed 64 candidates in the L. innocua σB regulon with ≥2.0-fold higher signals in the parent than in a ΔsigB mutant; 49 of the 64 genes overlap with the L. monocytogenes σB regulon, indicating extensive overlap in σB-controlled genes between the two species. Further transcriptional analysis using TaqMan quantitative real time RT-PCR was performed for selected genes that displayed contrasting fold changes among the four microarray data sets (two stress conditions per species). We report novel members of the L. monocytogenes σB regulon, as well as the initial definition of the L. innocua σB regulon. Our comparative studies of the σB stress response systems in L. monocytogenes and L. innocua revealed features of the σB regulon that are conserved and unique to the two species. Keywords: Listeria monocytogenes, Listeria innocua, SigB regulon, salt stress, stationary phase
2007-11-29 | GSE7492 | GEO
Project description:The ability to respond to stress is at the core of an organismâs survival. The hormones epinephrine and norepinephrine play a central role in stress responses in mammals, which require the synchronized interaction of the whole neuroendocrine system. Bacteria also sense and respond to epinephrine and norepinephrine as a means to gauge the metabolic and immune state of the host. Mammalian adrenergic receptors are G-coupled protein receptors (GPCRs), bacteria, however, sense these hormones through histidine sensor kinases (HKs). HKs autophosphorylate in response to multiple signals and transfer this phosphate to response regulators (RRs). Two bacterial adrenergic receptors have been identified in EHEC, QseC and QseE, with QseE being downstream of QseC in this signaling cascade. We mapped the QseC signaling cascade in the deadly pathogen enterohemorrhagic E. coli (EHEC), which exploits this signaling system to promote disease. Through QseC, EHEC activates expression of metabolic, virulence and stress response genes, synchronizing the cell response to these stress hormones. Coordination of these responses is achieved by QseC phosphorylating three of the thirty two EHEC RRs. The QseB RR, which is QseCâs cognate RR, activates the flagella regulon which controls bacteria motility and chemotaxis. The QseF RR, which is phosphorylated by the QseE adrenergic sensor, coordinates expression of virulence genes involved in formation of lesions in the intestinal epithelia by EHEC, and the bacterial SOS stress response. The third RR, KdpE, controls potassium uptake, osmolarity response, and also the formation of lesions in the intestine. Adrenergic regulation of bacterial gene expression shares several parallels with mammalian adrenergic signaling having profound effects in the whole organism. Understanding adrenergic regulation of a bacterial cell is a powerful approach to study the underlying mechanisms of stress and cellular survival. Experiment Overall Design: Microarray comparisons reveal some trends with respect to signaling cascades. Comparative methods were used to identify networks.
2009-11-16 | E-GEOD-15050 | 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 | GSE21427 | GEO
Project description:The ability to respond to stress is at the core of an organism’s survival. The hormones epinephrine and norepinephrine play a central role in stress responses in mammals, which require the synchronized interaction of the whole neuroendocrine system. Bacteria also sense and respond to epinephrine and norepinephrine as a means to gauge the metabolic and immune state of the host. Mammalian adrenergic receptors are G-coupled protein receptors (GPCRs), bacteria, however, sense these hormones through histidine sensor kinases (HKs). HKs autophosphorylate in response to multiple signals and transfer this phosphate to response regulators (RRs). Two bacterial adrenergic receptors have been identified in EHEC, QseC and QseE, with QseE being downstream of QseC in this signaling cascade. We mapped the QseC signaling cascade in the deadly pathogen enterohemorrhagic E. coli (EHEC), which exploits this signaling system to promote disease. Through QseC, EHEC activates expression of metabolic, virulence and stress response genes, synchronizing the cell response to these stress hormones. Coordination of these responses is achieved by QseC phosphorylating three of the thirty two EHEC RRs. The QseB RR, which is QseC’s cognate RR, activates the flagella regulon which controls bacteria motility and chemotaxis. The QseF RR, which is phosphorylated by the QseE adrenergic sensor, coordinates expression of virulence genes involved in formation of lesions in the intestinal epithelia by EHEC, and the bacterial SOS stress response. The third RR, KdpE, controls potassium uptake, osmolarity response, and also the formation of lesions in the intestine. Adrenergic regulation of bacterial gene expression shares several parallels with mammalian adrenergic signaling having profound effects in the whole organism. Understanding adrenergic regulation of a bacterial cell is a powerful approach to study the underlying mechanisms of stress and cellular survival.
2009-09-15 | GSE15050 | GEO
Project description:In Gram-positive organisms the general stress response is regulated by the alternative sigma factor sigma B (σB). In C. difficile this sigma factor has been implicated in protection against stressors such as reactive oxygen species and antimicrobial compounds. Here, we show that an anti-σB antibody can be used to demonstrate overexpression of σB in C. difficile and that this overexpression is tolerated for short periods of time, despite its toxicity. Toxicity associated with σB-overexpression leads to loss of the plasmid used for anhydrotetracycline-induced σB expression. By uncoupling σB from its native regulatory network, we refined the previously proposed σB regulon and confirmed a direct role for σB in the induction of selected genes using in vitro run-off transcription reactions. Finally, using a plate-based luciferase reporter assay we demonstrated that different antibiotics and hydrogen peroxide induce genes positively regulated by σB in a manner dependent on this sigma factor. Together, our work suggests that lethal exposure to antibiotics may result in the formation of toxic radicals that lead to σB-dependent gene activation.
2020-09-07 | GSE152515 | GEO