基因组学与应用生物学

葡萄糖是真核生物体内的重要能源物质。葡萄糖转运蛋白(GLUT1)是细胞获取葡萄糖的最基本需求。GLUT1功能的缺失会造成严重的疾病,尤其是可能造成永久的脑部损伤,包括早发型惊厥,智力缺陷等。此外,肿瘤细胞对于葡萄糖的大量需求也使得GLUT1可以作为肿瘤诊断的分子标记。因此,研究葡萄糖转运蛋白对于研发糖代谢障碍药物以及诊断肿瘤均有重要意义。本实验运用分子动力学模拟的方法,在NAnoscale Molecular Dynamics(NAMD)中使用Chemistry at HARvard Macromolecular Mechanics(CHARMM)力场,构建了GLUT1结合葡萄糖和未结合葡萄糖的膜系统,并分别进行了20 ns时长的分子动力学模拟。运用Visual Merchandising(VMD)和自写脚本对这一轨迹进行分析,探究葡萄糖转运蛋白转运葡萄糖的分子机理。结果表明,20 nano-seconds(ns)的模拟时长能够使这样两个体系构象达到稳定,并且从平均结构和通道直径来看,去除葡萄糖能够使得GLUT1的结构发生翻转,由向胞内释放葡萄糖变为从胞外摄取葡萄糖的构象。同时结合模式的分析表明葡萄糖主要依靠与Gln283和Gln282形成的3个较强的氢键。最后我们通过氢键跟踪分析,发现Asn288和Thr295在这种面向胞外的口袋张开过程中发挥了重要作用。这一结论对研发针对关键氨基酸的葡萄糖代谢药物有指导作用,并且可以为癌症诊断提供一定的理论基础。

Glucose is the most important energy resource of eukaryotic organisms. Glucose transporter 1 is the essential element in transporting glucose into all kinds of cells. Lacking ability of glut1 can cause disaster diseases,such as early-onset seizures, dysgnosia and so on. Otherwise, the large amount of energy needed by tumor cells indicates more glucose, which promotes the expression of glut1 in tumor. This could be an important bio-marker of cancers. In this research, we used NAMD to research the molecular mechanism of conformation transformation with CHARMM force field. 20 ns trajectories of both glucose binding and ligand free were conducted. VMD and home script were used to analyze the binding mode and conformation transformation. As a result, we find 20 ns is sufficient for both systems and ligand free has a turn over conformation change compared to glucose binding conformation. Hydrogen bond tracking also indicates Asn288 and Thr295 played an important role in mediating open of extracellular gate. This research should shed some light on the drug design of glucose metabolite disorder and cancer diagnosis.