title: Membrane-permeabilizing activities of Bacillus thuringiensis coleopteran-active toxin CryIIIB2 and CryIIIB2 domain I peptide.
abstract: Bacillus thuringiensis toxin CryIIIB2 exhibits activity against two agriculturally important pests, the Colorado potato beetle, Leptinotarsa decemlineata, and the Southern corn rootworm, Diabrotica undecimpunctata. CryIIIB2 shows significant structural similarity to Colorado potato beetle-active toxin CryIIIA, whose crystal structure has been determined elsewhere [J. Li, J. Carrol, and D. J. Ellar, Nature (London) 353:815-821, 1991]. A clone limited to the putative 7-alpha-helical bundle domain I peptide of CryIIIB2 was constructed by PCR. The truncated protein was expressed at high levels in Escherichia coli. Domain I peptide was isolated and compared with native CryIIIB2 toxin in promoting ion efflux from synthetic phospholipid vesicles and formation of ion channels in black lipid membranes. The results showed that CryIIIB2 domain I peptide is sufficient for ion channel formation and promotes ion efflux. Both native CryIIIB2 toxin and domain I peptide were inefficient channel-forming proteins that produced noisy ion channels of various conductance states. In ion efflux assays, native toxin promoted greater ion efflux from synthetic vesicles than did the truncated peptide.
authors.affiliation: Ecogen, Inc., Langhorne, Pennsylvania 19047.
authors.forename: M A
authors.initials: MA
authors.lastname: Von Tersch
authors.forename: S L
authors.initials: SL
authors.lastname: Slatin
authors.forename: C A
authors.initials: CA
authors.lastname: Kulesza
authors.forename: L H
authors.initials: LH
authors.lastname: English
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D001483:Base Sequence; D002463:Cell Membrane Permeability / Q000187:drug effects; D003001:Cloning, Molecular; D001517:Coleoptera / Q000187:drug effects*; D015342:DNA Probes / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004731:Endotoxins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D006460:Hemolysin Proteins; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010572:Pest Control, Biological; D016133:Polymerase Chain Reaction
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D015342:DNA Probes; D004269:DNA, Bacterial; D004731:Endotoxins; D006460:Hemolysin Proteins; D007473:Ion Channels; C030956:insecticidal crystal protein, Bacillus Thuringiensis