Hydration and recognition of methylated CpG steps in DNA
Hydration and recognition of methylated CpG steps in DNA
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DOI：
10.1093/emboj/17.9.2709
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发表时间：
1998-05-01
期刊：
影响因子：
11.4
通讯作者：
Timsit, Y
中科院分区：
文献类型：
--
作者：
Mayer-Jung, C;Moras, D;Timsit, Y
对 A-DNA 十聚物的三个高分辨率（1.7、2.15 和 2.2 埃）晶体结构中甲基化 CpG 步骤周围的水合模式的分析表明，胞嘧啶残基的甲基水合良好。在将天然结构与在其 CpG 步骤完全甲基化的十聚物 d(CCGCCGGCGG) 的两种结构不同形式进行比较时，本研究还表明，在某些结构和序列背景下，甲基化胞嘧啶碱基可以比未修饰的碱基更加水合。这些水分子似乎通过形成 C-H ... O 相互作用而稳定在甲基前面。此外，这些结构首次观察到镁阳离子与 A-DNA 主沟的结合，并揭示了甲基化双链体和天然双链体中金属结合的两种不同模式。这些发现表明甲基化胞嘧啶碱基可以通过其紧密结合的水分子被蛋白质或DNA极性残基识别。
The analysis of the hydration pattern around methylated CpG steps in three high resolution (1.7, 2.15 and 2.2 Angstrom) crystal structures of A-DNA decamers reveals that the methyl groups of cytosine residues are well hydrated, In comparing the native structure with two structurally distinct forms of the decamer d(CCGCCGGCGG) fully methylated at its CpG steps, this study shows also that in certain structural and sequence contexts, the methylated cytosine base can be more hydrated that the unmodified one. These water molecules seem to be stabilized in front of the methyl group through the formation C-H ... O interactions. In addition, these structures provide the first observation of magnesium cations bound to the major groove of A-DNA and reveal two distinct modes of metal binding in methylated and native duplexes. These findings suggest that methylated cytosine bases could be recognized by protein or DNA polar residues through their tightly bound water molecules.