Structural and Computational Biology Unit & Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany; Interdisciplinary Center for Scientific Computing, Heidelberg University, Mathematikon, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany.
Cell Rep. 2018 Mar 27;22(13):3660-3671. doi: 10.1016/j.celrep.2018.03.022.
Phenylalanine-glycine-rich nucleoporins (FG-Nups) are intrinsically disordered proteins, constituting the selective barrier of the nuclear pore complex (NPC). Previous studies showed that nuclear transport receptors (NTRs) were found to interact with FG-Nups by forming an "archetypal-fuzzy" complex through the rapid formation and breakage of interactions with many individual FG motifs. Here, we use single-molecule studies combined with atomistic simulations to show that, in sharp contrast, FG-Nup214 undergoes a coupled reconfiguration-binding mechanism when interacting with the export receptor CRM1. Association and dissociation rate constants are more than an order of magnitude lower than in the archetypal-fuzzy complex between FG-Nup153 and NTRs. Unexpectedly, this behavior appears not to be encoded selectively into CRM1 but rather into the FG-Nup214 sequence. The same distinct binding mechanisms are unperturbed in O-linked β-N-acetylglucosamine-modified FG-Nups. Our results have implications for differential roles of distinctly spatially distributed FG-Nup⋅NTR interactions in the cell.
苯丙氨酸-甘氨酸丰富核孔蛋白（FG-Nups）是固有无序蛋白，构成核孔复合体（NPC）的选择性屏障。先前的研究表明，核转运受体（NTR）通过与许多单个 FG 基序快速形成和断裂相互作用，形成“典型模糊”复合物，与 FG-Nups 相互作用。在这里，我们使用单分子研究结合原子模拟表明，与此形成鲜明对比的是，FG-Nup214 在与出口受体 CRM1 相互作用时经历了一种偶联的重新配置结合机制。缔合和离解速率常数比 FG-Nup153 和 NTRs 之间的典型模糊复合物低一个数量级以上。出乎意料的是，这种行为似乎不是选择性地编码到 CRM1 中，而是编码到 FG-Nup214 序列中。在 O-连接的β-N-乙酰葡糖胺修饰的 FG-Nups 中，相同的独特结合机制未受到干扰。我们的结果对不同空间分布的 FG-Nup⋅NTR 相互作用在细胞中的差异作用具有重要意义。
