G-四链体结构去稳定剂的作用机制与设计研究

G-四链体的形成影响着多种复杂而精细的生命过程，使用小分子靶向特定G-四链体，降低结构稳定性，可有效减少G-四链体形成带来的困扰。目前，G-四链体结构去稳定剂只是在实验中偶然发现的，缺乏靶向设计去稳定剂的方法。通过基于复合物结构的计算模拟，我们发现小分子先与G-四链体结合，两者动态互作，促成构象改变。为此，申请人提出，揭示构象的动态转变机制，有利于基于机制优化和设计去稳定剂。申请人在伪狂犬病毒基因 IE180 3' UTR区鉴定出一段促进病毒增殖的RNA G-四链体可形成序列，破坏该结构的小分子抑制病毒增殖。本项目针对这个序列，利用单分子实验对该序列构象系综进行动态分析，采用增强采样的分子动力学模拟揭示构象的动态转变机制,基于机制优化现有去稳定剂、发现结构新颖的高选择性去稳定剂。该设计方法的成功应用，将有助于设计小分子扰动核酸结构来验证核酸功能，拓展以核酸为靶点的药物研究体系。

The formation of G-quadruplex affects a variety of complex and delicate life processes. The problems could be reduced by using small molecules to target specific G-quadruplexes and reduce its structural stability. At present, G-quadruplexes destabilizers are discovered by chance, and there are no structure-based methods to design G-quadruplex destabilizers. Through modeling based on the complex crystal structures, we discovered that small molecules initially approached a single G-quadruplex, and then, their dynamic interaction promoted conformational transition. Thus, the applicant proposes that exploration for the dynamic conformational transformation mechanism could benefit for the optimization and design of the destabilizers. In the IE180 3' UTR region of pseudorabies virus, the applicant identified an RNA G-quadruplex forming sequence that promoted virus proliferation, and a molecule destroying the structure inhibited the virus proliferation. This project intends to analyze the conformational ensemble of this sequence by single molecular experiments, and the enhanced sampling molecular dynamics simulation will be employed to reveal the mechanism of dynamic conformational transition. Under the guide of the mechanism, the existing destabilizers could be optimized, and destabilizers with novel structures could be discovered to selectively destabilize a specific G-quadruplex structure. The success of the strategy will help to verify the nucleic acid function by designing small molecules that regulate nucleic acid structures, and to expand the drug discovery system targeting nucleic acids.