Wang Lei, Johnson Adam, Hanna Michael, Audhya Anjon
Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706.
Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706
Mol Biol Cell. 2016 Sep 1;27(17):2675-87. doi: 10.1091/mbc.E16-03-0151. Epub 2016 Jul 6.
Clathrin coat assembly on membranes requires cytosolic adaptors and accessory proteins, which bridge triskeleons with the lipid bilayer and stabilize lattice architecture throughout the process of vesicle formation. In Caenorhabditis elegans, the prototypical AP-2 adaptor complex, which is activated by the accessory factor Fcho1 at the plasma membrane, is dispensable during embryogenesis, enabling us to define alternative mechanisms that facilitate clathrin-mediated endocytosis. Here we uncover a synthetic genetic interaction between C. elegans Fcho1 (FCHO-1) and Eps15 (EHS-1), suggesting that they function in a parallel and potentially redundant manner. Consistent with this idea, we find that the FCHO-1 EFC/F-BAR domain and the EHS-1 EH domains exhibit highly similar membrane-binding and -bending characteristics in vitro. Furthermore, we demonstrate a critical role for EHS-1 when FCHO-1 membrane-binding and -bending activity is specifically eliminated in vivo. Taken together, our data highlight Eps15 as an important membrane-remodeling factor, which acts in a partially redundant manner with Fcho proteins during the earliest stages of clathrin-mediated endocytosis.
网格蛋白衣被在膜上的组装需要胞质衔接蛋白和辅助蛋白,它们在三腿蛋白与脂质双层之间起桥梁作用,并在囊泡形成的整个过程中稳定晶格结构。在秀丽隐杆线虫中,典型的AP-2衔接蛋白复合物在质膜上被辅助因子Fcho1激活,在胚胎发生过程中是可有可无的,这使我们能够确定促进网格蛋白介导的内吞作用的替代机制。在这里,我们发现秀丽隐杆线虫的Fcho1(FCHO-1)和Eps15(EHS-1)之间存在合成遗传相互作用,表明它们以平行且可能冗余的方式发挥作用。与这一观点一致,我们发现在体外FCHO-1的EFC/F-BAR结构域和EHS-1的EH结构域表现出高度相似的膜结合和膜弯曲特性。此外,我们证明了当FCHO-1的膜结合和膜弯曲活性在体内被特异性消除时,EHS-1具有关键作用。综上所述,我们的数据突出了Eps15作为一种重要的膜重塑因子,在网格蛋白介导的内吞作用的最早阶段与Fcho蛋白以部分冗余的方式发挥作用。