title: Auxin regulates SCF(TIR1)-dependent degradation of AUX/IAA proteins.
abstract: The plant hormone auxin is central in many aspects of plant development. Previous studies have implicated the ubiquitin-ligase SCF(TIR1) and the AUX/IAA proteins in auxin response. Dominant mutations in several AUX/IAA genes confer pleiotropic auxin-related phenotypes, whereas recessive mutations affecting the function of SCF(TIR1) decrease auxin response. Here we show that SCF(TIR1) is required for AUX/IAA degradation. We demonstrate that SCF(TIR1) interacts with AXR2/IAA7 and AXR3/IAA17, and that domain II of these proteins is necessary and sufficient for this interaction. Further, auxin stimulates binding of SCF(TIR1) to the AUX/IAA proteins, and their degradation. Because domain II is conserved in nearly all AUX/IAA proteins in Arabidopsis, we propose that auxin promotes the degradation of this large family of transcriptional regulators, leading to diverse downstream effects.
authors.affiliation: The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: W M
authors.initials: WM
authors.lastname: Gray
authors.forename: S
authors.initials: S
authors.lastname: Kepinski
authors.forename: D
authors.initials: D
authors.lastname: Rouse
authors.forename: O
authors.initials: O
authors.lastname: Leyser
authors.forename: M
authors.initials: M
authors.lastname: Estelle
mesh_terms: D020816:Amino Acid Motifs; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics; D006133:Growth Substances; D007210:Indoleacetic Acids / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010453:Peptide Synthases / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics; D044843:SKP Cullin F-Box Protein Ligases; D014157:Transcription Factors; D025801:Ubiquitin / Q000378:metabolism
chemical_list: C081977:AXR1 protein, Arabidopsis; C110728:AXR3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D006133:Growth Substances; D007210:Indoleacetic Acids; D009687:Nuclear Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D025801:Ubiquitin; C030737:indoleacetic acid; D044843:SKP Cullin F-Box Protein Ligases; D005966:Glucuronidase; D010453:Peptide Synthases