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

• Published in: 农业科学学报：英文版 no. 5; pp. 1036 - 1042
• Main Author: ZHOU Zi-shan LIN Hui-yan LI Ying SHU Chang-long SONG Fu-ping ZHANG Jie
• Format: Journal Article
• Language: English
• Published: 2014
• Subjects: 大肠杆菌; 小菜蛾幼虫; 杀虫活性; 毒素; 氨基酸残基; 活性片段; 苏云金芽孢杆菌; 阳性对照
• ISSN: 2095-3119

The novel crylAi 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 CrylAi. All truncated fragments were expressed in Escherichia coli strain BL21 （DE3）, and the insecticidal activity against 2ndinstar P. xylostella larvae was assessed using full-length CrylAi as a positive control. The results indicate that the minimal active fragment of the CrylAi toxin against P. xylostella is located between amino acid residues 36^1 and 605^1, which is smaller than the regions previously reported for CrylA. The first two amino acids （34T and 35P） on helix a-1 and whole helix a-2 of domain I and sheet 13-32 of domain III are necessary for CrylAi toxin to keep its toxicity against P. xylostella.