title: The Arabidopsis COP9 SIGNALOSOME INTERACTING F-BOX KELCH 1 protein forms an SCF ubiquitin ligase and regulates hypocotyl elongation.
abstract: The regulation of protein turnover by the ubiquitin proteasome system (UPS) is a major posttranslational mechanism in eukaryotes. One of the key components of the UPS, the COP9 signalosome (CSN), regulates 'cullin-ring' E3 ubiquitin ligases. In plants, CSN participates in diverse cellular and developmental processes, ranging from light signaling to cell cycle control. In this work, we isolated a new plant-specific CSN-interacting F-box protein, which we denominated CFK1 (COP9 INTERACTING F-BOX KELCH 1). We show that, in Arabidopsis thaliana, CFK1 is a component of a functional ubiquitin ligase complex. We also show that CFK1 stability is regulated by CSN and by proteasome-dependent proteolysis, and that light induces accumulation of the CFK1 transcript in the hypocotyl. Analysis of CFK1 knockdown, mutant, and overexpressing seedlings indicates that CFK1 promotes hypocotyl elongation by increasing cell size. Reduction of CSN levels enhances the short hypocotyl phenotype of CFK1-depleted seedlings, while complete loss of CSN activity suppresses the long-hypocotyl phenotype of CFK1-overexpressing seedlings. We propose that CFK1 (and its regulation by CSN) is a novel component of the cellular mechanisms controlling hypocotyl elongation.
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Franciosini
authors.forename: Benedetta
authors.initials: B
authors.lastname: Lombardi
authors.forename: Silvia
authors.initials: S
authors.lastname: Iafrate
authors.forename: Valeria
authors.initials: V
authors.lastname: Pecce
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mele
authors.forename: Leonardo
authors.initials: L
authors.lastname: Lupacchini
authors.forename: Gianmarco
authors.initials: G
authors.lastname: Rinaldi
authors.forename: Youichi
authors.initials: Y
authors.lastname: Kondou
authors.forename: Giuliana
authors.initials: G
authors.lastname: Gusmaroli
authors.forename: Shiori
authors.initials: S
authors.lastname: Aki
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Tsuge
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Deng
authors.forename: Minami
authors.initials: M
authors.lastname: Matsui
authors.forename: Paola
authors.initials: P
authors.lastname: Vittorioso
authors.forename: Paolo
authors.initials: P
authors.lastname: Costantino
authors.forename: Giovanna
authors.initials: G
authors.lastname: Serino
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000075686:COP9 Signalosome Complex; D048429:Cell Size / Q000528:radiation effects; D015536:Down-Regulation / Q000528:radiation effects; D044783:F-Box Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010447:Peptide Hydrolases / Q000378:metabolism; D010641:Phenotype; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055550:Protein Stability / Q000528:radiation effects; D059748:Proteolysis / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C587316:CFK1 protein, Arabidopsis; D044783:F-Box Proteins; D046912:Multiprotein Complexes; D012333:RNA, Messenger; D044843:SKP Cullin F-Box Protein Ligases; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D046988:Proteasome Endopeptidase Complex
keywords: Arabidopsis thaliana; COP9 signalosome; F-box protein; hypocotyl elongation; proteasome; seedling development.; ubiquitin