Abstract
DELLA proteins restrain the cell proliferation and enlargement that characterizes the growth of plant organs. Gibberellin stimulates growth via 26S proteasome-dependent destruction of DELLAs, thus relieving DELLA-mediated growth restraint. Here, we show that the Arabidopsis thaliana sleepy1gar2-1 (sly1gar2-1) mutant allele encodes a mutant subunit (sly1gar2-1) of an SCF(SLY1) E3 ubiquitin ligase complex. SLY1 (the wild-type form) and sly1gar2-1 both confer substrate specificity on this complex via specific binding to the DELLA proteins. However, sly1gar2-1 interacts more strongly with the DELLA target than does SLY1. In addition, the strength of the SCFSLY1-DELLA interaction is increased by target phosphorylation. Growth-promoting DELLA destruction is dependent on SLY1 availability, on the strength of the interaction between SLY1 and the DELLA target, and on promotion of the SCFSLY1-DELLA interaction by DELLA phosphorylation.
Copyright 2004 American Society of Plant Biologists
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alkyl and Aryl Transferases*
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Alleles
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Arabidopsis / drug effects
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Arabidopsis / genetics
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Arabidopsis / growth & development*
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Arabidopsis / metabolism
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Arabidopsis Proteins / chemistry
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Arabidopsis Proteins / genetics*
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Arabidopsis Proteins / metabolism*
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F-Box Proteins / chemistry
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F-Box Proteins / genetics
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F-Box Proteins / metabolism
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Genes, Plant / genetics
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Gibberellins / pharmacology
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Macromolecular Substances
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Mutation / genetics*
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Phenotype
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Phosphorylation
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Plant Proteins
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Protein Binding
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Substrate Specificity
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Transcription Factors / chemistry
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Ubiquitin-Protein Ligases / chemistry
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism*
Substances
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Arabidopsis Proteins
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F-Box Proteins
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GAI protein, Arabidopsis
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Gibberellins
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Macromolecular Substances
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Plant Proteins
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Transcription Factors
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Ubiquitin-Protein Ligases
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Alkyl and Aryl Transferases
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SLY1 protein, Arabidopsis