title: Autophagic Degradation of the 26S Proteasome Is Mediated by the Dual ATG8/Ubiquitin Receptor RPN10 in Arabidopsis.
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.
authors.affiliation: Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Marshall
authors.affiliation: Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA.
authors.forename: Faqiang
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Gemperline
authors.affiliation: Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Book
authors.affiliation: Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison, WI 53706, USA. Electronic address: vierstra@wisc.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Vierstra
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D007976:Leupeptins / Q000494:pharmacology; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D054875:Ubiquitination / Q000187:drug effects
chemical_list: C000597073:ATG8 protein, Arabidopsis; D029681:Arabidopsis Proteins; D000071190:Autophagy-Related Protein 8 Family; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D008869:Microtubule-Associated Proteins; C475163:RPN10 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde