740 / 2019-05-14 22:08:38

KP1 is a novel kinase for PIF1 (PHYTOCHROME INTERACTING FACTOR 1) in Arabidopsis

Phytochrome signaling, PIFs, Kinases, Arabidopsis

全体主题 > Photobiology

Plants perceive light to regulate photomorphogenesis through a family of photoreceptors called phytochromes. Phytochromes transduce the light signals to trigger a cascade of downstream gene regulations via a subfamily of bHLH transcription factors called PHYTOCHROME INTERACTING FACTORs (PIFs). As repressors in light signaling pathways, most PIFs are phosphorylated and degraded through the 26S/ubiquitin proteasome pathway in response to light. Intense research has been focused during the past decade to identify and characterize factors involved in the phosphorylation and degradation of PIFs. Here, we show the identification of a new protein kinase called KP1 (Kinase for PIF1) as a bona fide protein kinase for light-induced PIF1 phosphorylation and degradation. Through extensive biochemical, genetic and genomic analysis we provide strong evidence that KP1 can phosphorylate PIF1 in response to red light. In vivo evidences showed striking defects in light-induced PIF1 phosphorylation in kp1 background, supporting the role of KP1 as a PIF1 kinase. In addition, we found that the red/far-red light photoreceptor phytochrome B function is critical for KP1 mediated PIF1 phosphorylation and subsequent degradation and that phyB-KP1 interaction plays a critical role in this regulation. Therefore, we provided a mechanistic detail on how the phyB-KP1 complex selectively triggers rapid phosphorylation and degradation of PIF1 to regulate seed germination and photomorphogenesis.