In situ architecture of the nuclear pore complex of the higher plant Arabidopsis thaliana.

The nucleus is enclosed by the nuclear envelope, which contains nuclear pore complexes (NPCs). While NPCs have been well studied in vertebrates, yeast and algae, in situ structural data for higher plants is lacking. Here we show that individual nucleoporins of Arabidopsis thaliana and humans exhibit high structural similarity. We report an in situ NPC structure of higher plants, derived from A. thaliana root protoplasts using cryo-electron tomography, subtomogram averaging and homology-based integrative modelling. We present the AtNPC model based on predictions of A. thaliana nucleoporins (NUPs), supported by mass spectrometry. Here the AtNPC scaffold contains one Y-complex ring at the cytosolic and two at the nuclear ring. The AtNPC contains prominent NUP155 connector elements that are conserved in human NPCs but not in Chlamydomonas reinhardtii NPCs. Our model suggests that the ELYS homologue HOS1 plays an important role in the head-to-tail connection of Y-complexes in AtNPCs.