a Department of Cellular Biochemistry, University Medicine , Georg-August University , Goettingen , Germany.
Autophagy. 2019 Jun;15(6):1031-1050. doi: 10.1080/15548627.2019.1569929. Epub 2019 Jan 27.
Macroautophagy/autophagy is a highly conserved intracellular vesicle transport pathway that prevents accumulation of harmful materials within cells. The dynamic assembly and disassembly of the different autophagic protein complexes at the so-called phagophore assembly site (PAS) is strictly regulated. Rab GTPases are major regulators of cellular vesicle trafficking, and the Rab GTPase Ypt1 and its GEF TRAPPIII have been implicated in autophagy. We show that Gyp1 acts as a Ypt1 GTPase-activating protein (GAP) for selective autophagic variants, such as the Cvt pathway or the selective autophagic degradation of mitochondria (mitophagy). Gyp1 regulates the dynamic disassembly of the conserved Ypt1-Atg1 complex. Thereby, Gyp1 sets the stage for efficient Atg14 recruitment, and facilitates the critical step from nucleation to elongation of the phagophore. In addition, we identified Gyp1 as a new Atg8-interacting motif (AIM)-dependent Atg8 interaction partner. The Gyp1 AIM is required for efficient formation of the cargo receptor-Atg8 complexes. Our findings elucidate the molecular mechanisms of complex disassembly during phagophore formation and suggest potential dual functions of GAPs in cellular vesicle trafficking. Abbreviations AIM, Atg8-interacting motif; Atg, autophagy related; Cvt, cytoplasm-to-vacuole targeting; GAP, GTPase-activating protein; GEF, guanine-nucleotide exchange factor; GFP, green fluorescent protein; log phase, logarithmic growth phase; NHD, N-terminal helical domain; PAS, phagophore assembly site; PE, phosphatidylethanolamine; PtdIns3P, phosphatidylinositol-3-phosphate; WT, wild-type.
自噬是一种高度保守的细胞内囊泡运输途径，可防止细胞内有害物质的积累。不同自噬蛋白复合物在所谓的吞噬体组装位点（PAS）的动态组装和拆卸受到严格调节。Rab GTPases 是细胞囊泡运输的主要调节剂，Rab GTPase Ypt1 及其 GEF TRAPPIII 已被牵连到自噬中。我们表明 Gyp1 是选择性自噬变体（如 Cvt 途径或线粒体选择性自噬降解（mitophagy）的 Ypt1 GTPase 激活蛋白（GAP）。Gyp1 调节保守的 Ypt1-Atg1 复合物的动态拆卸。因此，Gyp1 为 Atg14 的有效募集设定了阶段，并促进了从成核到吞噬体伸长的关键步骤。此外，我们确定 Gyp1 是新的 Atg8 相互作用基序（AIM）依赖性 Atg8 相互作用伙伴。Gyp1 AIM 是有效形成货物受体-Atg8 复合物所必需的。我们的发现阐明了吞噬体形成过程中复合物拆卸的分子机制，并表明 GAP 在细胞囊泡运输中可能具有双重功能。缩写 AIM，Atg8 相互作用基序；Atg，自噬相关；Cvt，细胞质到液泡靶向；GAP，GTPase 激活蛋白；GEF，鸟嘌呤核苷酸交换因子；GFP，绿色荧光蛋白；对数期，对数生长期；NHD，N 端螺旋域；PAS，吞噬体组装位点；PE，磷脂酰乙醇胺；PtdIns3P，磷脂酰肌醇 3-磷酸；WT，野生型。
