Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang, 310024, China.
Cell Res. 2020 Jun;30(6):520-531. doi: 10.1038/s41422-020-0319-4. Epub 2020 May 6.
The nuclear pore complex (NPC) exhibits structural plasticity and has only been characterized at local resolutions of up to 15 Å for the cytoplasmic ring (CR). Here we present a single-particle cryo-electron microscopy (cryo-EM) structure of the CR from Xenopus laevis NPC at average resolutions of 5.5-7.9 Å, with local resolutions reaching 4.5 Å. Improved resolutions allow identification and placement of secondary structural elements in the majority of the CR components. The two Y complexes in each CR subunit interact with each other and associate with those from flanking subunits, forming a circular scaffold. Within each CR subunit, the Nup358-containing region wraps around the stems of both Y complexes, likely stabilizing the scaffold. Nup205 connects the short arms of the two Y complexes and associates with the stem of a neighboring Y complex. The Nup214-containing region uses an extended coiled-coil to link Nup85 of the two Y complexes and protrudes into the axial pore of the NPC. These previously uncharacterized structural features reveal insights into NPC assembly.
核孔复合体（NPC）表现出结构可塑性，其细胞质环（CR）的结构仅在最高 15Å 的局部分辨率下被表征过。在这里，我们呈现了来自非洲爪蟾 NPC 的 CR 的单颗粒冷冻电镜（cryo-EM）结构，平均分辨率为 5.5-7.9Å，局部分辨率达到 4.5Å。分辨率的提高使得 CR 组件的大部分都能够识别和定位二级结构元素。每个 CR 亚基中的两个 Y 复合物相互作用，并与相邻亚基的 Y 复合物结合，形成一个圆形支架。在每个 CR 亚基内，含有 Nup358 的区域包裹在两个 Y 复合物的茎干周围，可能稳定了支架。Nup205 连接两个 Y 复合物的短臂，并与相邻 Y 复合物的茎干结合。含有 Nup214 的区域使用扩展的卷曲螺旋将两个 Y 复合物的 Nup85 连接起来，并突出到 NPC 的轴向孔中。这些以前未被表征的结构特征揭示了 NPC 组装的见解。
