SeMNPV组织蛋白酶基因的克隆表达及其对病毒杀虫的影响

Cloning,Expression and Function Analysis of Cathepsin Gene Encoded by Spodoptera exigua Nucleopolyhedrovirus

对甜菜夜蛾核型多角体病毒(SeMNPV)的组织蛋白酶(v-cath)基因进行了克隆,序列分析及原核表达。此基因编码区长1014bp,预计编码一个338个氨基酸的蛋白产物,其蛋白的大小约42kD。序列分析表明,SeMNPV的V-CATH与其它杆状病毒的同源蛋白具有相似的保守结构,保留有相同的酶活性位点。根据几种已知的杆状病毒组织蛋白酶序列构建进化树,发现SeMNPV的V-CATH位于NPV组中一个单独的分支,它可能拥有特殊的进化历程。使用1.2μL的表达组织蛋白酶菌液和SeNPV共感染3龄末甜菜夜蛾幼虫,幼虫病毒致死率提高9.21%,病毒致死时间提前12 h,原核表达的组织蛋白酶对病毒杀虫速度有一定的影响。

A putative v-cathepsin （v-cath） gene of Spodoptera exigua nucleopolyhedrovirus （SeMNPV） was cloned, sequenced and expressed. The results showed that the gene size was 1014 nucleotides, encoding a 338 amino acids putative protein. The amino acid sequence alignment of ten baculoviral v-CATHs showed that the primary structure and the catalytic sites were conserved. A pholygenetic tree of these v-CATHs constructed by using maximum parsimony analysis indicated that the v-cath gene of SeMNPV had a different evolutionary history from that of other NPVs. When late 3th instar Spodoptera exigua larvae were infected with SeMNPV combinded with 1.2μL expressed bacteria and medium, the mortality was increased 9.21%, and LT50 was 12h shorter than the control. The v-CATH expressed in prokaryote has a significant effect on the killing speed of SeMNPV insecticide.