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

Wageningen Centre for Food Sciences, Wageningen, The Netherlands.
Journal of Bacteriology (Impact Factor: 2.81). 09/2005; 187(16):5846-51. DOI: 10.1128/JB.187.16.5846-5851.2005
Source: PubMed


The alternative sigma factor σB is an important regulator of the stress response of Bacillus cereus. Here, the role of the regulatory proteins RsbV, RsbW, and RsbY in regulating σB 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 σB 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 σA-dependent promoter and a σB-dependent promoter. The central role of RsbY in regulating the activity of σB indicates that in B. cereus, the σB activation pathway is markedly different from that in other gram-positive bacteria.

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    • "The stressosome acts to integrate a diverse array of signals to activate the σB stress response [24] and control the activity of the downstream regulatory module involving RsbU-RsbV-RsbW [15]. This Rsb-σB module is conserved in other Bacillus species, such as B. licheniformis and B. halodurans, whereas some other species, such as B. cereus, show variations in the regulatory components [25]. In B. cereus, the RsbV-RsbW-σB module is conserved but the phosphatase of RsbV ~ P is RsbY, which possesses a structurally different N-terminal sensing domain from RsbU, and there is a hybrid histidine kinase/response regulator protein, RsbK, which senses and integrates multiple signals [25] and that can activate RsbY [26]. "
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    • "In the human pathogen B. cereus, the mechanism of σB activation has only been studied more recently (van Schaik et al., 2004a,b, 2005, 2007; de Been et al., 2010, 2011). It has been shown that σB activation is governed by a single PP2C-type phosphatase, RsbY, which carries an N-terminal response receiver (REC) domain (van Schaik et al., 2005). The rsbY gene is unique to B. cereus and to closest relatives and is transcribed both from σA-dependent promoter (constitutive sigma factor) and σB-dependent promoter. "
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