A toxin protein from Xenorhabdus nematophila var. pekingensis and insecticidal activity against larvae of Helicoverpa armigera
A toxin protein from Xenorhabdus nematophila var. pekingensis and insecticidal activity against larvae of Helicoverpa armigera
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DOI：
10.1080/09583150903207578
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发表时间：
2009-10
影响因子：
1.4
通讯作者：
Xiu-fen Yang;D. Qiu;Yuliang Zhang;H. Zeng;Zheng Liu;Jing-jing Yuan;Huaiwen Yang
中科院分区：
文献类型：
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作者：
Xiu-fen Yang;D. Qiu;Yuliang Zhang;H. Zeng;Zheng Liu;Jing-jing Yuan;Huaiwen Yang
摘要嗜黄杆菌变种pekingensis是从北京土壤中分离到的一株斯氏线虫的共生菌，对多种昆虫具有很强的致病力。研究表明，该菌株对棉铃虫、小菜蛾和甜菜夜蛾幼虫具有较强的拒食活性。在此，我们报告了从细菌的细胞内毒蛋白的纯化，分子克隆和拒食活性。SDS-PAGE分析表明，纯化蛋白为单一条带，相对分子质量大于212 kDa。我们将该蛋白命名为XnAFP 2。通过MALDI-TOF技术获得的多肽片段覆盖了X射线毒素蛋白40%的氨基酸序列。嗜酸乳杆菌PMFI 1296.从黄单胞菌中扩增出编码XnAFP 2的全长cDNA序列（Genbank登录号FJ 222606）。黄毛藻原变种pekingensis，全长7575 bp。该基因与X的A2基因同源性高达99%。与X.（GenBank登录号AJ 308438）。该蛋白质可使H. armigera。以三龄幼虫为材料，在人工饲料中添加6.0 µg/g（w/w）毒素蛋白的棉铃虫，生长下降幅度达到97.9%。杀虫蛋白显著降低四龄幼虫体重，延长幼虫期，降低化蛹率和羽化率。选择性和非选择性叶盘法对5龄幼虫24 h的拒食率分别为78.4%和87.6%。
Abstract Xenorhabdus nematophila var. pekingensis, which is highly virulent for many insects, is a symbiotic bacterium of Steinernema carpocapsae isolated from Beijing soil in China. Previous studies demonstrated that the bacterium had high antifeedant activity against larvae of Helicoverpa armigera, Plutella xylostella and Spodoptera exigua. Herein, we report the purification, molecular cloning and antifeedant activity of an intracellular toxic protein from the bacterium. The purified protein displayed a single band and a relative molecular weight of over 212 kDa determined by SDS-PAGE. We designated the protein as XnAFP2. Peptide segments were obtained by MALDI-TOF and covered 40% of the amino acid sequence of a toxin protein from X. nematophilus PMFI1296. The full cDNA sequence encoding for XnAFP2 (Genbank accession number FJ222606) was amplified from X. nematophlia var. pekingensis and consists of 7575 bp. The gene showed homology with up to 99% identity to the A2 gene from X. nematophila strain BP (GenBank accession number AY282763) and 92% identity to the insecticidal toxin xptA2 gene from X. nematophila PMFI 1296 (GenBank accession number AJ308438). The protein caused a rapid cessation in feeding and reduction in larval weight of H. armigera. When fed to third instar larvae of H. armigera in an artificial diet at 6.0 µg/g (w/w) toxin protein, growth reduction reached 97.9%. The insecticidal protein greatly decreased fourth instar larval weight, lengthened larval stage, and reduced pupation and emergence rates. The antifeedant rate in choice and no-choice leaf disk tests against fifth instar larvae was 78.4 and 87.6% in 24 h, respectively.