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Structural insight into UV-B-activated UVR8 bound to COP1.
Yidong Wang1, Lixia Wang1, Zeyuan Guan1
1National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.
Science Advances
|April 20, 2022
Summary
UV-B light activates UVR8 to repress the COP1-SPA complex, inhibiting photomorphogenesis. RUP2 then dissociates UVR8, allowing COP1-SPA activity and promoting plant growth.
Area of Science:
- Plant Biology
- Molecular Biology
- Biochemistry
Background:
- The CONSTITUTIVE PHOTOMORPHOGENIC 1-SUPPRESSOR OF PHYA-105 (COP1-SPA) complex is a key regulator of plant photomorphogenesis.
- COP1-SPA functions as an E3 ubiquitin ligase, integrating signals from various photoreceptors.
- Understanding how light signaling pathways regulate COP1-SPA activity is crucial.
Purpose of the Study:
- To elucidate the regulatory mechanism of COP1-SPA in ultraviolet-B (UV-B) signaling.
- To determine the structural basis of UVR8-COP1 interaction in UV-B response.
- To investigate the role of RUP2 in modulating UVR8-COP1 complex dynamics.
Main Methods:
- In vitro reconstruction of the COP1-SPA regulation pathway in UV-B signaling.
- Cryo-electron microscopy to determine the structure of the UVR8-COP1 complex.
- Biochemical assays to analyze protein-protein interactions and complex formation.
Main Results:
- The UV-B receptor UVR8 interacts with COP1 through two distinct interfaces.
- These interfaces mediate competitive binding between UVR8 and HY5 for the COP1-SPA complex.
- RUP2 was shown to dissociate UVR8 from COP1, facilitating UVR8 redimerization.
Conclusions:
- A model for UV-B signaling is proposed where UV-B-activated UVR8 represses COP1-SPA activity.
- RUP2 acts as a derepressor by disrupting the UVR8-COP1 interaction.
- This study provides a structural and mechanistic framework for understanding photoreceptor regulation of photomorphogenesis.
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