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

Author(s): Naramoto, Satoshi; Otegui, Marisa S; Kutsuna, Natsumaro ; De Rycke, Riet M; Dainobu, Tomoko; Karampelias, Michael; Fujimoto, Masaru; Feraru, Elena; Miki, Daisuke; Fukuda, Hiroo; Nakano, Akihiko; Friml, Jiří
Article Title: Insights into the localization and function of the membrane trafficking regulator GNOM ARF-GEF at the Golgi apparatus in Arabidopsis
Affiliation IST Austria
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.
Journal Title: Plant Cell
Volume: 26
Issue 7
ISSN: 1040-4651
Publisher: American Society of Plant Biologists  
Date Published: 2014-07-01
Start Page: 3062
End Page: 3076
Sponsor: This work was supported by the Japanese Society for the Promotion of Science (30612022 to S.N. and 24770038 to N.K.), the NC-CARP project of the Ministry of Education, Culture, Sports, Science, and Technology in Japan to S.N. and H.F., the Odysseus Progra
DOI: 10.1105/tpc.114.125880
Notes: We thank Gerd Jürgens, Ian Moore, Ben Scheres, Karin Schumacher, and David Robinson for providing published materials and the ABRC and NASC for seed stocks. We also thank Jürgen Kleine-vehn, Stephanie Robert, Hirokazu Tanaka, and Takashi Ueda for helpful discussions and Martine De Cock for help in preparing the article.
Open access: yes (repository)