Identification of Bacillus thuringiensis Delta-Endotoxin Cry1C Domain III Amino Acid Residues Involved in Insect Specificity
AUTOR(ES)
de Maagd, Ruud A.
FONTE
American Society for Microbiology
RESUMO
Cry1C domain III amino acid residues involved in specificity for beet armyworm (Spodoptera exigua) were identified. For this purpose, intradomain III hybrids between Cry1E (nontoxic) and Cry1E-Cry1C hybrid G27 (toxic) were made. Crossover points of these hybrids defined six sequence blocks containing between 1 and 19 of the amino acid differences between Cry1E and G27. Blocks B, C, D, and E of G27 were shown to be required for optimal activity against S. exigua. Block E was also required for optimal activity against the tobacco hornworm (Manduca sexta), whereas block D had a negative effect on toxicity for this insect. The mutagenesis of individual amino acids in block B identified Trp-476 as the only amino acid in this block essential, although not sufficient by itself, for full S. exigua activity. In block D, we identified a seven-amino-acid insertion in G27 that was not in Cry1E. The deletion of either one of two groups of four consecutive amino acids in this insertion completely abolished activity against S. exigua but resulted in higher activity against M. sexta. Alanine substitutions of the first group had little effect on toxicity, whereas alanine substitutions of the second group had the same effect as its deletion. These results identify groups of amino acids as well as some individual residues in Cry1C domain III, which are strongly involved in S. exigua-specific activity as well as sometimes involved in M. sexta-specific activity.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=91580Documentos Relacionados
- Bacillus thuringiensis Delta-Endotoxin Cry1C Domain III Can Function as a Specificity Determinant for Spodoptera exigua in Different, but Not All, Cry1-Cry1C Hybrids
- 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.
- Location of the Bombyx mori specificity domain on a Bacillus thuringiensis delta-endotoxin protein.
- Single amino acid changes in domain II of Bacillus thuringiensis CryIAb delta-endotoxin affect irreversible binding to Manduca sexta midgut membrane vesicles.
