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Alanine-substituted mutant on Gly373 and Asn375 of Cry1Ai-h-loop 2 causes reduction in both toxicity and binding against Helicoverpa armigera
- LIU, Yu-xiao, ZHOU, Zi-shan, LIANG, Ge-mei, SONG, Fu-ping, ZHANG, Jie
- Journal of integrative agriculture 2019 v.18 no.5 pp. 1064-1071
- Helicoverpa armigera, binding capacity, enzyme-linked immunosorbent assay, insecticidal properties, mutants, toxicity
- Cry1Ai-h-loop 2 is a mutant of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera. The toxicity of Cry1Ai-h-loop 2, in contrast to the very low toxicity of Cry1Ai, is closely associated with the eleven residues in the loop 2 region. To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, alanine-substituted mutants were generated. The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity. ELISA binding and competition binding assays demonstrated that the reduction of toxicity in the mutant of interest was correlated with decreased binding affinity.