title: A novel-type phosphatidylinositol phosphate-interactive, Ca-binding protein PCaP1 in Arabidopsis thaliana: stable association with plasma membrane and partial involvement in stomata closure.
abstract: The Ca(2+)-binding protein-1 (PCaP1) of Arabidopsis thaliana is a new type protein that binds to phosphatidylinositol phosphates and Ca(2+)-calmodulin complex as well as free Ca(2+). Although biochemical properties, such as binding to ligands and N-myristoylation, have been revealed, the intracellular localization, tissue and cell specificity, integrity of membrane association and physiological roles of PCaP1 are unknown. We investigated the tissue and intracellular distribution of PCaP1 by using transgenic lines expressing PCaP1 linked with a green fluorescence protein (GFP) at the carboxyl terminus of PCaP1. GFP fluorescence was obviously detected in most tissues including root, stem, leaf and flower. In these tissues, PCaP1-GFP signal was observed predominantly in the plasma membrane even under physiological stress conditions but not in other organelles. The fluorescence was detected in the cytosol when the 25-residue N-terminal sequence was deleted from PCaP1 indicating essential contribution of N-myristoylation to the plasma membrane anchoring. Fluorescence intensity of PCaP1-GFP in roots was slightly decreased in seedlings grown in medium supplemented with high concentrations of iron for 1 week and increased in those grown with copper. In stomatal guard cells, PCaP1-GFP was strictly, specifically localized to the plasma membrane at the epidermal-cell side but not at the pore side. A T-DNA insertion mutant line of PCaP1 did not show marked phenotype in a life cycle except for well growth under high CO2 conditions. However, stomata of the mutant line did not close entirely even in high osmolarity, which usually induces stomata closure. These results suggest that PCaP1 is involved in the stomatal movement, especially closure process, in leaves and response to excessive copper in root and leaf as a mineral nutrient as a physiological role.
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Chisako
authors.initials: C
authors.lastname: Nagata
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Miwa
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Natsuki
authors.initials: N
authors.lastname: Tanaka
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Kato
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Momoe
authors.initials: M
authors.lastname: Suito
authors.affiliation: Discovery Research, RaQualia Pharma Inc, Nagoya, 464-8601, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Tsuchihira
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Yori
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Segami
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan. maeshima@agr.nagoya-u.ac.jp.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Maeshima
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003300:Copper / Q000633:toxicity; D049452:Green Fluorescent Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D054046:Plant Stomata / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; C521040:PCaP1 protein, Arabidopsis; D018129:Phosphatidylinositol Phosphates; D002245:Carbon Dioxide; D049452:Green Fluorescent Proteins; D003300:Copper; D002118:Calcium
keywords: Arabidopsis thaliana; Calcium-binding protein; Phosphatidylinositol phosphate; Plasma membrane; Signal transducing protein; Stomata