Sachweh Jenny, Börmel Mandy, Klumpe Sven, Becker Anja, Taniguchi Reiya, Kubańska Marta Anna, Pintschovius Verena, Kaindl Eva, Plitzko Jürgen M, Wilfling Florian, Beck Martin, Hampoelz Bernhard
Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Electron Microscopy Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany.
Cell. 2025 Aug 12. doi: 10.1016/j.cell.2025.07.025.
Nuclear pore complexes (NPCs) bridge across the nuclear envelope and mediate nucleocytoplasmic exchange. They consist of hundreds of nucleoporin building blocks and exemplify the structural complexity of macromolecular assemblies. To ensure transport directionality, different nucleoporin complexes are attached to the cytoplasmic and nuclear face of the NPC. How those asymmetric structures are faithfully assembled onto the symmetric scaffold architecture that exposes the same interaction surfaces to either side remained enigmatic. Here, we combine cryo-electron tomography, subtomogram averaging, and template matching with live imaging to address this question in budding yeast and Drosophila. We genetically induce ectopic nuclear pores and show that pores outside the nuclear envelope are symmetric. We furthermore demonstrate that the peripheral NPC configuration is affected by the nucleotide state of the small GTPase Ran. Our findings indicate that the nuclear transport system is self-regulatory, namely that the same molecular mechanism controls both transport and transport channel composition.
核孔复合体（NPCs）横跨核膜，介导核质交换。它们由数百个核孔蛋白构建模块组成，体现了大分子组装体的结构复杂性。为确保运输方向性，不同的核孔蛋白复合体附着在NPC的胞质面和核面。这些不对称结构如何忠实地组装到向两侧暴露相同相互作用表面的对称支架结构上，一直是个谜。在这里，我们将冷冻电子断层扫描、亚断层平均和模板匹配与活细胞成像相结合，在芽殖酵母和果蝇中解决这个问题。我们通过基因诱导异位核孔，发现核膜外的孔是对称的。此外，我们证明了外周NPC的构型受小GTPase Ran的核苷酸状态影响。我们的研究结果表明，核运输系统是自我调节的，即相同的分子机制控制运输和运输通道的组成。
