Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
Int J Mol Sci. 2022 May 23;23(10):5850. doi: 10.3390/ijms23105850.
Among types of trinucleotide repeats, there is some disproportion in the frequency of their occurrence in the human exome. This research presents new data describing the folding and thermodynamic stability of short, tandem RNA repeats of 23 types, focusing on the rare, yet poorly analyzed ones. UV-melting experiments included the presence of PEG or potassium and magnesium ions to determine their effect on the stability of RNA repeats structures. Rare repeats predominantly stayed single-stranded but had the potential for base pairing with other partially complementary repeat tracts. A coexistence of suitably complementary repeat types in a single RNA creates opportunities for interaction in the context of the secondary structure of RNA. We searched the human transcriptome for model RNAs in which different, particularly rare trinucleotide repeats coexist and selected the and RNAs to study intramolecular interactions between the repeat tracts that they contain. In vitro secondary structure probing results showed that the UAA and UUG repeat tracts, present in 3' UTR, form a double helix, which separates one of its structural domains. For the RNA ORF fragment containing four short AGG repeat tracts and the CGU tract, we proved the formation of quadruplexes that blocked reverse transcription.
在三核苷酸重复类型中，它们在人类外显子中的出现频率存在一些不均衡。本研究提供了新的数据，描述了 23 种短串联 RNA 重复的折叠和热力学稳定性，重点关注罕见但分析不足的重复。UV 融解实验包括 PEG 或钾和镁离子的存在，以确定它们对 RNA 重复结构稳定性的影响。罕见的重复主要保持单链，但具有与其他部分互补重复片段配对的潜力。在单个 RNA 中合适的互补重复类型共存为 RNA 二级结构背景下的相互作用创造了机会。我们在人类转录组中搜索具有不同的、特别是罕见的三核苷酸重复的模型 RNA，并选择 和 RNA 来研究它们所包含的重复片段之间的分子内相互作用。体外二级结构探测结果表明，存在于 3'UTR 中的 UAA 和 UUG 重复片段形成一个双链体，将其结构域之一分开。对于含有四个短 AGG 重复片段和 CGU 片段的 RNA ORF 片段，我们证明了形成阻止逆转录的四聚体。
