Locked nucleic acid (LNA) recognition of RNA:: NMR solution structures of LNA:RNA hybrids
Locked nucleic acid (LNA) recognition of RNA:: NMR solution structures of LNA:RNA hybrids
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DOI：
10.1021/ja012288d
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发表时间：
2002-05-29
影响因子：
15
通讯作者：
Jacobsen, JP
中科院分区：
文献类型：
--
作者：
Petersen, M;Bondensgaard, K;Jacobsen, JP
含有一个或多个2'-O,4'-C-亚甲基连接的双环核糖核苷单体的锁核酸（LNA）具有有效反义寡核苷酸的许多先决条件，例如与同源 RNA 和 DNA 杂交时具有前所未有的螺旋热稳定性。为了详细了解 LNA 的结构特征，从而产生其卓越的性能，我们利用 NMR 光谱进行了结构研究，现在报告了两种 LNA:RNA 杂交体的高分辨率结构，LNA 链分别为 d(5'-CTGAT(L)ATGC-3') 和 d(5-CT(L)GAT(L)AT(L)GC-3')，T-L 表示具有胸腺嘧啶碱基的修饰的LNA单体，以及未修饰的DNA:RNA杂合体。在结构中，LNA核苷酸的位置参与碱基堆积和沃森-克里克碱基配对，并且随着LNA核苷酸的包含，我们观察到双链体几何形状向A样双链体结构的逐渐变化。因此，通过包含三个 LNA 核苷酸，杂交体采用了几乎规范的 A 型双链体几何形状，因此看起来修饰数量在结构变化方面已达到饱和水平，并且进一步的掺入只会在双链体结构中提供微小的变化。我们试图合理化由LNA核苷酸诱导的构象转向，表明由LNA修饰引入的小沟边缘电子密度的变化导致T侧翼核苷酸的假旋转轮廓的改变，从而使这种糖平衡向N型构象转变。
Locked nucleic acids (LNAs) containing one or more 2'-O,4'-C-methylene-linked bicyclic ribonucleoside monomers possess a number of the prerequisites of an effective antisense oligonucleotide, e.g. unprecedented helical thermostability when hybridized with cognate RNA and DNA. To acquire a detailed understanding of the structural features of LNA giving rise to its remarkable properties, we have conducted structural studies by use of NMR spectroscopy and now report high-resolution structures of two LNA:RNA hybrids, the LNA strands being d(5'-CTGAT(L)ATGC-3') and d(5-CT(L)GAT(L)AT(L)GC-3'), respectively, T-L denoting a modified LNA monomer with a thymine base, along with the unmodified DNA:RNA hybrid, In the structures, the LNA nucleotides are positioned as to partake in base stacking and Watson-Crick base pairing, and with the inclusion of LNA nucleotides, we observe a progressive change in duplex geometry toward an A-like duplex structure. As such, with the inclusion of three LNA nucleotides, the hybrid adopts an almost canonical A-type duplex geometry, and thus it appears that the number of modifications has reached a saturation level with respect to structural changes, and that further incorporations would furnish only minute changes in the duplex structure. We attempt to rationalize the conformational steering induced by the LNA nucleotides by suggesting that the change in electronic density at the brim of the minor groove, introduced by the LNA modification, is causing an alteration of the pseudo rotational profile of the T-flanking nucleotide, thus shifting this sugar equilibrium toward N-type conformation.