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ARS Home » Pacific West Area » Albany, California » Plant Gene Expression Center » Research » Publications at this Location » Publication #344184
Title: PPKs mediate direct signal transfer from pytochrome photreceptors to transdcription factor PIF3

Author
item WI, N - University Of California
item XU, S - University Of California
item GONZALEZ-GRANDIO, E - University Of California
item CHALKLEY, R - University Of California
item HUHMER, A - Thermo Fisher Scientific
item BURLINGAME, A - University Of California
item WANG, Z - University Of California
item QUAIL, PETER - University Of California

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2017
Publication Date: 5/12/2017
Citation: Wi, N., Xu, S.L., Gonzalez-Grandio, E., Chalkley, R.J., Huhmer, A.F., Burlingame, A.L., Wang, Z.Y., Quail, P.H. 2017. PPKs mediate direct signal transfer from pytochrome photreceptors to transdcription factor PIF3. Nature Communications. 8:15236. doi:10.1038/ncomms15236.

Interpretive Summary: Plants constantly monitor ambient light conditions to adjust their growth and development for optimal photosynthesis and survival. The red and far-red wavelength information is perceived by the phytochrome (phy) family of sensory photoreceptors (phyA-E in Arabidopsis). Phytochromes change from an inactive state to an active state by interacting with transcription factors called PIF for Phytochrome Interacting Factor. By using protein analysis methods the authors identified a small family of protein kinases, designated photoregulatory protein kinases (PPKs) that rapidly associate with PIF3 and phyB in response to light-induction. This work represents a paradigm shift because it had been previously proposed that phytochromes themselves function intrinsically as protein kinases.

Technical 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.