新型Vip3-like蛋白的从头预测建模及其结构域分析

Initio Prediction Modeling of Novel Vip3-like and Its Domains Analysis

Vip3-like蛋白对小菜蛾等鳞翅目昆虫有杀虫活性,是苏云金芽孢杆菌营养期杀虫蛋白Vip3的同源蛋白.为建立Vip3-like三维结构的理论模型并对其结构域进行生物信息学分析,选择从头预测的方法对Vip3-like蛋白三维结构的理论模型进行预测分析.分析结果表明,Vip3-like蛋白由1个Vip3A-N超家族结构域和3个糖类结合结构域组成.与模式蛋白Vip3Aa相比,Vip3-like是一种分子量更大的蛋白质,且2种蛋白的表面静电势分布也存在差异.其Vip3A-N结构域仅由α螺旋和无规则卷曲组成,没有发现β折叠.3个糖类结合结构域主要由无规则卷曲和β折叠组成,仅存在1个α螺旋结构.结构域分析预示无规则卷曲和β折叠可能在Vip3-like和受体结合的过程中扮演着重要角色.通过比较分析,发现Vip3Aa和Vip3-like蛋白在三级结构上存在较大差异,仅仅在局部结构存在一定的相似性,Vip3-like可能并不属于Vip3Aa类蛋白家族而属于一种全新的Bt营养期杀虫蛋白质.

The Vip3 - like protein with the insecticidal activity against Lepidoptera larvae of PluteUa xylostella is a homologous vegetative insecticidal proteins produced by some Bacillus thuringiensis strains. To investigate the theoretical model of the three - dimensional structure of diamondback mothcidal Vip3 - like and its bioinformatics analysis, the theoretical model of Vip3Aa and Vip3 - like was predicted by ab initio prediction modeling by the Phyre2 engine with the intensive mode. The results show that Vip3 - like protein is a bigger molecule than vip3Aa composed of four distinct domains, and the Vip3A - N domain only consists of α - helix and loop structure without any β - sheet. As for the carbohydrate binding domains, only one α - helix is found in three carbohydrate binding domains, and the distribution of electrostatic potential of the two toxins is different. The 3D structure of Vip3 - like does not resemble the Vip3Aa structures very well but still shows some similarity which indicates the Vip3 - like may belong to a new Vip super family. Domain analysis indicates that the β - sheet and loop structure may play an important role during the binding process.