光肩星天牛气味结合蛋白AglaOBP12同源建模及与乙酸-顺-3-己烯酯的分子对接研究
Homology modeling of the odorant binding protein AglaOBP12 of Anoplophora glabripennis and its molecular docking to the host plant volatile cis-3-hexenyl acetate
赵新民** 李滔滔 彭晓赟 刘石泉
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DOI：10.7679/j.issn.2095-1353.2019.036
作者单位：湖南城市学院材料与化学工程学院黑茶金花湖南省重点实验室，益阳 413000
中文关键词：光肩星天牛；气味结合蛋白；AglaOBP12；乙酸-顺-3-己烯酯；同源建模；分子对接
英文关键词：Anoplophora glabripennis; odorant binding protein; AglaOBP12; cis-3-hexenyl acetate; homology model; molecular dockin
中文摘要：
【目的】 研究光肩星天牛Anoplophora glabripennis气味结合蛋白AglaOBP12与寄主植物挥发物乙酸-顺-3-己烯酯的相互作用机制，为利用化学生态手段调控光肩星天牛行为提供理论依据。【方法】 采用同源建模预测AglaOBP12三维结构，虚拟氨基酸突变构建两个突变子，利用Molegro Virtual Docker程序进行分子对接研究AglaOBP12与乙酸-顺-3-己烯酯的结合模式。模型的合理性评价采用GMQE、QMEAN、ramachandran图和Verify-3D。【结果】 AglaOBP12的三维结构由6个α-螺旋构成且形成锥形疏水口袋结构。6个保守半胱氨酸在螺旋结构之间形成稳定结构的3个二硫键。AglaOBP12的C端疏水性氨基酸位于结合口袋的出口并对口袋形成一定的遮挡。乙酸-顺-3-己烯酯位于疏水口袋中与疏水性氨基酸发生作用，而亲水头部羰基氧原子则与Asn123产生氢键。在与突变子N123A的对接中，乙酸-顺-3-己烯酯更接近疏水口袋的出口，乙酸-顺-3-己烯酯与C端Phe135形成氢键。而在与突变子F135E/L136E/V137E的对接中，乙酸-顺-3-己烯酯位于疏水口袋较深处，但未发现与Asn123氢键作用，相比野生型，两个突变子的对接空间能和范德华尔能增大，结合稳定性下降。【结论】 乙酸-顺-3-己烯酯位于AglaOBP12疏水口袋并通过氢键与Asn123形成稳定的复合物，AglaOBP12的Asn123和C端疏水氨基酸对结合乙酸-顺-3-己烯酯具有重要作用。
英文摘要：[Objectives] To investigate the binding mechanism between the Anoplophora glabripennis odorant binding protein AglaOBP12 and the host plant volatile cis-3-hexenyl acetate. [Methods] The three dimensional structure of AglaOBP was predicted by homology modeling. Two mutants were obtained by virtual amino acid mutation, and the binding mode of AglaOBP12 with cis-3-hexenyl acetate was analyzed with the Molegro Virtual Docker program. The model was evaluated by GMQE、QMEAN、Ramachandran plot and Verify-3D. [Results] AglaOBP12 has six helical structures that shape a hydrophobic pocket. Three disulphide connections in various helices caused by six conserved cysteines could be conducive to maintaining structural stability. The hydrophobic residues in the C terminus located at the export of the pocket restrained the ligand in the binding site. Cis-3-hexenyl acetate was bound in the hydrophobic pocket, and its carbonyl oxygen atom formed a hydrogen bond with Asn123 of AglaOBP12. Cis-3-hexenyl acetate was closer to the export in mutant N123A. Phe135 of AglaOBP12 was related to the hydrogen bond. No hydrogen bond was found between the ligand and the mutant F135E/ L136E/V1237E. Both docked mutants had less negative potential energy than the wild type. [Conclusion] Cis-3-hexenyl acetate was located in the hydrophobic pocket ofAglaOBP12 and formed a stable complex with a hydrogen bond with Asn123. Asn123 and the hydrophobic residues in the C terminus play an important role in binding the host plant volatile cis-3-hexenyl acetate.