Toxicity, Binding, and Permeability Analyses of FourBacillus thuringiensis Cry1 δ-Endotoxins Using Brush Border Membrane Vesicles of Spodoptera exigua and Spodoptera frugiperda

摘要: ABSTRACT The binding and pore formation properties of four Bacillus thuringiensis Cry1 toxins were analyzed by using brush border membrane vesicles from Spodoptera exigua andSpodoptera frugiperda, the results compared to toxicity bioassays. Cry1Fa was highly toxic Cry1Ac nontoxic S. frugiperda larvae, while Cry1Ca weakly frugiperda. In contrast, Cry1Bb active against but only marginally exigua. Bioassays performed with iodinated Cry1Bb, Cry1Fa, showed that effects iodination on toxin activity different. toxicities I-labeled species significantly less than unlabeled toxins, retained its insecticidal when it labeled 125I. Binding assays prevented vesicles. 125I-labeled Cry1Ac, bound high-affinities fromS. Competition experiments heterologous revealed two major sites. have a common site, Cry1C, second site. No obvious relationship between dissociation detected. also tested for ability alter permeability vesicles, as measured light scattering assay. proteins larvae permeabilized extent permeabilization did not necessarily correlate in vivo toxicity.