Mode of action of CryIIA: a Bacillus thuringiensis delta-endotoxin

English, Leigh; Robbins, H L; Tersch, M A Von; Kulesza, Caroline; Avé, D. A.; Coyle, Dolores; Jany, C S; Slatin, Stephen L.

doi:10.1016/0965-1748(94)90140-6

Cited by 77 publications

(53 citation statements)

References 29 publications

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“…In contrast, an early study of the mode of action of Cry2Aa proposed a unique mode of action for this protein in that binding was nonsaturable (13). The authors concluded that Cry2Aa "might bind to an essentially unlimited number of relatively low affinity sites" (13). The nonsaturable nature of Cry2A binding has been assumed or reiterated in subsequent reports (22,23,24).…”

Section: Homologous-competition Assays Withmentioning

confidence: 76%

“…Saturable binding to specific receptors has been shown amply with Cry1 proteins (reviewed in reference 37) and more limitedly with the coleopteran-active Cry3A (6,30,34,41) and the dipteran-specific Cry4 and Cry11 class proteins (1,11,31,35). In contrast, an early study of the mode of action of Cry2Aa proposed a unique mode of action for this protein in that binding was nonsaturable (13). The authors concluded that Cry2Aa "might bind to an essentially unlimited number of relatively low affinity sites" (13).…”

Section: Homologous-competition Assays Withmentioning

confidence: 99%

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Specific Binding of Bacillus thuringiensis Cry2A Insecticidal Proteins to a Common Site in the Midgut of Helicoverpa Species

Hernández‐Rodríguez

Vliet

Bautsoens

et al. 2008

Appl Environ Microbiol

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For a long time, it has been assumed that the mode of action of Cry2A toxins was unique and different from that of other three-domain Cry toxins due to their apparent nonspecific and unsaturable binding to an unlimited number of receptors. However, based on the homology of the tertiary structure among three-domain Cry toxins, similar modes of action for all of them are expected. To confirm this hypothesis, binding assays were carried out with 125 I-labeled Cry2Ab. Saturation assays showed that Cry2Ab binds in a specific and saturable manner to brush border membrane vesicles (BBMVs) of Helicoverpa armigera. Homologous-competition assays with125 I-Cry2Ab demonstrated that this toxin binds with high affinity to binding sites in H. armigera and Helicoverpa zea midgut. Heterologous-competition assays showed a common binding site for three toxins belonging to the Cry2A family (Cry2Aa, Cry2Ab, and Cry2Ae), which is not shared by Cry1Ac. Estimation of K d (dissociation constant) values revealed that Cry2Ab had around 35-fold less affinity than Cry1Ac for BBMV binding sites in both insect species. Only minor differences were found regarding R t (concentration of binding sites) values. This study questions previous interpretations from other authors performing binding assays with Cry2A toxins and establishes the basis for the mode of action of Cry2A toxins.

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Section: Homologous-competition Assays Withmentioning

confidence: 76%

Section: Homologous-competition Assays Withmentioning

confidence: 99%

Specific Binding of Bacillus thuringiensis Cry2A Insecticidal Proteins to a Common Site in the Midgut of Helicoverpa Species

Hernández‐Rodríguez

Vliet

Bautsoens

et al. 2008

Appl Environ Microbiol

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“…The action of Cry toxins as well as several other midgut-active insecticidal agents (2,28,32) commonly involve an osmotically induced cell lysis, although these agents are completely unrelated. For ␦-endotoxin, catalysis of and modulation of toxin-derived ion channels following receptor binding are established (31,37,39); however, additional mechanisms could account for other aspects of toxicity which are observed, such as larval behavioral changes, cessation of feeding, regurgitation, and gut paralysis (1,9,12). Based on two separate voltage clamping techniques, our data support the existence of a pore-forming step in the mode of action of Vip3A following the binding to midgut epithelial receptors.…”

Section: Discussionmentioning

confidence: 99%

The Mode of Action of the Bacillus thuringiensis Vegetative Insecticidal Protein Vip3A Differs from That of Cry1Ab δ-Endotoxin

Lee

Walters

Hart

et al. 2003

Appl Environ Microbiol

282

280

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The Vip3A protein, secreted by Bacillus spp. during the vegetative stage of growth, represents a new family of insecticidal proteins. In our investigation of the mode of action of Vip3A, the 88-kDa Vip3A full-length toxin (Vip3A-F) was proteolytically activated to an approximately 62-kDa core toxin either by trypsin (Vip3A-T) or lepidopteran gut juice extracts (Vip3A-G). Biotinylated Vip3A-G demonstrated competitive binding to lepidopteran midgut brush border membrane vesicles (BBMV). Furthermore, in ligand blotting experiments with BBMV from the tobacco hornworm, Manduca sexta (Linnaeus), activated Cry1Ab bound to 120-kDa aminopeptidase N (APN)-like and 250-kDa cadherin-like molecules, whereas Vip3A-G bound to 80-kDa and 100-kDa molecules which are distinct from the known Cry1Ab receptors. In addition, separate blotting experiments with Vip3A-G did not show binding to isolated Cry1A receptors, such as M. sexta APN protein, or a cadherin Cry1Ab ecto-binding domain. In voltage clamping assays with dissected midgut from the susceptible insect, M. sexta, Vip3A-G clearly formed pores, whereas Vip3A-F was incapable of pore formation. In the same assay, Vip3A-G was incapable of forming pores with larvae of the nonsusceptible insect, monarch butterfly, Danaus plexippus (Linnaeus). In planar lipid bilayers, both Vip3A-G and Vip3A-T formed stable ion channels in the absence of any receptors, supporting pore formation as an inherent property of Vip3A. Both Cry1Ab and Vip3A channels were voltage independent and highly cation selective; however, they differed considerably in their principal conductance state and cation specificity. The mode of action of Vip3A supports its use as a novel insecticidal agent.

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“…The technology introduced into Burkina Faso has been second-generation Bt cotton, expressing two different Bt proteins (Cry1Ac and Cry2Ab). Both are active against the lepidopteran pests of Burkina Faso and they represent different modes of action [97,98]. Resistance allele frequencies for individual Bt proteins are generally considered rare but are multiplied when specific combinations of Bt resistance alleles are considered, making an individual resistant to more than one Bt protein extremely rare.…”

Section: Insect Resistance Managementmentioning

confidence: 99%

Enhancing Sustainability of Cotton Production Systems in West Africa: A Summary of Empirical Evidence from Burkina Faso

2011

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Africa has been hesitant to adopt agricultural biotechnology, lagging behind global trends over the past decade. One exception is Burkina Faso, a West African country that commercially released 125,000 ha of Bt cotton in 2009. Bt cotton may serve as a working example of how African countries can enhance sustainability using modern, science-driven technology to increase production levels while reducing input use and energy consumption. This paper reports the potential impact that Bt cotton can have on sustainability in Burkina Faso's cotton sector based by summarizing empirical evidence from previously published studies. Based on the summary of published data collected from six years of field trials and producer surveys, Bt cotton increased cotton yields by an average of 21.3% and raised income by $106.14 per ha. Using an energy balance model, the introduction of Bt cotton would also result in a 6.6% saving in energy use. The significant increase in productivity and economic returns could be the catalyst for Burkina Faso, and other African countries, to emerge from the decade or so of stagnation and regain their competitive stance in world cotton markets while providing environmental and social benefits.

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Mode of action of CryIIA: a Bacillus thuringiensis delta-endotoxin

Cited by 77 publications

References 29 publications

Specific Binding of Bacillus thuringiensis Cry2A Insecticidal Proteins to a Common Site in the Midgut of Helicoverpa Species

Specific Binding of Bacillus thuringiensis Cry2A Insecticidal Proteins to a Common Site in the Midgut of Helicoverpa Species

The Mode of Action of the Bacillus thuringiensis Vegetative Insecticidal Protein Vip3A Differs from That of Cry1Ab δ-Endotoxin

Enhancing Sustainability of Cotton Production Systems in West Africa: A Summary of Empirical Evidence from Burkina Faso

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