A fusion protein containing a lepidopteran-specific toxin from the South Indian red scorpion (Mesobuthus tamulus) and snowdrop lectin shows oral toxicity to target insects
A fusion protein containing a lepidopteran-specific toxin from the South Indian red scorpion (Mesobuthus tamulus) and snowdrop lectin shows oral toxicity to target insects
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DOI：
10.1186/1472-6750-6-18
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发表时间：
2006-03-16
影响因子：
3.5
通讯作者：
Gatehouse, JA
中科院分区：
文献类型：
--
作者：
Trung, NP;Fitches, E;Gatehouse, JA
背景：尽管有证据表明植物凝集素在植物防御中发挥作用，但植物凝集素的低杀虫活性和物种特异性杀虫活性阻碍了植物凝集素在作物保护中的使用。雪花莲凝集素是一种经口服进入昆虫血淋巴的凝集素，可作为新型杀虫剂的基础。含有GNA的重组蛋白被表达为与多肽或蛋白质的融合，通常只有当注射到昆虫血淋巴中时才是有毒的，但由于GNA介导的摄取，重组蛋白有可能表现出口服毒性。结果：从红蝎(Mesobutus Tamulus)中合成了编码毒素Butait的基因，并将其组装成表达载体。一种结构只含有Butait，而另一种结构含有Butait与GNA多肽(Butait/GNA)的N端融合。以巴斯德毕赤酵母为表达宿主，表达并纯化了两种重组蛋白。重组Butait和Butait/GNA注射到番茄蛾幼虫体内具有剧毒作用，可引起迟发性麻痹，导致死亡或生长减慢。Butait/GNA在喂食甘蓝幼虫时具有慢性毒性，在仅GNA有效无毒的条件下，导致存活和体重增加减少。在口服融合蛋白的昆虫幼虫血淋巴中检测到完整的Butait/GNA，表明连接的多肽通过肠道运输。并观察了融合蛋白的蛋白水解性。在液体人工饲料中，Butait/GNA对同翅目褐飞虱的毒力明显高于GNA。结论：Butait/GNA重组融合蛋白对鳞翅目昆虫幼虫具有一定的毒力，无论是注射还是口服，GNA作为载体将潜在的有毒多肽和蛋白质运送到昆虫肠道。虽然Butait被认为是鳞翅目昆虫特有的，但融合蛋白具有更广泛的杀虫活性。基于植物凝集素的融合蛋白在作物保护中具有潜在的应用前景，既可以作为外源处理，也可以作为转基因植物的内源产物。
Background: Despite evidence suggesting a role in plant defence, the use of plant lectins in crop protection has been hindered by their low and species-specific insecticidal activity. Snowdrop lectin (Galanthus nivalis agglutinin; GNA) is transported to the haemolymph of insects after oral ingestion, and can be used as a basis for novel insecticides. Recombinant proteins containing GNA expressed as a fusion with a peptide or protein, normally only toxic when injected into the insect haemolymph, have the potential to show oral toxicity as a result of GNA-mediated uptake.Results: A gene encoding a toxin, ButaIT, from the red scorpion (Mesobuthus tamulus) was synthesised and assembled into expression constructs. One construct contained ButaIT alone, whereas the other contained ButaIT fused N-terminally to a GNA polypeptide (ButaIT/GNA). Both recombinant proteins were produced using the yeast Pichia pastoris as an expression host, and purified. Recombinant ButaIT and ButaIT/GNA were acutely toxic when injected into larvae of tomato moth (Lacanobia oleracea), causing slow paralysis, leading to mortality or decreased growth. ButaIT/GNA was chronically toxic when fed to L. oleracea larvae, causing decreased survival and weight gain under conditions where GNA alone was effectively non-toxic. Intact ButaIT/GNA was detected in larval haemolymph from insects fed the fusion protein orally, demonstrating transport of the linked polypeptide across the gut. Proteolysis of the fusion protein was also observed. ButaIT/GNA was significantly more toxic that GNA alone when fed to the homopteran Nilaparvata lugens (rice brown planthopper) in liquid artificial diet.Conclusion: The ButaIT/GNA recombinant fusion protein is toxic to lepidopteran larvae both when injected and when fed orally, showing the utility of GNA as a carrier to transport potentially toxic peptides and proteins across the insect gut. Although ButaIT has been claimed to be lepidopteran-specific, the fusion protein has more wide-ranging insecticidal activity. Fusion proteins based on plant lectins have potential applications in crop protection, both as exogenously applied treatments and as endogenous products in transgenic plants.