A specific binding protein from tenebriomolitor for the insecticidal toxin of bacillusthuringiensis subsp. Tenebrionis

Biopesticides based on the bacterium Bacillusthuringiensis have attracted wide attention as safe alternatives to chemical insecticides. In this paper, we report, for the first time, the identification of a single binding protein from a coleopteran insect, Tenebriomolitor, that is specific for the cryIII toxin of B. thuringiensis. The protein appeared as a single band of 144 kDa on radioligand and immunoblots of total proteins extracted from brush border membrane vesicles of the midgut of T. molitor. Radiolabelled cryIIIA toxin bound to the protein with a K_d value of 17.5 nM and could be specifically blocked by unlabelled toxin but not by toxins from other subspecies of B. thuringiensis. This study lays the groundwork to clone the cryIIIA toxin binding protein and to determine the molecular mechanism(s) of toxin action.