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Mol Cell. 2015 Jun 18;58(6):1053-66. doi: 10.1016/j.molcel.2015.04.023. Epub 2015 May 21.

Autophagic Degradation of the 26S Proteasome Is Mediated by the Dual ATG8/Ubiquitin Receptor RPN10 in Arabidopsis.

Author information

1
Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA.
2
Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA. Electronic address: vierstra@wisc.edu.

Abstract

Autophagic turnover of intracellular constituents is critical for cellular housekeeping, nutrient recycling, and various aspects of growth and development in eukaryotes. Here we show that autophagy impacts the other major degradative route involving the ubiquitin-proteasome system by eliminating 26S proteasomes, a process we termed proteaphagy. Using Arabidopsis proteasomes tagged with GFP, we observed their deposition into vacuoles via a route requiring components of the autophagy machinery. This transport can be initiated separately by nitrogen starvation and chemical or genetic inhibition of the proteasome, implying distinct induction mechanisms. Proteasome inhibition stimulates comprehensive ubiquitylation of the complex, with the ensuing proteaphagy requiring the proteasome subunit RPN10, which can simultaneously bind both ATG8 and ubiquitin. Collectively, we propose that Arabidopsis RPN10 acts as a selective autophagy receptor that targets inactive 26S proteasomes by concurrent interactions with ubiquitylated proteasome subunits/targets and lipidated ATG8 lining the enveloping autophagic membranes.

PMID:
26004230
PMCID:
PMC4903074
DOI:
10.1016/j.molcel.2015.04.023
[Indexed for MEDLINE]
Free PMC Article

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