Insights into the localization and function of the membrane trafficking regulator GNOM ARF-GEF at the Golgi apparatus in Arabidopsis

Satoshi Naramoto, Marisa S. Otegui, Natsumaro Kutsuna, Riet de Rycke, Tomoko Dainobu, Michael Karampelias, Masaru Fujimoto, Elena Feraru, Daisuke Miki, Hiroo Fukuda, Akihiko Nakano, Jiří Friml

    Research output: Contribution to journalArticlepeer-review

    77 Citations (Scopus)

    Abstract

    GNOM is one of the most characterized membrane trafficking regulators in plants, with crucial roles in development. GNOM encodes an ARF-guanine nucleotide exchange factor (ARF-GEF) that activates small GTPases of the ARF (ADP ribosylation factor) class to mediate vesicle budding at endomembranes. The crucial role of GNOM in recycling of PIN auxin transporters and other proteins to the plasma membrane was identified in studies using the ARF-GEF inhibitor brefeldin A (BFA). GNOM, the most prominent regulator of recycling in plants, has been proposed to act and localize at so far elusive recycling endosomes. Here, we report the GNOM localization in context of its cellular function in Arabidopsis thaliana. State-of-the-art imaging, pharmacological interference, and ultrastructure analysis show that GNOM predominantly localizes to Golgi apparatus. Super-resolution confocal live imaging microscopy identified GNOM and its closest homolog GNOM-like 1 at distinct subdomains on Golgi cisternae. Short-term BFA treatment stabilizes GNOM at the Golgi apparatus, whereas prolonged exposures results in GNOM translocation to trans-Golgi network (TGN)/early endosomes (EEs). Malformed TGN/EE in gnom mutants suggests a role for GNOM in maintaining TGN/EE function. Our results redefine the subcellular action of GNOM and reevaluate the identity and function of recycling endosomes in plants.

    Original languageEnglish
    Pages (from-to)3062-3076
    Number of pages15
    JournalPlant Cell
    Volume26
    Issue number7
    DOIs
    Publication statusPublished - 2014 Jul

    ASJC Scopus subject areas

    • Plant Science
    • Cell Biology

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