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Arabidopsis COP1/SPA1 Complex and FHY1/FHY3 Associate with Distinct Phosphorylated Forms of Phytochrome A in Balancing Light Signaling

TypeWhite Paper Summary

Fine tuning of light signaling is crucial to plant development. Following light-triggered nuclear translocation, the photoreceptor phytochrome A (phyA) regulates gene expression under continuous far-red light and is rapidly destabilized upon red light irradiation by E3 ubiquitin ligases, including COP1. Here we provide evidence that the light signaling repressors SPA proteins contribute to COP1-mediated phyA degradation and that a COP1/SPA1 protein complex is tightly associated with phyA ubiquitination activity. Furthermore, a phosphorylated phyA form accumulates in the nucleus and preferentially associates with the COP1/SPA1 complex. In contrast, underphosphorylated phyA predominantly associates with the phyA-signaling intermediates FHY3 and FHY1. However, COP1 associates with underphosphorylated phyA in the absence of FHY3 or FHY1, suggesting that phyA associations with FHY3 and FHY1 protect underphosphorylated phyA from being recognized by the COP1/SPA complex. We propose that light-induced phyA phosphorylation acts as a switch controlling differential interactions of the photoreceptor with signal propagation or attenuation machineries.

Keywords
Authors
Name:Peter K Jackson
Name:Mark H Ellisman
Name:J Li
Name:A Dixit
Name:Guy Perkins
Name:Laszlo Tora
Name:H Wang
Name:Ryuji Yamaguchi
Name:S J Martin
Name:Xing Wang Deng
Name:Celia Pilar Martinez Jimenez
Name:Dimitris Kafetzopoulos
Name:Iannis Talianidis
Name:Kiran Mukhyala
Name:Tomomi Kuwana
Name:Donald D Newmeyer
Name:Clare Sheridan
Name:Zuzana Valnickova
Name:Irantzu Pallarés
Name:Maria Solà
Name:torsten Kristensen
Name:Jan J Enghild
Name:Francesc X Aviles
Name:F. Xavier Gomis Rüth
Name:Yusuke Saijo
Name:Danmeng Zhu
Organizations
Organization:University of California

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