The Atg1 complex, Atg9, and Vac8 recruit PI3K complex I to the pre-autophagosomal structure

Hitomi et al. reveal that phosphatidylinositol 3-kinase complex I, essential for autophagosome biogenesis, is recruited to the autophagosome precursor via the interactions with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9. 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.

Automated summary

Hitomi et al. reveal that the phosphatidylinositol 3-kinase complex I is recruited to the autophagosome precursor via interactions with Vac8, Atg1 complex, and Atg9. These interactions cooperate to target the phosphatidylinositol 3-kinase complex I to the pre-autophagosomal structure and provide a molecular basis for its localization during autophagosome biogenesis.