真菌のゲノミクスと生物学
オープンアクセス

概要

How do Two Domains of Atg15 Work for Autophagosomal Membrane Degradation?

Eri Hirata, Kuninori Suzuki

During autophagy in Saccharomyces cerevisiae, cytosolic components are engulfed by double-membrane compartments called autophagosomes, transported to the vacuole, and degraded there. The cytoplasm-to-vacuole targeting (Cvt) pathway delivers the vacuolar hydrolase aminopeptidase I (Ape1) through double-membrane compartments termed Cvt vesicles. These pathways share common mechanisms including the degradation of their compartments. The outer membranes of autophagosomes and Cvt vesicles fuse with the vacuole membrane and inner membranebound structures and, autophagic bodies and Cvt bodies, are released into the vacuole lumen. The membranes of autophagic bodies and Cvt bodies are degraded by a vacuolar lipase, Atg15, to allow other vacuolar hydrolases to access their cargoes for degradation. Atg15 is the only vacuolar lipase in S. cerevisiae and has a transmembrane domain at the N-terminus and a lipase domain at the C-terminus. Recently, our group has clarified the roles of these two domains in vivo. Here we review how Atg15 functions for degradation of the membranes of autophagic bodies and Cvt bodies in the vacuole.