The Arabidopsis mutant sleepy1gar2-1 protein promotes plant growth by increasing the affinity of the SCFSLY1 E3 ubiquitin ligase for DELLA protein substrates

Plant Cell. 2004 Jun;16(6):1406-18. doi: 10.1105/tpc.021386. Epub 2004 May 25.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkyl and Aryl Transferases*
  • Alleles
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • F-Box Proteins / chemistry
  • F-Box Proteins / genetics
  • F-Box Proteins / metabolism
  • Genes, Plant / genetics
  • Gibberellins / pharmacology
  • Macromolecular Substances
  • Mutation / genetics*
  • Phenotype
  • Phosphorylation
  • Plant Proteins
  • Protein Binding
  • Substrate Specificity
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Ubiquitin-Protein Ligases / chemistry
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • Arabidopsis Proteins
  • F-Box Proteins
  • GAI protein, Arabidopsis
  • Gibberellins
  • Macromolecular Substances
  • Plant Proteins
  • Transcription Factors
  • Ubiquitin-Protein Ligases
  • Alkyl and Aryl Transferases
  • SLY1 protein, Arabidopsis