拒食蛋白XnAFP2三个结构域片段的表达及其生物活性分析

嗜线虫致病杆菌北京变种Xenorhabdus nematophila var. pekingensis CB6菌株产生的蛋白XnAFP2对多种昆虫有拒食活性。生物信息学分析表明,XnAFP2包含DomainⅠ、DomainⅡ和DomainⅢ3个功能结构域。为确定其主效活性区域,分别对3个结构域进行了克隆、表达和生物活性测定。结果表明,3个蛋白片段对棉铃虫Helicoverpa armigera3龄幼虫的生长抑制率分别为17.4%、39.8%和20.2%,对玉米螟Ostrinia furnacalis3龄幼虫的生长抑制率分别为20.2%3、8.6%和21.7%,对小菜蛾Plutella xylostella3龄幼虫的非选择性拒食率分别为25.7%、44.1%和26.8%。研究结果表明,DomainⅡ是拒食蛋白XnAFP2的主效活性区域。

Expression of the Three Domains in XnAFP2 and Analysis of Their Insect Antifeedant Activity

XnAFP2 is a protein with insect antifeedant activity purified from Xenorhabdus nematophila var.pekingensis strain CB6.Bioinformatics analysis indicated that XnAFP2 contains three functional domains,Domain Ⅰ,Domain Ⅱand Domain Ⅲ.To illustrate which domain is the main active region,cloning and expression of the three domains were performed and their biological activities were determined.Bioassay results showed that the inhibition rates of the three domains on the growth of the 3rd instar larvae of Helicoverpa armigera and Ostrinia furnacalis were 17.4%,39.8%,20.2%,and 20.2%,38.6%,21.7%,respectively.The non-selective antifeedant rates against the 3rd instar larvae of Plutella xylostella were 25.7%,44.1% and 26.8%,respectively.These results indicate that the antifeedant activity of XnAFP2 is mainly dependent on its Domain Ⅱ.