The Minimal Active Fragment of the Cry1Ai Toxin is Located Between 36I and 605I

• Published in: Journal of Integrative Agriculture Vol. 13; no. 5; pp. 1036 - 1042
• Main Authors: ZHOU, Zi-shan, LIN, Hui-yan, LI, Ying, SHU, Chang-long, SONG, Fu-ping, ZHANG, Jie
• Format: Journal Article
• Language: English
• Published: Science Press 01.05.2014; 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; Elsevier
• Subjects: active fragment; Bacillus thuringiensis; Bacillus thuringiensis Cry1Ai toxin active fragment toxicity Plutella xylostella; Cry1Ai toxin; Plutella xylostella; toxicity; toxicity; Plutella xylostella; active fragment; Cry1Ai toxin; Bacillus thuringiensis
• ISSN: 2095-3119; 2352-3425
• DOI: 10.1016/S2095-3119(13)60532-8

The novel cry1Ai gene that cloned from Bacillus thuringiensis strain SC6H8 encoded a protein exhibiting strong toxicity against Plutella xylostella and Chilo suppressalis in our previous study. Using the available information for the active fragments of other Cry toxins, eight truncated fragments were constructed to identify the minimal active fragment of Cry1Ai. All truncated fragments were expressed in Escherichia coli strain BL21 (DE3), and the insecticidal activity against 2nd- instar P. xylostella larvae was assessed using full-length Cry1Ai as a positive control. The results indicate that the minimal active fragment of the Cry1Ai toxin against P. xylostella is located between amino acid residues 36I and 605I, which is smaller than the regions previously reported for Cry1A. The first two amino acids (34T and 35P) on helix α-1 and whole helix α-2 of domain I and sheet β-32 of domain III are necessary for Cry1Ai toxin to keep its toxicity against P. xylostella.