X-ray analysis of an RNA tetraplex (UGGGGU)4 with divalent Sr2+ ions at subatomic resolution (0.61Ã…)
X-ray analysis of an RNA tetraplex (UGGGGU)4 with divalent Sr2+ ions at subatomic resolution (0.61Ã…)
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DOI：
10.1073/pnas.241374798
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发表时间：
2001-11-20
影响因子：
11.1
通讯作者：
Sundaralingam, M
中科院分区：
文献类型：
--
作者：
Deng, JP;Xiong, Y;Sundaralingam, M
RNA 中的四链鸟嘌呤四链体已被鉴定参与重要的生物学功能，例如逆转录病毒 RNA 的二聚化、翻译抑制和 mRNA 周转。然而，这些生物过程的结构基础仍然很大程度上未知。在这里，我们以超高分辨率（0.61 埃）报告了 RNA 四链体结构 (UGGGGU)(4)。空间群为 P42(1)2，晶胞常数为 a = b = 36.16 埃和 c = 74.09 埃。使用同晶溴代衍生物b,UGGGGU的一组三波长数据，通过多波长反常色散法求解该结构，并精化至0.61埃分辨率。不对称单元中的每条链均与对称相关分子形成平行四链体。四链体分子以相反极性（头对头或尾对高）彼此堆叠，形成伪连续柱。所有 5' 端尿苷都围绕 G2 的主链旋转、摆动并与相邻的 G 四链体形成独特的八链体，而 3' 端尿苷则堆叠在一起并形成尿苷四联体。所有碱基都是反碱基，核糖处于混合 C2'- 和 C3'- 褶皱模式。在每个其他鸟嘌呤四分体平面中都观察到锶离子，位于四重轴上，并与双锥反棱镜几何结构中相邻鸟嘌呤碱基的八个 O6 原子相关联。在结构中可以清楚地观察到氢。
Four-stranded guanine tetraplexes in RNA have been identified to be involved in crucial biological functions, such as dimerization of retroviral RNA, translational repression, and mRNA turnover. However, the structural basis for these biological processes is still largely unknown. Here we report the RNA tetraplex structure (UGGGGU)(4) at ultra-high resolution (0.61 Angstrom). The space group is P42(1)2, and cell constants are a = b = 36.16 Angstrom and c = 74.09 Angstrom. The structure was solved by the multiple-wavelength anomalous dispersion method using a set of three-wavelength data of the isomorphous bromo derivative b,UGGGGU and refined to 0.61-Angstrom resolution. Each of the four strands in the asymmetric unit forms a parallel tetraplex with symmetry-related molecules. The tetraplex molecules stack on one another in opposite polarity (head-to-head or tail-to-tall) to form a pseudocontinuous column. All of the 5'-end uridines rotate around the backbone of G2, swing out, and form unique octaplexes with the neighboring G tetraplexes, whereas the 3'-end uridines are stacked-in and form uridine tetrads. All of the bases are anti, and the riboses are in the mixed C2'- and C3'-puckering mode. Strontium ions are observed in every other guanine tetrad plane, sitting on the fourfold axis and associated to the eight O6 atoms of neighboring guanine bases in a bipyramidal-antiprism geometry. The hydrogens are clearly observed in the structure.