The plant unique ESCRT component FREE1 regulates autophagosome closure

Nat Commun. 2023 Mar 30;14(1):1768. doi: 10.1038/s41467-023-37185-6.


The energy sensor AMP-activated protein kinase (AMPK) can activate autophagy when cellular energy production becomes compromised. However, the degree to which nutrient sensing impinges on the autophagosome closure remains unknown. Here, we provide the mechanism underlying a plant unique protein FREE1, upon autophagy-induced SnRK1α1-mediated phosphorylation, functions as a linkage between ATG conjugation system and ESCRT machinery to regulate the autophagosome closure upon nutrient deprivation. Using high-resolution microscopy, 3D-electron tomography, and protease protection assay, we showed that unclosed autophagosomes accumulated in free1 mutants. Proteomic, cellular and biochemical analysis revealed the mechanistic connection between FREE1 and the ATG conjugation system/ESCRT-III complex in regulating autophagosome closure. Mass spectrometry analysis showed that the evolutionary conserved plant energy sensor SnRK1α1 phosphorylates FREE1 and recruits it to the autophagosomes to promote closure. Mutagenesis of the phosphorylation site on FREE1 caused the autophagosome closure failure. Our findings unveil how cellular energy sensing pathways regulate autophagosome closure to maintain cellular homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagosomes* / metabolism
  • Autophagy
  • Endosomal Sorting Complexes Required for Transport / metabolism
  • Endosomes / metabolism
  • Proteomics*


  • Endosomal Sorting Complexes Required for Transport