Qi Qige, Yang Chunfan, Xia Ye, Guo Shaoshi, Song Di, Su Hongmei
Beijing National Laboratory for Molecular Science, Institute of Chemistry , Chinese Academy of Science , Beijing 100190 , China.
University of Chinese Academy of Science , Beijing 100049 , China.
J Phys Chem Lett. 2019 May 2;10(9):2143-2150. doi: 10.1021/acs.jpclett.9b00637. Epub 2019 Apr 17.
Human telomeric RNA (TERRA) containing thousands of G-rich repeats has the propensity to form parallel-stranded G-quadruplexes. The emerging crucial roles of TERRA G-quadruplexes in RNA biology fuel increasing attention for studying anticancer ligand binding with such structures, which, however, remains scarce. Here we utilized multiple steady-state and time-resolved spectroscopy analyses in conjunction with NMR methods and investigated thoroughly the binding behavior of TMPyP4 to a TERRA G-quadruplex dimer formed by the 10-nucleotide sequence r(GGGUUAGGGU). It is clearly identified that TMPyP4 intercalates into the 5'-5' stacking interface of two G-quadruplex blocks with a binding stoichiometry of 1:1 and binding constant of 1.92 × 10 M. This is consistent with the unique TERRA structural features of the enlarged π-π stacking plane of the A·(G·G·G·G)·A hexad at 5'-ends of each G-quadruplex block. The preferential binding of π-ligand porphyrin to the 5'-5' stacking interface of the native TERRA G-quadruplex dimer is first ascertained by the combination of dynamics and structural characterization.
含有数千个富含鸟嘌呤重复序列的人类端粒RNA（TERRA）倾向于形成平行链G-四链体。TERRA G-四链体在RNA生物学中日益凸显的关键作用，引发了人们对研究抗癌配体与此类结构结合的更多关注，然而，相关研究仍然匮乏。在此，我们结合核磁共振方法，利用多种稳态和时间分辨光谱分析，深入研究了TMPyP4与由10个核苷酸序列r(GGGUUAGGGU)形成的TERRA G-四链体二聚体的结合行为。明确鉴定出TMPyP4以1:1的结合化学计量比插入到两个G-四链体结构域的5'-5'堆积界面，结合常数为1.92×10 M。这与每个G-四链体结构域5'-末端A·(G·G·G·G)·A六联体扩大的π-π堆积平面的独特TERRA结构特征一致。通过动力学和结构表征相结合，首次确定了π-配体卟啉对天然TERRA G-四链体二聚体5'-5'堆积界面的优先结合。
