Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action

Bel, Yolanda; Ferré, Juan; Hernández‐Martínez, Patricia

doi:10.3390/toxins12120785

Cited by 25 publications

(20 citation statements)

References 20 publications

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“…It is notably the most widely used bioinsecticide in organic farming. Its activity relies on the production of Cry and Cyt toxins in the insect gut after bacterial ingestion (Bel et al 2020). The Bt effects on the microbiota vary according to the insect host and the conditions of Bt exposure (toxin variants, Bt formulation, concentrations…).…”

Section: Insecticidesmentioning

confidence: 99%

Reciprocal interactions between anthropogenic stressors and insect microbiota

Antonelli

Duval

Luis

et al. 2022

Environ Sci Pollut Res

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Insects play many important roles in nature due to their diversity, ecological role, and impact on agriculture or human health. They are directly influenced by environmental changes and in particular anthropic activities that constitute an important driver of change in the environmental characteristics. Insects face numerous anthropogenic stressors and have evolved various detoxication mechanisms to survive and/or resist to these compounds. Recent studies highligted the pressure exerted by xenobiotics on insect life-cycle and the important role of insect-associated bacterial microbiota in the insect responses to environmental changes. Stressor exposure can have various impacts on the composition and structure of insect microbiota that in turn may influence insect biology. Moreover, bacterial communities associated with insects can be directly or indirectly involved in detoxification processes with the selection of certain microorganisms capable of degrading xenobiotics. Further studies are needed to assess the role of insect-associated microbiota as key contributor to the xenobiotic metabolism and thus as a driver for insect adaptation to polluted habitats.

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Section: Insecticidesmentioning

confidence: 99%

Reciprocal interactions between anthropogenic stressors and insect microbiota

Antonelli

Duval

Luis

et al. 2022

Environ Sci Pollut Res

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“…The middle domain II is also uncommon, as it is composed of three antiparallel β-sheets arranged in a circular mode to form a hydrophobic core with some highly variable and exposed loop regions ( Figure 1C ), which are often suggested to confer the binding specificity of the Cry toxin with the mid-intestinal epithelial cell membrane receptors of target insects ( Bravo et al, 2007 ; Evdokimov et al, 2014 ). Domain III, in contrast, forms a regular β-sandwich structure composed of two antiparallel β-sheets ( Figure 1D ; Palma et al, 2014 ; Xu et al, 2014 ), which typically participates in the specific binding with receptors such as N-acetylgalactosamine in the APN ( Bel et al, 2020 ), as well as in forming pores on the cell membranes ( Xu et al, 2014 ; Mendoza-Almanza et al, 2020 ). Besides, other domains in the protoxins may also participate in the stabilization of the various unique Cry toxin structures, in their selective dissolution and specific receptor recognition ( Palma et al, 2014 ).…”

Section: The Main Structure Of Cry Toxinmentioning

confidence: 99%

“…In the long-term evolution, insects usually adopt the strategy of receptor gene mutations to weaken the effective binding between receptors and cognate Cry toxins to protect themselves from damage by the Bt and Cry toxins ( Bel et al, 2020 ).…”

Section: The Resistance Mechanisms Of Insects Against Cry Toxinsmentioning

confidence: 99%

Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects

Luo

et al. 2021

Front. Microbiol.

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In this article, we review the latest works on the insecticidal mechanisms of Bacillus thuringiensis Cry toxins and the resistance mechanisms of insects against Cry toxins. Currently, there are two models of insecticidal mechanisms for Cry toxins, namely, the sequential binding model and the signaling pathway model. In the sequential binding model, Cry toxins are activated to bind to their cognate receptors in the mid-intestinal epithelial cell membrane, such as the glycophosphatidylinositol (GPI)-anchored aminopeptidases-N (APNs), alkaline phosphatases (ALPs), cadherins, and ABC transporters, to form pores that elicit cell lysis, while in the signaling pathway model, the activated Cry toxins first bind to the cadherin receptor, triggering an extensive cell signaling cascade to induce cell apoptosis. However, these two models cannot seem to fully describe the complexity of the insecticidal process of Cry toxins, and new models are required. Regarding the resistance mechanism against Cry toxins, the main method insects employed is to reduce the effective binding of Cry toxins to their cognate cell membrane receptors by gene mutations, or to reduce the expression levels of the corresponding receptors by trans-regulation. Moreover, the epigenetic mechanisms, host intestinal microbiota, and detoxification enzymes also play significant roles in the insects’ resistance against Cry toxins. Today, high-throughput sequencing technologies like transcriptomics, proteomics, and metagenomics are powerful weapons for studying the insecticidal mechanisms of Cry toxins and the resistance mechanisms of insects. We believe that this review shall shed some light on the interactions between Cry toxins and insects, which can further facilitate the development and utilization of Cry toxins.

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“…Some of these bacteria have been exploited for commercial purpose. For example, B. thuringiensis is used as an effective insecticidal agent, on the account that it harbours a plasmid that encodes a variety of insecticidal toxins [ 3 , 4 ]. Some of the B. cereus group species are recognized as important pathogens, e.g.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the pathogenicity of aBacillus cereusisolate from the Mariana Trench

et al. 2022

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Bacillus cereus is an important opportunistic pathogen widely distributed in the environment. In this study, we reported the isolation and characterization of a B. cereus isolate, MB1, from the Challenger Deep of the Mariana Trench. MB1 is aerobic, motile, and able to form endospores. It possesses 5966 genes distributed on a circular chromosome and two plasmids. The MB1 genome contains 14 sets of 23S, 5S, and 16S ribosomal RNA operons, 106 tRNA genes, 4 sRNA genes, 12 genomic islands, 13 prophages, and 302 putative virulence genes, including enterotoxins and cytolysins. Infection studies showed that MB1 was able to cause acute and lethal infection in fish and mice, and was highly toxic to mammalian cells. MB1 induced, in a dose-dependent manner, pyroptotic cell death, characterized by activation of caspase-1, cleavage of gasdermin D, and release of IL-1β and IL-18. MB1 spores exhibited swimming and haemolytic capacity, but were severely attenuated in pathogenicity, which, however, was regained to the full extent when the spores germinated under suitable conditions. Taken together, these results provide new insights into the biological and pathogenic mechanism of deep sea B. cereus .

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Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action

Abstract: Bacillus thuringiensis (Bt)-based products are the most successful microbial insecticides to date [...]

Cited by 25 publications

References 20 publications

Reciprocal interactions between anthropogenic stressors and insect microbiota

Reciprocal interactions between anthropogenic stressors and insect microbiota

Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects

Characterization of the pathogenicity of aBacillus cereusisolate from the Mariana Trench

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