Dataset Information

Interaction of Fluorescently Labeled Cadherin G Protein-coupled Receptor with the Cry1Ab Toxin of Bacillus thuringiensis.

ABSTRACT: The Cry1Ab toxin produced by Bacillus thuringiensis binds to a conserved structural motif in the 12th ectodomain module (EC12) of BT-R1, a cadherin G protein-coupled receptor (GPCR) contained in the membrane of midgut epithelial cells of the tobacco hornworm Manduca sexta. Toxin binding transmits a signal into the cells and turns on a multi-step signal transduction pathway, culminating in cell death. Using chromatographically purified Cry1Ab and EC12 proteins, we demonstrated the direct formation of a stable complex between these two proteins in solution and visualized it on a native polyacrylamide gel. Moreover, we generated a fluorescent EC12 probe by converting the 36th residue to cysteine to enable maleimide-mediated conjugation of Alexa-488 fluorescent dye to EC12 by site-directed mutagenesis. In addition, we changed the 44th residue of EC12 to tryptophan, which greatly improved accuracy of protein quantification and traceability. Using the fluorescently labeled EC12 probe for direct and competitive binding assays, we were able to determine binding specificity in solution. These accomplishments will facilitate identification and characterization of the interface sequences for both the Cry1Ab toxin and BT-R1.

SUBMITTER: Liu L

PROVIDER: S-EPMC6049086 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Interaction of Fluorescently Labeled Cadherin G Protein-coupled Receptor with the Cry1Ab Toxin of Bacillus thuringiensis.

Liu Li L Boyd Stefanie S Kavoussi Mehraban M Bulla Lee A LA Winkler Duane D DD

Journal of proteomics & bioinformatics 20180514 4

The Cry1Ab toxin produced by Bacillus thuringiensis binds to a conserved structural motif in the 12th ectodomain module (EC12) of BT-R1, a cadherin G protein-coupled receptor (GPCR) contained in the membrane of midgut epithelial cells of the tobacco hornworm Manduca sexta. Toxin binding transmits a signal into the cells and turns on a multi-step signal transduction pathway, culminating in cell death. Using chromatographically purified Cry1Ab and EC12 proteins, ...[more]

PMID: 30026652

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Project description:Alteration of binding sites for Bacillus thuringiensis (Bt) toxins in insect midgut is the major mechanism of high-level resistance to Bt toxins in insects. The midgut cadherin is known to be a major binding protein for Bt Cry1A toxins and linkage of Bt-resistance to cadherin gene mutations has been identified in lepidopterans. The resistance to Bt toxin Cry1Ac evolved in greenhouse populations of Trichoplusia ni has been identified to be associated with the down-regulation of an aminopeptidase N (APN1) gene by a trans-regulatory mechanism and the resistance gene has been mapped to the locus of an ABC transporter (ABCC2) gene. However, whether cadherin is also involved with Cry1Ac-resistance in T. ni requires to be understood. Here we report that the Cry1Ac-resistance in T. ni is independent of alteration of the cadherin. The T. ni cadherin cDNA was cloned and the cadherin sequence showed characteristic features known to cadherins from Lepidoptera. Various T. ni cadherin gene alleles were identified and genetic linkage analysis of the cadherin alleles with Cry1Ac-resistance showed no association of the cadherin gene with the Cry1Ac-resistance in T. ni. Analysis of cadherin transcripts showed no quantitative difference between the susceptible and Cry1Ac-resistant T. ni larvae. Quantitative proteomic analysis of midgut BBMV proteins by iTRAQ-2D-LC-MS/MS determined that there was no quantitative difference in cadherin content between the susceptible and the resistant larvae and the cadherin only accounted for 0.0014% (mol%) of the midgut BBMV proteins, which is 1/300 of APN1 in molar ratio. The cadherin from both the susceptible and resistant larvae showed as a 200-kDa Cry1Ac-binding protein by toxin overlay binding analysis, and nano-LC-MS/MS analysis of the 200-kDa cadherin determined that there is no quantitative difference between the susceptible and resistant larvae. Results from this study indicate that the Cry1Ac-resistance in T. ni is independent of cadherin alteration.

Dataset Information

Interaction of Fluorescently Labeled Cadherin G Protein-coupled Receptor with the Cry1Ab Toxin of Bacillus thuringiensis.

Publications

Interaction of Fluorescently Labeled Cadherin G Protein-coupled Receptor with the Cry1Ab Toxin of Bacillus thuringiensis.

Similar Datasets

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