title: Plant Raf-like kinase integrates abscisic acid and hyperosmotic stress signaling upstream of SNF1-related protein kinase2.
abstract: Plant response to drought and hyperosmosis is mediated by the phytohormone abscisic acid (ABA), a sesquiterpene compound widely distributed in various embryophyte groups. Exogenous ABA as well as hyperosmosis activates the sucrose nonfermenting 1 (SNF1)-related protein kinase2 (SnRK2), which plays a central role in cellular responses against drought and dehydration, although the details of the activation mechanism are not understood. Analysis of a mutant of the moss Physcomitrella patens with reduced ABA sensitivity and reduced hyperosmosis tolerance revealed that a protein kinase designated "ARK" (for "ABA and abiotic stress-responsive Raf-like kinase") plays an essential role in the activation of SnRK2. ARK encoded by a single gene in P. patens belongs to the family of group B3 Raf-like MAP kinase kinase kinases (B3-MAPKKKs) mediating ethylene, disease resistance, and salt and sugar responses in angiosperms. Our findings indicate that ARK, as a novel regulatory component integrating ABA and hyperosmosis signals, represents the ancestral B3-MAPKKKs, which multiplied, diversified, and came to have specific functions in angiosperms.
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
authors.forename: Masashi
authors.initials: M
authors.lastname: Saruhashi
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
authors.forename: Totan
authors.initials: T
authors.lastname: Kumar Ghosh
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
authors.forename: Kenta
authors.initials: K
authors.lastname: Arai
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Ishizaki
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hagiwara
authors.affiliation: Department of Bioproduction Technology, Junior College of Tokyo University of Agriculture, Tokyo 156-8502, Japan;
authors.forename: Kenji
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Tokyo 156-8502, Japan;
authors.forename: Yuh
authors.initials: Y
authors.lastname: Shiwa
authors.affiliation: Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8538, Japan;
authors.forename: Keiichi
authors.initials: K
authors.lastname: Izumikawa
authors.affiliation: Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8538, Japan; Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom;
authors.forename: Harunori
authors.initials: H
authors.lastname: Yoshikawa
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Tokyo 102-0007 Japan;
authors.forename: Taishi
authors.initials: T
authors.lastname: Umezawa
authors.affiliation: Department of BioScience, Tokyo University of Agriculture, Tokyo 156-8502, Japan;
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sakata
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan; Institute for Environmental Science and Technology, Saitama University, Saitama 338-8570, Japan takezawa@mail.saitama-u.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takezawa
mesh_terms: D000595:Amino Acid Sequence; D019068:Bryopsida / Q000201:enzymology / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D009997:Osmotic Pressure / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D048490:raf Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D048490:raf Kinases
keywords: Physcomitrella patens; Raf-like kinase; SnRK2; abscisic acid