title: BEX1/ARF1A1C is required for BFA-sensitive recycling of PIN auxin transporters and auxin-mediated development in Arabidopsis.
abstract: Correct positioning of membrane proteins is an essential process in eukaryotic organisms. The plant hormone auxin is distributed through intercellular transport and triggers various cellular responses. Auxin transporters of the PIN-FORMED (PIN) family localize asymmetrically at the plasma membrane (PM) and mediate the directional transport of auxin between cells. A fungal toxin, brefeldin A (BFA), inhibits a subset of guanine nucleotide exchange factors for ADP-ribosylation factor small GTPases (ARF GEFs) including GNOM, which plays a major role in localization of PIN1 predominantly to the basal side of the PM. The Arabidopsis genome encodes 19 ARF-related putative GTPases. However, ARF components involved in PIN1 localization have been genetically poorly defined. Using a fluorescence imaging-based forward genetic approach, we identified an Arabidopsis mutant, bfa-visualized exocytic trafficking defective1 (bex1), in which PM localization of PIN1-green fluorescent protein (GFP) as well as development is hypersensitive to BFA. We found that in bex1 a member of the ARF1 gene family, ARF1A1C, was mutated. ARF1A1C localizes to the trans-Golgi network/early endosome and Golgi apparatus, acts synergistically to BEN1/MIN7 ARF GEF and is important for PIN recycling to the PM. Consistent with the developmental importance of PIN proteins, functional interference with ARF1 resulted in an impaired auxin response gradient and various developmental defects including embryonic patterning defects and growth arrest. Our results show that ARF1A1C is essential for recycling of PIN auxin transporters and for various auxin-dependent developmental processes.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, 560-0043 Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Tomasz
authors.initials: T
authors.lastname: Nodzyłski
authors.forename: Saeko
authors.initials: S
authors.lastname: Kitakura
authors.forename: Mugurel I
authors.initials: MI
authors.lastname: Feraru
authors.forename: Michiko
authors.initials: M
authors.lastname: Sasabe
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kleine-Vehn
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kakimoto
authors.forename: Jiři
authors.initials: J
authors.lastname: Friml
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology*; D003001:Cloning, Molecular; D004705:Endocytosis / Q000187:drug effects*; D004843:Epistasis, Genetic / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D063245:Plant Development / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; D020727:ADP-Ribosylation Factors
keywords: Arabidopsis thaliana; Auxin; Embryogenesis; Exocytosis; PIN-FORMED