title: SKP1-SnRK protein kinase interactions mediate proteasomal binding of a plant SCF ubiquitin ligase.
abstract: Arabidopsis Snf1-related protein kinases (SnRKs) are implicated in pleiotropic regulation of metabolic, hormonal and stress responses through their interaction with the kinase inhibitor PRL1 WD-protein. Here we show that SKP1/ASK1, a conserved SCF (Skp1-cullin-F-box) ubiquitin ligase subunit, which suppresses the skp1-4 mitotic defect in yeast, interacts with the PRL1-binding C-terminal domains of SnRKs. The same SnRK domains recruit an SKP1/ASK1-binding proteasomal protein, alpha4/PAD1, which enhances the formation of a trimeric SnRK complex with SKP1/ASK1 in vitro. By contrast, PRL1 reduces the interaction of SKP1/ASK1 with SnRKs. SKP1/ASK1 is co-immunoprecipitated with a cullin SCF subunit (AtCUL1) and an SnRK kinase, but not with PRL1 from Arabidopsis cell extracts. SKP1/ASK1, cullin and proteasomal alpha-subunits show nuclear co-localization in differentiated Arabidopsis cells, and are observed in association with mitotic spindles and phragmoplasts during cell division. Detection of SnRK in purified 26S proteasomes and co-purification of epitope- tagged SKP1/ASK1 with SnRK, cullin and proteasomal alpha-subunits indicate that the observed protein interactions between SnRK, SKP1/ASK1 and alpha4/PAD1 are involved in proteasomal binding of an SCF ubiquitin ligase in Arabidopsis.
authors.affiliation: Max-Planck Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Farrás
authors.forename: A
authors.initials: A
authors.lastname: Ferrando
authors.forename: J
authors.initials: J
authors.lastname: Jásik
authors.forename: T
authors.initials: T
authors.lastname: Kleinow
authors.forename: L
authors.initials: L
authors.lastname: Okrész
authors.forename: A
authors.initials: A
authors.lastname: Tiburcio
authors.forename: K
authors.initials: K
authors.lastname: Salchert
authors.forename: C
authors.initials: C
authors.lastname: del Pozo
authors.forename: J
authors.initials: J
authors.lastname: Schell
authors.forename: C
authors.initials: C
authors.lastname: Koncz
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins; D001665:Binding Sites; D017124:Conserved Sequence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010453:Peptide Synthases / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D044843:SKP Cullin F-Box Protein Ligases; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010447:Peptide Hydrolases; D010453:Peptide Synthases; D010940:Plant Proteins; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D011994:Recombinant Proteins; D044843:SKP Cullin F-Box Protein Ligases; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators; C120363:ASK1 protein, Arabidopsis; C093857:rpn11 protein, S pombe; C490996:At5g01820 protein, Arabidopsis; C061553:ATP dependent 26S protease