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

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

Author information

1
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.
2
Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA.
3
Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt am Main, Germany.
4
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.

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.

PMID:
25817386
PMCID:
PMC4426065
DOI:
10.1016/j.str.2015.02.012
[Indexed for MEDLINE]
Free PMC Article

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