Introduction of Culex toxicity into Bacillus thuringiensis Cry4Ba by protein engineering
Autor(es): Abdullah, MAF; Alzate, O; Mohammad, M; McNall, RJ; Adang, MJ; Dean, DH
Resumo: Bacillus thuringiensis mosquitocidal toxin Cry4Ba has no significant natural activity against Culex quinquefasciatus or Culex pipiens (50% lethal concentrations [LC(50)], >80,000 and >20,000 ng/ml, respectively). We introduced amino acid substitutions in three putative loops of domain II of Cry4Ba. The mutant proteins were tested on four different species of mosquitoes, Aedes aegypti, Anopheles quadrimaculatus, C. quinquefasciatus, and C. pipiens. Putative loop 1 and 2 exchanges eliminated activity towards A. aegypti and A. quadrimaculatus. Mutations in a putative loop 3 resulted in a final increase in toxicity of >700-fold and >285-fold against C. quinquefasciatus (LC(50) congruent to 114 ng/ml) and C. pipiens (LC(50) congruent to 37 ng/ml), respectively. The enhanced protein (mutein) has very little negative effect on the activity against Anopheles or Aedes. These results suggest that the introduction of short variable Sequences of the loop regions from one toxin into another might provide a general rational design approach to enhancing B. thuringiensis Cry toxins.
Palavras-Chave: Brush-Border-Membrane; Israelensis Delta-Endotoxin; Cultured Midgut Cells; Gypsy-Moth Larvae; Subsp Israelensis; Domain-Ii; Irreversible Binding; Manduca-Sexta; Insecticidal Proteins; Mosquitocidal Toxins
Imprenta: Applied and Environmental Microbiology, v. 69, n. 9, p. 5343-5353, 2003
Identificador do objeto digital: 10.1128/AEM.69.9.5343-5353.2003
Descritores: Aedes aegypti - Cell
Data de publicação: 2003
