Unfolding rates of 1:1 and 2:1 complex of CX-5461 and c-MYC promoter G-quadruplexes revealed by single-molecule force spectroscopy  

作　　者：Hui Peng Yashuo Zhang Qun Luo Xinyu Wang Huijuan You 

机构地区：[1]Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation,School of Pharmacy,Tongji Medical College,Huazhong University of Science and Technology,Wuhan 430030,China [2]College of Physics Science and Technology,Yangzhou University,Yangzhou 225009,China

出　　处：《Biophysics Reports》2024年第3期180-189,共10页生物物理学报（英文版）

基　　金：financially supported in part by grants from the National Natural Science Foundation of China (32171225)。

摘　　要：CX-5461, also known as pidnarulex, is a strong G4 stabilizer and has received FDA fast-track designation for BRCA1-and BRCA2-mutated cancers. However, quantitative measurements of the unfolding rates of CX-5461-G4 complexes which are important for the regulation function of G4s, remain lacking.Here, we employ single-molecule magnetic tweezers to measure the unfolding force distributions of c-MYC G4s in the presence of different concentrations of CX-5461. The unfolding force distributions exhibit three discrete levels of unfolding force peaks, corresponding to three binding modes. In combination with a fluorescent quenching assay and molecular docking to previously reported ligand-c-MYC G4 structure, we assigned the 69 pN peak corresponding to the 1:1(ligand:G4) complex where CX-5461binds at the G4's 5'-end. The 84 p N peak is attributed to the 2:1 complex where CX-5461 occupies both the 5' and 3'. Furthermore, using the Bell-Arrhenius model to fit the unfolding force distributions,we determined the zero-force unfolding rates of 1:1, and 2:1 complexes to be(2.4 ± 0.9) × 10^(-8) s^(-1) and(1.4 ± 1.0) × 10^(-9) s^(-1) respectively. These findings provide valuable insights for the development of G4-targeted ligands to combat c-MYC-driven cancers.

关 键 词：SINGLE-MOLECULE G-QUADRUPLEX Magnetic tweezers STOICHIOMETRY Force spectroscopy Pidnarulex 

分 类 号：Q75[生物学—分子生物学]