The Alternative Sigma Factor σ<sup>B</sup>of<i>Bacillus cereus</i>: Response to Stress and Role in Heat Adaptation

Schaik, Willem van; Tempelaars, Marcel H.; Wouters, Jeroen A.; Vos, Willem M. de; Abee, Tjakko

doi:10.1128/jb.186.2.316-325.2004

Cited by 75 publications

(114 citation statements)

References 48 publications

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“…CCCP treatment has been shown to result in increased B protein levels, while simultaneously reducing intracellular ATP in Bacillus cereus (39). As shown in Fig.…”

Section: Discussionmentioning

confidence: 69%

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

Chaturongakul

Boor

2004

Appl Environ Microbiol

110

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Sigma B (B ) is a stress-responsive alternative sigma factor that has been identified in various gram-positive bacteria. Seven different regulators of sigma B (Rsbs) are located in the sigB operons of both Bacillus subtilis and Listeria monocytogenes. In B. subtilis, these proteins contribute to regulation of B activity by conveying environmental and energy stress signals through two well-established branches of a signal transduction pathway. RsbT contributes to regulation of B activity in response to environmental stresses, while RsbV contributes to B activation under both environmental and energy stresses in B. subtilis. To probe L. monocytogenes Rsb roles in B -mediated responses to various stresses, in-frame deletions were created in rsbT and rsbV. Phenotypic characterization of the L. monocytogenes rsbT and rsbV null mutants revealed that both mutants were similar to the ⌬sigB strain in their abilities to survive under environmental stress conditions (exposure to synthetic gastric fluid, pH 2.5, acidified brain heart infusion broth [BHI], or oxidative stress [13 mM cumene hydroperoxide]). Under energy stress conditions (carbon starvation in defined media, entry into stationary phase, or reduced intracellular ATP), both ⌬rsbT and ⌬rsbV showed survival reductions similar to that of the ⌬sigB strain. These observations suggest that the pathways for Rsb-dependent regulation of B activity differ between L. monocytogenes and B. subtilis. As B also activates transcription of the L. monocytogenes prfAP2 promoter, we evaluated virulence-associated characteristics of ⌬prfAP1rsbT and ⌬prfAP1rsbV double mutants in hemolysis and tissue culture assays. Both double mutants showed identical phenotypes to ⌬prfAP1P2 and ⌬prfAP1sigB double mutants, i.e., reduced hemolysis activity and reduced plaque size in mouse fibroblast cells. These findings indicate that RsbT and RsbV both contribute to B activation in L. monocytogenes during exposure to environmental and energy stresses as well as during tissue culture infection.Listeria monocytogenes, a gram-positive, non-spore-forming rod-shaped bacterium, is recognized as a foodborne pathogen. This organism is capable of surviving in a broad range of ecological niches (e.g., in farm environments and food processing plants) and in a wide range of hosts, including humans and many species of animals. In L. monocytogenes, the alternative sigma factor B ( B ) contributes to survival under stressful environmental conditions, such as exposure to low pH, oxidizing conditions, and starvation (17, 18). Loss of B also reduces L. monocytogenes virulence in a murine model (32, 44).The sigB gene, which encodes B , lies seventh in the sigB operon. This operon also includes seven additional genes, which encode the following regulator of sigma B proteins: RsbR, RsbS, RsbT, RsbU, RsbV, RsbW, and RsbX (4,19,25,44,45). In B. subtilis, activation of B by the Rsb proteins is achieved through a complex phosphorylation/dephosphorylation cascade in response to various cellular stimuli, which have been catego...

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“…CCCP treatment has been shown to result in increased B protein levels, while simultaneously reducing intracellular ATP in Bacillus cereus (39). As shown in Fig.…”

Section: Discussionmentioning

confidence: 69%

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

Chaturongakul

Boor

2004

Appl Environ Microbiol

110

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“…The organization of the Bacillus cereus sigB operon is identical to that of B. anthracis sigB, and likewise, the sigB operon is autoregulated by B and is induced by heat shock and entry into stationary phase (208). Through use of a combination of two-dimensional gels and Northern hybridizations, 15 B. cereus genes and proteins were determined to be B dependent, including RsbV and the KatE catalase (209).…”

Section: Stress Response Alternative Sigma Factorsmentioning

confidence: 99%

“…Through use of a combination of two-dimensional gels and Northern hybridizations, 15 B. cereus genes and proteins were determined to be B dependent, including RsbV and the KatE catalase (209). The activity of currently recognized B. cereus virulence factors, including protease, lecithinase, and hemolytic activity, as well as production of nonhemolytic enterotoxin, was not affected by disruption of sigB (208), suggesting that B does not directly contribute to B. cereus virulence.…”

Section: Stress Response Alternative Sigma Factorsmentioning

confidence: 99%

“…1B) (12). While both energy and environmental stresses have been (100,199,200), gadA (100), opuCA (57,100,199,200) inlA (100,103,200), prfA (101,151,191) Decreased invasion (103) (196,201), type IV pili (196,201) Higher LD 50 in G. mellonella and mice (196) (55,208). In Bacillus anthracis, only B , RsbV, and RsbW are encoded in the sigB operon (Fig.…”

Section: Stress Response Alternative Sigma Factorsmentioning

confidence: 99%

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Alternative Sigma Factors and Their Roles in Bacterial Virulence

Kazmierczak

Wiedmann

Boor

2005

Microbiol Mol Biol Rev

311

317

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SUMMARY Sigma factors provide promoter recognition specificity to RNA polymerase holoenzyme, contribute to DNA strand separation, and then dissociate from the core enzyme following transcription initiation. As the regulon of a single sigma factor can be composed of hundreds of genes, sigma factors can provide effective mechanisms for simultaneously regulating expression of large numbers of prokaryotic genes. One newly emerging field is identification of the specific roles of alternative sigma factors in regulating expression of virulence genes and virulence-associated genes in bacterial pathogens. Virulence genes encode proteins whose functions are essential for the bacterium to effectively establish an infection in a host organism. In contrast, virulence-associated genes can contribute to bacterial survival in the environment and therefore may enhance the capacity of the bacterium to spread to new individuals or to survive passage through a host organism. As alternative sigma factors have been shown to regulate expression of both virulence and virulence-associated genes, these proteins can contribute both directly and indirectly to bacterial virulence. Sigma factors are classified into two structurally unrelated families, the σ70 and the σ54 families. The σ70 family includes primary sigma factors (e.g., Bacillus subtilis σA) as well as related alternative sigma factors; σ54 forms a distinct subfamily of sigma factors referred to as σN in almost all species for which these proteins have been characterized to date. We present several examples of alternative sigma factors that have been shown to contribute to virulence in at least one organism. For each sigma factor, when applicable, examples are drawn from multiple species.

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“…In several gram-positive bacteria, such as Bacillus subtilis, Staphylococcus aureus, and Listeria monocytogenes, the alternative sigma factor B plays an important role in redirecting gene expression under stress conditions (reviewed in references 10, 20, and 28). In B. cereus, B is activated upon environmental stress and entry into stationary phase (5,26). Phenotypic analysis of the sigB deletion mutant of B. cereus showed that B is involved in the adaptive heat stress response (26).…”

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confidence: 99%

Analysis of the Role of RsbV, RsbW, and RsbY in Regulating σ ^B Activity in Bacillus cereus

et al. 2005

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The alternative sigma factor B is an important regulator of the stress response of Bacillus cereus. Here, the role of the regulatory proteins RsbV, RsbW, and RsbY in regulating B activity in B. cereus is analyzed. Functional characterization of RsbV and RsbW showed that they act as an anti-sigma factor antagonist and an anti-sigma factor, respectively. RsbW can also act as a kinase on RsbV. These data are in line with earlier functional characterizations of RsbV and RsbW homologs in B. subtilis. The rsbY gene is unique to B. cereus and its closest relatives and is predicted to encode a protein with an N-terminal CheY domain and a C-terminal PP2C domain. In an rsbY deletion mutant, the B response upon stress exposure was almost completely abolished, but the response could be restored by complementation with full-length rsbY. Expression analysis showed that rsbY is transcribed from both a A -dependent promoter and a B -dependent promoter. The central role of RsbY in regulating the activity of B indicates that in B. cereus, the B activation pathway is markedly different from that in other gram-positive bacteria.

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The Alternative Sigma Factor σ^BofBacillus cereus: Response to Stress and Role in Heat Adaptation

Cited by 75 publications

References 48 publications

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

Alternative Sigma Factors and Their Roles in Bacterial Virulence

Analysis of the Role of RsbV, RsbW, and RsbY in Regulating σ ^B Activity in Bacillus cereus

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The Alternative Sigma Factor σBofBacillus cereus: Response to Stress and Role in Heat Adaptation

Cited by 75 publications

References 48 publications

RsbT and RsbV Contribute to σB-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

RsbT and RsbV Contribute to σB-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

Alternative Sigma Factors and Their Roles in Bacterial Virulence

Analysis of the Role of RsbV, RsbW, and RsbY in Regulating σ B Activity in Bacillus cereus

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Product

Resources

About

The Alternative Sigma Factor σ^BofBacillus cereus: Response to Stress and Role in Heat Adaptation

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

RsbT and RsbV Contribute to σ^B-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes

Analysis of the Role of RsbV, RsbW, and RsbY in Regulating σ ^B Activity in Bacillus cereus