title: Receptors on the brush border membrane of the insect midgut as determinants of the specificity of Bacillus thuringiensis delta-endotoxins.
abstract: To investigate the biochemical basis of the differences in the insecticidal spectrum of Bacillus thuringiensis insecticidal crystal proteins (ICPs), we performed membrane binding and toxicity assays with three different ICPs and three lepidopteran species. The three ICPs have different toxicity patterns in the three selected target species. Binding studies with these 125I-labeled ICPs revealed high-affinity saturable binding to brush border membrane vesicles of the sensitive species. ICPs with no toxicity against a given species did not bind saturably to vesicles of that species. Together with previous data that showed a correlation between toxicity and ICP binding, our data support the statement that differences in midgut ICP receptors are a major determinant of differences in the insecticidal spectrum of the entire lepidopteran-specific ICP family. Receptor site heterogeneity in the insect midgut occurs frequently and results in sensitivity to more than one type of ICP.
authors.affiliation: Plant Genetic Systems, Rijksuniversiteit Gent, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Van Rie
authors.forename: S
authors.initials: S
authors.lastname: Jansens
authors.forename: H
authors.initials: H
authors.lastname: Höfte
authors.forename: D
authors.initials: D
authors.lastname: Degheele
authors.forename: H
authors.initials: H
authors.lastname: Van Mellaert
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism* / Q000633:toxicity; D001427:Bacterial Toxins / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D004731:Endotoxins; D006460:Hemolysin Proteins; D007313:Insecta / Q000378:metabolism*; D007915:Lepidoptera / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D013045:Species Specificity
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis