Division of Cell Biology, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
Leibniz Institute of Virology, Hamburg, Germany.
EMBO J. 2023 Dec 1;42(23):e114473. doi: 10.15252/embj.2023114473. Epub 2023 Oct 24.
The microtubule motor dynein mediates polarised trafficking of a wide variety of organelles, vesicles and macromolecules. These functions are dependent on the dynactin complex, which helps recruit cargoes to dynein's tail and activates motor movement. How the dynein-dynactin complex orchestrates trafficking of diverse cargoes is unclear. Here, we identify HEATR5B, an interactor of the adaptor protein-1 (AP1) clathrin adaptor complex, as a novel player in dynein-dynactin function. HEATR5B was recovered in a biochemical screen for proteins whose association with the dynein tail is augmented by dynactin. We show that HEATR5B binds directly to the dynein tail and dynactin and stimulates motility of AP1-associated endosomal membranes in human cells. We also demonstrate that the Drosophila HEATR5B homologue is an essential gene that selectively promotes dynein-based transport of AP1-bound membranes to the Golgi apparatus. As HEATR5B lacks the coiled-coil architecture typical of dynein adaptors, our data point to a non-canonical process orchestrating motor function on a specific cargo. We additionally show that HEATR5B promotes association of AP1 with endosomal membranes independently of dynein. Thus, HEATR5B co-ordinates multiple events in AP1-based trafficking.
微管马达动力蛋白 dynein 介导各种细胞器、囊泡和大分子的极化运输。这些功能依赖于 dynactin 复合物，该复合物有助于将 cargo 募集到 dynein 的尾部并激活马达运动。dynein-dynactin 复合物如何协调各种 cargo 的运输尚不清楚。在这里，我们确定 HEATR5B，即衔接蛋白-1 (AP1) 网格蛋白衔接复合物的一个相互作用蛋白，是 dynein-dynactin 功能的一个新的参与者。HEATR5B 在生化筛选中被回收，该筛选用于鉴定与 dynein 尾部结合并被 dynactin 增强的蛋白质。我们表明 HEATR5B 直接与 dynein 尾部和 dynactin 结合，并刺激人类细胞中与 AP1 相关的内体膜的运动。我们还证明，果蝇 HEATR5B 同源物是一种必需基因，它选择性地促进 AP1 结合的膜以 dynein 为基础向高尔基体的运输。由于 HEATR5B 缺乏 dynein 接头典型的卷曲螺旋结构，我们的数据表明存在一种非典型的过程来协调特定货物的马达功能。我们还表明，HEATR5B 促进了 AP1 与内体膜的独立于 dynein 的结合。因此，HEATR5B 协调了基于 AP1 的运输中的多个事件。
