Unexpected A-form formation of 4′-thioDNA in solution, revealed by NMR, and the implications as to the mechanism of nuclease resistance
Unexpected A-form formation of 4′-thioDNA in solution, revealed by NMR, and the implications as to the mechanism of nuclease resistance
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DOI：
10.1093/nar/gkn011
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发表时间：
2008-04-01
影响因子：
14.9
通讯作者：
Katahira, Masato
中科院分区：
文献类型：
--
作者：
Matsugami, Akimasa;Ohyama, Takako;Katahira, Masato
完全修饰的4'-硫代DNA是一种仅包含2'-脱氧-4'-硫代核苷的寡核苷酸，除了与RNA更好的杂交之外，还表现出对核酸内切酶的抗性。因此，4'-硫代DNA作为功能性寡核苷酸具有广阔的应用前景。完全修饰的 4'-thioDNA 被发现表现得像 RNA 分子，但除了圆二色性分析的结果外，没有任何关于其结构的细节。在这里，我们通过 NMR 确定了完全修饰的 4'-thioDNA 的结构，其序列为 d(CGCGAATTCGCG)。大多数糖具有 C3'-endo 构象。大沟窄而深，小沟宽而浅。因此，完全修饰的 4'-thioDNA 在局部和整体上都呈现出 RNA 的 A 型特征。报道的 4'-硫代 DNA 的唯一结构表明，含有一些 2'-脱氧-4'-硫代核苷的部分修饰的 4'-硫代 DNA 在晶体形式中呈 B 型。我们首次确定了溶液中 4'-thioDNA 的结构，并证明了两种结构之间意想不到的差异。讨论了 A 型形成的起源。完全修饰的 4'-thioDNA 所报告的显着生化特性（包括核酸酶抗性）根据已阐明的结构得到了合理化。
Fully modified 4'-thioDNA, an oligonucleotide only comprising 2'-deoxy-4'-thionucleosides, exhibited resistance to an endonuclease, in addition to preferable hybridization with RNA. Therefore, 4'-thioDNA is promising for application as a functional oligonucleotide. Fully modified 4'-thioDNA was found to behave like an RNA molecule, but no details of its structure beyond the results of circular dichroism analysis are available. Here, we have determined the structure of fully modified 4'-thioDNA with the sequence of d(CGCGAATTCGCG) by NMR. Most sugars take on the C3'-endo conformation. The major groove is narrow and deep, while the minor groove is wide and shallow. Thus, fully modified 4'-thioDNA takes on the A-form characteristic of RNA, both locally and globally. The only structure reported for 4'-thioDNA showed that partially modified 4'-thioDNA that contained some 2'-deoxy-4'-thionucleosides took on the B-form in the crystalline form. We have determined the structure of 4'-thioDNA in solution for the first time, and demonstrated unexpected differences between the two structures. The origin of the formation of the A-form is discussed. The remarkable biochemical properties reported for fully modified 4'-thioDNA, including nuclease-resistance, are rationalized in the light of the elucidated structure.