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ARS Home » Pacific West Area » Albany, California » Plant Gene Expression Center » Research » Publications at this Location » Publication #214511
Title: Photoactivated Phytochrome Induces Rapid PIF3 Phosphorylation Prior to Proteasome-Mediated Degradation

Author
item AL-SADY, BASSEM - UCB-ARS PLNT GENE EXP CTR
item NI, WEIMIN - UCB-ARS PLNT GENE EXP CTR
item KIRCHER, STEFAN - ALBERT-LUDW FREIBURG GER
item SCHAFER, EBERHARD - ALBERT-LUDW FREIBURG GER
item QUAIL, PETER - UCB-ARS PLNT GENE EXP CTR

Submitted to: Molecular Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2006
Publication Date: 8/4/2006
Citation: Al-Sady, B., Ni, W., Kircher, S., Schafer, E., Quail, P.H. 2006. Photoactivated Phytochrome Induces Rapid PIF3 Phosphorylation Prior to Proteasome-Mediated Degradation. Molecular Cell. 23(3):439-446.

Interpretive Summary: Following light-induced nuclear translocation, specific members of the phytochrome (phy) family of sensory photoreceptors (phyA to phyE) interact with basic helix-loop-helix transcription factors, such as PIF3, and induce changes in target-gene expression. The biochemical mechanism comprising signal transfer from phy to PIF3 has remained undefined, but results in rapid degradation of PIF3. We show that photoactivation of phy induces rapid in vivo phosphorylation of PIF3 preceding degradation These data suggest that phy-induced phosphorylation of proteins such as PIF3 may represent the primary intermolecular signaling transaction of the activated photoreceptor, tagging the target protein for proteosomal degradation.

Technical Abstract: Following light-induced nuclear translocation, specific members of the phytochrome (phy) photoreceptor family (phyA to phyE) interact with bHLH transcription factors, such as PIF3, and induce changes in target-gene expression. The biochemical mechanism comprising signal transfer from phy to PIF3 has remained undefined but results in rapid degradation of PIF3. We provide evidence that photoactivation of phy induces rapid in vivo phosphorylation of PIF3 preceding degradation. Both phyA and phyB redundantly induce this PIF3 phosphorylation, as well as nuclear speckle formation and degradation, by direct interaction with PIF3 via separate binding sites. These data suggest that phy-induced phosphorylation of proteins such as PIF3 may represent the primary intermolecular signaling transaction of the activated photoreceptor, tagging the target protein for proteosomal degradation, possibly in nuclear speckles.