Delta-endotoxins form cation-selective channels in planar lipid bilayers

• Published in: Biochemical and biophysical research communications Vol. 169; no. 2; pp. 765 - 772
• Main Authors: Slatin, Stephen L., Abrams, Charles K., English, Leigh
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.1990
• Subjects: Bacillus thuringiensis; Bacterial Proteins; Bacterial Toxins; calcium; Cholesterol; Electrophoresis, Polyacrylamide Gel; endotoxins; Endotoxins - isolation & purification; Hemolysin Proteins; Ion Channels; Lipid Bilayers; Membrane Potentials; Phosphatidylcholines; Phospholipids
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/0006-291X(90)90397-6

Delta-endotoxins CryIA(c) and CryIIIA, two members of a large family of toxic proteins from Bacillus thuringiensis, were each allowed to interact with planar lipid bilayers and were analyzed for their ability to form ion-conducting channels. Both of these toxins made clearly resolved channels in the membranes and exhibited several conductance states, which ranged from 200 pS to about 4000 pS (in 300 mM KCl). The channels formed by both toxins were highly cation-selective, but not ideally so. The permeability ratio of K + to Cl − was about 25 for both channels. The ability of these proteins to form such channels may account for their toxic action on sensitive cells, and suggests that this family of toxins may act by a common mechanism.