Regulation of toxin and virulence gene transcription in Bacillus thuringiensis

Lereclus, Didier; Agaisse, Hervé; Grandvalet, Cosette; Salamitou, Sylvie; Gominet, Myriam

doi:10.1016/s1438-4221(00)80024-7

Cited by 107 publications

(100 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The observation that B does not play a role in the production of virulence factors and the nonhemolytic enterotoxin Nhe was not unexpected, since in the B. cereus group the production of these factors is governed by the pleiotropic regulator PlcR and B seems not to be involved in transcription of the plcR gene (27,28). However, a sigB null mutant may show a weakened stress response.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2004

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

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

et al. 2004

View full text Add to dashboard Cite

show abstract

“…It has been shown previously that inhA1 expression is repressed by abrB and is therefore dependent on Spo0A, which represses abrB expression (26). In sharp contrast, inhA2 expression is activated by PlcR (16) and is thus negatively regulated by Spo0A, which represses plcR expression (40). In comparison with inhA1 and inhA2, inhA3 expression is independent of PlcR and Spo0A; no statistical difference in ␤-galactosidase activities between the wild-type strain and the ⌬spo0A or the ⌬plcR mutant strain was observed (Fig.…”

Section: Vol 192 2010mentioning

confidence: 93%

“…These include enterotoxins (Hbl, Nhe), cytolysins (CytK), and phospholipases (phosphatidylcholine-specific phospholipase C), which may contribute to diarrhea by disrupting the epithelial layer (27,49). When the bacteria enter the sporulation process, plcR transcription, and consequently PlcR-regulated gene expression, is repressed by the key sporulation regulator Spo0A (40). Deletion of plcR reduces, but does not abolish, the virulence of the bacteria in insects and mice, and during endophthalmitis in rabbits (6,52), suggesting that other factors may be involved.…”

mentioning

confidence: 99%

The InhA Metalloproteases ofBacillus cereusContribute Concomitantly to Virulence

et al. 2010

View full text Add to dashboard Cite

The virulence of Bacillus cereus requires that bacteria have the capacity to colonize their host, degrade specific tissues, and circumvent the host immune system. To study this aspect of pathogenesis, we focused on three metalloproteases, InhA1, InhA2, and InhA3, which share more than 66% identity. The expression of these metalloprotease genes was assessed by transcriptional fusions with a lacZ reporter gene. The expression profiles suggest a complementary time course of InhA production. Indeed, the genes are simultaneously expressed but are oppositely controlled during stationary phase. We constructed single and multiple inhA mutants and assessed the bacterial locations of the proteins as well as their individual or additive roles in macrophage escape and toxicity, antibacterial-peptide cleavage, and virulence. InhA1, a major component of the spore exosporium, is the only InhA metalloprotease involved in bacterial escape from macrophages. A mutant lacking inhA1, inhA2, and inhA3 shows a strong decrease in the level of virulence for insects. Taken together, these results show that the InhA metalloproteases of B. cereus are important virulence factors that may allow the bacteria to counteract the host immune system.

show abstract

“…A large number of B. thuringiensis genes, encoding potential virulence factors, are regulated by a pleiotropic transcriptional activator named PlcR (1,25). The transcription of the plcR gene is both autoregulated (25) and under the control of the sporulation key factor Spo0A (26). Alignment of the promoter regions of about 15 PlcR-regulated genes from B. thuringiensis and B. cereus revealed the presence of a highly conserved palindromic sequence (TATGNAN 4 TNCATA), named the PlcR box (1,30).…”

mentioning

confidence: 99%

The Bacillus thuringiensis PlcR-Regulated Gene inhA2 Is Necessary, but Not Sufficient, for Virulence

et al. 2003

View full text Add to dashboard Cite

We previously reported that Bacillus thuringiensis strain 407 Cry 32؊ secretes a zinc-requiring metalloprotease, InhA2, that is essential for virulence in orally infected insects. Analysis of the inhA2-lacZ transcriptional fusion showed that inhA2 expression is repressed in a PlcR ؊ background. Using DNase I footprinting experiments, we demonstrated that PlcR activates inhA2 transcription directly by binding to a DNA sequence showing a one-residue mismatch with the previously reported PlcR box. It was previously reported that PlcR is essential for B. thuringiensis virulence in oral infection by contributing to the synergistic properties of the spores on the insecticidal activity of the Cry1C protein. We used complementation experiments to investigate whether the PlcR ؊ phenotype was due to the absence of InhA2. The results indicated that overexpression of inhA2 in the ⌬plcR strain did not restore the wild-type phenotype. However, virulence was fully restored in the ⌬inhA2 complemented mutant. Thus, inhA2 is the first example of a PlcR-regulated gene found to be directly involved in virulence. However, it is not sufficient for pathogenicity when the other members of the PlcR regulon are lacking. This suggests that InhA2 may act in concert with other PlcR-regulated gene products to provide virulence.

show abstract

Regulation of toxin and virulence gene transcription in Bacillus thuringiensis

Cited by 107 publications

References 23 publications

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

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

The InhA Metalloproteases ofBacillus cereusContribute Concomitantly to Virulence

The Bacillus thuringiensis PlcR-Regulated Gene inhA2 Is Necessary, but Not Sufficient, for Virulence

Contact Info

Product

Resources

About

Regulation of toxin and virulence gene transcription in Bacillus thuringiensis

Cited by 107 publications

References 23 publications

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

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

The InhA Metalloproteases ofBacillus cereusContribute Concomitantly to Virulence

The Bacillus thuringiensis PlcR-Regulated Gene inhA2 Is Necessary, but Not Sufficient, for Virulence

Contact Info

Product

Resources

About

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

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