School of Life Sciences, Southern University of Science and Technology, Shenzhen, China.
State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, China.
Nature. 2023 Jun;618(7964):411-418. doi: 10.1038/s41586-023-06128-y. Epub 2023 May 31.
The nuclear pore complex (NPC) is the bidirectional gate that mediates the exchange of macromolecules or their assemblies between nucleus and cytoplasm. The assembly intermediates of the ribosomal subunits, pre-60S and pre-40S particles, are among the largest cargoes of the NPC and the export of these gigantic ribonucleoproteins requires numerous export factors. Here we report the cryo-electron microscopy structure of native pre-60S particles trapped in the channel of yeast NPCs. In addition to known assembly factors, multiple factors with export functions are also included in the structure. These factors in general bind to either the flexible regions or subunit interface of the pre-60S particle, and virtually form many anchor sites for NPC binding. Through interactions with phenylalanine-glycine (FG) repeats from various nucleoporins of NPC, these factors collectively facilitate the passage of the pre-60S particle through the central FG repeat network of the NPC. Moreover, in silico analysis of the axial and radial distribution of pre-60S particles within the NPC shows that a single NPC can take up to four pre-60S particles simultaneously, and pre-60S particles are enriched in the inner ring regions close to the wall of the NPC with the solvent-exposed surface facing the centre of the nuclear pore. Our data suggest a translocation model for the export of pre-60S particles through the NPC.
核孔复合体（NPC）是介导核质和细胞质之间大分子或其复合物相互交换的双向门。核糖体亚基、pre-60S 和 pre-40S 颗粒的组装中间体是 NPC 中最大的货物之一，这些巨大的核糖核蛋白的输出需要许多输出因子。在这里，我们报道了在酵母 NPC 通道中捕获的天然 pre-60S 颗粒的冷冻电镜结构。除了已知的组装因子外，许多具有输出功能的因子也包含在结构中。这些因子通常与 pre-60S 颗粒的柔性区域或亚基界面结合，并为 NPC 结合形成许多锚定点。通过与 NPC 中各种核孔蛋白的苯丙氨酸-甘氨酸（FG）重复序列相互作用，这些因子共同促进 pre-60S 颗粒通过 NPC 中央 FG 重复网络的传递。此外，对 NPC 内 pre-60S 颗粒的轴向和径向分布的计算机分析表明，单个 NPC 可以同时容纳多达四个 pre-60S 颗粒，并且 pre-60S 颗粒在靠近 NPC 壁的内环区域富集，溶剂暴露的表面朝向核孔的中心。我们的数据表明了 pre-60S 颗粒通过 NPC 输出的易位模型。
