Affiliation:
1. Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521
2. Instituto de Biotecnología, Universidad Nacional Autónoma de México. Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
Abstract
ABSTRACT
Cry11Ba is one of the most toxic proteins to mosquito larvae produced by
Bacillus thuringiensis
. It binds
Aedes aegypti
brush border membrane vesicles (BBMV) with high affinity, showing an apparent dissociation constant (
K
d
) of 8.2 nM. We previously reported that an anticadherin antibody competes with Cry11Ba binding to BBMV, suggesting a possible role of cadherin as a toxin receptor. Here we provide evidence of specific cadherin repeat regions involved in this interaction. Using cadherin fragments as competitors, a C-terminal fragment which contains cadherin repeat 7 (CR7) to CR11 competed with Cry11Ba binding to BBMV. This binding was also efficiently competed by the CR9, CR10, and CR11 peptide fragments. Moreover, we show CR11 to be an important region of interaction with Cry11Ba toxin. An alkaline phosphatase (AaeALP1) and an aminopeptidase-N (AaeAPN1) also competed with Cry11Ba binding to
Ae. aegypti
BBMV. Finally, we found that Cry11Ba and Cry4Ba share binding sites. Synthetic peptides corresponding to loops α8, β2-β3 (loop 1), β8-β9, and β10-β11 (loop 3) of Cry4Ba compete with Cry11Ba binding to BBMV, suggesting Cry11Ba and Cry4Ba have common sites involved in binding
Ae. aegypti
BBMV. The data suggest that three different
Ae. aegypti
midgut proteins, i.e., cadherin, AaeALP1, and AaeAPN1, are involved in Cry11Ba binding to
Ae. aegypti
midgut brush border membranes.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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