Structural and biochemical analyses of the nuclear pore complex component ELYS identify residues responsible for nucleosome binding.

The nuclear pore complex embedded within the nuclear envelope is the essential architecture for trafficking macromolecules, such as proteins and RNAs, between the cytoplasm and nucleus. The nuclear pore complex assembly occurs on chromatin in the post-mitotic phase of the cell cycle. ELYS (MEL-28/AHCTF1) binds to the nucleosome, which is the basic chromatin unit, and promotes assembly of the complex around the chromosomes in cells. Here we show that the Arg-Arg-Lys (RRK) stretch of the C-terminal ELYS region plays an essential role in the nucleosome binding. The cryo-EM structure and the crosslinking mass spectrometry reveal that the ELYS C-terminal region directly binds to the acidic patch of the nucleosome. These results provide mechanistic insight into the ELYS-nucleosome interaction, which promotes the post-mitotic nuclear pore complex formation around chromosomes in cells.