Structural Studies of a Trinucleotide Repeat Sequence Using 2-Aminopurine
Structural Studies of a Trinucleotide Repeat Sequence Using 2-Aminopurine
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DOI：
10.1021/bi802225y
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发表时间：
2009-03-24
期刊：
影响因子：
2.9
通讯作者：
Petty, Jeffrey T.
中科院分区：
文献类型：
--
作者：
Degtyareva, Natalya N.;Reddish, Michael J.;Petty, Jeffrey T.
重复三核苷酸序列的二级结构导致多种神经退行性疾病的发生，这些研究考虑了形成茎环发夹的(CAG)(8)序列。使用 2-氨基嘌呤取代该重复序列中六个位置的腺嘌呤来评估该发夹的结构和热力学性质。圆二色光谱和热变性实验表明二级结构没有受到修饰的干扰。使用2-氨基嘌呤的荧光强度、相对于变性状态的强度变化以及荧光对丙烯酰胺猝灭的敏感性来监测发夹的局部结构。为了建立 (CAG)(8) 中的茎和环特征，使用了茎、环和暴露碱基基序的已知参考点。在环附近，碱基变得更加暴露于溶剂，这表明与这种重复发夹相关的不稳定性影响整体二级结构。这些结果为解释其他重复（CAG）结构所采用的结构提供了基础。
The secondary structure of repeated trinucleotide sequences results in the development of several neurodegenerative diseases, and these studies consider the (CAG)(8) sequence that forms a stem-loop hairpin. The structural and thermodynamic properties of this hairpin are assessed using 2-aminopurine substitutions for adenine at six positions in this repeated sequence. Circular dichroism spectra and thermal denaturation experiments show that the secondary structure is not disturbed by the modifications. The local structure of the hairpin was monitored using the fluorescence intensities of 2-aminopurines, the changes in the intensity relative to the denatured state, and the sensitivity of the fluorescence to quenching by acrylamide. To establish the stem and loop characteristics in (CAG)(8), known reference points for stem, loop, and exposed base motifs were used. In the vicinity of the loop, the bases become more solvent exposed, which suggests that the instability associated with this repeated hairpin influences the global secondary structure. These results provide the basis to interpret the structures adopted by other repeated (CAG) structures.