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 alpha-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 alpha-8, beta-4 and loop 3) competed binding of Cry11Aa to membrane vesicles from Aedes aegypti midgut microvilli. The role of loop alpha-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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Aedes / growth & development
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Aedes / metabolism*
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Amino Acid Sequence
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Animals
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Bacillus thuringiensis Toxins
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Bacterial Proteins / chemistry*
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Bacterial Proteins / metabolism
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Bacterial Toxins / chemistry*
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Bacterial Toxins / metabolism
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Endotoxins / chemistry*
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Endotoxins / metabolism
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Hemolysin Proteins
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Insect Proteins / chemistry
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Insect Proteins / metabolism*
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Larva / metabolism
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Molecular Sequence Data
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Peptide Library
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Protein Interaction Mapping
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Protein Structure, Tertiary
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Receptors, Cell Surface / chemistry
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Receptors, Cell Surface / metabolism*
Substances
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Bacillus thuringiensis Toxins
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Bacterial Proteins
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Bacterial Toxins
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Cry toxin receptors
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Endotoxins
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Hemolysin Proteins
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Insect Proteins
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Peptide Library
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Receptors, Cell Surface
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insecticidal crystal protein, Bacillus Thuringiensis