Marmorale Lucas J, Jin Huan, Reidy Thomas G, Palomino-Alonso Brandon, Zysnarski Christopher, Jordan-Javed Fatima, Lahiri Sagar, Duncan Mara C
Department of Cell and Developmental Biology, University of Michigan, Ann Arbor MI.
Present address: Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ.
bioRxiv. 2023 Nov 27:2023.08.24.554671. doi: 10.1101/2023.08.24.554671.
The highly conserved HEATR5 proteins are best known for their roles in membrane traffic mediated by the adaptor protein complex-1 (AP1). HEATR5 proteins rely on fast-evolving co-factors to bind to AP1. However, how HEATR5 proteins interact with these co-factors is unknown. Here, we report that the budding yeast HEATR5 protein, Laa1, functions in two biochemically distinct complexes. These complexes are defined by a pair of mutually exclusive Laa1-binding proteins, Laa2 and the previously uncharacterized Lft1/Yml037c. Despite limited sequence similarity, biochemical analysis and structure predictions indicate that Lft1 and Laa2 bind Laa1 via structurally similar mechanisms. Both Laa1 complexes function in intra-Golgi recycling. However, only the Laa2-Laa1 complex binds to AP1 and contributes to its localization. Finally, structure predictions indicate that human HEATR5 proteins bind to a pair of fast-evolving interacting partners via a mechanism similar to that observed in yeast. These results reveal mechanistic insight into how HEATR5 proteins bind their co-factors and indicate that Laa1 performs functions besides recruiting AP1.
高度保守的HEATR5蛋白因其在衔接蛋白复合物1（AP1）介导的膜运输中的作用而最为人所知。HEATR5蛋白依赖快速进化的辅助因子与AP1结合。然而，HEATR5蛋白如何与这些辅助因子相互作用尚不清楚。在这里，我们报告出芽酵母的HEATR5蛋白Laa1在两种生化性质不同的复合物中发挥作用。这些复合物由一对相互排斥的Laa1结合蛋白Laa2和先前未被鉴定的Lft1/Yml037c所定义。尽管序列相似性有限，但生化分析和结构预测表明，Lft1和Laa2通过结构相似的机制与Laa1结合。两个Laa1复合物都在高尔基体内部循环中发挥作用。然而，只有Laa2-Laa1复合物与AP1结合并有助于其定位。最后，结构预测表明，人类HEATR5蛋白通过与酵母中观察到的类似机制与一对快速进化的相互作用伙伴结合。这些结果揭示了关于HEATR5蛋白如何结合其辅助因子的机制性见解，并表明Laa1除了招募AP1外还执行其他功能。
