title: Atg27 is required for autophagy-dependent cycling of Atg9.
abstract: Autophagy is a catabolic pathway for the degradation of cytosolic proteins or organelles and is conserved among all eukaryotic cells. The hallmark of autophagy is the formation of double-membrane cytosolic vesicles, termed autophagosomes, which sequester cytoplasm; however, the mechanism of vesicle formation and the membrane source remain unclear. In the yeast Saccharomyces cerevisiae, selective autophagy mediates the delivery of specific cargos to the vacuole, the analog of the mammalian lysosome. The transmembrane protein Atg9 cycles between the mitochondria and the pre-autophagosomal structure, which is the site of autophagosome biogenesis. Atg9 is thought to mediate the delivery of membrane to the forming autophagosome. Here, we characterize a second transmembrane protein Atg27 that is required for specific autophagy in yeast. Atg27 is required for Atg9 cycling and shuttles between the pre-autophagosomal structure, mitochondria, and the Golgi complex. These data support a hypothesis that multiple membrane sources supply the lipids needed for autophagosome formation.
authors.affiliation: Life Sciences Institute, and Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Wei-Lien
authors.initials: WL
authors.lastname: Yen
authors.forename: Julie E
authors.initials: JE
authors.lastname: Legakis
authors.forename: Usha
authors.initials: U
authors.lastname: Nair
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Klionsky
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D010588:Phagosomes / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
chemical_list: C519194:ATG27 protein, S cerevisiae; C434065:ATG9 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins