Identification of amino acid residues of Bacillus thuringiensis delta-endotoxin CryIAa associated with membrane binding and toxicity to Bombyx mori.
Alanine substitution (A3) or deletion (D3) of residues 365 to 371 of Bacillus thuringiensis CryIAa insect toxin removed nearly all toxicity for Bombyx mori (> 1,000-fold less active than the wild type). The loss of larvicidal activity in the mutants was not caused by increased sensitivity to larval gut enzymes but could be attributed to significantly reduced binding to B. mori brush border membrane vesicles. Some or all of the affected amino acid residues may interact directly or indirectly with the B. mori membrane receptor(s). Such receptor binding appears to be directly correlated with insect toxicity.
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Ohio State Biochemistry Program, Ohio State University, Columbus 43210.
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D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D001427:Bacterial Toxins / Q000737:chemistry / Q000633:toxicity*; D001665:Binding Sites; D001667:Binding, Competitive; D012831:Bombyx; D004731:Endotoxins / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D006460:Hemolysin Proteins; D007700:Kinetics; D007928:Lethal Dose 50; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis