Phytochrome A mediates rapid red light-induced phosphorylation of Arabidopsis FAR-RED ELONGATED HYPOCOTYL1 in a low fluence response.
Phytochrome A (phyA) is the primary photoreceptor for mediating the far-red high irradiance response in Arabidopsis thaliana. FAR-RED ELONGATED HYPOCOTYL1 (FHY1) and its homolog FHY1-LIKE (FHL) define two positive regulators in the phyA signaling pathway. These two proteins have been reported to be essential for light-regulated phyA nuclear accumulation through direct physical interaction with phyA. Here, we report that FHY1 protein is phosphorylated rapidly after exposure to red light. Subsequent exposure to far-red light after the red light pulse reverses FHY1 phosphorylation. Such a phenomenon represents a classical red/far-red reversible low fluence response. The phosphorylation of FHY1 depends on functioning phyA but not on other phytochromes and cryptochromes. Furthermore, we demonstrate that FHY1 and FHL directly interact with phyA by bimolecular fluorescence complementation and that both FHY1 and FHL interact more stably with the Pr form of phyA in Arabidopsis seedlings by coimmunoprecipitation. Finally, in vitro kinase assays confirmed that a recombinant phyA is able to robustly phosphorylate FHY1. Together, our results suggest that phyA may differentially regulate FHY1 and FHL activity through direct physical interaction and red/far-red light reversible phosphorylation to fine-tune their degradation rates and resulting light responses.
Shen
Yunping
Y
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Conecticut 06520-8104, USA.
Zhou
Zhenzhen
Z
Feng
Suhua
S
Li
Jigang
J
Tan-Wilson
Anna
A
Qu
Li-Jia
LJ
Wang
Haiyang
H
Deng
Xing Wang
XW
D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D056931:Cryptochromes; D005420:Flavoproteins / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D010766:Phosphorylation / Q000528:radiation effects; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051942:Phytochrome A / Q000502:physiology*; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; C524723:FHL protein, Arabidopsis; C441269:FHY1 protein, Arabidopsis; D005420:Flavoproteins; C497973:PHYA protein, Arabidopsis; D051942:Phytochrome A; D014157:Transcription Factors; D010834:Phytochrome