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The sigmaB regulon of B. cereus ATCC14579

ABSTRACT: 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

ORGANISM(S): Bacillus cereus ATCC 14579

PROVIDER: GSE6005 | GEO | 2007/04/10

SECONDARY ACCESSION(S): PRJNA97797

REPOSITORIES: GEO

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The sigmaB regulon of B. cereus ATCC14579

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

A novel hybrid kinase is essential for regulating the ÏB-mediated stress response of Bacillus cereus.

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 30Â°C versus B. cereus WT 42Â°C (10 min heat shock) (2) B. cereus WT 42Â°C versus B. cereus FM1404 42Â°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

Overexpression analysis of sigZ of B. cereus ATCC 14579.

Project description:The Bacillus cereus ATCC 14579 alternative σ factor σZ and its putative regulon have been characterized. σZ shows overall similarity with ECF σ factors and sigZ constitutes an operon together with asfZ encoding its putative anti-σ factor. Expression analysis revealed sigZ to be induced by an array of stresses, including exposure to ethanol, alkaline pH and heat shock, and a typical promoter binding site for the sigZ-operon was identified by 5’RACE. Phenotypic characterization of B. cereus ATCC 14579 and its sigZ-deletion strain revealed diminished growth performance and sporulation capacity. The σZ-regulon was successfully established by transcriptome analysis of a nisin inducible sigZ-overexpression strain. Overexpression of sigZ was shown to affect expression of 42 genes, including 33 genes encoding proteins located in the extracytoplasm. The identified σZ regulon contained genes encoding proteins situated in the extracytoplasm involved in cell surface modifications and transport. The regulation of genes encoding cell surface modification proteins implies σZ to be involved in the regulation of interaction of B. cereus ATCC 14579 with its environments, which includes human intestinal cells, possibly influencing its virulence status. Keywords: Comparative transcriptome study

2008-05-11 | GSE9860 | GEO

A novel hybrid kinase is essential for regulating the σB-mediated stress response of Bacillus cereus.

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 σB 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 σB 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 σB-mediated stress response. Truncation of the RsbK RR receiver domain demonstrated the importance of this domain for σB 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 σB activation pathway in other low-GC Grampositives.

2009-12-17 | GSE14589 | GEO

The single ECF sigma factor of Xylella fastidiosa is involved in the heat shock response

Project description:Genome sequence analysis of the bacterium Xylella fastidiosa revealed the presence of two genes, named rpoE and rseA, predicted to encode an ECF sigma factor and an anti-sigma factor, respectively. In this work, an rpoE null mutant was constructed in the citrus strain J1a12 and shown to be sensitive to exposure to heat shock and ethanol. To identify the X. fastidiosa σE regulon, global gene expression profiles were obtained by DNA microarray analysis of bacterial cells under heat shock identifying 23 sigmaE-dependent genes. Keywords: stress response, heat shock, rpoE mutant strain

2006-11-17 | GSE4960 | GEO

Dissection of the heat-shock response in Mycobacterium tuberculosis using mutants and microarrays

Project description:Regulation of the expression of heat-shock proteins plays an important role in the pathogenesis of Mycobacterium tuberculosis. The heat-shock response of bacteria involves genome-wide changes in gene expression. A combination of targeted mutagenesis and whole-genome expression profiling was used to characterize transcription factors responsible for control of genes encoding the major heat-shock proteins of M.tuberculosis. Two heat-shock regulons were identified. HspR acts as a transcriptional repressor for the members of the Hsp70 (DnaK) regulon, and HrcA similarly regulates the Hsp60 (GroE)response. These two specific repressor circuits overlap with broader transcriptional changes mediated by alternative sigma factors during exposure to high temperatures. Several previously undescribed heat-shock genes were identified as members of the HspR and HrcA regulons. A novel HspR-controlled operon encodes a member of the low-molecular-mass a-crystallin family. This protein is one of the most prominent features of the M.tuberculosis heatshock response and is related to a major antigen induced in response to anaerobic stress. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-2

2007-03-07 | E-BUGS-2 | biostudies-arrayexpress

The temperature-regulation of Pseudomonas aeruginosa cmaX-cfrX-cmpX operon reveals an intriguing molecular network involving the sigma factors AlgU and SigX

Project description:Pseudomonas aeruginosa is a highly adaptable Gram-negative opportunistic pathogen, notablydue to its large number of transcription regulators. The extracytoplasmic sigma factor (ECF sigma AlgU, responsible for alginate biosynthesis, is also involved in responses to cell wall stress and heat shock via the RpoH alternative sigma factor. The SigX ECF sigma emerged as a major regulator involved in the envelope stress response via membrane remodelling, virulence and biofilm formation. However, their functional interactions to coordinate the envelope homeostasis in response to environmental variations remain to be determined. The regulation of the putative cmaX-cfrX-cmpX operon located directly upstream sigX was investigated by applying sudden temperature shifts from 37°C. We identified a SigX- and an AlgU- dependent promoter region upstream of cfrX and cmaX, respectively. We show that cmaX expression is increased upon heat shock through an AlgU-dependent but RpoH independent mechanism. In addition, the ECF sigma SigX is activated in response to valinomycin, an agent altering the membrane structure, and up-regulates cfrX-cmpX transcription in response to cold shock. Altogether, these data provide new insights into the regulation exerted by SigX and networks that are involved in maintaining envelope homeostasis.

2020-10-05 | PXD021299 | Pride

Response of Bacillus cereus ATCC 14579 to challenges with sublethal concentrations of enterocin AS-48

Project description:Enterocin AS-48 is produced by Enterococcus faecalis S48 to compete with other bacteria in their environment. Due to its activity against various Gram positive and some Gram negative bacteria it has clear potential for use as a food preservative. Here, we studied the effect of enterocin AS-48 challenges on vegetative cells of Bacillus cereus ATCC 14579 by use of transcriptome analysis.

2010-04-08 | GSE15600 | GEO

Overexpression analysis of sigZ of B. cereus ATCC 14579.

2008-05-10 | E-GEOD-9860 | biostudies-arrayexpress

Characterization of a key region involved in the NO stress response of Bacillus cereus

Project description:Bacterial response to nitric oxide (NO) is of major importance for bacterial survival, as NO stress is a main actor of the eukaryote immune response. Several pathogenic bacteria have developed gene regulation systems involved in detoxification and in repairing the damages caused by NO. However, bacterial mechanisms of NO resistance are poorly described for Gram positive bacteria and especially Bacillus cereus. This food born and opportunistic pathogen does not have the common weapon against NO described in other pathogenic or non-pathogenic bacteria, such as the transcriptional regulators norR and nsrR, nor NO reductases. Using a transcriptomic approach, we investigated the mechanisms used by B. cereus to fight against NO stress. A cluster of 6 genes was identified to be particularly overexpressed in the early response to NO stress. This cluster contains an iron-sulphur cluster repair enzyme, a nitrite reductase and three enzymes involved in siroheme biosynthesis. We show a co-expression and a close genetic localization implying a functional link between those genes. This cluster may play a pivotal role in the defence mechanisms used by B. cereus to fight against NO stress during infection.

2021-06-02 | GSE168681 | GEO

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