Fernandez, L.E.; Perez, C.; Segovia, L.; Rodriguez, M.H.; Gill, S.S.; Bravo, A.; Soberon, M.
Cry11Aa toxin from Bacillus thuringiensis binds its receptor in Aedes aegypti mosquito larvae through loop alpha-8 of domain II
FEBS LETTERS, 579:3508-3514, JUL 4 2005

Bacillus thuringiensis subs israelensis produces Cry toxins active against mosquitoes. Receptor binding is a key determinant for specificity of Cry toxins composed of three domains. We found that exposed loop alpha-8 of Cry11Aa toxin, located in domain 11, is an important epitope involved in receptor interaction. Synthetic peptides corresponding to exposed regions in domain II (loop alpha-8, beta-4 and loop 3) competed binding of Cry11Aa to membrane vesicles from Aedes aegypti midgut microvilli. The role of loop a-8 of Cry11A in receptor interaction was demonstrated by phage display and site-directed mutagenesis. We isolated a peptide-displaying phage (P5.tox), that recognizes loop alpha-8 in Cry11Aa, interferes interaction with the midgut receptor and attenuates toxicity in bioassay. Loop alpha-8 mutants affected in toxicity and receptor binding were characterized. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI:10.1016/j.febslet.2005.05.032

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