Atg9 小泡招募衔接蛋白 Trs85 和 Ypt1 至自噬体形成部位。
Atg9 vesicles recruit vesicle-tethering proteins Trs85 and Ypt1 to the autophagosome formation site.
机构信息
Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
出版信息
J Biol Chem. 2012 Dec 28;287(53):44261-9. doi: 10.1074/jbc.M112.411454. Epub 2012 Nov 5.
Atg9 is a transmembrane protein that is essential for autophagy. In the budding yeast Saccharomyces cerevisiae, it has recently been revealed that Atg9 exists on cytoplasmic small vesicles termed Atg9 vesicles. To identify the components of Atg9 vesicles, we purified the Atg9 vesicles and subjected them to mass spectrometry. We found that their protein composition was distinct from other organellar membranes and that Atg9 and Atg27 in particular are major components of Atg9 vesicles. In addition to these two components, Trs85, a specific subunit of the transport protein particle III (TRAPPIII) complex, and the Rab GTPase Ypt1 were also identified. Trs85 directly interacts with Atg9, and the Trs85-containing TRAPPIII complex facilitates the association of Ypt1 onto Atg9 vesicles. We also showed that Trs85 and Ypt1 are localized to the preautophagosomal structure in an Atg9-dependent manner. Our data suggest that Atg9 vesicles recruit the TRAPPIII complex and Ypt1 to the preautophagosomal structure. The vesicle-tethering machinery consequently acts in the process of autophagosome formation.
Atg9 是一种跨膜蛋白，对自噬至关重要。在芽殖酵母酿酒酵母中，最近发现 Atg9 存在于称为 Atg9 小泡的细胞质小泡上。为了鉴定 Atg9 小泡的成分，我们纯化了 Atg9 小泡并对其进行了质谱分析。我们发现，它们的蛋白质组成与其他细胞器膜不同，特别是 Atg9 和 Atg27 是 Atg9 小泡的主要成分。除了这两个成分外，还鉴定出了特定于运输蛋白颗粒 III（TRAPPIII）复合物的 Trs85 和 Rab GTPase Ypt1。Trs85 与 Atg9 直接相互作用，含有 Trs85 的 TRAPPIII 复合物促进 Ypt1 与 Atg9 小泡结合。我们还表明，Trs85 和 Ypt1 以 Atg9 依赖的方式定位于前自噬体结构。我们的数据表明，Atg9 小泡募集 TRAPPIII 复合物和 Ypt1 到前自噬体结构。因此，囊泡连接机制在自噬体形成过程中起作用。
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