Intramolecular folding in human ILPR fragment with three C-rich repeats.
Intramolecular folding in human ILPR fragment with three C-rich repeats.
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DOI：
10.1371/journal.pone.0039271
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Mao H
中科院分区：
文献类型：
--
作者：
Dhakal S;Lafontaine JL;Yu Z;Koirala D;Mao H
在人类基因组的重要功能区域，富鸟嘌呤(G)和富胞嘧啶(C)序列的4个串联重复序列的富集预示着这些序列中可能形成的四链DNA结构，如G-四重体和i-motif的生物学意义。然而，关于G或C富序列少于4个串联重复序列的分子内非b DNA结构形成的报道很少。在这里，我们利用单分子水平的机械展开、电泳迁移位移测定（EMSA）、圆二色性（CD）和紫外（UV）光谱，报道了在人胰岛素相关多态性区（ILPR）中，在3个富含胞嘧啶的串联重复序列5'-TGTC4ACAC4TGTC4ACA （ILPR- i3）中发现了分子内折叠的非b DNA结构。对具有系统C到T突变的序列的热变性分析表明，该结构是由两个末端C4束之间的一堆半质子化胞嘧啶对所控制的。对ILPR-I3和5 ' -C4TGT片段的混合物进行机械展开和Br2足迹实验进一步表明，该结构是分子间i-motif形成的构建块。这种构象在酸性或中性pH下的存在符合ILPR i-motif结构的单链折叠途径。
Enrichment of four tandem repeats of guanine (G) rich and cytosine (C) rich sequences in functionally important regions of human genome forebodes the biological implications of four-stranded DNA structures, such as G-quadruplex and i-motif, that can form in these sequences. However, there have been few reports on the intramolecular formation of non-B DNA structures in less than four tandem repeats of G or C rich sequences. Here, using mechanical unfolding at the single-molecule level, electrophoretic mobility shift assay (EMSA), circular dichroism (CD), and ultraviolet (UV) spectroscopy, we report an intramolecularly folded non-B DNA structure in three tandem cytosine rich repeats, 5'-TGTC4ACAC4TGTC4ACA (ILPR-I3), in the human insulin linked polymorphic region (ILPR). The thermal denaturation analyses of the sequences with systematic C to T mutations have suggested that the structure is linchpinned by a stack of hemiprotonated cytosine pairs between two terminal C4 tracts. Mechanical unfolding and Br2 footprinting experiments on a mixture of the ILPR-I3 and a 5′-C4TGT fragment have further indicated that the structure serves as a building block for intermolecular i-motif formation. The existence of such a conformation under acidic or neutral pH complies with the strand-by-strand folding pathway of ILPR i-motif structures.
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影响因子：
2.9
作者：
MARKY, LA;BRESLAUER, KJ
通讯作者：
BRESLAUER, KJ
DOI：
10.1073/pnas.0508584102
发表时间：
2005-11-29
影响因子：
11.1
作者：
Laurence, TA;Kong, XX;Weiss, S
通讯作者：
Weiss, S
影响因子：
14.9
作者：
GRAY, DM;CUI, T;RATLIFF, RL
通讯作者：
RATLIFF, RL
影响因子：
64.8
作者：
BROWN, F;NEWMAN, J;FELLNER, P
通讯作者：
FELLNER, P
DOI：
10.1126/science.1172926
发表时间：
2009-07-31
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Hodges C;Bintu L;Lubkowska L;Kashlev M;Bustamante C
通讯作者：
Bustamante C