title: Evidence that phytochrome functions as a protein kinase in plant light signalling.
abstract: It has been suggested that plant phytochromes are autophosphorylating serine/threonine kinases. However, the biochemical properties and functional roles of putative phytochrome kinase activity in plant light signalling are largely unknown. Here, we describe the biochemical and functional characterization of Avena sativa phytochrome A (AsphyA) as a potential protein kinase. We provide evidence that phytochrome-interacting factors (PIFs) are phosphorylated by phytochromes in vitro. Domain mapping of AsphyA shows that the photosensory core region consisting of PAS-GAF-PHY domains in the N-terminal is required for the observed kinase activity. Moreover, we demonstrate that transgenic plants expressing mutant versions of AsphyA, which display reduced activity in in vitro kinase assays, show hyposensitive responses to far-red light. Further analysis reveals that far-red light-induced phosphorylation and degradation of PIF3 are significantly reduced in these transgenic plants. Collectively, these results suggest a positive relationship between phytochrome kinase activity and photoresponses in plants.
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Ah-Young
authors.initials: AY
authors.lastname: Shin
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Yun-Jeong
authors.initials: YJ
authors.lastname: Han
authors.affiliation: Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Ayoung
authors.initials: A
authors.lastname: Baek
authors.affiliation: College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Taeho
authors.initials: T
authors.lastname: Ahn
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Thai Son
authors.initials: TS
authors.lastname: Nguyen
authors.affiliation: Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Minky
authors.initials: M
authors.lastname: Son
authors.affiliation: Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Keun Woo
authors.initials: KW
authors.lastname: Lee
authors.affiliation: BioVision Inc., Milpitas, California 95035, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Faculty of Biotechnology and Subtropical Horticulture Research Institute, Jeju National University, Jeju 690-756, Korea.
authors.forename: Pill-Soon
authors.initials: PS
authors.lastname: Song
authors.affiliation: Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Jeong-Il
authors.initials: JI
authors.lastname: Kim
mesh_terms: D018554:Avena / Q000502:physiology*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D055537:Light Signal Transduction / Q000502:physiology*; D009154:Mutation; D010766:Phosphorylation / Q000502:physiology; D051942:Phytochrome A / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology*; D000072417:Protein Domains / Q000502:physiology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051942:Phytochrome A