Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology , Yokohama, Japan.
School of Life Science and Technology, Tokyo Institute of Technology , Yokohama, Japan.
J Cell Biol. 2023 Aug 7;222(8). doi: 10.1083/jcb.202210017. Epub 2023 Jul 12.
In macroautophagy, cellular components are sequestered within autophagosomes and transported to lysosomes/vacuoles for degradation. Although phosphatidylinositol 3-kinase complex I (PI3KCI) plays a pivotal role in the regulation of autophagosome biogenesis, little is known about how this complex localizes to the pre-autophagosomal structure (PAS). In Saccharomyces cerevisiae, PI3KCI is composed of PI3K Vps34 and conserved subunits Vps15, Vps30, Atg14, and Atg38. In this study, we discover that PI3KCI interacts with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9 via the Atg14 C-terminal region, the Atg38 C-terminal region, and the Vps30 BARA domain, respectively. While the Atg14-Vac8 interaction is constitutive, the Atg38-Atg1 complex interaction and the Vps30-Atg9 interaction are enhanced upon macroautophagy induction depending on Atg1 kinase activity. These interactions cooperate to target PI3KCI to the PAS. These findings provide a molecular basis for PAS targeting of PI3KCI during autophagosome biogenesis.
在巨自噬中，细胞成分被隔离在自噬体中，并被运输到溶酶体/液泡中进行降解。尽管磷脂酰肌醇 3-激酶复合物 I (PI3KCI) 在自噬体生物发生的调节中起着关键作用，但对于该复合物如何定位到前自噬体结构 (PAS) 知之甚少。在酿酒酵母中，PI3KCI 由 PI3K Vps34 和保守亚基 Vps15、Vps30、Atg14 和 Atg38 组成。在这项研究中，我们发现 PI3KCI 通过 Atg14 C 末端区域、Atg38 C 末端区域和 Vps30 BARA 结构域分别与液泡膜锚 Vac8、PAS 支架 Atg1 复合物和前自噬小泡成分 Atg9 相互作用。虽然 Atg14-Vac8 相互作用是组成性的，但 Atg38-Atg1 复合物相互作用和 Vps30-Atg9 相互作用在巨自噬诱导时会增强，这取决于 Atg1 激酶活性。这些相互作用共同将 PI3KCI 靶向到 PAS。这些发现为自噬体生物发生过程中 PI3KCI 到 PAS 的靶向提供了分子基础。
