HIV-1整合酶核心区野生型和F185K突变型活性和溶解性的比较及分子动力学模拟分析

表达纯化了野生型(WT)及F185K突变型HIV-1整合酶核心区蛋白(IN_C)，并对二者的溶解性和活性进行了比较．实验结果表明：F185K 突变后IN_C溶解性显著提高，活性有一定程度降低．对WT和F185K IN_C体系进行了1800 ps的分子动力学模拟．模拟结果表明：F185K IN_C功能loop区柔性和蛋白质整体运动性降低，使蛋白质活性降低，F185K突变后盐桥网络的变化驱动了IN_C局部构象改变，引起IN_C表面的部分疏水残基被包埋，亲水残基暴露，相对亲水溶剂可接近面积增大，同时，突变后IN_C与水之间形成氢键的数量增加，与水之间作用加强，以上变化使IN_C溶解性提高．分子动力学模拟与实验结果相吻合．为理解蛋白质溶解性和对蛋白质进行可溶性改造提供了一定的理论依据．

Activity, Solubility Comparison and Molecular Dynamics Simulation Analysis of Wild Type and F185K Mutant Type HIV-1 Integrase Catalytic Domain

Wild type (WT) and F185K mutant type of HIV-1 integrase catalytic domain (IN_C) were expressed and purified, and their solubility and activity were compared. The experiment results show that the solubility of F185K mutated IN_C was dramatically increased, whereas the activity was reduced to some extent. Subsequently, 1 800 ps molecular dynamics (MD) simulations for the WT and F185K type of IN_C in water were performed. The MD simulation results demonstrate that the flexibility of the catalytic loop region and the total mobility of F185K IN_C was reduced, which causes the decrease of activity. After the F185K mutation, changes of the salt bridge network drove the conformational change of IN_C, resulted in the burying of some hydrophobic residues and exposure of some other hydrophilic residues on the protein surface. Therefore, the relative hydrophilic solvent accessible surface of IN_C was increased. Moreover, the F185K mutation increased the hydrogen number between the IN_C protein and water molecule, as a consequence, the protein-water interaction was enhanced. These above changes contribute to the solubility increase of IN_C. It is found that the results obtained from MD simulation are in good agreement with the experiment data. The above mentioned results provides valuable insight for the understanding of protein solubility and will be helpful in protein engineering for increasing the solubility of proteins.