Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
Center for Plant Systems Biology, VIB, Ghent, Belgium.
Nat Plants. 2022 Dec;8(12):1467-1483. doi: 10.1038/s41477-022-01280-1. Epub 2022 Dec 1.
Endocytosis controls the perception of stimuli by modulating protein abundance at the plasma membrane. In plants, clathrin-mediated endocytosis is the most prominent internalization pathway and relies on two multimeric adaptor complexes, the AP-2 and the TPLATE complex (TPC). Ubiquitination is a well-established modification triggering endocytosis of cargo proteins, but how this modification is recognized to initiate the endocytic event remains elusive. Here we show that TASH3, one of the large subunits of TPC, recognizes ubiquitinated cargo at the plasma membrane via its SH3 domain-containing appendage. TASH3 lacking this evolutionary specific appendage modification allows TPC formation but the plants show severely reduced endocytic densities, which correlates with reduced endocytic flux. Moreover, comparative plasma membrane proteomics identified differential accumulation of multiple ubiquitinated cargo proteins for which we confirm altered trafficking. Our findings position TPC as a key player for ubiquitinated cargo internalization, allowing future identification of target proteins under specific stress conditions.
内吞作用通过调节质膜上蛋白质的丰度来控制对刺激的感知。在植物中，网格蛋白介导的内吞作用是最突出的内化途径，依赖于两个多聚体衔接复合物，即 AP-2 和 TPLATE 复合物（TPC）。泛素化是一种公认的修饰，可触发货物蛋白的内吞作用，但这种修饰如何被识别以启动内吞作用仍然难以捉摸。在这里，我们表明 TPC 的大亚基之一 TASH3 通过其含有 SH3 结构域的附属物在质膜上识别泛素化的货物。缺乏这种进化特有的附属物修饰的 TASH3 允许 TPC 形成，但植物显示出严重降低的内吞密度，这与内吞通量的降低相关。此外，比较质膜蛋白质组学鉴定了多种泛素化货物蛋白的差异积累，我们证实了这些蛋白的运输发生了改变。我们的发现将 TPC 定位为泛素化货物内化的关键参与者，允许在特定应激条件下鉴定目标蛋白。
