Department of Biological Sciences, Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA.
Department of Chemistry, Binghamton University, P.O. Box 6000, Binghamton, NY 13902, USA.
Biomolecules. 2023 Sep 26;13(10):1445. doi: 10.3390/biom13101445.
Dynein motors facilitate the majority of minus-end-directed transport events on microtubules. The dynein adaptor Bicaudal D2 (BicD2) recruits the dynein machinery to several cellular cargo for transport, including Nup358, which facilitates a nuclear positioning pathway that is essential for the differentiation of distinct brain progenitor cells. Previously, we showed that Nup358 forms a "cargo recognition α-helix" upon binding to BicD2; however, the specifics of the BicD2-Nup358 interface are still not well understood. Here, we used AlphaFold2, complemented by two additional docking programs (HADDOCK and ClusPro) as well as mutagenesis, to show that the Nup358 cargo-recognition α-helix binds to BicD2 between residues 747 and 774 in an anti-parallel manner, forming a helical bundle. We identified two intermolecular salt bridges that are important to stabilize the interface. In addition, we uncovered a secondary interface mediated by an intrinsically disordered region of Nup358 that is directly N-terminal to the cargo-recognition α-helix and binds to BicD2 between residues 774 and 800. This is the same BicD2 domain that binds to the competing cargo adapter Rab6, which is important for the transport of Golgi-derived and secretory vesicles. Our results establish a structural basis for cargo recognition and selection by the dynein adapter BicD2, which facilitates transport pathways that are important for brain development.
动力蛋白马达促进了大多数微管的负端导向运输事件。动力蛋白接头 Bicaudal D2（BicD2）将动力蛋白机械募集到几种细胞货物上进行运输，包括 Nup358，它促进了核定位途径，这对不同脑祖细胞的分化至关重要。先前，我们表明 Nup358 在与 BicD2 结合后形成“货物识别α-螺旋”；然而，BicD2-Nup358 界面的具体细节仍不清楚。在这里，我们使用 AlphaFold2，辅以另外两个对接程序（HADDOCK 和 ClusPro）以及突变，表明 Nup358 货物识别α-螺旋以反平行方式结合到 BicD2 的残基 747 和 774 之间，形成一个螺旋束。我们确定了两个对稳定界面很重要的分子间盐桥。此外，我们发现了一个由 Nup358 的无规卷曲区域介导的次要界面，该区域直接位于货物识别α-螺旋的 N 端，与 BicD2 的残基 774 和 800 结合。这是与竞争货物适配器 Rab6 结合的相同 BicD2 结构域，Rab6 对高尔基体衍生和分泌小泡的运输很重要。我们的结果为动力蛋白接头 BicD2 的货物识别和选择建立了结构基础，这促进了对大脑发育很重要的运输途径。
