Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R1 in Manduca sexta:

Dorsch, J. A.; Candas, Mehmet; Griko, Natalya B.; Maaty, Walid S.; Midboe, Eric G.; Vadlamudi, Ratna K.; Bulla, Lee A.

doi:10.1016/s0965-1748(02)00040-1

Cited by 120 publications

(172 citation statements)

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“…When we reported synergism of Cry1Ab toxicity to M. sexta by CR12-MPED from Bt-R 1 , the results were unexpected (23), because others had reported inhibition of toxicity in similar experiments (21,22,43). Enhancement of Cry4Ba toxicity to A. gambiae larvae by CR11-MPED indicates that the toxicity enhancement properties of cadherin fragments extends at least to Cry toxins active against dipteran larvae.…”

Section: Discussionmentioning

confidence: 95%

Anopheles gambiae Cadherin AgCad1 Binds the Cry4Ba Toxin of Bacillus thuringiensis israelensis and a Fragment of AgCad1 Synergizes Toxicity

et al. 2008

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A midgut cadherin AgCad1 cDNA was cloned from Anopheles gambiae larvae and analyzed for its possible role as a receptor for the Cry4Ba toxin of Bacillus thuringiensis strain israelensis. The AgCad1 cadherin encodes a putative 1735-residue protein organized into an extracellular region of 11 cadherin repeats (CR) and a membrane-proximal extracellular domain (MPED). AgCad1 mRNA was detected in midgut of larvae by polymerase chain reaction (PCR). The AgCad1 protein was localized, by immunochemistry of sectioned larvae, predominately to the microvilli in posterior midgut. The localization of Cry4Ba binding was determined by the same technique, and toxin bound microvilli in posterior midgut. The AgCad1 protein was present in brush border membrane fractions prepared from larvae, and Cry4Ba toxin bound the same-sized protein on blots of those fractions. The AgCad1 protein was expressed transiently in Drosophila melanogaster Schneider 2 (S2) cells. 125 I-Cry4Ba toxin bound AgCad1 from S2 cells in a competitive manner. Cry4Ba bound to beads extracted 200 kDa AgCad1 and a 29 kDa fragment of AgCad1 from S2 cells. A peptide containing the AgCad1 region proximal to the cell (CR11-MPED) was expressed in Escherichia coli. Although Cry4Ba showed limited binding to CR11-MPED, the peptide synergized the toxicity of Cry4Ba to larvae. AgCad1 in the larval brush border is a binding protein for Cry4Ba toxin. On the basis of binding results and CR11-MPED synergism of Cry4Ba toxicity, AgCad1 is probably a Cry4Ba receptor.Mosquitoes in the genus Anopheles vector plasmodia that cause malaria, a major public health problem in the world. In some habitats, Anopheline species are controlled by nonchemical larvicides based on the bacterium Bacillus thuringiensis (Bt) 1 serovariety israelensis de Barjac. The specific toxicity of Bti to Anopheles and Aedes spp. is due to the protein components of the parasporal crystal (reviewed in ref 1).The parasporal crystal of Bti is composed of three major insecticidal Cry proteins (Cry4Aa, Cry4Ba, and Cry11Aa) and cytolytic proteins (Cyt1 and Cyt2). The Cry4Ba insecticidal protein is highly toxic to Anopheles and Aedes larvae but not to Culex larvae (2,3). The Cry4Ba toxin crystal structure shows that it is very similar to other Cry toxins with their three-domain † This research was supported by National Institutes of Health Grant R01 AI 29092 to D. H. Dean (The Ohio State University) and M.J.A. Inhibition of toxicity is accepted evidence for function as a Cry toxin receptor. Typically, a peptide fragment of the receptor (21) or a phage mimic of the receptor (20) attenuates Cry in vivo toxicity to larvae. Recently, we reported an opposite effect in which a fragment of Bt-R 1 cadherin, the Cry1A receptor from Manduca sexta (21,22), not only bound toxin but enhanced Cry1A toxicity against lepidopteran larvae (23). If the binding residues within cadherin repeat 12 (CR) were removed, the resulting peptide lost the ability to bind toxin and lost its function as a toxin synergist.In this work, we descri...

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Section: Discussionmentioning

confidence: 95%

Anopheles gambiae Cadherin AgCad1 Binds the Cry4Ba Toxin of Bacillus thuringiensis israelensis and a Fragment of AgCad1 Synergizes Toxicity

et al. 2008

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“…31,50 BT-R 1 homologs are the principal determinant for Cry1A toxin action in lepidopteran insects. [30][31][32][33][34][35] No BT-R 1 homologs has been identified in vertebrates, suggesting that these particular cadherin receptors represent a unique family of proteins in invertebrates, particularly insects, and may explain why Cry toxins are not toxic to mammalian cells. Perhaps, Cry toxins once constituted virulence factors with the ability to destroy cells through oligomerization and incorporation of toxin molecules into cell membranes.…”

Section: Discussionmentioning

confidence: 99%

“…Previously, we showed that blocking the binding of Cry1Ab toxin to BT-R 1 using the toxin-binding region (TBR) of BT-R 1 thwarts the lethal effect of the toxin in M. sexta larvae. 32,42,43 In this study, we used a 12 kDa fragment (Figure 4a) containing TBR linked to maltose-binding protein (MBP), which facilitated expression and purification of the fragment (Figure 4b). MBP did not interact with the toxin (Figure 4b).…”

Section: Inhibition Of Toxin-receptor Interaction Prevents Cry1ab-indmentioning

confidence: 99%

“…The cadherin receptor BT-R 1 , identified in the tobacco hornworm Manduca sexta, [30][31][32] represents a family of cadherins that are expressed in the midgut epithelium of various insects susceptible to Cry1A toxins. Cry toxins bind to their respective cadherin receptors with high affinity and specificity, the disruption or absence of which results in loss of susceptibility to Cry toxin.…”

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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“…Cadherin Cry1A toxin binding region (TBR1), 865 NITIHITDTNN 875 , was identified on M. sexta gene Bt-R 1 and implicated in binding loop 2 of CRY1A domain II (Gomez et al, 2001(Gomez et al, , 2002a. A second binding region (TBR2) was identified in B. mori cadherin repeat 9 (CR9; Nagamatsu et al, 1999) and M. sexta cadherin CR11 (Dorsch et al, 2002). Cadherin TBR2 was narrowed to 12 amino acids of Bt-R 1 , 1331 IPLPASILTVTV 1342 , and predicted to interact with loop a-8 of CRY1A domain II (Gomez et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Sequence variation in the cadherin gene of Ostrinia nubilalis: a tool for field monitoring

Coates

Sumerford

Hellmich

et al. 2005

Insect Biochemistry and Molecular Biology

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Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R1 in Manduca sexta:

Cited by 120 publications

References 48 publications

Anopheles gambiae Cadherin AgCad1 Binds the Cry4Ba Toxin of Bacillus thuringiensis israelensis and a Fragment of AgCad1 Synergizes Toxicity

Anopheles gambiae Cadherin AgCad1 Binds the Cry4Ba Toxin of Bacillus thuringiensis israelensis and a Fragment of AgCad1 Synergizes Toxicity

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

Sequence variation in the cadherin gene of Ostrinia nubilalis: a tool for field monitoring

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