Cry11Aa toxin from Bacillus thuringiensis binds its receptor in Aedes aegypti mosquito larvae through loop alpha-8 of domain II.
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.
Fernández
Luisa E
LE
Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
Pérez
Claudia
C
Segovia
Lorenzo
L
Rodríguez
Mario H
MH
Gill
Sarjeet S
SS
Bravo
Alejandra
A
Soberón
Mario
M
D000330:Aedes / Q000254:growth & development / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D004731:Endotoxins / Q000737:chemistry* / Q000378:metabolism; D006460:Hemolysin Proteins; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D008969:Molecular Sequence Data; D019151:Peptide Library; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C095416:Cry toxin receptors; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D019151:Peptide Library; D011956:Receptors, Cell Surface; C030956:insecticidal crystal protein, Bacillus Thuringiensis