title: Facile preparation and characterization of the toxin from Bacillus thuringiensis var. kurstaki.
abstract: We report a simple three-step method of generating a homogeneous toxic fragment (toxin) in high yield from B. thuringiensis var. kurstaki. Purified crystals were digested with trypsin at pH 10.5, followed by (NH4)2SO4 precipitation and dialysis. For the HD73 strain the preparation is toxic to eastern-spruce-budworm (Choristoneura fuminiferana) larvae. It gives a single 66 kDa band on polyacrylamide-gel electrophoresis and a single band with an isoelectric point of 5.5 on an isoelectric-focusing gel. A single isoleucine N-terminus was detected, and the first 20 amino acids were found to be identical with those predicted from the gene nucleotide sequence. A single lysine C-terminus was detected, and the amino acid composition was in excellent agreement with tryptic cleavages at arginine-28 and lysine-623 of the protoxin. Raman spectroscopic analysis gave values of 20% alpha-helix, 35% beta-sheet and 45% unordered structure. The resistance of the toxin to most proteinases and its susceptibility to proteolysis by papain and Pronases indicates a compact multidomain structure.
authors.affiliation: Department of Chemistry, University of Ottawa, Ontario, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Bietlot
authors.forename: P R
authors.initials: PR
authors.lastname: Carey
authors.forename: C
authors.initials: C
authors.lastname: Choma
authors.forename: H
authors.initials: H
authors.lastname: Kaplan
authors.forename: T
authors.initials: T
authors.lastname: Lessard
authors.forename: M
authors.initials: M
authors.lastname: Pozsgay
mesh_terms: D001413:Bacillus thuringiensis / Q000032:analysis*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000302:isolation & purification; D001427:Bacterial Toxins / Q000302:isolation & purification; D004731:Endotoxins / Q000302:isolation & purification*; D006460:Hemolysin Proteins; D010572:Pest Control, Biological; D011487:Protein Conformation; D011498:Protein Precursors / Q000302:isolation & purification
chemical_list: D000083722:Bacillus thuringiensis Toxins; C029103:Bacillus thuringiensis protoxin; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011498:Protein Precursors; C030956:insecticidal crystal protein, Bacillus Thuringiensis