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Nat Commun. 2017 Dec 4;8(1):1905. doi: 10.1038/s41467-017-02062-6.

Mechanism of early light signaling by the carboxy-terminal output module of Arabidopsis phytochrome B.

Author information

1
Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA.
2
Department of Biology, Duke University, Durham, NC, 27708, USA.
3
Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan.
4
Department of Statistics, University of California, Riverside, CA, 92521, USA.
5
Howard Hughes Medical Institute, Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
6
Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA. meng.chen@ucr.edu.

Abstract

Plant phytochromes are thought to transduce light signals by mediating the degradation of phytochrome-interacting transcription factors (PIFs) through the N-terminal photosensory module, while the C-terminal module, including a histidine kinase-related domain (HKRD), does not participate in signaling. Here we show that the C-terminal module of Arabidopsis phytochrome B (PHYB) is sufficient to mediate the degradation of PIF3 specifically and to activate photosynthetic genes in the dark. The HKRD is a dimerization domain for PHYB homo and heterodimerization. A D1040V mutation, which disrupts the dimerization of HKRD and the interaction between C-terminal module and PIF3, abrogates PHYB nuclear accumulation, photobody biogenesis, and PIF3 degradation. By contrast, disrupting the interaction between PIF3 and PHYB's N-terminal module has little effect on PIF3 degradation. Together, this study demonstrates that the dimeric form of the C-terminal module plays important signaling roles by targeting PHYB to subnuclear photobodies and interacting with PIF3 to trigger its degradation.

PMID:
29199270
PMCID:
PMC5712524
DOI:
10.1038/s41467-017-02062-6
[Indexed for MEDLINE]
Free PMC Article

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