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Journal of Integrative Agriculture  2019, Vol. 18 Issue (5): 1064-1071    DOI: 10.1016/S2095-3119(18)61933-1
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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
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, P.R.China
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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.
Keywords:  Bacillus thuringiensis        Cry1Ai        Domain II-loop2        Helicoverpa armigera        binding affinity  
Received: 02 February 2018   Accepted:
Fund: This work was supported by the National Key R&D Program of China (2017YFD0200400) and the National Natural Science Foundation of China (31272115).
Corresponding Authors:  Correspondence ZHANG Jie, Tel: +86-10-62816520, E-mail:    
About author:  LIU Yu-xiao, E-mail:;

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LIU Yu-xiao, ZHOU Zi-shan, LIANG Ge-mei, SONG Fu-ping, ZHANG Jie. 2019. Alanine-substituted mutant on Gly373 and Asn375 of Cry1Ai-h-loop 2 causes reduction in both toxicity and binding against Helicoverpa armigera. Journal of Integrative Agriculture, 18(5): 1064-1071.

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