Folding Dynamics of Parallel and Antiparallel G-Triplexes under the Influence of Proximal DNA.
Folding Dynamics of Parallel and Antiparallel G-Triplexes under the Influence of Proximal DNA.
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DOI：
10.1021/acs.jpcb.8b08110
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
Xi-Ming Lu;Hui Li;Jing You;Wei Li;Peng-Ye Wang;Ming Li;Shuoxing Dou;X. Xi
中科院分区：
文献类型：
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作者：
Xi-Ming Lu;Hui Li;Jing You;Wei Li;Peng-Ye Wang;Ming Li;Shuoxing Dou;X. Xi
G-三链体是由富含G的序列形成的一种DNA结构。先前的研究表明，它是G-四链体折叠的中间体，具有反平行结构。然而，这种G-三链体结构的折叠动力学至今尚未得到很好的研究。此外，是否存在平行的G-三链体结构仍然未知。本研究利用单分子荧光共振能量转移和圆二色性光谱方法，研究了G-三链体的折叠动力学，首次在单分子水平上揭示了G-三链体同时具有平行和反平行结构。此外，我们还研究了近端DNA对G-三链体折叠的影响。我们已经发现，在G-三链体序列的任一末端的单链TTA和双链DNA都可以降低其折叠速度。更有趣的是，当位于G-三链体序列的5'端时，近端DNA将有利于平行于反平行G-三链体结构的折叠。由于G-三链体是G-四链体折叠的中间体，因此本研究结果也可能在动力学、稳定性和邻近DNA的影响方面对G-四链体结构的折叠特性有新的认识。
The G-triplex is a kind of DNA structure formed by G-rich sequences. Previous studies have shown that it is an intermediate for the folding of G-quadruplex and has an antiparallel structure. The folding dynamics of this G-triplex structure, however, have not been well studied until now. In addition, whether a parallel G-triplex structure exists, remains unknown. In this study, by using single-molecule fluorescence resonance energy transfer and circular dichroism spectroscopy methods, we have studied the folding dynamics of the G-triplex and revealed at the single-molecule level, for the first time, that G-triplexes have both parallel and antiparallel structures. Moreover, we have investigated the effects of proximal DNA on G-triplex folding. We have found that both single-stranded TTA and double-stranded DNA at either end of a G-triplex sequence can reduce its folding speed. More interestingly, when located at the 5' end of a G-triplex sequence, the proximal DNA will favor the folding of parallel over antiparallel G-triplex structures. As G-triplex is an intermediate for G-quadruplex folding, the present results may also shed new light on the folding properties of G-quadruplex structures, in terms of dynamics, stability, and the effects of proximal DNA.