title: Arabidopsis AXR6 encodes CUL1 implicating SCF E3 ligases in auxin regulation of embryogenesis.
abstract: The AXR6 gene is required for auxin signaling in the Arabidopsis embryo and during postembryonic development. One of the effects of auxin is to stimulate degradation of the Aux/IAA auxin response proteins through the action of the ubiquitin protein ligase SCF(TIR1). Here we show that AXR6 encodes the SCF subunit CUL1. The axr6 mutations affect the ability of mutant CUL1 to assemble into stable SCF complexes resulting in reduced degradation of the SCF(TIR1) substrate AXR2/IAA7. In addition, we show that CUL1 is required for lateral organ initiation in the shoot apical meristem and the inflorescence meristem. These results indicate that the embryonic axr6 phenotype is related to a defect in SCF function and accumulation of Aux/IAA proteins such as BDL/IAA12. In addition, we show that CUL1 has a role in auxin response throughout the life cycle of the plant.
authors.affiliation: Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
authors.forename: Lawrence
authors.initials: L
authors.lastname: Hobbie
authors.forename: Anngela
authors.initials: A
authors.lastname: Chapman
authors.forename: Sunethra
authors.initials: S
authors.lastname: Dharmasiri
authors.forename: Nihal
authors.initials: N
authors.lastname: Dharmasiri
authors.forename: Carlos
authors.initials: C
authors.lastname: del Pozo
authors.forename: Didier
authors.initials: D
authors.lastname: Reinhardt
authors.forename: Mark
authors.initials: M
authors.lastname: Estelle
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D018076:DNA, Complementary; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000502:physiology*; D008025:Ligases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D044767:Ubiquitin-Protein Ligases
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D007210:Indoleacetic Acids; D044767:Ubiquitin-Protein Ligases; D008025:Ligases