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Arabidopsis ABCB21 is a Facultative Auxin Importer/Exporter Regulated by Cytoplasmic Auxin Concentration

Kamimoto, Yoshihisa ; Terasaka, Kazuyoshi ; Hamamoto, Masafumi ; Takanashi, Kojiro ; Fukuda, Shoju ; Shitan, Nobukazu ; Sugiyama, Akifumi ; Suzuki, Hideyuki ; Shibata, Daisuke ; Wang, Bangjun ; Pollmann, Stephan ; Geisler, Markus ; Yazaki, Kazufumi

In: Plant and Cell Physiology, 2012, vol. 53, no. 12, p. 2090-2100

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    Titre
    • Arabidopsis ABCB21 is a Facultative Auxin Importer/Exporter Regulated by Cytoplasmic Auxin Concentration
    Auteur
    • Kamimoto, Yoshihisa. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Terasaka, Kazuyoshi. Graduate School of Pharmaceutical Sciences, Nagoya City University, Japan
    • Hamamoto, Masafumi. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Takanashi, Kojiro. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Fukuda, Shoju. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Shitan, Nobukazu. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Sugiyama, Akifumi. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    • Suzuki, Hideyuki. Kazusa DNA Research Institute, 2-6-7 Kazusakamatari, Kisarazu, Chiba, 292-0818 Japan
    • Shibata, Daisuke. Kazusa DNA Research Institute, 2-6-7 Kazusakamatari, Kisarazu, Chiba, 292-0818 Japan
    • Wang, Bangjun. Institute of Plant Biology, Basel-Zurich Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
    • Pollmann, Stephan. Ruhr-Universität Bochum, Lehrstuhl für Pflanzenphysiologie, Germany
    • Geisler, Markus. Institute of Plant Biology, Basel-Zurich Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland
    • Yazaki, Kazufumi. Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho Uji, 611-0011 Japan
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Plant and Cell Physiology, 2012, vol. 53, no. 12, p. 2090-2100. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:289592
    Summary
    The phytohormone auxin is critical for plant growth and many developmental processes. Members of the P-glycoprotein (PGP/ABCB) subfamily of ATP-binding cassette (ABC) transporters have been shown to function in the polar movement of auxin by transporting auxin over the plasma membrane in both monocots and dicots. Here, we characterize a new Arabidopsis member of the ABCB subfamily, ABCB21/PGP21, a close homolog of ABCB4, for which conflicting transport directionalities have been reported. ABCB21 is strongly expressed in the abaxial side of cotyledons and in junctions of lateral organs in the aerial part, whereas in roots it is specifically expressed in pericycle cells. Membrane fractionation by sucrose density gradient centrifugation followed by Western blot showed that ABCB21 is a plasma membrane-localized ABC transporter. A transport assay with Arabidopsis protoplasts suggested that ABCB21 was involved in IAA transport in an outward direction, while naphthalene acetic acid (NAA) was a less preferable substrate for ABCB21. Further functional analysis of ABCB21 using yeast import and export assays showed that ABCB21 mediates the 1-N-naphthylphthalamic acid (NPA)-sensitive translocation of auxin in an inward direction when the cytoplasmic IAA concentration is low, whereas this transporter mediates outward transport under high internal IAA. An increase in the cytoplasmic IAA concentration by pre-loading of IAA into yeast cells abolished the IAA uptake activity by ABCB21 as well as ABCB4. These findings suggest that ABCB21 functions as a facultative importer/exporter controlling auxin concentrations in plant cells