Baytshtok Vladimir, DiMattia Michael A, Lima Christopher D
Structural Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
These authors contributed equally.
bioRxiv. 2024 Dec 26:2024.10.04.616749. doi: 10.1101/2024.10.04.616749.
The human nucleoporin RanBP2/Nup358 interacts with SUMO1-modified RanGAP1 and the SUMO E2 Ubc9 at the nuclear pore complex (NPC) to promote export and disassembly of exportin Crm1/Ran(GTP)/cargo complexes. In mitosis, RanBP2/SUMO1-RanGAP1/Ubc9 remains intact after NPC disassembly and is recruited to kinetochores and mitotic spindles by Crm1 where it contributes to mitotic progression. Interestingly, RanBP2 binds SUMO1-RanGAP1/Ubc9 via motifs that also catalyze SUMO E3 ligase activity. Here, we resolve cryo-EM structures of a RanBP2 C-terminal fragment in complex with Crm1, SUMO1-RanGAP1/Ubc9, and two molecules of Ran(GTP). These structures reveal several unanticipated interactions with Crm1 including a nuclear export signal (NES) for RanGAP1, the deletion of which mislocalizes RanGAP1 and the Ran GTPase in cells. Our structural and biochemical results support models in which RanBP2 E3 ligase activity is dependent on Crm1, the RanGAP1 NES and Ran GTPase cycling.
人类核孔蛋白RanBP2/Nup358在核孔复合体（NPC）处与SUMO1修饰的RanGAP1和SUMO E2 Ubc9相互作用，以促进输出蛋白Crm1/Ran（GTP）/货物复合体的输出和拆卸。在有丝分裂过程中，RanBP2/SUMO1-RanGAP1/Ubc9在NPC拆卸后保持完整，并被Crm1招募到动粒和有丝分裂纺锤体上，在那里它有助于有丝分裂进程。有趣的是，RanBP2通过也催化SUMO E3连接酶活性的基序结合SUMO1-RanGAP1/Ubc9。在这里，我们解析了RanBP2 C末端片段与Crm1、SUMO1-RanGAP1/Ubc9和两个Ran（GTP）分子形成的复合物的冷冻电镜结构。这些结构揭示了与Crm1的几种意外相互作用，包括RanGAP1的核输出信号（NES），其缺失会使RanGAP1和Ran GTP酶在细胞中定位错误。我们的结构和生化结果支持了RanBP2 E3连接酶活性依赖于Crm1、RanGAP1 NES和Ran GTP酶循环的模型。
