TORC1 regulates ESCRT-0 complex formation on the vacuolar membrane and microautophagy induction in yeast.

Microautophagy is promoted after nutrient starvation and inactivation of target of rapamycin complex 1 (TORC1) kinase. Invagination of vacuolar membranes by endosomal sorting complex required for transport (ESCRT) is required for microautophagy. Vps27, a subunit of ESCRT-0, is recruited onto vacuolar membranes via dephosphorylation after TORC1 inactivation. Here, we showed that Hse1, another ESCRT-0 subunit, is also recruited onto vacuolar membranes after TORC1 inactivation, promoting formation of ESCRT-0 complex on vacuolar membranes. Hse1 recruitment was dependent on Vps27, whereas Vps27 recruitment was independent of Hse1. Not only Vps27 but also Hse1 was required for ESCRT-III recruitment onto vacuolar membranes and microautophagy induction after TORC1 inactivation. This study revealed that ESCRT-0 (Vps27-Hse1) complex formation on vacuolar membranes is important for microautophagy inactivation after TORC1 inactivation.