Location of the Bombyx mori specificity domain on a Bacillus thuringiensis delta-endotoxin protein.

AUTOR(ES)

Ge, A Z

RESUMO

Bacillus thuringiensis produces different types of insecticidal crystal proteins (ICPs) or delta-endotoxins. In an effort to identify the insect specificity of ICP toxins, two icp genes were cloned into the Escherichia coli expression vector pKK223-3, and bioassays were performed with purified crystals. The type A protein [from an icpA1, or 4.5-kilobase (kb) gene, from B. thuringiensis var. kurstaki HD-1] was found to be 400 times more active against Bombyx mori than type C protein (from an icpC73, or 6.6-kb gene, from B. thuringiensis var. kurstaki HD-244). The type C protein was 9 times more active against Trichoplusia ni than the type A protein, while both have similar activity against Manduca sexta. To locate the specificity domain of the type A protein for B. mori, site-directed mutagenesis was used to introduce or remove restriction enzyme sites, facilitating the exchange of regions of the two genes. The hybrid genes were overexpressed, and purified ICP was used in bioassays. The B. mori specificity domain for the ICP A toxin is located in the amino-terminal portion of the hypervariable region between amino acids 332 and 450.

Documentos Relacionados

• Specificity of Bacillus thuringiensis Delta-Endotoxin
• Identification of amino acid residues of Bacillus thuringiensis delta-endotoxin CryIAa associated with membrane binding and toxicity to Bombyx mori.
• Site-directed mutations in a highly conserved region of Bacillus thuringiensis delta-endotoxin affect inhibition of short circuit current across Bombyx mori midguts.
• Expression of a cloned Bacillus thuringiensis delta-endotoxin gene in Bacillus subtilis.
• Identification of Bacillus thuringiensis Delta-Endotoxin Cry1C Domain III Amino Acid Residues Involved in Insect Specificity