60S 核糖体生物发生需要 5S 核糖核蛋白颗粒的旋转。

60S ribosome biogenesis requires rotation of the 5S ribonucleoprotein particle.

机构信息

Gene Center and Center of Integrated Protein Science Munich (CiPS-M), Department of Chemistry and Biochemistry, University of Munich, 81377 Munich, Germany.

Heidelberg University Biochemistry Center (BZH), 69120 Heidelberg, Germany.

出版信息

Nat Commun. 2014 Mar 24;5:3491. doi: 10.1038/ncomms4491.

DOI:10.1038/ncomms4491

PMID:24662372

Abstract

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° 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.

摘要

在真核生物核糖体生物发生过程中，新生核糖体 RNA(rRNA) 形成包含核糖体蛋白和组装因子的前核糖体颗粒。随后，这些不成熟的 rRNA 被加工和重塑。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。我们使用 cryo-EM 对 pre-60S 颗粒进行了表征，与成熟亚基相比，5S rRNA 及其相关核糖体蛋白 L18 和 L5（5S 核糖核蛋白（RNP））几乎旋转了 180°。结果，从中央突出物底部伸出的相邻 25S rRNA 螺旋发生变形。通过将其三维结构拟合到 cryo-EM 密度中，附近的组装因子（Rsa4 和 Nog1）稳定了这种改变的拓扑结构。我们认为，在 60S 生物发生过程中，5S RNP 会进行半圆形运动以采用其最终位置，在引导中央突出物侧翼的 25S rRNA 螺旋达到其最终拓扑结构方面发挥类似 chaperone 的功能。