Bacillus thuringiensisCrylA(a) Insecticidal Toxin: Crystal Structure and Channel Formation

Grochulski, P.; Masson, Luke; Borisova, S.N.; Pusztai-Carey, Marianne; Schwartz, J. L.; Brousseau, Roland; Cygler, Mirosław

doi:10.1006/jmbi.1995.0630

Cited by 489 publications

(533 citation statements)

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“…22,25 This assumption is based on studies of Cry toxin interaction with synthetic lipid rafts and BBMV prepared from insect midgut tissue. 46 Although this mechanism, as proposed, has been generally accepted, no direct relationship between pore formation and cytotoxicity has been demonstrated because artificial membrane systems are not physiologically active.…”

Section: Discussionmentioning

confidence: 99%

“…Most significantly, incorporation of Cry1Ab oligomers into cell membrane does not result in the formation of lytic pores and, therefore, argues against the 'pore-formation model' postulated previously. [22][23][24][25] In the pore-forming model of Cry toxin action, the toxin monomers are considered precursors to oligomeric assembly. 21,25 The formation of toxin oligomer also has been postulated to be the result of the interaction of monomers that were bound to the cadherin receptor.…”

Section: Discussionmentioning

confidence: 99%

“…19 Lipid bilayerand BBMV-associated Cry toxin molecules have been reported to appear in oligomeric (dimeric and tetrameric) and monomeric forms, 20,21 and these associations have been correlated with changes in membrane permeability. 22 The oligomeric forms of Cry toxin were presumed to be pores that cause cell death by osmotic lysis. In other words, Cry toxin action was believed to involve the formation of lytic pores that are the result of assembly of toxin molecules as oligomers in membrane.…”

Section: Introductionmentioning

confidence: 99%

“…In other words, Cry toxin action was believed to involve the formation of lytic pores that are the result of assembly of toxin molecules as oligomers in membrane. [22][23][24][25] However, there is no definitive correlation between the association of Cry toxin oligomer complexes and toxic action. Studies of mutated Cry toxin proteins have shown that neither the toxin oligomer complex nor commensurate changes in membrane vesicle permeability correlate directly with toxicity.…”

Section: Introductionmentioning

confidence: 99%

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Cytotoxicity of Bacillus thuringiensis Cry1Ab toxin depends on specific binding of the toxin to the cadherin receptor BT-R1 expressed in insect cells

et al. 2005

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The specific role of cadherin receptors in cytotoxicity involving Cry toxins of Bacillus thuringiensis and their interactions with cell membrane has not been defined. To elucidate the involvement of toxin-membrane and toxinreceptor interactions in cytotoxicity, we established a cellbased system utilizing High Five insect cells stably expressing BT-R 1 , the cadherin receptor for Cry1Ab toxin. Cry1Ab toxin is incorporated into cell membrane in both oligomeric and monomeric form. Monomeric toxin binds specifically to BT-R 1 whereas incorporation of oligomeric toxin is nonspecific and lipid dependent. Toxin oligomers in the cell membrane do not produce lytic pores and do not kill insect cells. Rather, cell death correlates with binding of the Cry1Ab toxin monomer to BT-R 1 , which apparently activates a Mg 2 þ -dependent cellular signaling pathway.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cytotoxicity of Bacillus thuringiensis Cry1Ab toxin depends on specific binding of the toxin to the cadherin receptor BT-R1 expressed in insect cells

et al. 2005

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“…In addition, in has been reported that a salt bridge within the α-helix that forms the coiled-coil stabilizes this structure and is important to trigger the coiled-coil [24]. The residue R93 of Cry1A toxins participate in a salt-bridged [16] suggesting that this helix could may play an important role in toxin oligomerization.…”

Section: Mutagenesis Of Helix α-3 Of Different Cry Toxinsmentioning

confidence: 99%

The pre-pore from Bacillus thuringiensis Cry1Ab toxin is necessary to induce insect death in Manduca sexta

et al. 2008

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The insecticidal Cry toxins from Bacillus thuringiensis bacteria are pore-forming toxins that lyse midgut epithelial cells in insects. We have previously proposed that they form pre-pore oligomeric intermediates before membrane insertion.For formation of these oligomers coiled-coil structures are important, and helix α-3 from Cry toxins could form coiled-coils. Our data shows that different mutations in helix α-3 are affected in pore formation and toxicity. Mutants affected in toxicity bind Bt-R 1 receptor with a similar K D as the wild type toxin but do not form oligomers nor induce pore formation in planar lipid bilayers, indicating that the pre-pore oligomer is an obligate intermediate in the intoxication of Cry1Ab toxin and that interaction of monomeric Cry1Ab with Bt-R 1 is not enough to kill susceptible larvae.

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Structural trees for protein superfamilies

Ефимов

1997

Proteins

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Structural trees for large protein superfamilies, such as beta proteins with the aligned beta sheet packing, beta proteins with the orthogonal packing of alpha helices, two-layer and three-layer alpha/beta proteins, have been constructed. The structural motifs having unique overall folds and a unique handedness are taken as root structures of the trees. The larger protein structures of each superfamily are obtained by a stepwise addition of alpha helices and/or beta strands to the corresponding root motif, taking into account a restricted set of rules inferred from known principles of the protein structure. Among these rules, prohibition of crossing connections, attention to handedness and compactness, and a requirement for alpha helices to be packed in alpha-helical layers and beta strands in beta layers are the most important. Proteins and domains whose structures can be obtained by stepwise addition of alpha helices and/or beta strands to the same root motif can be grouped into one structural class or a superfamily. Proteins and domains found within branches of a structural tree can be grouped into subclasses or subfamilies. Levels of structural similarity between different proteins can easily be observed by visual inspection. Within one branch, protein structures having a higher position in the tree include the structures located lower. Proteins and domains of different branches have the structure located in the branching point as the common fold.

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Bacillus thuringiensisCrylA(a) Insecticidal Toxin: Crystal Structure and Channel Formation

Cited by 489 publications

References 0 publications

Cytotoxicity of Bacillus thuringiensis Cry1Ab toxin depends on specific binding of the toxin to the cadherin receptor BT-R1 expressed in insect cells

Cytotoxicity of Bacillus thuringiensis Cry1Ab toxin depends on specific binding of the toxin to the cadherin receptor BT-R1 expressed in insect cells

The pre-pore from Bacillus thuringiensis Cry1Ab toxin is necessary to induce insect death in Manduca sexta

Structural trees for protein superfamilies

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