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

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 in this paper 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.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [3] ;  [5] ;  [1]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Plant and Microbial Biology; US Dept. of Agriculture (USDA)., Albany, CA (United States). Agriculture Research Service, Plant Gene Expression Center
  2. Univ. of California, San Francisco, CA (United States). Dept. of Pharmaceutical Chemistry; Carnegie Inst. of Science, Stanford, CA (United States). Dept. of Plant Biology; Thermo Fisher Scientific, San Jose, CA (United States)
  3. Univ. of California, San Francisco, CA (United States). Dept. of Pharmaceutical Chemistry
  4. Thermo Fisher Scientific, San Jose, CA (United States)
  5. Carnegie Inst. of Science, Stanford, CA (United States). Dept. of Plant Biology
Publication Date:
Grant/Contract Number:
FG03-87ER13742; FG02-08ER15973
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Univ. of California, Berkeley, CA (United States); Carnegie Inst. of Washington, Argonne, IL (United States)
Sponsoring Org:
USDOE; National Institutes of Health (NIH)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1368171