title: Constitutive photomorphogenesis 1 and multiple photoreceptors control degradation of phytochrome interacting factor 3, a transcription factor required for light signaling in Arabidopsis.
abstract: Light, in a quality- and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochrome, promotes interaction of phytochrome A (phyA) and phyB with transcription factors including phytochrome interacting factor 3 (PIF3), and is thought to trigger a transcriptional cascade to regulate the expression of approximately 2500 genes in Arabidopsis thaliana. Here, we show that controlled degradation of the transcription factor PIF3 is a major regulatory step in light signaling. We demonstrate that accumulation of PIF3 in the nucleus in dark requires constitutive photomorphogenesis 1 (COP1), a negative regulator of photomorphogenesis, and show that red (R) and far-red light (FR) induce rapid degradation of the PIF3 protein. This process is controlled by the concerted action of the R/FR absorbing phyA, phyB, and phyD photoreceptors, and it is not affected by COP1. Rapid light-induced degradation of PIF3 indicates that interaction of PIF3 with these phytochrome species is transient. In addition, we provide evidence that the poc1 mutant, a postulated PIF3 overexpressor that displays hypersensitivity to R but not to FR, lacks detectable amounts of the PIF3 protein. Thus, we propose that PIF3 acts transiently, and its major function is to mediate phytochrome-induced signaling during the developmental switch from skotomorphogenesis to photomorphogenesis and/or dark to light transitions.
authors.affiliation: Biologie II/Institut für Botanik, University of Freiburg, Freiburg, Germany D-79104.
authors.forename: Diana
authors.initials: D
authors.lastname: Bauer
authors.forename: András
authors.initials: A
authors.lastname: Viczián
authors.forename: Stefan
authors.initials: S
authors.lastname: Kircher
authors.forename: Tabea
authors.initials: T
authors.lastname: Nobis
authors.forename: Roland
authors.initials: R
authors.lastname: Nitschke
authors.forename: Tim
authors.initials: T
authors.lastname: Kunkel
authors.forename: Kishore C S
authors.initials: KC
authors.lastname: Panigrahi
authors.forename: Eva
authors.initials: E
authors.lastname: Adám
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Fejes
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schäfer
authors.forename: Ferenc
authors.initials: F
authors.lastname: Nagy
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins; D008027:Light; D009154:Mutation / Q000235:genetics; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A; D051939:Phytochrome B; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational / Q000528:radiation effects; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D015398:Signal Transduction / Q000528:radiation effects*; D014157:Transcription Factors / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010834:Phytochrome; D051942:Phytochrome A; D051939:Phytochrome B; D014157:Transcription Factors; D044767:Ubiquitin-Protein Ligases; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis; C471983:AT2G32950 protein, Arabidopsis