The nucleoporin Nup50 activates the Ran guanyl-nucleotide exchange factor RCC1 to promote mitotic NPC assembly [article]

Guillaume Holzer, Paola De Magistris, Cathrin Gramminger, Ruchika Sachdev, Adriana Magalska, Allana Schooley, Anja Scheufen, Birgitt Lennartz, Marianna Tatarek-Nossol, Hongqi Lue, Monika I Linder, Ulrike Kutay (+3 others)
2021 bioRxiv   pre-print
During mitotic exit, thousands of nuclear pore complexes (NPCs) assemble concomitant with the nuclear envelope to build a transport-competent nucleus. We show here that Nup50 plays a crucial role in NPC assembly that is independent of its well-established function in nuclear transport. RNAi-mediated downregulation in cells or immunodepletion of the protein in Xenopus egg extracts interferes with NPC assembly. We define a conserved central region of 46 residues in Nup50 that is crucial for
more » ... and MEL28/ELYS binding, and NPC interaction. Surprisingly, neither NPC interaction nor binding of Nup50 to importin α, β, the GTPase Ran or chromatin is crucial for its function in the assembly process. Instead, we discovered that an N-terminal fragment of Nup50 can stimulate the Ran guanine exchange factor RCC1 and NPC assembly, indicating that Nup50 acts via the Ran system in mitotic NPC reformation. In support of this conclusion, Nup50 mutants defective in RCC1 binding and stimulation cannot replace the wild type protein in in vitro NPC assembly assays.
doi:10.1101/2021.03.31.437874 fatcat:lpor5ndylfdkdjnux4m3rgnxgq