title: AXR1-ECR1-dependent conjugation of RUB1 to the Arabidopsis Cullin AtCUL1 is required for auxin response.
abstract: Mutations in the AXR1 gene result in a reduction in auxin response and diverse defects in auxin-regulated growth and development. In a previous study, we showed that AXR1 forms a heterodimer with the ECR1 protein. This enzyme activates the ubiquitin-related protein RUB1 in vitro. Furthermore, we showed that the Skp1-Cul1/Cdc53-F-box (SCF) subunit AtCUL1 is modified by RUB1 in vivo. In this report, we demonstrate that the formation of RUB-AtCUL1 is dependent on AXR1 and ECR1 in vivo. The expression of AXR1 and ECR1 is restricted to zones of active cell division and cell elongation, consistent with their role in growth regulation. These results provide strong support for a model in which RUB conjugation of AtCUL1 affects the function of SCF E3s that are required for auxin response.
authors.affiliation: Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Texas 78712, USA.
authors.forename: Juan C
authors.initials: JC
authors.lastname: del Pozo
authors.forename: Sunethra
authors.initials: S
authors.lastname: Dharmasiri
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
authors.forename: Loni
authors.initials: L
authors.lastname: Walker
authors.forename: William M
authors.initials: WM
authors.lastname: Gray
authors.forename: Mark
authors.initials: M
authors.lastname: Estelle
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006133:Growth Substances; D007210:Indoleacetic Acids / Q000494:pharmacology*; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010453:Peptide Synthases / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D044843:SKP Cullin F-Box Protein Ligases; D014452:Ubiquitins
chemical_list: C081977:AXR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C112755:ECR1 protein, Arabidopsis; D006133:Growth Substances; D007210:Indoleacetic Acids; D010940:Plant Proteins; C513170:RUB1 protein, Arabidopsis; D014452:Ubiquitins; D015084:2,4-Dichlorophenoxyacetic Acid; D044843:SKP Cullin F-Box Protein Ligases; D010453:Peptide Synthases