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δ ‐Endotoxins induce cation channels in Spodoptera frugiperda brush border membranes in suspension and in planar lipid bilayers
Author(s) -
Argelia Lorence,
Alberto Darszon,
Claudia Díaz-Camino,
Arturo Liévano,
Rodolfo Quintero,
Alejandra Bravo
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00092-n
Subject(s) - spodoptera , vesicle , biophysics , chemistry , brush border , membrane , lipid bilayer , ion channel , permeability (electromagnetism) , bacillus thuringiensis , biochemistry , receptor , biology , bacteria , genetics , gene , recombinant dna
Membrane potential measurements using a fluorescent dye indicated that two specific toxins active against Spodoptera frugiperda larvae (CryIC and CryID) cause immediate permeability changes in midgut epithelial brush border membrane vesicles (BBMV). The initial response and the sustained permeability change are cationic, notvery K + selective, and occur at in vivo lethal doses (nM). The toxin response has a different ion selectivity and is more sensitive to Ba 2+ than the intrinsic cation permeability of BBMV. Experiments incorporating BBMV into planar lipid bilayers (PLB) demonstrated that these vesicles contain cation channels (31, 47 and 76 pS). A 2–40 fold conductance increase was induced by nM concentrations of toxin in PLB containing BBMV. Cationic single channel transitions of 50, 106, 360 and 752 pS were resolved. Thus, Bacillus thuringiensis δ ‐endotoxins induce an increase in cation membrane permeability involving ion channels in BBMV‐containing functional receptors.