Assembly and dynamics of the autophagy-initiating Atg1 complex

作者：Stjepanovic, Goran; Davies, Christopher W.; Stanley, Robin E.; Ragusa, Michael J.; Kim, Do Jin; Hurley, James H.^*

来源：Proceedings of the National Academy of Sciences, 2014, 111(35): 12793-12798.

DOI：10.1073/pnas.1407214111

• analytical ultracentrifugation
• isothermal titration calorimetry
• membrane tethering
• intrinsically disordered proteins
• protein structure

The autophagy-related 1 (Atg1) complex of Saccharomyces cerevisiae has a central role in the initiation of autophagy following starvation and TORC1 inactivation. The complex consists of the protein kinase Atg1, the TORC1 substrate Atg13, and the trimeric Atg17-Atg31-Atg29 scaffolding subcomplex. Autophagy is triggered when Atg1 and Atg13 assemble with the trimeric scaffold. Here we show by hydrogen-deuterium exchange coupled to mass spectrometry that the mutually interacting Atg1 early autophagy targeting/tethering domain and the Atg13 central domain are highly dynamic in isolation but together form a stable complex with similar to 100-nM affinity. The Atg1-Atg13 complex in turn binds as a unit to the Atg17-Atg31-Atg29 scaffold with similar to 10-mu M affinity via Atg13. The resulting complex consists primarily of a dimer of pentamers in solution. These results lead to a model for autophagy initiation in which Atg1 and Atg13 are tightly associated with one another and assemble transiently into the pentameric Atg1 complex during starvation.

• 出版日期2014-9-2
• 单位NIH