1. PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3.
- Author
-
Ni, Weimin, Xu, Shou-Ling, González-Grandío, Eduardo, Chalkley, Robert J, Huhmer, Andreas FR, Burlingame, Alma L, Wang, Zhi-Yong, and Quail, Peter H
- Subjects
Arabidopsis ,Isoenzymes ,Protein-Serine-Threonine Kinases ,Arabidopsis Proteins ,Gene Expression Regulation ,Plant ,Protein Processing ,Post-Translational ,Amino Acid Sequence ,Phosphorylation ,Light ,Basic Helix-Loop-Helix Transcription Factors ,Phytochrome B ,Ubiquitination ,Light Signal Transduction ,Proteolysis ,Gene Expression Regulation ,Plant ,Protein Processing ,Post-Translational ,Genetics ,Biotechnology - 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.
- Published
- 2017