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Snapshots of nuclear pore complexes in action captured by cryo-electron tomography


Nuclear pore complexes reside in the nuclear envelope of eukaryotic cells and mediate the nucleocytoplasmic exchange of macromolecules1. Traffic is regulated by mobile transport receptors that target their cargo to the central translocation channel, where phenylalanine-glycine-rich repeats serve as binding sites2. The structural analysis of the nuclear pore is a formidable challenge given its size, its location in a membranous environment and its dynamic nature. Here we have used cryo-electron tomography3 to study the structure of nuclear pore complexes in their functional environment, that is, in intact nuclei of Dictyostelium discoideum. A new image-processing strategy compensating for deviations of the asymmetric units (protomers) from a perfect eight-fold symmetry enabled us to refine the structure and to identify new features. Furthermore, the superposition of a large number of tomograms taken in the presence of cargo, which was rendered visible by gold nanoparticles, has yielded a map outlining the trajectories of import cargo. Finally, we have performed single-molecule Monte Carlo simulations of nuclear import to interpret the experimentally observed cargo distribution in the light of existing models for nuclear import.

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Figure 1: Plasticity of intact NPCs is revealed by displacement analysis.
Figure 2: Refined structure of the Dictyostelium NPC.
Figure 3: Visualization of single molecules during nuclear import: experimental data and simulations.


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We thank F. Melchior for the Ran(Q69L) protein, S. Musser for the NLS–2×GFP plasmid, G. Gerisch and J. Glavy for valuable discussions, and A. Leis for critical reading of the manuscript. This work was supported in part by the European Union 3DEM Network of Excellence.

The structure has been deposited at the Macromolecular Structure database (EBI) under accession code EMD-1394.

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Correspondence to Wolfgang Baumeister or Ohad Medalia.

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Supplementary information

Supplementary Information

The file contains Supplementary Methods, Supplementary Tables S1-S2 and Supplementary Figures S1-S6 with Legends. (PDF 1637 kb)

Supplementary Video 1

The file contains Supplementary Video 1 which shows structural heterogeneity of the Nuclear Pore Complex. (MOV 5663 kb)

Supplementary Video 2

The file contains Supplementary Video 2 which shows structure of a protomer superimposed with the entire NPC shown as a cutaway view. (MOV 5305 kb)

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Beck, M., Lučić, V., Förster, F. et al. Snapshots of nuclear pore complexes in action captured by cryo-electron tomography. Nature 449, 611–615 (2007).

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