Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA, 91125, USA.
Nat Commun. 2018 Jun 13;9(1):2319. doi: 10.1038/s41467-018-04459-3.
The nuclear pore complex (NPC) controls the passage of macromolecules between the nucleus and cytoplasm, but how the NPC directly participates in macromolecular transport remains poorly understood. In the final step of mRNA export, the DEAD-box helicase DDX19 is activated by the nucleoporins Gle1, Nup214, and Nup42 to remove Nxf1•Nxt1 from mRNAs. Here, we report crystal structures of Gle1•Nup42 from three organisms that reveal an evolutionarily conserved binding mode. Biochemical reconstitution of the DDX19 ATPase cycle establishes that human DDX19 activation does not require IP, unlike its fungal homologs, and that Gle1 stability affects DDX19 activation. Mutations linked to motor neuron diseases cause decreased Gle1 thermostability, implicating nucleoporin misfolding as a disease determinant. Crystal structures of human Gle1•Nup42•DDX19 reveal the structural rearrangements in DDX19 from an auto-inhibited to an RNA-binding competent state. Together, our results provide the foundation for further mechanistic analyses of mRNA export in humans.
核孔复合体 (NPC) 控制着核质与细胞质之间的大分子物质的通过，但 NPC 如何直接参与大分子物质的运输仍知之甚少。在 mRNA 输出的最后一步，DEAD-box 解旋酶 DDX19 被核孔蛋白 Gle1、Nup214 和 Nup42 激活，从而将 Nxf1·Nxt1 从 mRNA 上移除。在这里，我们报道了来自三种生物的 Gle1·Nup42 的晶体结构，揭示了一种进化保守的结合模式。DDX19 ATP 酶循环的生化重建表明，人类 DDX19 的激活不需要 IP，这与真菌同源物不同，并且 Gle1 的稳定性会影响 DDX19 的激活。与运动神经元疾病相关的突变导致 Gle1 热稳定性降低，这表明核孔蛋白的错误折叠是疾病的决定因素。人源 Gle1·Nup42·DDX19 的晶体结构揭示了 DDX19 从自动抑制状态到 RNA 结合状态的结构重排。总之，我们的结果为进一步分析人类的 mRNA 输出的机制提供了基础。
