Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY.
Courant Institute of Mathematical Sciences, New York, NY.
J Gen Physiol. 2017 Oct 2;149(10):951-966. doi: 10.1085/jgp.201711769. Epub 2017 Sep 8.
The phenylalanine-glycine-repeat nucleoporins (FG-Nups), which occupy the lumen of the nuclear pore complex (NPC), are critical for transport between the nucleus and cytosol. Although NPCs differ in composition across species, they are largely conserved in organization and function. Transport through the pore is on the millisecond timescale. Here, to explore the dynamics of nucleoporins on this timescale, we use coarse-grained computational simulations. These simulations generate predictions that can be experimentally tested to distinguish between proposed mechanisms of transport. Our model reflects the conserved structure of the NPC, in which FG-Nup filaments extend into the lumen and anchor along the interior of the channel. The lengths of the filaments in our model are based on the known characteristics of yeast FG-Nups. The FG-repeat sites also bind to each other, and we vary this association over several orders of magnitude and run 100-ms simulations for each value. The autocorrelation functions of the orientation of the simulated FG-Nups are compared with in vivo anisotropy data. We observe that FG-Nups reptate back and forth through the NPC at timescales commensurate with experimental measurements of the speed of cargo transport through the NPC. Our results are consistent with models of transport where FG-Nup filaments are free to move across the central channel of the NPC, possibly informing how cargo might transverse the NPC.
苯丙氨酸-甘氨酸重复核孔蛋白（FG-Nups）占据核孔复合体（NPC）的腔，对于核质和细胞质之间的物质运输至关重要。尽管 NPC 在不同物种之间的组成有所不同，但它们在结构和功能上基本保持一致。物质通过核孔的运输时间尺度为毫秒级。为了在这个时间尺度上探索核孔蛋白的动力学，我们使用了粗粒化计算模拟。这些模拟产生的预测可以通过实验进行测试，以区分提出的运输机制。我们的模型反映了 NPC 的保守结构，其中 FG-Nup 纤维延伸到腔中，并沿着通道的内部锚定。我们模型中的纤维长度基于酵母 FG-Nups 的已知特性。FG 重复位点也相互结合，我们在几个数量级上改变这种结合，并对每个值运行 100 毫秒的模拟。模拟 FG-Nups 的取向的自相关函数与体内各向异性数据进行比较。我们观察到，FG-Nups 在 NPC 中来回蠕动，其时间尺度与通过 NPC 运输货物的速度的实验测量值相符。我们的结果与 FG-Nup 纤维可以在 NPC 的中央通道中自由移动的运输模型一致，这可能为货物如何穿过 NPC 提供了线索。
