Journal article

Publication year: 2021

Pages: 3273-3282

Journal: Plant, Cell and Environment

Volume number: 44

Issue number: 10

ISSN: 0140-7791

eISSN: 1365-3040

Open access status: Hybrid

DOI Link: https://doi.org/10.1111/pce.14148

Publisher: Wiley

Abstract: 
The Arabidopsis COP1/SPA complex acts as a cullin4-based E3 ubiquitin ligase to suppress photomorphogenesis in darkness. It is a tetrameric complex of two COP1 and two SPA proteins. Both COP1 and SPA are essential for the activity of this complex, and they both contain a C-terminal WD-repeat domain responsible for substrate recruitment and binding of DDB1. Here, we used a WD domain swap-approach to address the cooperativity of COP1 and SPA proteins. We found that expression of a chimeric COP1 carrying the WD-repeat domain of SPA1 mostly complemented the cop1-4-mutant phenotype in darkness, indicating that the WD repeat of SPA1 can replace the WD repeat of COP1. In the light, SPA1-WD partially substituted for COP1-WD. In contrast, expression of a chimeric SPA1 protein carrying the WD repeat of COP1 did not rescue the spa-mutant phenotype. Together, our findings demonstrate that a SPA1-type WD repeat is essential for COP1/SPA activity, while a COP1-type WD is in part dispensible. Moreover, a complex with four SPA1-WDs is more active than a complex with only two SPA1-WDs. A homology model of SPA1-WD based on the crystal structure of COP1-WD uncovered two insertions and several amino acid substitutions at the predicted substrate-binding pocket of SPA1-WD.

Harvard Citation style: Kerner, K., Nagano, S., Lubbe, A. and Hoecker, U. (2021) Functional comparison of the WD-repeat domains of SPA1 and COP1 in suppression of photomorphogenesis, Plant, Cell and Environment, 44(10), pp. 3273-3282. https://doi.org/10.1111/pce.14148

APA Citation style: Kerner, K., Nagano, S., Lubbe, A., & Hoecker, U. (2021). Functional comparison of the WD-repeat domains of SPA1 and COP1 in suppression of photomorphogenesis. Plant, Cell and Environment. 44(10), 3273-3282. https://doi.org/10.1111/pce.14148