Fluorescence imaging based screen identifies ARF GEF component of early endosomal trafficking Journal Article

Author(s): Tanaka, Hirokazu; Kitakura, Saeko; De Rycke, Riet M; De Groodt, Ruth; Friml, Jiří
Article Title: Fluorescence imaging based screen identifies ARF GEF component of early endosomal trafficking
Abstract: Endocytic vesicle trafficking is crucial for regulating activity and localization of plasma membrane components, but the process is still poorly genetically defined in plants. Membrane proteins of the PIN-FORMED (PIN) family exhibit polar localization in plant cells and facilitate cellular efflux of the plant hormone auxin, thereby regulating multiple developmental processes [1, 2]. PIN proteins undergo constitutive endocytosis and GNOM ARF GEF-dependent recycling [3-5], and their localization is under extensive regulation by developmental and environmental cues [6-9]. We designed a fluorescence imaging-based screen to identify Arabidopsis thaliana mutants defective in internalization of proteins including PINs from the plasma membrane. We identified three mutant loci, BFA-visualized endocytic trafficking defective1 (ben1) through ben3 that do not efficiently accumulate PIN1-GFP in intracellular compartments after inhibition of recycling and secretion by fungal toxin brefeldin A (BFA). Fine mapping revealed that BEN1 encodes an ARF GEF vesicle trafficking regulator from the functionally uncharacterized BIG class. ben1 mutant has been previously implicated in pathogen response [10] and shows cell polarity, BFA sensitivity, and growth defects. BEN1 is involved in endocytosis of plasma membrane proteins and localizes to early endocytic compartments distinct from GNOM-positive endosomes. Our results identify BEN1 as the ARF GEF mediating early endosomal traffic.
Keywords: Mutation; Biological Transport; plant roots; Recombinant Fusion Proteins; Cell polarity; endosomes; Arabidopsis; Arabidopsis Proteins; Guanine Nucleotide Exchange Factors; Membrane Transport Proteins; trans-Golgi Network; ADP-Ribosylation Factors; Alcohol Oxidoreductases
Journal Title: Current Biology
Volume: 19
Issue 5
ISSN: 0960-9822
Publisher: Cell Press  
Date Published: 2009-03-10
Start Page: 391
End Page: 397
DOI: 10.1016/j.cub.2009.01.057
Open access: no