title: Solution structure of the Atg1 complex: implications for the architecture of the phagophore assembly site.
abstract: The biogenesis of autophagosomes commences at the phagophore assembly site (PAS), a protein-vesicle ultrastructure that is organized by the Atg1 complex. The Atg1 complex consists of the Atg1 protein kinase, the intrinsically disordered region-rich Atg13, and the dimeric double crescent-shaped Atg17-Atg31-Atg29 subcomplex. We show that the PAS contains a relatively uniform ∼28 copies of Atg17, and upon autophagy induction, similar numbers of Atg1 and Atg13 molecules. We then apply ensemble refinement of small-angle X-ray scattering to determine the solution structures of the Atg1-Atg13 and Atg17-Atg31-Atg29 subcomplexes and the Atg1 complex, using a trimmed minipentamer tractable to biophysical studies. We observe tetramers of Atg1 pentamers that assemble via Atg17-Atg31-Atg29. This leads to a model for the higher organization of the Atg1 complex in PAS scaffolding.
authors: Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany. Electronic address: juergen.koefinger@biophys.mpg.de.
authors: Jürgen
authors: J
authors: Köfinger
authors: Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA.
authors: Michael J
authors: MJ
authors: Ragusa
authors: Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA.
authors: Il-Hyung
authors: IH
authors: Lee
authors: Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany.
authors: Gerhard
authors: G
authors: Hummer
authors: Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA; Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Electronic address: jimhurley@berkeley.edu.
authors: James H
authors: JH
authors: Hurley
mesh_terms: D001343:Autophagy; D001665:Binding Sites; D005656:Fungal Proteins / Q000737:chemistry*; D007716:Kluyveromyces / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism; D010588:Phagosomes / Q000737:chemistry / Q000378:metabolism*; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D012995:Solubility
chemical_list: D005656:Fungal Proteins; D046912:Multiprotein Complexes