Expression of the Bacillus thuringiensis vip3A insecticidal toxin gene is activated at the onset of stationary phase by VipR, an autoregulated transcription factor - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2022

Expression of the Bacillus thuringiensis vip3A insecticidal toxin gene is activated at the onset of stationary phase by VipR, an autoregulated transcription factor

Résumé

The Vegetative insecticidal protein Vip3A is a toxin produced by some Bacillus thuringiensis (Bt) strains from the mid-log phase growth stage to sporulation. Although the Vip3A toxin is important for the entomopathogenicity of Bt, the precise expression kinetics and the regulation of the vip3A gene expression are still unknown. Here, we identified the VipR, the transcriptional regulator that controls the activation of vip3A expression. vipR is located on the Bt kurstaki HD1 pBMB299 plasmid, the same plasmid that harbors vip3A. Using the Bt kurstaki HD73- Cry- which is unable to express vip3A unlike the kurstaki HD1 strain which naturally harbors vip3A, and promoter-lacZ transcription fusions, we confirmed that VipR is essential for the expression of vip3A. We demonstrated that vipR transcription is positively autoregulated and that VipR activates the expression of vip3A at the onset of stationary phase. We have determined the promoters of vipR and vip3A, and identified a putative VipR target site located a few bp upstream from a Sigma A-specific - 10 region in the promoter of the vip3A and vipR genes. Moreover, we showed that vip3A and vipR expression is drastically increased in a ∆spo0A mutant unable to initiate sporulation. In conclusion, our results show that vip3A expression depends on a specific regulator active during early stationary phase independently of the sporulation process.
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Dates et versions

hal-04329893 , version 1 (07-12-2023)

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  • HAL Id : hal-04329893 , version 1

Citer

Emilie Verplaetse, Haibo Chen, Leyla Slamti, D. Lereclus. Expression of the Bacillus thuringiensis vip3A insecticidal toxin gene is activated at the onset of stationary phase by VipR, an autoregulated transcription factor. International Congress on Invertebrate Pathology and Microbial Control 54th Annual Meeting of the Society for Invertebrate Pathology., Aug 2022, Nelson Mandela Bay-Virtual meeting, South Africa. ⟨hal-04329893⟩
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