Bradford Mary Katherine, Whitworth Karen, Wendland Beverly
Department of Biology, Johns Hopkins University, Baltimore, MD 21218.
Department of Biology, Johns Hopkins University, Baltimore, MD 21218
Mol Biol Cell. 2015 Apr 1;26(7):1371-85. doi: 10.1091/mbc.E14-11-1510. Epub 2015 Jan 28.
Endocytosis is a well-conserved process by which cells invaginate small portions of the plasma membrane to create vesicles containing extracellular and transmembrane cargo proteins. Dozens of proteins and hundreds of specific binding interactions are needed to coordinate and regulate these events. Saccharomyces cerevisiae is a powerful model system with which to study clathrin-mediated endocytosis (CME). Pan1 is believed to be a scaffolding protein due to its interactions with numerous proteins that act throughout the endocytic process. Previous research characterized many Pan1 binding interactions, but due to Pan1's essential nature, the exact mechanisms of Pan1's function in endocytosis have been difficult to define. We created a novel Pan1-degron allele, Pan1-AID, in which Pan1 can be specifically and efficiently degraded in <1 h upon addition of the plant hormone auxin. The loss of Pan1 caused a delay in endocytic progression and weakened connections between the coat/actin machinery and the membrane, leading to arrest in CME. In addition, we determined a critical role for the central region of Pan1 in endocytosis and viability. The regions important for endocytosis and viability can be separated, suggesting that Pan1 may have a distinct role in the cell that is essential for viability.
内吞作用是一个高度保守的过程,通过该过程细胞内陷一小部分质膜以形成含有细胞外和跨膜货物蛋白的囊泡。协调和调节这些事件需要数十种蛋白质和数百种特异性结合相互作用。酿酒酵母是研究网格蛋白介导的内吞作用(CME)的强大模型系统。由于Pan1与在整个内吞过程中起作用的众多蛋白质相互作用,因此它被认为是一种支架蛋白。先前的研究对许多Pan1结合相互作用进行了表征,但由于Pan1的本质特性,其在内吞作用中发挥功能的确切机制一直难以确定。我们创建了一个新的Pan1-降解决定子等位基因Pan1-AID,在添加植物激素生长素后,Pan1可以在不到1小时的时间内被特异性且高效地降解。Pan1的缺失导致内吞进程延迟,并削弱了包被/肌动蛋白机制与膜之间的连接,从而导致CME停滞。此外,我们确定了Pan1中央区域在内吞作用和细胞活力中的关键作用。对细胞内吞作用和活力重要的区域可以分开,这表明Pan1在细胞中可能具有对活力至关重要的独特作用。