摘要
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.
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.
基金
supported by the National Natural Science Foundation of China (31272115)
the National 973 Program of China (2009CB118902)
