X‐ray crystal structure of the B component of Hemolysin BL from <i>Bacillus cereus</i>

Madegowda, Mahendra; Eswaramoorthy, S.; Burley, S.K.; Swaminathan, Subramanyam

doi:10.1002/prot.21888

Cited by 75 publications

(101 citation statements)

References 29 publications

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“…5). In HblB, this head is predicted to contain a transmembrane domain that may insert into the membrane of the target cell (47). The head of HlyE has been shown to undergo a conformational change upon membrane association, causing this region of the protein to swing away from the rest of the protein and into the membrane of a target cell (48).…”

Section: Resultsmentioning

confidence: 99%

YaxAB, a Yersinia enterocolitica Pore-Forming Toxin Regulated by RovA

et al. 2013

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The transcriptional regulator RovA positively regulates transcription of the Yersinia enterocolitica virulence gene inv. Invasin, encoded by inv, is important for establishment of Y. enterocolitica infection. However, a rovA mutant is more attenuated for virulence than an inv mutant, implying that RovA regulates additional virulence genes. When the Y. enterocolitica RovA regulon was defined by microarray analysis, YE1984 and YE1985 were among the genes identified as being upregulated by RovA. Since these genes are homologous to Xenorhabdus nematophila cytotoxin genes xaxA and xaxB, we named them yaxA and yaxB, respectively. In this work, we demonstrate the effects of YaxAB on the course of infection in the murine model. While a yaxAB mutant (⌬yaxAB) is capable of colonizing mice at the same level as the wild type, it slightly delays the course of infection and results in differing pathology in the spleen. Further, we found that yaxAB encode a probable cytotoxin capable of lysing mammalian cells, that both YaxA and YaxB are required for cytotoxic activity, and that the two proteins associate. YaxAB-mediated cell death occurs via osmotic lysis through the formation of distinct membrane pores. In silico tertiary structural analysis identified predicted structural homology between YaxA and proteins in pore-forming toxin complexes from Bacillus cereus (HBL-B) and Escherichia coli (HlyE). Thus, it appears that YaxAB function as virulence factors by inducing cell lysis through the formation of pores in the host cell membrane. This characterization of YaxAB supports the hypothesis that RovA regulates expression of multiple virulence factors in Y. enterocolitica.

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Section: Resultsmentioning

confidence: 99%

YaxAB, a Yersinia enterocolitica Pore-Forming Toxin Regulated by RovA

et al. 2013

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“…Using B. cereus strain NVH 0075/95, it was shown that Nhe acts as a pore-forming toxin inducing cell lysis (9). Based on the crystal structure of the B component of the homologous three-component Hbl toxin (2,15), sequence identities between all six Hbl and Nhe proteins indicate that NheB and NheC (9) show strong structural similarities to ClyA, a 34-kDa pore-forming hemolysin of several enteropathogenic Gram-negative Enterobacteriaceae (12,19,23). They all comprise a 4-to 5-helix bundle connected to a head subdomain with a characteristic hydrophobic ␤-tongue (24).…”

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confidence: 99%

Cytotoxicity of the Bacillus cereus Nhe Enterotoxin Requires Specific Binding Order of Its Three Exoprotein Components

et al. 2010

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“…Hbl is composed of three distinct protein components, L2, L1, and B, which are all required to obtain full enterotoxigenic activity (7). The x-ray crystal structure of the B component has recently been elucidated, indicating that this toxin may form a pore similar to other soluble channel-forming proteins (10). The tripartite Hbl complex is encoded by genes clustered into a polycistronic operon with the transcriptional order hblC, hblD, and hblA (11).…”

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confidence: 99%

Expanding the Known Repertoire of Virulence Factors Produced by Bacillus cereus through Early Secretome Profiling in Three Redox Conditions

Clair

Roussi

Armengaud

et al. 2010

Molecular & Cellular Proteomics

107

144

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The pathogen Bacillus cereus causes diarrheal disease in humans. In the small intestine, B. cereus has to deal with anaerobiosis, low oxidoreduction potential, and carbohydrate limitation conditions. To gain insight into the virulence potential of low density B. cereus cells in such an environment, we cultured bacteria in low and high oxidoreduction potential anoxic conditions and in fully oxic conditions and compared their full secretomes. A unique pattern of proteins assigned to virulence factors was revealed. Among the 57 virulence-related factors, 31 were found for the first time in the B. cereus secretome. The putative fourth component of hemolysin BL (HblB), enterotoxin FM, hemolysin II, and three new putative conserved enterotoxins were uncovered. Cross-comparison of the relative abundance of secreted proteins reveals that a restricted set comprising 19 proteins showed significant changes in response to redox condition changes. We complemented these results with transcriptomics data and confirmed the cytotoxicity of the B. cereus secretome toward Caco-2 human epithelial cells. Our data suggest that (i) the redox-dependent regulatory pathway may modulate the expression of a subset of virulence factors to ensure an appropriate response in a specific redox environment, and (ii) an early growth phase-dependent pathway could regulate the expression of several virulence factors, allowing B. cereus to infect a host whatever the redox conditions. This early growth phase-dependent pathway may function, at least partially, independently of the pleiotropic virulence gene regulator PlcR and may therefore be more specific to the B. cereus group.

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X‐ray crystal structure of the B component of Hemolysin BL from Bacillus cereus

Cited by 75 publications

References 29 publications

YaxAB, a Yersinia enterocolitica Pore-Forming Toxin Regulated by RovA

YaxAB, a Yersinia enterocolitica Pore-Forming Toxin Regulated by RovA

Cytotoxicity of the Bacillus cereus Nhe Enterotoxin Requires Specific Binding Order of Its Three Exoprotein Components

Expanding the Known Repertoire of Virulence Factors Produced by Bacillus cereus through Early Secretome Profiling in Three Redox Conditions

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