Role of locked nucleic acid modified complementary strand in quadruplex/Watson-Crick duplex equilibrium
Role of locked nucleic acid modified complementary strand in quadruplex/Watson-Crick duplex equilibrium
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DOI：
10.1021/jp072705u
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发表时间：
2007-10-25
影响因子：
3.3
通讯作者：
Maiti, Souvik
中科院分区：
文献类型：
--
作者：
Kumar, Niti;Maiti, Souvik
在人类基因组中，形成四链体的富含G的序列与它们的富含C的互补链一起沿着存在;这表明四链体和沃森克里克双链体之间存在平衡，这允许它们各自的生物学功能的执行。我们已经通过采用锁核酸（LNA）修饰的互补链研究了这种平衡对药物的敏感性，并证明了稳定的端粒四链体d[（G（3）TTA）（3）G（3）]的成功侵入。荧光，UV，ITC，和SPR的研究进行了解的结合过程中涉及的预形成的四链体和LNA修饰的互补链相比，涉及未修饰的互补链。我们的数据表明，互补链中的LNA修饰使平衡向双链体状态移动。这些修饰赋予双链体增加的热力学稳定性，并增加双链体和四链体之间的相对自由能（AAG度）差异的大小，从而有利于双链体群体相对于四链体的优势。LNA修饰的互补链的这种上级能力可以被利用来为探索性的方法铺平道路，在该方法中，它与端粒四链体杂交并驱动双链体形成，并且抑制引导端粒延伸的端粒酶的RNA模板对富含3'G的突出端的识别。
In the human genome, the G-rich sequences that form quadruplexes are present along with their C-rich complementary strands; this suggests the existence of equilibrium between a quadruplex and a WatsonCrick duplex which allows the execution of their respective biological functions. We have investigated the sensitivity of this equilibrium to pharmacological agents by employing locked nucleic acid (LNA) modified complementary strands, and demonstrated successful invasion of the stable telomeric quadruplex d[(G(3)TTA)(3)G(3). Fluorescence, UV, ITC, and SPR studies were performed to understand the binding process involving the preformed quadruplex and LNA-modified complementary strands compared with that involving the unmodified complementary strand. Our data indicate that LNA modifications in the complementary strand shift the equilibrium toward the duplex state. These modifications confer increased thermodynamic stability to the duplex and increase the magnitude of relative free energy (AAG degrees) difference between duplex and quadruplex, thus favoring the predominance of duplex population over quadruplex. This superior ability of LNA-modified complementary strand can be exploited to pave an exploratory approach in which it hybridizes to a telomeric quadruplex and drives duplex formation, and inhibits the recognition of 3' G-rich overhang by RNA template of telomerase which guides telomere extension.