Vegetatively expressed insecticidal proteins (VIPs) produced by Bacillus thuringiensis fall into several classes of which the third, VIP3, is known for their activity against several key Lepidopteran pests of commercial broad acre crops and because their mode of action does not overlap with that of crystalline insecticidal proteins. The details of the VIP3 structure and mode of action have remained obscure for the quarter century that has passed since their discovery. In the present article, we report the first crystal structure of a full-length VIP3 protein. Crystallization of this target required multiple rounds of construct optimization and screening-over 200 individual sequences were expressed and tested. This protein adopts a novel global fold that combines domains with hitherto unreported topology and containing elements seemingly borrowed from carbohydrate-binding domains, lectins, or from other insecticidal proteins.

中文翻译：

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Vip3B家族杀虫蛋白的晶体结构揭示了新的折叠和独特的四聚体组装。

苏云金芽孢杆菌产生的植物表达的杀虫蛋白（VIP）分为几类，第三类VIP3以其对商品化广域农作物的几种关键鳞翅目害虫的活性而闻名，并且由于其作用方式与结晶方式不重叠杀虫蛋白。自发现以来，四分之一世纪以来，VIP3的结构和作用方式的细节一直不清楚。在本文中，我们报告了全长VIP3蛋白的第一个晶体结构。该靶标的结晶需要多轮构建优化，并筛选和表达了200多个独立序列。