Irreversible binding kinetics of Bacillus thuringiensis CryIA delta-endotoxins to gypsy moth brush border membrane vesicles is directly correlated to toxicity.
To examine the binding of Bacillus thuringiensis delta-endotoxins, CryIAa, CryIAb, and CryIAc, to Lymantria dispar (gypsy moth) brush border membrane vesicles (BBMV), saturation kinetic analyses were conducted according to a two-step interaction scheme [formula: see text] for delta-endotoxin binding to BBMV, rather than the one-step reversible binding presented in prior reports. The order of toxicity of the delta-endotoxins, as measured by the dose required for a 50% inhibition of weight gain (ID50), was CryIAa (77.3 ng) > CryIAb (157 ng) > CryIAc (187 ng). While both the maximum extent of binding, Bmax, and the half-maximum insertion rate concentration, K1/2, was observed to be indirectly related to toxicity, the rate constant of irreversible binding, k2, was found to be directly correlated to toxicity.
Liang
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Department of Biochemistry, Ohio State University, Columbus 43210, USA.
Patel
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Dean
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D000818:Animals; D001413:Bacillus thuringiensis / Q000472:pathogenicity*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism* / Q000633:toxicity; D001427:Bacterial Toxins / Q000378:metabolism*; D004731:Endotoxins / Q000378:metabolism* / Q000633:toxicity; D006460:Hemolysin Proteins; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism; D009036:Moths / Q000187:drug effects / Q000378:metabolism*; D010572:Pest Control, Biological
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis