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Updated: Dec 21, 2025

Luciferase Complementation Imaging Assay in Nicotiana benthamiana Leaves for Transiently Determining Protein-protein Interaction Dynamics
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Structural insights into BIC-mediated inactivation of Arabidopsis cryptochrome 2

Ling Ma1, Xiang Wang1, Zeyuan Guan1

  • 1National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan, China.

Nature Structural & Molecular Biology
|May 14, 2020
PubMed

Insights

Blue-light inhibitors (BICs) bind to plant cryptochromes (CRYs), revealing CRY2 inactivation mechanisms. This research elucidates how BICs suppress CRY2 photoactivation by disrupting electron transfer and promoting monomer formation.

Area of Science:

  • Plant molecular biology
  • Photobiology
  • Structural biology

Background:

  • Cryptochromes (CRYs) are blue-light receptors in plants crucial for various physiological responses.
  • Photoactivated CRYs oligomerize, enhancing interactions with downstream partners, but inactivation mechanisms remain poorly understood.

Purpose of the Study:

  • To elucidate the mechanism by which blue-light inhibitors of cryptochromes (BICs) suppress CRY2 photoactivation.
  • To determine the structural basis of BIC binding to CRY2.

Main Methods:

  • X-ray crystallography was used to determine the structures of CRY2N (CRY2 PHR domain) and the BIC2-CRY2N complex.
  • Structural analysis focused on the interaction between BIC2 and CRY2N.

Main Results:

  • Crystal structures of CRY2N and the BIC2-CRY2N complex were obtained at 2.7 and 2.5 Å resolution, respectively.
  • BIC2 adopts an extended conformation, winding around CRY2N.
  • BIC2 inhibits CRY2 photoreduction by restraining electron and proton transfer and promotes CRY2 monomer formation by interacting with the CRY2 oligomer.

Conclusions:

  • The study reveals the molecular mechanism of CRY2 inactivation by BICs.
  • Understanding CRY2 inactivation provides a foundation for further research into cryptochrome protein function.

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