title: Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome.
abstract: Critical to the maintenance of circadian rhythmicity is the cyclic expression of at least some components of the central oscillator. High-amplitude cycling of mRNA and protein abundance, protein phosphorylation and nuclear/cytoplasmic shuttling have all been implicated in the maintenance of circadian period. Here we use a newly characterized Arabidopsis suspension cell culture to establish that the rhythmic changes in the levels of the clock-associated F-box protein, ZTL, are posttranscriptionally controlled through different circadian phase-specific degradation rates. This proteolysis is proteasome dependent, implicating ZTL itself as substrate for ubiquitination. This demonstration of circadian phase-regulated degradation of an F-box protein, which itself controls circadian period, suggests a novel regulatory feedback mechanism among known circadian systems.
authors.affiliation: Department of Plant Biology/Plant Biotechnology Center, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Woe-Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Ruishuang
authors.initials: R
authors.lastname: Geng
authors.forename: David E
authors.initials: DE
authors.lastname: Somers
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002940:Circadian Rhythm; D003546:Cysteine Endopeptidases / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D017440:Photoperiod; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D018749:RNA, Plant; C410503:ZTL protein, Arabidopsis; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex