The Vip3Ag4 Insecticidal Protoxin from Bacillus thuringiensis Adopts A Tetrameric Configuration That Is Maintained on Proteolysis.
The Vip3Ag4 Insecticidal Protoxin from Bacillus thuringiensis Adopts A Tetrameric Configuration That Is Maintained on Proteolysis.
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DOI：
10.3390/toxins9050165
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发表时间：
2017-05-14
期刊：
影响因子：
4.2
通讯作者：
Berry C
中科院分区：
文献类型：
--
作者：
Palma L;Scott DJ;Harris G;Din SU;Williams TL;Roberts OJ;Young MT;Caballero P;Berry C
苏云金芽孢杆菌在营养生长过程中产生的Vip3蛋白对鳞翅目昆虫具有杀虫活性，其作用机制可能涉及气孔形成和细胞凋亡。这些蛋白质是我们杀虫蛋白质武器库的有希望的补充，但它们的活性的分子细节尚不清楚。作为这些蛋白质结构特征的第一步，我们分析了它们的二级结构，并用透射电子显微镜解析了Vip3Ag4蛋白质四聚体复合体的表面拓扑结构。确定了对胰酶降解敏感的位点，胰酶裂解的蛋白质似乎保留了类似于八聚体复合体的结构，该八聚体复合体由~65 kDa和~21 kDa的蛋白分解产物各四个副本组成。该毒素的这种加工形式可能代表活性毒素。本研究中产生的蛋白质的质量和单分散性使Vip3Ag4成为使用冷冻电子显微镜进行更详细结构分析的候选对象。
The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy. Sites sensitive to proteolysis by trypsin are identified and the trypsin-cleaved protein appears to retain a similar structure as an octomeric complex comprising four copies each of the ~65 kDa and ~21 kDa products of proteolysis. This processed form of the toxin may represent the active toxin. The quality and monodispersity of the protein produced in this study make Vip3Ag4 a candidate for more detailed structural analysis using cryo-electron microscopy.