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Nat Commun. 2017 May 11;8:15236. doi: 10.1038/ncomms15236.

PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3.

Author information

1
Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
2
U.S. Department of Agriculture/Agriculture Research Service, Plant Gene Expression Center, Albany, California 94710, USA.
3
Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA.
4
Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA.
5
Thermo Fisher Scientific, San Jose, California 95134, USA.

Abstract

Upon light-induced nuclear translocation, phytochrome (phy) sensory photoreceptors interact with, and induce rapid phosphorylation and consequent ubiquitin-mediated degradation of, transcription factors, called PIFs, thereby regulating target gene expression and plant development. Nevertheless, the biochemical mechanism of phy-induced PIF phosphorylation has remained ill-defined. Here we identify a family of nuclear protein kinases, designated Photoregulatory Protein Kinases (PPK1-4; formerly called MUT9-Like Kinases (MLKs)), that interact with PIF3 and phyB in a light-induced manner in vivo. Genetic analyses demonstrate that the PPKs are collectively necessary for the normal light-induced phosphorylation and degradation of PIF3. PPK1 directly phosphorylates PIF3 in vitro, with a phosphosite pattern that strongly mimics the light-induced pattern in vivo. These data establish that the PPKs are directly involved in catalysing the photoactivated-phy-induced phosphorylation of PIF3 in vivo, and thereby are critical components of a transcriptionally centred signalling hub that pleiotropically regulates plant growth and development in response to multiple signalling pathways.

PMID:
28492231
PMCID:
PMC5437280
DOI:
10.1038/ncomms15236
[Indexed for MEDLINE]
Free PMC Article

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