title: The Atg1-kinase complex tethers Atg9-vesicles to initiate autophagy.
abstract: Autophagosomes are double-membrane vesicles that sequester cytoplasmic material for lysosomal degradation. Their biogenesis is initiated by recruitment of Atg9-vesicles to the phagophore assembly site. This process depends on the regulated activation of the Atg1-kinase complex. However, the underlying molecular mechanism remains unclear. Here we reconstitute this early step in autophagy from purified components in vitro. We find that on assembly from its cytoplasmic subcomplexes, the Atg1-kinase complex becomes activated, enabling it to recruit and tether Atg9-vesicles. The scaffolding protein Atg17 targets the Atg1-kinase complex to autophagic membranes by specifically recognizing the membrane protein Atg9. This interaction is inhibited by the two regulatory subunits Atg31 and Atg29. Engagement of the Atg1-Atg13 subcomplex restores the Atg9-binding and membrane-tethering activity of Atg17. Our data help to unravel the mechanism that controls Atg17-mediated tethering of Atg9-vesicles, providing the molecular basis to understand initiation of autophagosome-biogenesis.
authors.affiliation: Molecular Membrane and Organelle Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
authors.forename: Yijian
authors.initials: Y
authors.lastname: Rao
authors.affiliation: Molecular Membrane and Organelle Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
authors.forename: Marco G
authors.initials: MG
authors.lastname: Perna
authors.affiliation: Molecular Membrane and Organelle Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Hofmann
authors.affiliation: Molecular Membrane and Organelle Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
authors.forename: Viola
authors.initials: V
authors.lastname: Beier
authors.affiliation: Molecular Membrane and Organelle Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wollert
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000235:genetics*; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002942:Circular Dichroism; D020285:Cryoelectron Microscopy; D000067493:Dynamic Light Scattering; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D008081:Liposomes; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D018613:Microscopy, Confocal; D001678:Organelle Biogenesis; D011494:Protein Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013347:Subcellular Fractions; D053719:Tandem Mass Spectrometry
chemical_list: C413216:ATG13 protein, S cerevisiae; C506770:ATG29 protein, S cerevisiae; C434065:ATG9 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; C505602:Atg17 protein, S cerevisiae; C520043:Atg31 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D008081:Liposomes; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C477823:ATG1 protein, S cerevisiae; D000469:Alkaline Phosphatase; C510355:PHO8 protein, S cerevisiae