Single-molecule investigation of G-quadruplex folds of the human telomere sequence in a protein nanocavity
Single-molecule investigation of G-quadruplex folds of the human telomere sequence in a protein nanocavity
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DOI：
10.1073/pnas.1415944111
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发表时间：
2014-10-07
影响因子：
11.1
通讯作者：
Burrows, Cynthia J.
中科院分区：
文献类型：
--
作者：
An, Na;Fleming, Aaron M.;Burrows, Cynthia J.
人类端粒DNA由5‘-TTAGGG-3’序列的串联重复序列组成，可以折叠成各种G-四链，包括杂交折叠、篮子折叠和螺旋桨折叠。在这份报告中，我们展示了利用α-溶血素离子通道通过DNA-蛋白质相互作用提供依赖于结构的电信号，在纳米尺度上分析这些微妙的拓扑变化。虽然混合体和篮子折叠的尺寸允许它们进入蛋白质前厅，但螺旋桨折叠超过了闩锁区域的大小，只产生了短暂的碰撞。在将25聚体的聚-2‘-脱氧腺苷延伸到这些结构上后，也评估了解离动力学。去折叠过程发生的位置和G-四联体的分子形状在决定其去折叠轮廓方面都起着重要的作用。这些结果为a-溶血素作为区分纳米结构的分子筛的应用以及DNA二级结构可能给纳米孔技术带来的潜在技术障碍提供了见解。
Human telomeric DNA consists of tandem repeats of the sequence 5'-TTAGGG-3' that can fold into various G-quadruplexes, including the hybrid, basket, and propeller folds. In this report, we demonstrate use of the alpha-hemolysin ion channel to analyze these subtle topological changes at a nanometer scale by providing structure-dependent electrical signatures through DNA-protein interactions. Whereas the dimensions of hybrid and basket folds allowed them to enter the protein vestibule, the propeller fold exceeds the size of the latch region, producing only brief collisions. After attaching a 25-mer poly-2'-deoxyadenosine extension to these structures, unraveling kinetics also were evaluated. Both the locations where the unfolding processes occur and the molecular shapes of the G-quadruplexes play important roles in determining their unfolding profiles. These results provide insights into the application of a-hemolysin as a molecular sieve to differentiate nanostructures as well as the potential technical hurdles DNA secondary structures may present to nanopore technology.