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Regulation of Arabidopsis photoreceptor CRY2 by two distinct E3 ubiquitin ligases

Yadi Chen1, Xiaohua Hu1, Siyuan Liu1

  • 1College of Life Sciences, Basic Forestry and Proteomics Research Center, Fujian Agriculture and Forestry University, Fuzhou, China.

Nature Communications
|April 13, 2021
PubMed

Insights

Light-response proteins (CRYs) are regulated by E3 ligases. This study identifies Cul3-LRBs as a second E3 ligase for CRY2 in Arabidopsis, crucial for blue-light responses.

Area of Science:

  • Plant molecular biology
  • Photoreceptor signaling
  • Ubiquitin-proteasome system

Background:

  • Cryptochromes (CRYs) are vital photoreceptors and molecular clock components in many species.
  • CRYs are typically regulated by polyubiquitination and proteolysis, involving multiple E3 ubiquitin ligases.
  • While animal CRYs are regulated by several E3 ligases, only Cul4COP1/SPAs was previously identified for plant CRYs.

Purpose of the Study:

  • To identify additional E3 ubiquitin ligases that regulate CRY2 in Arabidopsis.
  • To elucidate the mechanism by which these E3 ligases control CRY2 abundance and plant photoresponses.

Main Methods:

  • Genetic analysis in Arabidopsis.
  • Biochemical assays to study protein-protein interactions.
  • Analysis of CRY2 polyubiquitination and degradation.
  • Phenotypic analysis of hypocotyl elongation under blue light.

Main Results:

  • Cul3LRBs was identified as the second E3 ligase for CRY2 in Arabidopsis.
  • Light-Response Bric-a-Brack/Tramtrack/Broad (LRBs) exhibit blue-light-specific and CRY2-dependent activity.
  • LRBs interact with photoexcited and phosphorylated CRY2 at its CCE domain, promoting its polyubiquitination and degradation.
  • Cul4COP1/SPAs and Cul3LRBs target CRY2 via distinct structural elements.

Conclusions:

  • Cul3LRBs acts as a crucial E3 ligase for CRY2, complementing the role of Cul4COP1/SPAs.
  • Differential regulation of CRY2 by two distinct E3 ligase complexes allows plants to optimize photoresponses under varying light conditions.

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