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A novel Bacillus thuringiensis (PS149B1) binary toxin specific for the Western corn rootworm Diabrotica virgifera virgifera LeConte forms ion channels in lipid membranes

DOIResolve DOI: https://doi.org/10.1021/bi048946z
AuthorSearch for: 1; Search for: ; Search for: 1; Search for: 1; Search for: 1; Search for: 1
Affiliation
  1. National Research Council Canada. NRC Biotechnology Research Institute
FormatText, Article
Subjectenvironmental; Escherichia coli; proteins; ion channels; Escherichia coli
Abstract
The binary Bacillus thuringiensis PS149B1 insecticidal crystal (Cry) protein is comprised of two components, Cry34Ab1, a 14-kDa protein, and Cry35Ab1, a 44-kDa protein, the combination of which forms a novel binary toxin active on western corn rootworm larvae. The permeabilizing behavior of the native binary toxin and its two individual components expressed as recombinant proteins was studied using calcein efflux determination in liposomes and by ion channel activity measurements in planar lipid bilayers (PLBs). Data obtained with solubilized native PS149B1 binary protein revealed it to be a pore-forming toxin that can permeabilize liposomes and form ion channels (apprx300-900 pS) in PLBs at pH 5.5 but not pH 9.0. The 14-kDa component of the toxin also formed ion channels (apprx15-300 pS) at pH 5.5 but did not insert easily in PLBs. While the 44-kDa moiety did seldomly form resolvable ion channels (apprx15-750 pS) in PLBs, it did destabilize the membranes. It showed pH-dependent truncation to a stable 40-kDa protein. The purified 40-kDa truncated product formed channels (apprx10-450 pS) in PLBs at pH 5.5. At that same pH, while a 3:1 molar mixture (14:44 kDa) of the individual components of the toxin induced channel activity that resembled that of the 14-kDa component alone, the 3:1 molar mixture of the 14-kDa component and 40-kDa truncated product induced channel activity (apprx20-800 pS) similar to that of PS149B1 in planar lipid bilayers. We conclude that the overall membrane permeabilization process of Cry34Ab1/Cry35Ab1 is a result of ion channel formation.
Date published
In
  • Biochemistry 43, no. 38 (2004): 12349–12357.
LanguageEnglish
Peer reviewedYes
NRC numberNRC-BRI-47216
NPARC number3539994
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Record identifiere7b88766-f54b-40d1-8137-0a7852dbe522
Record created2009-03-01
Record modified2022-11-18

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