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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Motifs
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Arabidopsis
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / physiology
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Gene Expression Regulation, Plant
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Glucuronidase / genetics
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Growth Substances*
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Indoleacetic Acids / genetics
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Indoleacetic Acids / metabolism*
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Indoleacetic Acids / physiology*
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Mutation
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Peptide Synthases / genetics
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Peptide Synthases / physiology*
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Plant Proteins / genetics
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Plant Proteins / metabolism
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Plants, Genetically Modified
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Protein Binding
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Recombinant Fusion Proteins / genetics
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SKP Cullin F-Box Protein Ligases
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Transcription Factors
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Ubiquitin / metabolism
Substances
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AXR1 protein, Arabidopsis
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AXR3 protein, Arabidopsis
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Arabidopsis Proteins
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Growth Substances
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Indoleacetic Acids
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Nuclear Proteins
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Plant Proteins
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Recombinant Fusion Proteins
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Transcription Factors
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Ubiquitin
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indoleacetic acid
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SKP Cullin F-Box Protein Ligases
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Glucuronidase
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Peptide Synthases