Interaction ofBacillus thuringiensisToxins with Larval Midgut Binding Sites ofHelicoverpa armigera(Lepidoptera: Noctuidae)
Open Access
- 1 March 2004
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 70 (3), 1378-1384
- https://doi.org/10.1128/aem.70.3.1378-1384.2004
Abstract
In 1996, Bt-cotton (cotton expressing a Bacillus thuringiensis toxin gene) expressing the Cry1Ac protein was commercially introduced to control cotton pests. A threat to this first generation of transgenic cotton is the evolution of resistance by the insects. Second-generation Bt-cotton has been developed with either new B. thuringiensis genes or with a combination of cry genes. However, one requirement for the “stacked” gene strategy to work is that the stacked toxins bind to different binding sites. In the present study, the binding of 125I-labeled Cry1Ab protein (125I-Cry1Ab) and 125I-Cry1Ac to brush border membrane vesicles (BBMV) of Helicoverpa armigera was analyzed in competition experiments with 11 nonlabeled Cry proteins. The results indicate that Cry1Aa, Cry1Ab, and Cry1Ac competed for common binding sites. No other Cry proteins tested competed for either 125I-Cry1Ab or 125I-Cry1Ac binding, except Cry1Ja, which competed only at the highest concentrations used. Furthermore, BBMV from four H. armigera populations were also tested with 125I-Cry1Ac and Cry1Ab to check the influence of the insect population on the binding results. Finally, the inhibitory effect of selected sugars and lectins was also determined. 125I-Cry1Ac binding was strongly inhibited by N-acetylgalactosamine, sialic acid, and concanavalin A and moderately inhibited by soybean agglutinin. In contrast, 125I-Cry1Ab binding was only significantly inhibited by concanavalin A. These results show that Cry1Ac and Cry1Ab use different epitopes for binding to BBMV.Keywords
This publication has 55 references indexed in Scilit:
- Resistance to the Cry1Ac δ-Endotoxin of Bacillus thuringiensis in the Cotton Bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)Journal of Economic Entomology, 2003
- Shared Binding Sites in Lepidoptera for Bacillus thuringiensis Cry1Ja and Cry1A ToxinsApplied and Environmental Microbiology, 2001
- Importance of Cry1 δ-Endotoxin Domain II Loops for Binding Specificity in Heliothis virescens (L.)Applied and Environmental Microbiology, 2001
- Genetic and Biochemical Approach for Characterization of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Field Population of the Diamondback Moth, Plutella xylostellaApplied and Environmental Microbiology, 2000
- The Heliothis virescens 170kDa aminopeptidase functions as “Receptor A” by mediating specific Bacillus thuringiensis Cry1A δ-endotoxin binding and pore formationInsect Biochemistry and Molecular Biology, 1997
- Bacillus thuringiensisCrystal Proteins CRY1Ab and CRY1Fa Share a High Affinity Binding Site inPlutella xylostella(L.)Biochemical and Biophysical Research Communications, 1996
- Immunologically unrelated Heliothis sp. and Spodoptera sp. midgut membrane‐proteins bind Bacillus thuringiensis CryIA(b) δ‐endotoxinEuropean Journal of Biochemistry, 1993
- Identification and characterization of Heliothis virescens midgut membrane proteins binding Bacillus thuringiensisδ‐endotoxinsEuropean Journal of Biochemistry, 1991
- The toxicity of twoBacillus thuringiensis δ-endotoxins to gypsy moth larvae is inversely related to the affinity of binding sites on midgut brush border membranes for the toxinsCellular and Molecular Life Sciences, 1990
- A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye bindingAnalytical Biochemistry, 1976