Ribosomal RNA (rRNA) carries extensive 2'-O-methyl marks at functionally important sites. This simple chemical modification is thought to confer stability, promote RNA folding and contribute to generate a heterogenous ribosome population with a yet-uncharacterized function. 2'-O-methylation occurs both in archaea and eukaryotes and is accomplished by the Box C/D RNP enzyme in an RNA-guided manner. Extensive and partially conflicting structural information exists for the archaeal enzyme, while no structural data is available for the eukaryotic enzyme. The yeast Box C/D RNP consists of a guide RNA, the RNA-primary binding protein Snu13, the two scaffold proteins Nop56 and Nop58 and the enzymatic module Nop1. Here we present the high-resolution structure of the eukaryotic Box C/D methyltransferase Nop1 from Saccharomyces cerevisiae bound to the N-terminal domain of Nop56. We discuss similarities and differences between the interaction modes of the two proteins in archaea and eukaryotes and demonstrate that eukaryotic Nop56 recruits the methyltransferase to the Box C/D RNP through a protein-protein interface that differs substantially from the archaeal orthologues. This study represents a first achievement in understanding the evolution of the structure and function of these proteins from archaea to eukaryotes.

中文翻译：

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真核纤维蛋白与 Nop56 N 末端结构域相互作用的高分辨率结构


核糖体 RNA (rRNA) 在重要功能位点携带广泛的 2'-O-甲基标记。这种简单的化学修饰被认为可以赋予稳定性，促进 RNA 折叠，并有助于产生具有尚未表征的功能的异源核糖体群体。 2'-O-甲基化发生在古细菌和真核生物中，并由 Box C/D RNP 酶以 RNA 引导的方式完成。古细菌酶存在广泛且部分冲突的结构信息，而真核酶没有可用的结构数据。酵母 Box C/D RNP 由指导 RNA、RNA 初级结合蛋白 Snu13、两个支架蛋白 Nop56 和 Nop58 以及酶模块 Nop1 组成。在这里，我们展示了来自酿酒酵母的真核 Box C/D 甲基转移酶 Nop1 的高分辨率结构，该酶与 Nop56 的 N 端结构域结合。我们讨论了古细菌和真核生物中两种蛋白质相互作用模式的异同，并证明真核生物 Nop56 通过与古细菌直系同源物显着不同的蛋白质-蛋白质界面将甲基转移酶招募到 Box C/D RNP。这项研究代表了理解这些蛋白质从古细菌到真核生物的结构和功能进化的第一个成就。