The Arabidopsis mutant sleepy1gar2-1 protein promotes plant growth by increasing the affinity of the SCFSLY1 E3 ubiquitin ligase for DELLA protein substrates.
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.
Fu
Xiangdong
X
John Ines Centre, Norwich NR4 7UH, United Kingdom.
Richards
Donald E
DE
Fleck
Barbara
B
Xie
Daoxin
D
Burton
Nicolas
N
Harberd
Nicholas P
NP
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*
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