Structure of Cry2Aa Suggests an Unexpected Receptor Binding Epitope

Morse, R. J.; Yamamoto, Takashi; Stroud, Rhonda M.

doi:10.1016/s0969-2126(01)00601-3

Cited by 253 publications

(191 citation statements)

References 44 publications

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“…Similarly, altered and/or slower protoxin processing has been associated with reduced susceptibility and resistance in Lepidoptera (Zalunin et al, 2015), supporting that both appropriate processing and kinetics of toxin core production may have an effect on specificity. Although the smaller toxins such as Cry2 and Cry3 do not undergo extensive processing at the C-terminus, they are cleaved at the Nterminus and there is evidence that this cleavage is required for toxicity and could potentially determine specificity Morse et al, 2001). An additional N-terminal cleavage is proposed to occur as part of the mechanism of action of some toxins, and mutants where toxins have been pre-cleaved at this site show an altered specificity in that they can partially overcome a resistant phenotype .…”

Section: Specificity Level Iii: Toxin Processing and Stabilitymentioning

confidence: 99%

Specificity determinants for Cry insecticidal proteins: Insights from their mode of action

Jurat-Fuentes

Crickmore

2017

Journal of Invertebrate Pathology

149

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Section: Specificity Level Iii: Toxin Processing and Stabilitymentioning

confidence: 99%

Specificity determinants for Cry insecticidal proteins: Insights from their mode of action

Jurat-Fuentes

Crickmore

2017

Journal of Invertebrate Pathology

149

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“…Thus far, the three-dimensional structures of Bt Cry toxins have been determined by X-ray crystallography in almost all the major specificity classes, including the lepidoteran-specific Cry1Aa (PDB code: 1CIY) (Grochulski JMB 1995) [15], the lepidopteran/dipteran-dual specific Cry2Aa (PDB code: 1I5P) (Morse Structure 2001) [16], the coleopteran-specific Cry3Aa (PDB code: 1DLC) (Li Nature 1991) [17] and Cry3Bb (PDB code: 1JI6) (Galitsky ACD 2001) [18], the dipteran-specific Cry4Aa (PDB code: 2C9K) (Boonserm J Bacteriol 2006) [19] and Cry4Ba (PDB code: 1W99) (Boonserm JMB 2005) [20], and more recently another coleopteran-specific Cry8Ea (PDB code: 3EB7) (Guo JSB 2009) [21]. Undoubtedly, all these known structures have been a valuable contribution to the Bt research area since they have been providing a greater understanding for the structural basis of their insect specificity and gut epithelial cell lysis.…”

Section: Structural Description Of the Three-domain Toxinsmentioning

confidence: 99%

Mosquito Resistance to Bacterial Larvicidal Toxins

Wirth¹

2013

TOTNJ

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Abstract:The insecticidal character of the three-domain Cry -endotoxins produced by Bacillus thuringiensis during sporulation is believed to be caused by their capability to generate lytic pores in the target larval midgut cell membranes. This review describes toxic mechanisms with emphasis on the structural basis of pore formation by two closely related dipteran-specific toxins, Cry4Aa and Cry4Ba, which are highly toxic to mosquito larvae. One proposed toxic mechanism via an "umbrella-like" structure involves membrane penetration and pore formation by the 4-5 transmembrane hairpin. The lipid-induced -conformation of 7 could possibly serve as a lipid anchor required for an efficient insertion of the pore-forming hairpin into the bilayer membrane. Though current electron crystallographic data are still inadequate to provide such critical insights into the structural details of the Cry toxin-induced pore architecture, this pivotal evidence clearly reveals that the 65-kDa active toxin in association with the lipid membrane could exist in at least two different trimeric conformations, implying the closed and open states of a functional pore.

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“…The crystal structures of several trypsin-activated Cry proteins (Cry1Aa, Cry3Aa, Cry3Bb and Cry2Aa) have been elucidated [6][7][8][9], revealing a similar three-domain structure. The N-terminal domain I consists of seven α-helices, and is thought to be responsible for toxin insertion into the cell membrane, leading to pore formation.…”

Section: Introductionmentioning

confidence: 99%

Mutations in the Bacillus thuringiensis Cry1Ca toxin demonstrate the role of domains II and III in specificity towards Spodoptera exigua larvae

Herrero

González‐Cabrera

Ferré

et al. 2004

Biochemical Journal

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Several mutants of the Bacillus thuringiensis Cry1Ca toxin affected with regard to specific activity towards Spodoptera exigua were studied. Alanine was used to replace single residues in loops 2 and 3 of domain II (mutant pPB19) and to replace residues 541-544 in domain III (mutant pPB20). Additionally, a Cry1Ca mutant combining all mutations was constructed (mutant pPB21). Toxicity assays showed a marked decrease in toxicity against S. exigua for all mutants, while they retained their activity against Manduca sexta, confirming the importance of these residues in determining insect specificity. Parameters for binding to the specific receptors in BBMV (brush border membrane vesicles) of S. exigua were determined for all toxins. Compared with Cry1Ca, the affinity of mutant pPB19 was slightly affected (2-fold lower), whereas the affinity of the mutants with an altered domain III (pPB20 and pPB21) was approx. 8-fold lower. Activation of Cry1Ca protoxin by incubation with S. exigua or M. sexta BBMV revealed the transient formation of an oligomeric form of Cry1Ca. The presence of this oligomeric form was tested in the activation of the different Cry1Ca mutants, and we found that those mutated in domain II (pPB19 and pPB21) could not generate the oligomeric form when activated by S. exigua BBMV. In contrast, when oligomerization was tested using BBMV prepared from M. sexta, all of the Cry1Ca mutants showed the formation of a similar oligomeric form as did the wild-type toxin. Our results show how modification of insect specificity can be achieved by manipulation of different parts of the toxin structure involved in different steps of the mode of action of B. thuringiensis toxins.

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Structure of Cry2Aa Suggests an Unexpected Receptor Binding Epitope

Cited by 253 publications

References 44 publications

Specificity determinants for Cry insecticidal proteins: Insights from their mode of action

Specificity determinants for Cry insecticidal proteins: Insights from their mode of action

Mosquito Resistance to Bacterial Larvicidal Toxins

Mutations in the Bacillus thuringiensis Cry1Ca toxin demonstrate the role of domains II and III in specificity towards Spodoptera exigua larvae

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