A cytolytic delta-endotoxin from Bacillus thuringiensis var. israelensis forms cation-selective channels in planar lipid bilayers.
In order to determine the mechanism of action of the 27 kDa mosquitocidal delta-endotoxin of Bacillus thuringiensis var. israelensis we have studied its effects on the conductance of planar lipid bilayers. The toxin formed cation-selective channels in the bilayers, permeable to K+ and Na+ but not to N-methylglucamine or Cl-, showing very fast, cooperative opening and closing. Channel opening was greatly reduced in the presence of divalent cations (Ca2+, Mg2+) and the effect was reversed when these ions were removed. These results are consistent with our proposal that B. thuringiensis toxins act by a mechanism of colloid-osmotic lysis.
Knowles
B H
BH
Department of Biochemistry, University of Cambridge, England.
Blatt
M R
MR
Tester
M
M
Horsnell
J M
JM
Carroll
J
J
Menestrina
G
G
Ellar
D J
DJ
D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004553:Electric Conductivity; D004731:Endotoxins; D006460:Hemolysin Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D008954:Models, Biological; D010539:Permeability; D010714:Phosphatidylethanolamines
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine