Abstract
The plant hormone auxin, in particular indole-3-acetic acid (IAA), is a key regulator of virtually every aspect of plant growth and development. Auxin regulates transcription by rapidly modulating levels of Aux/IAA proteins throughout development. Recent studies demonstrate that auxin perception occurs through a novel mechanism. Auxin binds to TIR1, the F-box subunit of the ubiquitin ligase complex SCF(TIR1), and stabilizes the interaction between TIR1 and Aux/IAA substrates. This interaction results in Aux/IAA ubiquitination and subsequent degradation. Regulation of the Aux/IAA protein family by TIR1 and TIR1-like auxin receptors (AFBs) links auxin action to transcriptional regulation and provides a model by which the vast array of auxin influences on development may be understood. Moreover, auxin receptor function is the first example of small-molecule regulation of an SCF ubiquitin ligase and may have important implications for studies of regulated protein degradation in other species, including animals.
MeSH terms
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Animals
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Arabidopsis Proteins / chemistry
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Arabidopsis Proteins / metabolism
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F-Box Proteins / chemistry
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F-Box Proteins / metabolism
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Gene Expression Regulation, Plant
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Indoleacetic Acids / metabolism*
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Models, Molecular
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Plant Development*
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Plant Growth Regulators / metabolism*
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Plant Proteins / chemistry
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Plant Proteins / genetics
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Plant Proteins / metabolism*
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Plants / metabolism
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Proteasome Endopeptidase Complex / metabolism
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Protein Conformation
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Receptors, Cell Surface / chemistry
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Receptors, Cell Surface / genetics
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Receptors, Cell Surface / metabolism*
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SKP Cullin F-Box Protein Ligases / metabolism
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Signal Transduction / physiology*
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Transcription Factors / metabolism
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Transcription, Genetic
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Ubiquitin / metabolism
Substances
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Arabidopsis Proteins
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F-Box Proteins
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Indoleacetic Acids
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Plant Growth Regulators
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Plant Proteins
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Receptors, Cell Surface
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TIR1 protein, Arabidopsis
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Transcription Factors
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Ubiquitin
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auxin receptor, plant
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indoleacetic acid
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SKP Cullin F-Box Protein Ligases
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Proteasome Endopeptidase Complex