嗜酸氧化亚铁硫杆菌的谷胱甘肽还原酶的结构模建和底物分子对接

摘要

极端环境微生物嗜酸氧化亚铁硫杆菌的谷胱甘肽还原酶(GR)可能在它的抵抗极端酸性,有毒和氧化性的生物浸出环境中发挥至关重要的作用.通过同源模建技术和分子动力学模拟,它的一个三维结构被构建,优化和检验了.获得的结构被进一步用于搜索绑定位点,跟辅因子黄素腺嘌呤二核苷酸(FAD)和底物谷胱甘肽(GSSG)进行分子柔性对接,并以此识别关健残基.对接结果显示,位于活性残基Cys42和Cys47之间的二硫键夹在FAD的活性位点和底物GSSG的二硫键之间.它们之间的距离非常靠近,这跟底物反应机理的初始步骤的情况十分一致.相互作用能表明8个酶中残基Cys42,Cys47,GIu443B,Glu444B,His438B,Ser14,Thr447B和Lys51是固定或激活GSSG的关键残基,这跟以前的实验事实相吻合.此外,根据相互作用能我们还新发现7个重要残基(Arg449B,Pro439B,Thr440B,Thr310,Va143,Gly46 and Va148).所有这些残基在其它物种中的相应物中也都是保守的.这些结果有助于进一步的实验研究和理解其催化机理,进而揭示这种细菌的抗毒机理,服务于工业应用.%Through the homology modeling techniques and molecular dynamics simulations, a 3D model of glutathione reductase was created, refined and checked. The structure obtained was further used to search binding sites, carry out the flexible dockings with the cofactor FAD and the substrate oxidized glutathione disulfide(GSSG), and identify the key residues. The docking results showed that the disulfide bridge between the active residues of Cys42 and Cys47 was sandwiched between the active site of FAD and the disulfide bridge in GSSG. The distance between them was very close, which was well in line with the initial process of substrate reaction mechanism. The interaction energy analysis indicated that the eight residues were key residues for fixing or activating the GSSG; and seven new important residues were first found and identified. All of these residues were conserved in other species. The results may be helpful for further experimental investigation, understanding its catalytic mechanism and subsequently insight into the anti-toxicity of the bacteria could serve for industry.