Placement of protein and RNA structures into a 5 Å-resolution map of the 50S ribosomal subunit
Placement of protein and RNA structures into a 5 Å-resolution map of the 50S ribosomal subunit
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DOI：
10.1038/23641
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发表时间：
1999-08-26
期刊：
影响因子：
64.8
通讯作者：
Steitz, TA
中科院分区：
文献类型：
--
作者：
Ban, N;Nissen, P;Steitz, TA
我们利用四种重原子衍生物、晶间密度平均和密度修饰程序得到的相，在5.0埃分辨率下计算出了来自细菌Haloarcula marismortui的大50S核糖体亚基的电子密度图。超过300个a型RNA双工碱基对，以及非a型RNA双工、单链片段和四环的区域都被纳入了这张图谱。交叉在亚基上的RNA长棒是由短而独立的双螺旋堆积而成的，并不是所有的双螺旋都是a型的，在许多地方，蛋白质将两个或更多的双螺旋交联。多肽出口通道由钨簇化合物结合在一个重原子衍生化晶体中标记。我们通过拟合核糖体蛋白L6、L11和L14的晶体结构、肌毒素-蓖麻毒素环RNA和结合L11的RNA序列，确定了翻译因子结合中心的结构。我们可以将延伸因子a或延伸因子Tu与氨基酰化的转移RNA和GTP络合在因子结合中心上，其方式与生化和电子显微镜研究的结果一致。
We have calculated at 5.0 Angstrom resolution an electron-density map of the large 50S ribosomal subunit from the bacterium Haloarcula marismortui by using phases derived from four heavy-atom derivatives, intercrystal density averaging and density-modification procedures. More than 300 base pairs of A-form RNA duplex have been fitted into this map, as have regions of non-A-form duplex, single-stranded segments and tetraloops. The long rods of RNA crisscrossing the subunit arise from the stacking of short, separate double helices, not all of which are A-form, and in many places proteins crosslink two or more of these rods. The polypeptide exit channel was marked by tungsten cluster compounds bound in one heavy-atom-derivatized crystal. We have determined the structure of the translation-factor-binding centre by fitting the crystal structures of the ribosomal proteins L6, L11 and L14, the sarcin-ricin loop RNA, and the RNA sequence that binds L11 into the electron density. We can position either elongation factor a or elongation factor Tu complexed with an aminoacylated transfer RNA and GTP onto the factor-binding centre in a manner that is consistent with results from biochemical and electron microscopy studies.