Multicampus Research Programs and Initiatives (MRPI); a funding opportunity through UC Research Initiatives (UCRI)
Solution Structure of the Atg1 Complex: Implications for the Architecture of the Phagophore Assembly Site
- Author(s): Köfinger, Jürgen
- Ragusa, Michael J.
- Lee, Il-Hyung
- Hummer, Gerhard
- Hurley, James H.
- et al.
Published Web Locationhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC4426065/
SummaryThe 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 (SAXS) to determine the solution structures of the Atg1-Atg13 and Atg17-Atg31-Atg29 subcomplexes and the Atg1 complex, using a trimmed “mini-pentamer” 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.