Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Department of Plant Protection, Faculty of Agriculture, Benha University, Banha, Qalyubia 13736, Egypt.
Int J Biol Macromol. 2023 Jul 15;243:125152. doi: 10.1016/j.ijbiomac.2023.125152. Epub 2023 Jun 1.
Odorant-binding proteins (OBPs) are thought to bind and deliver hydrophobic odorants from the environment to receptors on insect sensory neurons, and have been used to screen behaviorally active compounds of insects. In order to screen behaviorally active compounds for Monochamus alternatus by OBPs, we cloned full length of Obp12 coding sequence from M. alternatus and proved secretion property of MaltOBP12, then tested binding affinities of recombinant MaltOBP12 to 12 pine volatiles in vitro. We confirmed MaltOBP12 has binding affinities to 9 pine volatiles. The structure of MaltOBP12 and protein-ligand interactions were further analyzed by homology modeling, molecular docking, site-directed mutagenesis, and ligand-binding assays. These results demonstrated that the binding pocket of MaltOBP12 consists of several large aromatic and hydrophobic residues, and four aromatic residues (Tyr50, Phe109, Tyr112, Phe122) are essential for odorant-binding; ligands adopt extensive hydrophobic interactions with an overlapping subset of residues in the binding pocket. Finally, based on non-directional hydrophobic interactions, MaltOBP12 binds odorants flexibly. These findings will not only help us understand how OBPs flexibly bind odorants but also promote to screen of behaviourally active compounds by computer methods to prevent M. alternatus in the future.
气味结合蛋白（OBPs）被认为能够将环境中的疏水性气味结合并传递给昆虫感觉神经元上的受体，并且已经被用于筛选昆虫的行为活性化合物。为了通过 OBPs 筛选马尾松墨天牛的行为活性化合物，我们从马尾松墨天牛中克隆了全长 Obp12 编码序列，并证明了 MaltOBP12 的分泌特性，然后在体外测试了重组 MaltOBP12 对 12 种松树挥发物的结合亲和力。我们证实 MaltOBP12 对 9 种松树挥发物具有结合亲和力。通过同源建模、分子对接、定点突变和配体结合分析进一步分析了 MaltOBP12 的结构和蛋白-配体相互作用。这些结果表明，MaltOBP12 的结合口袋由几个大的芳香族和疏水性残基组成，四个芳香族残基（Tyr50、Phe109、Tyr112、Phe122）对于气味结合是必需的；配体与结合口袋中的一组重叠的残基形成广泛的疏水性相互作用。最后，基于非定向疏水相互作用，MaltOBP12 能够灵活地结合气味。这些发现不仅有助于我们理解 OBPs 如何灵活地结合气味，而且还促进了通过计算机方法筛选行为活性化合物，以防止未来马尾松墨天牛的发生。
