NMR研究人类蛋白Sin3A-PAH2调控TNBC相关基因转录的分子机制

转录辅助调控因子Sin3A是三阴性乳腺癌（TNBC）的重要致病蛋白。Sin3A的PAH2结构域能结合多种转录因子，发挥抑制基因转录的作用，是潜在的癌症治疗靶点。自由态Sin3A-PAH2呈两种构象，并且在毫秒时间尺度进行构象交换。目前，两种构象的结构均未被解析。申请人前期发现其中一种构象与SID结合态相似，因此猜想Sin3A-PAH2的两种构象分别为不利于SID结合的基态和利于SID结合的激发态。本项目计划通过样品制备和NMR实验条件优化，使Sin3A-PAH2分别稳定在基态和激发态构象并解析结构，并利用CEST等方法分析两种构象的动态交换。进一步探讨激发态与SID结合态结构的异同以及结合动力学，论证“构象选择”模型。本项目预期首次解析自由态Sin3A-PAH2的结构，阐释其中的构象转换以及与SID配体结合的动态学机制，加深对于Sin3A功能的认识，有助于相关疾病如TNBC的精准治疗。

Sin3A is an important pathogenic protein of triple negative breast cancer (TNBC). The PAH2 domain of Sin3A can bind the SID domain of various transcription factors to inhibit gene transcription, which is a potential target for cancer therapy. The free state of Sin3A-PAH2 adopts two conformations that exchange on a millisecond time scale. At present, the structures of both conformations have not been solved. We found that one of the conformations was similar to the SID-bound state, so it was assumed that the two conformations of Sin3A-PAH2 were the ground state not binding to SID and the excited state binding to SID strongly. Through optimizations of sample preparation and NMR experimental conditions, this project plans to stabilize Sin3A-PAH2 in the ground state and excited state conformation respectively, solve the structures, and analyze the dynamic exchange of the two conformations using CEST and other methods. Then, the similarities and differences of the structures of the excited state and the SID-bound state as well as the SID-binding dynamics are further explored, so as to demonstrate the conformational selection model of Sin3A-PAH2/SID binding. This project is expected to report the free-state structure of Sin3A-PAH2 for the first time, elucidate the dynamic conformational exchange and the binding mechanism of Sin3A-PAH2 for SID ligand, and deepen the understanding of Sin3A function, which is helpful for the precise treatment of SIN3A-related diseases such as TNBC.