ATG8ylation-orchestrated vacuolar membrane remodeling facilitates plant alkaline stress tolerance.

Abstract

While ATG8ylation, the C-terminal lipidation of mammalian and plant Atg8 (ATG8)-family proteins, is a well-established driver of autophagosome formation, emerging evidence reveals its non-canonical role in modifying single-membrane organelles under diverse environmental stresses. In a recent study, we found that disruption of the vacuolar proton gradient by alkaline stress rapidly triggers the translocation of ATG8 to the vacuolar membrane in plants. ATG8ylation facilitates membrane invagination through a mechanism independent of both ESCRT and the cytoskeleton. Concurrently, ATG8 recruits ATG2 to endoplasmic reticulum (ER)-vacuolar membrane contact sites, a process that may contribute to damaged membrane repair. Together, these processes enable plants to rapidly recover from vacuolar pH imbalance and adapt to alkaline conditions. Our findings advance the understanding of ATG8ylation in vacuolar membrane homeostasis and damage response, highlighting its conserved role in organellar stability and stress adaptation.Abbreviations: ATG, autophagy related; ER, endoplasmic reticulum; ESCRT, endosomal sorting complexes required for transport; PM, plasma membrane; ROS, reactive oxygen species; TGN, trans-Golgi network; V-ATPase, vacuolar-type H+-translocating ATPase.