60S ribosome biogenesis requires rotation of the 5S ribonucleoprotein particle
60S ribosome biogenesis requires rotation of the 5S ribonucleoprotein particle
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DOI：
10.1038/ncomms4491
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发表时间：
2014-03-01
影响因子：
16.6
通讯作者：
Beckmann, Roland
中科院分区：
文献类型：
--
作者：
Leidig, Christoph;Thoms, Matthias;Beckmann, Roland
在真核核糖体生物发生过程中，新生核糖体 RNA (rRNA) 形成含有核糖体蛋白和组装因子的前核糖体颗粒。随后，这些未成熟的 rRNA 被加工和重塑。人们对 rRNA 的过早组装状态及其在核糖体生物发生过程中的结构重排知之甚少。使用冷冻电镜，我们表征了 60S 前颗粒，其中 5S rRNA 及其相关核糖体蛋白 L18 和 L5（5S 核糖核蛋白 (RNP)）与成熟亚基相比旋转了近 180 度。因此，从中央突起基部突出的相邻 25S rRNA 螺旋发生变形。这种改变的拓扑结构通过附近的组装因子（Rsa4 和 Nog1）来稳定，这些组装因子是通过将其三维结构拟合到冷冻电镜密度中来识别的。我们认为，5S RNP 在 60S 生物发生过程中进行半圆运动以占据其最终位置，在引导中央突起的侧翼 25S rRNA 螺旋达到其最终拓扑方面发挥类似伴侣的功能。
During eukaryotic ribosome biogenesis, nascent ribosomal RNA (rRNA) forms pre-ribosomal particles containing ribosomal proteins and assembly factors. Subsequently, these immature rRNAs are processed and remodelled. Little is known about the premature assembly states of rRNAs and their structural rearrangement during ribosome biogenesis. Using cryo-EM we characterize a pre-60S particle, where the 5S rRNA and its associated ribosomal proteins L18 and L5 (5S ribonucleoprotein (RNP)) are rotated by almost 180 degrees when compared with the mature subunit. Consequently, neighbouring 25S rRNA helices that protrude from the base of the central protuberance are deformed. This altered topology is stabilized by nearby assembly factors (Rsa4 and Nog1), which were identified by fitting their three-dimensional structures into the cryo-EM density. We suggest that the 5S RNP performs a semicircular movement during 60S biogenesis to adopt its final position, fulfilling a chaperone-like function in guiding the flanking 25S rRNA helices of the central protuberance to their final topology.