title: BEX5/RabA1b regulates trans-Golgi network-to-plasma membrane protein trafficking in Arabidopsis.
abstract: Constitutive endocytic recycling is a crucial mechanism allowing regulation of the activity of proteins at the plasma membrane and for rapid changes in their localization, as demonstrated in plants for PIN-FORMED (PIN) proteins, the auxin transporters. To identify novel molecular components of endocytic recycling, mainly exocytosis, we designed a PIN1-green fluorescent protein fluorescence imaging-based forward genetic screen for Arabidopsis thaliana mutants that showed increased intracellular accumulation of cargos in response to the trafficking inhibitor brefeldin A (BFA). We identified bex5 (for BFA-visualized exocytic trafficking defective), a novel dominant mutant carrying a missense mutation that disrupts a conserved sequence motif of the small GTPase, RAS GENES FROM RAT BRAINA1b. bex5 displays defects such as enhanced protein accumulation in abnormal BFA compartments, aberrant endosomes, and defective exocytosis and transcytosis. BEX5/RabA1b localizes to trans-Golgi network/early endosomes (TGN/EE) and acts on distinct trafficking processes like those regulated by GTP exchange factors on ADP-ribosylation factors GNOM-LIKE1 and HOPM INTERACTOR7/BFA-VISUALIZED ENDOCYTIC TRAFFICKING DEFECTIVE1, which regulate trafficking at the Golgi apparatus and TGN/EE, respectively. All together, this study identifies Arabidopsis BEX5/RabA1b as a novel regulator of protein trafficking from a TGN/EE compartment to the plasma membrane.
authors: Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Ghent, Belgium.
authors: Elena
authors: E
authors: Feraru
authors: Mugurel I
authors: MI
authors: Feraru
authors: Rin
authors: R
authors: Asaoka
authors: Tomasz
authors: T
authors: Paciorek
authors: Riet
authors: R
authors: De Rycke
authors: Hirokazu
authors: H
authors: Tanaka
authors: Akihiko
authors: A
authors: Nakano
authors: Jirí
authors: J
authors: Friml
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D021381:Protein Transport; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; D019204:GTP-Binding Proteins