title: The Arabidopsis mutant sleepy1gar2-1 protein promotes plant growth by increasing the affinity of the SCFSLY1 E3 ubiquitin ligase for DELLA protein substrates.
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.
authors.affiliation: John Ines Centre, Norwich NR4 7UH, United Kingdom.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Fu
authors.forename: Donald E
authors.initials: DE
authors.lastname: Richards
authors.forename: Barbara
authors.initials: B
authors.lastname: Fleck
authors.forename: Daoxin
authors.initials: D
authors.lastname: Xie
authors.forename: Nicolas
authors.initials: N
authors.lastname: Burton
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Harberd
mesh_terms: D019883:Alkyl and Aryl Transferases; D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D044783:F-Box Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017343:Genes, Plant / Q000235:genetics; D005875:Gibberellins / Q000494:pharmacology; D046911:Macromolecular Substances; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D010766:Phosphorylation; D010940:Plant Proteins; D011485:Protein Binding; D013379:Substrate Specificity; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D044783:F-Box Proteins; C109555:GAI protein, Arabidopsis; D005875:Gibberellins; D046911:Macromolecular Substances; D010940:Plant Proteins; D014157:Transcription Factors; D044767:Ubiquitin-Protein Ligases; D019883:Alkyl and Aryl Transferases; C476121:SLY1 protein, Arabidopsis