G-Quadruplex Motifs Arranged in Tandem Occurring in Telomeric Repeats and the Insulin-Linked Polymorphic Region
G-Quadruplex Motifs Arranged in Tandem Occurring in Telomeric Repeats and the Insulin-Linked Polymorphic Region
复制标题
DOI：
10.1021/bi2003235
复制
发表时间：
2011-09-06
期刊：
影响因子：
2.9
通讯作者：
Viglasky, Viktor
中科院分区：
文献类型：
--
作者：
Bauer, Lubos;Tluckova, Katarina;Viglasky, Viktor
到目前为止，在人类基因组中已经报道了各种G-四链结构。有许多研究一般集中在四链形成序列上，但很少有研究集中在同一分子中的两个或两个以上四链，这些四链最常见于端粒DNA和其他串联重复序列，例如胰岛素连接多态区域(ILPR)。虽然人类端粒由许多重复序列组成，但由于结构的复杂性，较少讨论高阶G-四链结构。本研究利用圆二色谱、紫外光谱和温度梯度凝胶电泳法对d(G(4)TgT)、d(G(3)T(2)A)和(或)d(G(4)T(2)A)的4-12个重复序列进行了研究。这些序列作为端粒中四链排列和溶液中ILPR的模型。我们的主要发现如下。(1)富G重复数对G-四链体稳定性有很大影响。(Ii)证实了四链-四链相互作用的证据。(3)首次在单次实验中直接观察到不同构象物的熔融行为。我们的结果与其他量热和光谱数据以及通过单分子研究、原子力显微镜和光学镊子机械展开获得的数据一致。我们认为端粒的末端只能由几个串联的四链(少于三个)组成。我们的发现提高了我们对基因富含G的调节部分和端粒末端长重复序列中G-四链形成机制的理解。
To date, various G-quadruplex structures have been reported in the human genome. There are numerous studies focusing on quadruplex-forming sequences in general, but few studies have focused on two or more quadruplexes in the same molecule, which are most commonly found in telomeric DNA and other tandem repeats, e.g., insulin-linked polymorphic region (ILPR). Although the human telomere consists of a number of repeats, higher-order G-quadruplex structures are discussed less often because of the complexity of the structures. In this study, sequences consisting of 4-12 repeats of d(G(4)TGT), d(G(3)T(2)A), and/or d(G(4)T(2)A) have been studied by circular dichroism, ultraviolet spectroscopy, and temperature-gradient gel electrophoresis. These sequences serve as a model for the arrangement of quadruplexes in the telomere and ILPR in solution. Our major findings are as follows. (i) The number of G-rich repeats has a great influence on G-quadruplex stability. (ii) The evidence of quadruplex-quadruplex interaction is confirmed. (iii) For the first time, we directly observed the melting behavior of different conformers in a single experiment. Our results agree with other calorimetric and spectroscopic data and data obtained by single-molecule studies, atomic force microscopy, and mechanical unfolding by optical tweezers. We propose that the end of telomeres can be formed by only a few tandem quadruplexes (fewer than three). Our findings improve our understanding of the mechanism of G-quadruplex formation in long repeats in G-rich-regulating parts of genes and telomere-ends.