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首页> 外文期刊>Biochemistry >Stability and structure of telomeric DNA sequences forming quadruplexes containing four G-tetrads with different topological arrangements.
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Stability and structure of telomeric DNA sequences forming quadruplexes containing four G-tetrads with different topological arrangements.

机译：端粒DNA序列的稳定性和结构，形成包含四个具有不同拓扑排列的G-四联体的四链体。

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摘要

Telomeres are DNA-protein structures at the ends of eukaryotic chromosomes, the DNA of which comprise noncoding repeats of guanine-rich sequences. Telomeric DNA plays a fundamental role in protecting the cell from recombination and degradation. Telomeric sequences can form quadruplex structures stabilized by guanine quartets. These structures can be constructed from one, two, or four oligonucleotidic strands. Here, we report the thermodynamic characterization of the stability, analyzed by differential scanning calorimetry, of three DNA quadruplexes of different molecularity, all containing four G-tetrads. The conformational properties of these quadruple helices were studied by circular dichroism. The investigated oligomers form well-defined G-quadruplex structures in the presence of sodium ions. Two have the truncated telomeric sequence from Oxytricha, d(TGGGGT) and d(GGGGTTTTGGGG), which form a tetramolecular and bimolecular quadruplex, respectively. The third sequence, d(GGGGTTGGGGTGTGGGGTTGGGG) was designed to form a unimolecular quadruplex. The thermodynamic parameters of these quadruplexes have been determined. The tetramolecular structure is thermodynamically more stable than the bimolecular one, which, in turn, is more stable than the unimolecular one. The experimental data were discussed in light of the molecular-modeling study.
机译：端粒是真核染色体末端的DNA-蛋白质结构，其DNA包含富含鸟嘌呤序列的非编码重复。端粒DNA在保护细胞免于重组和降解中起着基本作用。端粒序列可以形成由鸟嘌呤四联体稳定的四链体结构。这些结构可以由1、2或4个寡核苷酸链构建。在这里，我们报告了通过差示扫描量热法分析的三个不同分子的DNA四链体的稳定性的热力学特性，它们都包含四个G-四联体。通过圆二色性研究了这些四重螺旋的构象性质。研究的低聚物在钠离子存在下形成定义明确的G-四链体结构。两个具有来自Oxytricha的截短的端粒序列，d（TGGGGT）和d（GGGGTTTTGGGG），分别形成四分子和双分子四链体。设计第三序列d（GGGGTTGGGGTGTGGGGTTGGGG）以形成单分子四链体。已经确定了这些四链体的热力学参数。四分子结构在热力学上比双分子结构稳定，而双分子结构又比单分子结构稳定。根据分子模型研究讨论了实验数据。

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