Characteristics of channel pores formed by Bacillus thuringiensis mosquito-larvicidal Cry4Aa toxin

Cry4Aa toxin produced by Bacillus thuringiensis subsp. israelensis exhibits specific toxicity to larvae of medically important mosquito genera. In the present study, we analyzed characteristics channel pores formed recombinant in a solvent-free planar lipid bilayer. Stable currents were observed electrophysiologic measurements, and single-channel conductance was 187 ± 10 pS symmetrical buffer containing 150 mM KCl. The cation-selective, with an estimated PK/PCl permeability ratio 4.9. addition, exhibited apparent cation preference order Na+ > K+, Ca2+, K+ Ca2+. Although effect limited, seemed be correlated toxicity. Culex pipiens reared NaCl solution greater sensitivity Cry4Aa, particularly early period after exposure. presence cations that preferentially translocate through may facilitate excessive influx water into midgut cells, leading colloid-osmotic lysis. Whereas CaCl2 had some on mosquito-larvicidal activity KCl no effect. mitigated variety ion channels cell membrane.