An intramolecular quadruplex of (GGA)4 triplet repeat DNA with a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad, and its dimeric interaction
An intramolecular quadruplex of (GGA)4 triplet repeat DNA with a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad, and its dimeric interaction
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DOI：
10.1006/jmbi.2001.5047
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发表时间：
2001-10-19
影响因子：
5.6
通讯作者：
Katahira, M
中科院分区：
文献类型：
--
作者：
Matsugami, A;Ouhashi, K;Katahira, M
在生理K+条件下，已确定了含有GGA三联体序列的四个串联重复的d（GGAGGAGGAGGA）的结构。d（GGAGGAGGAGGA）折叠成由G：G：G：G四联体和G（：A）：G（：A）：G（：A）：G七联体组成的分子内四链体。d（GGAGGAGGAGGA）的四个G-G片段由于在GGA和GAGG片段中的每一个处的主链的六个连续转角而彼此平行排列。两个四链体形成通过两个四链体的七端之间的堆叠相互作用稳定的二聚体。D结构的比较（GGAGGAGGAGGA），其具有d（GGAGGAN）的报道结构（N = G或T）的GGA三联体的两个串联重复序列，发现虽然两种结构在一定程度上相似，但GGA三联体重复序列的延伸导致了明显的结构差异：12-mer的分子内四链体与7-mer的分子间四链体;四链体中的七肽对六肽;以及每个四链体三个剪切G：A碱基对两个剪切G：A碱基对加一个A：A碱基对。也有人建议，d（GGAGGAGGAGGA）在低盐浓度条件下形成类似的四链体。这与d（GGAGGAN）（N = G或T）的情况相反，其在低盐浓度条件下形成双链体。在此基础上，讨论了天然GGA三联体重复DNA的结构。
The structure of d(GGAGGAGGAGGA) containing four tandem repeats of a GGA triplet sequence has been determined under physiological K+ conditions. d(GGAGGAGGAGGA) folds into an intramolecular quadruplex composed of a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad. Four G-G segments of d(GGAGGAGGAGGA) are aligned parallel with each other due to six successive turns of the main chain at each of the GGA and GAGG segments. Two quadruplexes form a dimer stabilized through a stacking interaction between the heptads of the two quadruplexes. Comparison of the structure of d(GGAGGAGGAGGA) with the reported structure of d(GGAGGAN) (N = G or T) containing two tandem repeats of the GGA triplet revealed that although the two structures resemble each other to some extent, the extension of the repeats of the GGA triplet leads to distinct structural differences: intramolecular quadruplex for 12-mer versus intermolecular quadruplex for 7-mer; heptad versus hexad in the quadruplex; and three sheared G:A base-pairs versus two sheared G:A base-pairs plus one A:A base-pair per quadruplex. It was also suggested that d(GGAGGAGGAGGA) forms a similar quadruplex under low salt concentration conditions. This is in contrast to the case of d(GGAGGAN) (N = G or T), which forms a duplex under low salt concentration conditions. On the basis of these results, the structure of naturally occurring GGA triplet repeat DNA is discussed.