The Human Nuclear Pore Complex as Revealed by Cryo-Electron Tomography
The Human Nuclear Pore Complex as Revealed by Cryo-Electron Tomography
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DOI：
10.1016/j.str.2012.03.025
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发表时间：
2012-06-06
期刊：
影响因子：
5.7
通讯作者：
Medalia, Ohad
中科院分区：
文献类型：
--
作者：
Maimon, Tal;Elad, Nadav;Medalia, Ohad
核孔复合物（NPCs）是通过核膜连接细胞质和核质的唯一通道。这些巨大的分子机器，分子量超过100 MDa，允许小分子和离子的自由扩散，同时介导大分子的选择性能量依赖核胞质运输。在这里，我们将低温电子断层扫描应用于人成纤维细胞，重建其核包膜，而无需进行任何纯化步骤。从这些重建中，我们提取了包含单个npc的亚层析图，并利用硅亚层析图平均程序以类似6.6 nm的分辨率确定哺乳动物孔隙复合物的结构。除了揭示人类鼻咽癌的典型特征外，我们的分析还发现了内外侧通道和融合的桥状结构，提示了周围核通道的其他途径。最后，我们从结构分析中得出结论，人类鼻咽癌在结构上与低等真核生物的鼻咽癌在尺寸和组织上不同，但与两栖动物（青蛙）的鼻咽癌相似。
Nuclear pore complexes (NPCs) are the sole passage through the nuclear envelope, connecting the cytoplasm to the nucleoplasm. These gigantic molecular machines, over 100 MDa in molecular weight, allow free diffusion of small molecules and ions while mediating selective energy-dependent nucleocytoplasmic transport of large macromolecules. Here, we applied cryo-electron tomography to human fibroblast cells, reconstructing their nuclear envelopes without applying any purification steps. From these reconstructions, we extracted subtomograms containing individual NPCs and utilized in silico subtomogram averaging procedures to determine the structure of the mammalian pore complex at a resolution of similar to 6.6 nm. Beyond revealing the canonical features of the human NPC, our analysis identified inner lateral channels and fusing bridge-like structures, suggesting alternative routes of peripheral nuclear passage. Finally, we concluded from our structural analysis that the human NPC is structurally distinct from that of lower eukaryotes in terms of dimension and organization but resembles its amphibian (frog) counterpart.