Location of the Bombyx mori specificity domain on a Bacillus thuringiensis delta-endotoxin protein.

Ge, Albert Z.; Shivarova, N.; Dean, Donald H.

doi:10.1073/pnas.86.11.4037

Cited by 120 publications

(76 citation statements)

References 23 publications

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“…However, ICPs of Cry1 specific to lepidopterans have significantly different insecticidal spectra even with their high homology, and furthermore, the mechanisms of the ICPs specificity are still unclear completely. For example, Cry1Aa poses a 17-fold toxicity against B. mori more than Cry1Ab (Ihara et al, 1993) and 400-fold more than Cry1Ac (Ge et al, 1989). The toxicity of Cry1Ab of Bt strain AF101 against B. mori is about 6-11 times lower than that of Cry1Ab of strain HD-1 (Kim et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Effect of the pollen of transgenic rice line, TT9-3 with a fused cry1Ab/cry1Ac gene from Bacillus thuringiensis Berliner on non-target domestic silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombyxidae)

Yao

Yè

Jiang

et al. 2006

Appl. Entomol. Zool.

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Some cry genes from Bacillus thuringiensis Berliner (Bt) have been transferred into rice plants for resistance to lepidopterans. The ecological risks of Bt rice, especially the non-target effects of Bt rice pollen on the domestic silkworm, Bombyx mori Linnaeus in mulberry-rice mixed cropping area should be clarified cautiously. In light of B. mori fully domesticated and not surviving independently in the field, a series of laboratory bioassays were conducted to evaluate the effect of the pollen from an indica transgenic rice line, TT9-3 with a fused cry1Ab/cry1Ac gene on B. mori based on the investigation of rice pollen deposition under normal field conditions and the quantitation of the fused insecticidal protein expression in the pollen. No significant adverse effects were observed on the survival, growth and development of B. mori young larvae, even after the neonates had been exposed to Bt pollen at the highest density of 3,395.0 grains/cm 2 for 48 h which the pollen density is far higher than the highest pollen density on mulberry leaf, 1,635.9 grains/cm 2 , naturally occurred in the field. According to these results and considering the extensive biotic and non-biotic factors such as the type of Bt genes used and expressed in Bt rice line TT9-3 which are safe to B. mori, the relatively low exposure amount of insecticidal protein in the Bt pollen, and other conditions which influence the silkworm's exposure to Bt pollens, it suggests that the pollen from Bt rice line, TT9-3 poses little effect on silkworm rearing in natural settings.

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Section: Discussionmentioning

confidence: 99%

Effect of the pollen of transgenic rice line, TT9-3 with a fused cry1Ab/cry1Ac gene from Bacillus thuringiensis Berliner on non-target domestic silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombyxidae)

Yao

Yè

Jiang

et al. 2006

Appl. Entomol. Zool.

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“…In contrast, neither Cry1Ab nor Cry1Ac were reported to bind to purified native B. mori APN by use of SPR analysis (80), and thus it not clear whether the interaction between APN and these toxins is biologically relevant. Of the three toxins, Cry1Aa is the most toxic towards B. mori larvae, and only limited toxicity has been observed with Cry1Ac (49,99,104).…”

Section: Apnmentioning

confidence: 99%

Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

Pigott

Ellar

2007

Microbiol Mol Biol Rev

602

598

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SUMMARY Bacillus thuringiensis produces crystalline protein inclusions with insecticidal or nematocidal properties. These crystal (Cry) proteins determine a particular strain's toxicity profile. Transgenic crops expressing one or more recombinant Cry toxins have become agriculturally important. Individual Cry toxins are usually toxic to only a few species within an order, and receptors on midgut epithelial cells have been shown to be critical determinants of Cry specificity. The best characterized of these receptors have been identified for lepidopterans, and two major receptor classes have emerged: the aminopeptidase N (APN) receptors and the cadherin-like receptors. Currently, 38 different APNs have been reported for 12 different lepidopterans. Each APN belongs to one of five groups that have unique structural features and Cry-binding properties. While 17 different APNs have been reported to bind to Cry toxins, only 2 have been shown to mediate toxin susceptibly in vivo. In contrast, several cadherin-like proteins bind to Cry toxins and confer toxin susceptibility in vitro, and disruption of the cadherin gene has been associated with toxin resistance. Nonetheless, only a small subset of the lepidopteran-specific Cry toxins has been shown to interact with cadherin-like proteins. This review analyzes the interactions between Cry toxins and their receptors, focusing on the identification and validation of receptors, the molecular basis for receptor recognition, the role of the receptor in resistant insects, and proposed models to explain the sequence of events at the cell surface by which receptor binding leads to cell death.

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“…The exposed loop architecture has structural affinity for binding to glycoprotein receptors of the target insect www.scienceasia.org 32 . Mutations in defined regions of the Cry1Aa toxin (equivalent to residues in the β6-β7 loop of Cry1Ab17) have been identified as essential for binding to the membrane of midgut cells of Bombyx mori 28,33 . In the Cry1Ab17 model this region is longer than in its counterparts.…”

Section: Resultsmentioning

confidence: 99%

“…These loops are thought to participate in receptor binding and hence in determining the specificity of the toxin for attachment on insect receptors. Ge et al 28 managed to alter toxicity of Cry1Ac by exchanging the 332-450 amino acids in Domain II with the equivalent segment of Cry1Aa. A similar approach has yet to be performed in Cry1Ab17.…”

Section: Resultsmentioning

confidence: 99%

Untitled

Kashyap¹,

Singh²,

Amla³

2010

ScienceAsia

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ABSTRACT:We predict the first theoretical structural model of the newly reported Cry1Ab17 δ-endotoxin produced by Bacillus thuringiensis using homology modelling. Both Cry1Ab17 and Cry1Aa share a common structure; both contain three flexible domains that participate in the formation of a pore and determine the receptor binding specificity. The main differences between the two is in the length of loops, and in Cry1Ab17, the absence of α7b, α10a, α10b, α12a, β19, β20 and presence of additional β0 β1b, α9b components. A few of the components such as α8a, α8b, α9a, α9b, and α11a differ in their locations. A better understanding of the 3-D structure of Cry1Ab17 will be helpful in designing the domain swapping experiments to improve its insecticidal toxicity.

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Location of the Bombyx mori specificity domain on a Bacillus thuringiensis delta-endotoxin protein.

Cited by 120 publications

References 23 publications

Effect of the pollen of transgenic rice line, TT9-3 with a fused cry1Ab/cry1Ac gene from Bacillus thuringiensis Berliner on non-target domestic silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombyxidae)

Effect of the pollen of transgenic rice line, TT9-3 with a fused cry1Ab/cry1Ac gene from Bacillus thuringiensis Berliner on non-target domestic silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombyxidae)

Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

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