Cytoplasmic dynein-1 is a molecular motor that drives nearly all minus-end-directed microtubule-based transport in human cells, performing functions that range from retrograde axonal transport to mitotic spindle assembly1,2. Activated dynein complexes consist of one or two dynein dimers, the dynactin complex and an 'activating adaptor', and they show faster velocity when two dynein dimers are present3-6. Little is known about the assembly process of this massive ~4 MDa complex. Here, using purified recombinant human proteins, we uncover a role for the dynein-binding protein LIS1 in promoting the formation of activated dynein-dynactin complexes that contain two dynein dimers. Complexes activated by proteins representing three families of activating adaptors-BicD2, Hook3 and Ninl-all show enhanced motile properties in the presence of LIS1. Activated dynein complexes do not require sustained LIS1 binding for fast velocity. Using cryo-electron microscopy, we show that human LIS1 binds to dynein at two sites on the motor domain of dynein. Our research suggests that LIS1 binding at these sites functions in multiple stages of assembling the motile dynein-dynactin-activating adaptor complex.

中文翻译：

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LIS1 促进激活的细胞质动力蛋白-1 复合物的形成。


细胞质动力蛋白-1 是一种分子马达，可驱动人体细胞中几乎所有基于负端定向的微管运输，执行从逆行轴突运输到有丝分裂纺锤体组装等功能1,2。激活的动力蛋白复合物由一个或两个动力蛋白二聚体、动力蛋白复合物和“激活适配器”组成，当存在两个动力蛋白二聚体时，它们显示出更快的速度3-6。人们对这个巨大的约 4 MDa 复合体的组装过程知之甚少。在这里，使用纯化的重组人蛋白，我们发现了动力蛋白结合蛋白 LIS1 在促进含有两个动力蛋白二聚体的活化动力蛋白-动力蛋白复合物形成中的作用。由代表三个激活接头家族（BicD2、Hook3 和 Ninl）的蛋白质激活的复合物在 LIS1 存在下均显示出增强的运动特性。激活的动力蛋白复合物不需要持续的 LIS1 结合来实现快速。使用冷冻电子显微镜，我们发现人类 LIS1 在动力蛋白运动域的两个位点与动力蛋白结合。我们的研究表明，LIS1 在这些位点的结合在组装运动动力蛋白-动力蛋白激活接头复合物的多个阶段中发挥作用。