用分子模拟方法研究HIV-1整合酶突变体的耐药性机理

二酮酸类化合物(DKAs)是目前最有前景的HIV-1整合酶(integrase, IN)抑制剂．为了解DKAs引起的多种耐药株共有的耐药性机理，选择3种S-1360引起的IN耐药突变体，用分子对接和分子动力学模拟，研究了野生型和突变型IN与S-1360的结合模式，基于该结合模式探讨了3种耐药突变体所共有的耐药性机理．结果表明：在突变体中，S-1360结合到耐药突变IN核心区中的位置靠近功能loop 3区却远离与 DNA结合的关键残基，结合位置不同导致S-1360的抑制作用部分丧失；残基138到166区域的柔性对IN发挥生物学功能很重要，S-1360能与DNA结合的关键残基N155及K159形成氢键，这2个氢键作用降低了该区域的柔性，突变体中无类似氢键，因而该区域柔性增高；在突变体中，S-1360的苯环远离病毒DNA结合区，不能阻止病毒DNA末端暴露给宿主DNA；T66I突变导致残基Ⅰ的长侧链占据IN的活性口袋，阻止抑制剂以与野生型中相同的方式结合到活性中心，这均是产生抗药性的重要原因．这些模拟结果与实验结果吻合，可为抗IN的抑制剂设计和改造提供帮助．

A Study on Drug Resistance Mechanism of HIV-1 Integrase Mutants by Molecular Modeling

The drug resistant mutations in human immunodefieiency virus type 1 (HIV-1) are a major impediment to successful highly active antiretrovirai therapy (HAART) and new drug design. In order to understand the drug resistance mechanism of HIV-1 integrase (IN) mutually existed for multiple drug-resistant strains to the most potent IN inhibitors diketo acids (DKAs), three S-1360-resistant HIV-1 strains were selected and molecular docking and molecular dynamics (MD) simulations were performed to obtain the inhibitor binding modes. Based on the binding modes, compelling differences between the wild-type and the 3 mutants for IN have been observed. The results showed that: 1) In the mutants, the inhibitor is close to the funetional loop 3 region but far away from the DNA binding site. Different binding sites lead to the decrease in susceptibility to S-1360 in mutants compared to the wild-type IN. 2) The fluctuations in the region of residues 138～166 are important to the biological function of IN. 2 hydrogen-bonds between S-1360 with residues N155 and K159 restrict the flexibility of the region. Drug resistant mutations result in a lack of the interaction, consequently, the less susceptible to S-1360. 3) In the 3 mutant IN complexes, the benzyl ring of S-1360 is far from the viral DNA binding site, thus, S-1360 can not prevent the end of the viral DNA from exposure to human DNA. 4) After T66I mutation, the long side chain of I occupied the active pocket in the 3 mutants, consequently, the inhibitor could not move into the same binding site or have the same orientation. All the above contribute to drug resistance. These results will be useful for the rational inhibitor modify and design.