定点突变技术研究苏云金杆菌Cry1类晶体蛋白结构与功能的进展

Progress on the Structure and Function of Bacillus thuringiensis Cry1 Insecticidal Proteins by Site-directed Mutagenesis

近年来利用定点突变技术研究苏云金杆菌(Bacillus thuringiesis,Bt)杀虫晶体蛋白(Insecticidal crystal proteins,ICP)作用机制已取得良好进展.杀虫晶体蛋白不同结构域上氨基酸残基的突变将影响其稳定性,与受体的结合,不可逆的昆虫中肠膜插入及离子通道活性的强弱等.突变研究表明,结构域Ⅰ参与不可逆结合及插入昆虫中肠膜过程;结构域Ⅱ参与受体结合,包括初始结合与不可逆结合;结构域Ⅲ在杀虫特异性和维持三维结构的稳定性方面起重要作用,同时,可能参与离子通道的形成,受体结合和插入昆虫中肠膜过程.利用各种定点突变技术对各位点进行突变可以研究单一位点的功能,到目前为止,已有很多关于这方面的研究,并且筛选到了毒力提高的工程菌株.

Using site-directed mutagenesis to investigate the structure and function of Bacillus thuringiensis insecticidal crysta, proteins have made great progresses. Mutations on different domains can have effects on toxin stability ,binding to receptors, irreversible insertion into membrane, the ion channel activity and so on. The research of mutation proved that domain Ⅰ is involved in irreversible binding and insertion into membrane; domain Ⅱ is involved in binding to receptors, concluding initial binding and irreversible binding; domain Ⅲ is important in maintaining the stability of structure,and it is also involved in ion channel formation,binding to receptors and insertion into membrane. Some sites were mutated by different sitedirected mutagenesis, to explore the function of single sites. Many researches in this field have been made and some combinant strains with higher toxicity were selected out.