SINAT E3 Ligases Control the Light-Mediated Stability of the Brassinosteroid-Activated Transcription Factor BES1 in Arabidopsis

Dev Cell. 2017 Apr 10;41(1):47-58.e4. doi: 10.1016/j.devcel.2017.03.014.


The plant hormones brassinosteroids (BRs) participate in light-mediated regulation of plant growth, although the underlying mechanisms are far from being fully understood. In addition, the function of the core transcription factor in the BR signaling pathway, BRI1-EMS-SUPPRESSOR 1 (BES1), largely depends on its phosphorylation status and its protein stability, but the regulation of BES1 is not well understood. Here, we report that SINA of Arabidopsis thaliana (SINATs) specifically interact with dephosphorylated BES1 and mediate its ubiquitination and degradation. Our genetic data demonstrated that SINATs inhibit BR signaling in a BES1-dependent manner. Interestingly, we found that the protein levels of SINATs were decreased in the dark and increased in the light, which changed BES1 protein levels accordingly. Thus, our study not only uncovered a new mechanism of BES1 degradation but also provides significant insights into how light conditionally regulates plant growth through controlling accumulation of different forms of BES1.

Keywords: BES1; SINAT; brassinosteroids; degradation; hypocotyl elongation; light.

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis / radiation effects*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism*
  • Brassinosteroids / pharmacology*
  • DNA-Binding Proteins
  • Gene Knockdown Techniques
  • Light*
  • Models, Biological
  • Nuclear Proteins / metabolism*
  • Protein Binding / drug effects
  • Protein Binding / radiation effects
  • Protein Stability / drug effects
  • Protein Stability / radiation effects
  • Proteolysis / drug effects
  • Proteolysis / radiation effects
  • RING Finger Domains
  • Signal Transduction / drug effects
  • Signal Transduction / radiation effects
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination / drug effects
  • Ubiquitination / radiation effects


  • Arabidopsis Proteins
  • BES1 protein, Arabidopsis
  • Brassinosteroids
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Ubiquitin-Protein Ligases