Fu Bai-Wen, Xu Lian, Zheng Mei-Xia, Chen Qing-Xi, Shi Yan, Zhu Yu-Jing
School of Life Sciences, Xiamen University, Xiamen, 361005, China.
Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.
AMB Express. 2022 Jul 14;12(1):92. doi: 10.1186/s13568-022-01430-w.
Vegetative insecticidal proteins 3A (Vip3A) were important insecticidal proteins for control of lepidopteran pests. Previous study demonstrated that Vip3Aa and Vip3Ad showed significant difference in insecticidal activities against Spodoptera exigua, while the molecular mechanism remained ambiguous. Here we demonstrated that the difference in insecticidal activities between Vip3Aa and Vip3Ad might be caused by the difference in stability of Vip3Aa and Vip3Ad in S. exigua midgut protease. Vip3Aa was quite stable while Vip3Ad could be further degraded. Molecular dynamics simulation revealed that Vip3Aa was more stable than Vip3Ad, with smaller RMSD and RMSF value. Amino acid sequence alignment indicated that three were three extra prolines (P591, P605 and P779) located on Vip3Aa. We further identified that residue P591 played a crucial role on stability and insecticidal activity of Vip3Aa. Taken together, our study demonstrated that the stability was essential for the insecticidal activity of Vip3A toxins, which might provide new insight into the action mode of Vip3A toxins and contribute to the design Vip3A variants with improved stability and insecticidal activity.
营养期杀虫蛋白3A（Vip3A）是防治鳞翅目害虫的重要杀虫蛋白。先前的研究表明，Vip3Aa和Vip3Ad对甜菜夜蛾的杀虫活性存在显著差异，但其分子机制仍不明确。在此，我们证明Vip3Aa和Vip3Ad杀虫活性的差异可能是由于它们在甜菜夜蛾中肠蛋白酶中的稳定性不同所致。Vip3Aa相当稳定，而Vip3Ad会被进一步降解。分子动力学模拟显示，Vip3Aa比Vip3Ad更稳定，其均方根偏差（RMSD）和均方根波动（RMSF）值更小。氨基酸序列比对表明，Vip3Aa上有三个额外的脯氨酸（P591、P605和P779）。我们进一步确定，残基P591对Vip3Aa的稳定性和杀虫活性起着关键作用。综上所述，我们的研究表明稳定性对于Vip3A毒素的杀虫活性至关重要，这可能为Vip3A毒素的作用模式提供新的见解，并有助于设计出具有更高稳定性和杀虫活性的Vip3A变体。
