Department of Biological Sciences, Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, United States.
Department of Chemistry, Binghamton University, Binghamton, United States.
Elife. 2022 Mar 1;11:e74714. doi: 10.7554/eLife.74714.
Nup358, a protein of the nuclear pore complex, facilitates a nuclear positioning pathway that is essential for many biological processes, including neuromuscular and brain development. Nup358 interacts with the dynein adaptor Bicaudal D2 (BicD2), which in turn recruits the dynein machinery to position the nucleus. However, the molecular mechanisms of the Nup358/BicD2 interaction and the activation of transport remain poorly understood. Here for the first time, we show that a minimal Nup358 domain activates dynein/dynactin/BicD2 for processive motility on microtubules. Using nuclear magnetic resonance titration and chemical exchange saturation transfer, mutagenesis, and circular dichroism spectroscopy, a Nup358 α-helix encompassing residues 2162-2184 was identified, which transitioned from a random coil to an α-helical conformation upon BicD2 binding and formed the core of the Nup358-BicD2 interface. Mutations in this region of Nup358 decreased the Nup358/BicD2 interaction, resulting in decreased dynein recruitment and impaired motility. BicD2 thus recognizes Nup358 through a 'cargo recognition α-helix,' a structural feature that may stabilize BicD2 in its activated state and promote processive dynein motility.
核孔复合体蛋白 Nup358 促进了一种对许多生物学过程至关重要的核定位途径，包括神经肌肉和大脑发育。Nup358 与胞质动力蛋白接头蛋白 Bicaudal D2（BicD2）相互作用，BicD2 又反过来招募胞质动力蛋白来定位核。然而，Nup358/BicD2 相互作用和运输的激活的分子机制仍知之甚少。在这里，我们首次表明，一个最小的 Nup358 结构域可以激活动力蛋白/动力蛋白/ BicD2，使其在微管上进行连续运动。通过核磁共振滴定和化学交换饱和转移、突变和圆二色性光谱分析，确定了一个包含残基 2162-2184 的 Nup358 α-螺旋，该螺旋在与 BicD2 结合后从无规卷曲转变为α-螺旋构象，并形成了 Nup358-BicD2 界面的核心。该区域的 Nup358 突变降低了 Nup358/BicD2 的相互作用，导致动力蛋白募集减少和运动受损。因此，BicD2 通过“货物识别α-螺旋”识别 Nup358，这种结构特征可能稳定 BicD2 的激活状态并促进动力蛋白的连续运动。
