Estimation of the radius of the pores formed by the Bacillus thuringiensis Cry1C δ-endotoxin in planar lipid bilayers

摘要: Pore formation constitutes a key step in the mode of action Bacillus thuringiensis δ-endotoxins and various activated Cry toxins have been shown to form ionic channels receptor-free planar lipid bilayers at high concentrations. Multiple conductance levels observed with several toxins, suggesting that result from multimeric assembly variable number toxin molecules. To test this possibility, size formed by Cry1C was estimated non-electrolyte exclusion technique polyethylene glycols molecular weights. In symmetrical 300 mM KCl solutions, induced channel activity 15 distinct ranging 21 246 pS distributed two main populations. Both smallest largest mean values both populations were systematically reduced presence hydrated radii up 1.05 nm, indicating these solutes can penetrate pores toxin. Larger had little effect on levels, they excluded pores. Our results indicate forms clusters composed having similar pore radius between 1.0 1.3 nm gating synchronously.