title: Larvicidal activity of chimeric Bacillus thuringiensis protoxins.
abstract: Bacillus thuringiensis subspecies kurstaki (Btk) and subspecies berliner (Btb) both produce lepidopteran-specific larvicidal protoxins with different activities against the same insect species. Toxic activity resides in the amino-terminal half of both protoxins, whereas the carboxy-terminal half of the molecules is not required for toxicity. The protoxins are 90% homologous, with a major cluster of differences in the amino-terminal half, and a 26 consecutive amino-acid insertion within the carboxy-terminal half of the Btk protoxin. Protoxin chimeras composed of the amino-terminal half of one subspecies and the carboxy-terminal half of the other were generated. Wild-type and chimeric protoxins were compared in bioassays against tobacco hornworm larvae. The amino-terminal half, the toxin itself, dictates specific larvicidal activity.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie 82071-3944.
authors.forename: K C
authors.initials: KC
authors.lastname: Raymond
authors.forename: T R
authors.initials: TR
authors.lastname: John
authors.forename: L A
authors.initials: LA
authors.lastname: Bulla
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics* / Q000633:toxicity; D002678:Chimera; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D007814:Larva; D009036:Moths / Q000187:drug effects; D010957:Plasmids; D011498:Protein Precursors / Q000235:genetics* / Q000633:toxicity; D015183:Restriction Mapping
chemical_list: C029103:Bacillus thuringiensis protoxin; D001427:Bacterial Toxins; D011498:Protein Precursors