Figure 5. Cry11Aa toxin binds the G10 cadherin fragment with high affinity.

(A) The cadherin fragment G10 shows dose-dependent binding (insert, ●) to immobilized Cry11Aa (0.4 μg), but a cadherin fragment from the Heliothis virescens cadherin [24] (insert, ■) does not bind Cry11Aa. Bound G10 was determined with an anti-AaeCad antiserum followed by incubation with secondary antibody and colour detection. The binding affinity, 16.7 nM, of Cry11Aa toxin to the cadherin fragment was determined in a competition assay using 80 nM G10 with increasing concentrations of Cry11Aa toxin (0–1000 nM). OD₄₀₅, A ₄₀₅. (B) The Cry11Aa loop α8 mutant V262A (○) retains its ability to bind the G10 fragment and competes with Cry11Aa binding, whereas the mutant E266A (▲) does not bind the Aedes cadherin fragment. Wild-type Cry11Aa binding is shown as ■ in (A, main graph) and (B). Maximal binding was normalized to the maximal absorbance obtained in the absence of G10. Error bars indicate standard deviation obtained using three separate experiments.