Solution structure of the Atg1 complex: implications for the architecture of the phagophore assembly site

Structure. 2015 May 5;23(5):809-818. doi: 10.1016/j.str.2015.02.012. Epub 2015 Mar 26.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Autophagy
  • Binding Sites
  • Fungal Proteins / chemistry*
  • Kluyveromyces / chemistry
  • Kluyveromyces / metabolism*
  • Models, Molecular
  • Multiprotein Complexes / chemistry*
  • Multiprotein Complexes / metabolism
  • Phagosomes / chemistry
  • Phagosomes / metabolism*
  • Protein Multimerization
  • Scattering, Small Angle
  • Solubility

Substances

  • Fungal Proteins
  • Multiprotein Complexes