title: DENEDDYLASE1 deconjugates NEDD8 from non-cullin protein substrates in Arabidopsis thaliana.
abstract: The evolutionarily conserved 8-kD protein NEDD8 (NEURAL PRECURSOR CELL EXPRESSED, DEVELOPMENTALLY DOWN-REGULATED8) belongs to the family of ubiquitin-like modifiers. Like ubiquitin, NEDD8 is conjugated to and deconjugated from target proteins. Many targets and functions of ubiquitylation have been described; by contrast, few targets of NEDD8 have been identified. In plants as well as in non-plant organisms, the cullin subunits of cullin-RING E3 ligases are NEDD8 conjugates with a demonstrated functional role for the NEDD8 modification. The existence of other non-cullin NEDD8 targets has generally been questioned. NEDD8 is translated as a precursor protein and proteolytic processing exposes a C-terminal glycine required for NEDD8 conjugation. In animals and yeast, DENEDDYLASE1 (DEN1) processes NEDD8. Here, we show that mutants of a DEN1 homolog from Arabidopsis thaliana have no detectable defects in NEDD8 processing but do accumulate a broad range of NEDD8 conjugates; this provides direct evidence for the existence of non-cullin NEDD8 conjugates. We further identify AUXIN RESISTANT1 (AXR1), a subunit of the heterodimeric NEDD8 E1 activating enzyme, as a NEDD8-modified protein in den1 mutants and wild type and provide evidence that AXR1 function may be compromised in the absence of DEN1 activity. Thus, in plants, neddylation may serve as a regulatory mechanism for cullin and non-cullin proteins.
authors.affiliation: Plant Systems Biology, Technische Universität München, 85354 Freising, Germany Proteomics and Bioanalytics, Technische Universität München, 85354 Freising, Germany claus.schwechheimer@wzw.tum.de.
authors.forename: Julia
authors.initials: J
authors.lastname: Mergner
authors.affiliation: Proteomics and Bioanalytics, Technische Universität München, 85354 Freising, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Heinzlmeir
authors.affiliation: Proteomics and Bioanalytics, Technische Universität München, 85354 Freising, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kuster
authors.affiliation: Plant Systems Biology, Technische Universität München, 85354 Freising, Germany claus.schwechheimer@wzw.tum.de.
authors.forename: Claus
authors.initials: C
authors.lastname: Schwechheimer
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D013379:Substrate Specificity / Q000187:drug effects; D025801:Ubiquitin / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D044842:Cullin Proteins; C513170:RUB1 protein, Arabidopsis; D025801:Ubiquitin; D014452:Ubiquitins; D015084:2,4-Dichlorophenoxyacetic Acid