title: Atg9 sorting from mitochondria is impaired in early secretion and VFT-complex mutants in Saccharomyces cerevisiae.
abstract: In eukaryotic cells, the turnover of long-lived proteins and large cytoplasmic structures is mediated by autophagy. Components that have to be eliminated are sequestered into double-membrane vesicles called autophagosomes and delivered into the lysosome or vacuole where they are destroyed by resident hydrolases. The integral membrane protein Atg9 is essential for both autophagy and the cytoplasm-to-vacuole targeting pathway, a selective biosynthetic process in Saccharomyces cerevisiae that is mechanistically and morphologically similar to autophagy. Atg9 cycles between the pre-autophagosomal structure, the putative site of double-membrane vesicle biogenesis and mitochondria. To understand the function of Atg9, and also its trafficking mode between these two locations, we identified mutants that affect specific Atg9 transport steps. We recently reported that five Atg proteins and phosphatidylinositol-3-phosphate regulate Atg9 recycling from the pre-autophagosomal structure. Here, we describe a different category of mutants that blocks Atg9 sorting from mitochondria. All mutants have been previously shown to be required for the normal progression of both the Cvt pathway and autophagy, but their precise role in these transport routes was unknown.
authors.affiliation: Department of Cell Biology, Cell Microscopy Center and Institute of Biomembranes, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Reggiori
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Klionsky
mesh_terms: D000199:Actins / Q000378:metabolism; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D008562:Membrane Glycoproteins / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: C434065:ATG9 protein, S cerevisiae; D000199:Actins; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D020662:Guanine Nucleotide Exchange Factors; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; C071239:SEC12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C077554:Sed5 protein, S cerevisiae; C492177:VPS53 protein, S cerevisiae