Cry11Aa toxin from Bacillus thuringiensis binds its receptor in Aedes aegypti mosquito larvae through loop α‐8 of domain II

Open Access
Publisher Website
Google Scholar
Abstract
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 α‐8 of Cry11Aa toxin, located in domain II, is an important epitope involved in receptor interaction. Synthetic peptides corresponding to exposed regions in domain II (loop α‐8, β‐4 and loop 3) competed binding of Cry11Aa to membrane vesicles from Aedes aegypti midgut microvilli. The role of loop α‐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 α‐8 in Cry11Aa, interferes interaction with the midgut receptor and attenuates toxicity in bioassay. Loop α‐8 mutants affected in toxicity and receptor binding were characterized.