Coordinated Activation of ARF1 GTPases by ARF-GEF GNOM Dimers Is Essential for Vesicle Trafficking in Arabidopsis.

Autor:	Brumm S; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany., Singh MK; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany., Nielsen ME; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany.; University of Copenhagen, Faculty of Science, Section for Plant and Soil Science, 1871 Frederiksberg C, Denmark., Richter S; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany., Beckmann H; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany., Stierhof YD; Center for Plant Molecular Biology, Microscopy, University of Tübingen, 72076 Tübingen, Germany., Fischer AM; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany., Kumaran M; Temasek Life Sciences Laboratory, National University of Singapore, 117604 Singapore., Sundaresan V; Department of Plant Biology and Department of Plant Sciences, University of California, Davis, California 95616., Jürgens G; Center for Plant Molecular Biology, Developmental Genetics, University of Tübingen, 72076 Tübingen, Germany gerd.juergens@zmbp.uni-tuebingen.de.
Jazyk:	angličtina
Zdroj:	The Plant cell [Plant Cell] 2020 Aug; Vol. 32 (8), pp. 2491-2507. Date of Electronic Publication: 2020 Jun 02.
DOI:	10.1105/tpc.20.00240
Abstrakt:	Membrane trafficking maintains the organization of the eukaryotic cell and delivers cargo proteins to their subcellular destinations, such as sites of action or degradation. The formation of membrane vesicles requires the activation of the ADP-ribosylation factor ARF GTPase by the SEC7 domain of ARF guanine-nucleotide exchange factors (ARF-GEFs), resulting in the recruitment of coat proteins by GTP-bound ARFs. In vitro exchange assays were done with monomeric proteins, although ARF-GEFs form dimers in vivo. This feature is conserved across eukaryotes, although its biological significance is unknown. Here, we demonstrate the proximity of ARF1•GTPs in vivo by fluorescence resonance energy transfer-fluorescence lifetime imaging microscopy, mediated through coordinated activation by dimers of Arabidopsis ( Arabidopsis thaliana ) ARF-GEF GNOM, which is involved in polar recycling of the auxin transporter PIN-FORMED1. Mutational disruption of ARF1 spacing interfered with ARF1-dependent trafficking but not with coat protein recruitment. A mutation impairing the interaction of one of the two SEC7 domains of the GNOM ARF-GEF dimer with its ARF1 substrate reduced the efficiency of coordinated ARF1 activation. Our results suggest a model of coordinated activation-dependent membrane insertion of ARF1•GTP molecules required for coated membrane vesicle formation. Considering the evolutionary conservation of ARFs and ARF-GEFs, this initial regulatory step of membrane trafficking might well occur in eukaryotes in general. (© 2020 American Society of Plant Biologists. All rights reserved.)
Databáze:	MEDLINE
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