AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Lee, M. K.
Right arrow Articles by Dean, D. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Lee, M. K.
Right arrow Articles by Dean, D. H.
Agricola
Right arrow Articles by Lee, M. K.
Right arrow Articles by Dean, D. H.

 Previous Article  |  Next Article 

Appl. Environ. Microbiol., 11 1995, 3836-3842, Vol 61, No. 11
Copyright © 1995, American Society for Microbiology

Resistance to Bacillus thuringiensis CryIA delta-endotoxins in a laboratory-selected Heliothis virescens strain is related to receptor alteration

MK Lee, F Rajamohan, F Gould and DH Dean
Department of Biochemistry, Ohio State University Columbus 43210, USA.

The Bacillus thuringiensis toxin-binding properties of midgut epithelial cells from two strains of Heliothis virescens were compared. One H. virescens strains (YHD2) which was selected against CryIAc toxin had over 10,000-fold resistance to CryIAc toxin relative to the susceptible strain and was cross-resistant to CryIAa and CryIAb. The second H. virescens strain (YDK) was susceptible to these toxins in the order CryIAc > CryIAb > CryIAa. Receptor-binding properties of CryIAa, CryIAb, and CryIAc toxins were compared between the susceptible and resistant strains. Saturation and competition-binding experiments were performed with brush border membrane vesicles prepared from midguts of the susceptible and resistant insects and 125I-labeled toxins. In the susceptible strain, saturable, specific, and high-affinity binding of all three toxins was observed. The relative binding-site concentration was directly correlated with toxicity (CryIAc > CryIAb > CryIAa). In the resistant strains, the binding affinities of CryIAb and CryIAc were similar to that observed with the susceptible strain and ony minor differences in binding-site concentration (Bmax) were observed. The major difference between the two strains was the total lack of binding of CryIAa toxin to the brush border membrane vesicles of the resistant strain. Heterologous competition-binding experiments and ligand blot analysis supported the hypothesis that there were multiple binding sites for the toxins. On the basis of results of the present study, we propose that alterations in binding proteins shared by all three toxins are a major factor in resistance. This suggests that not all receptors of CryIAc might be involved in toxic function.


This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 1995 by the American Society for Microbiology. All rights reserved.