The Arabidopsis GNOM ARF-GEF mediates endosomal recycling, auxin transport, and auxin-dependent plant growth.
Exchange factors for ARF GTPases (ARF-GEFs) regulate vesicle trafficking in a variety of organisms. The Arabidopsis protein GNOM is a brefeldin A (BFA) sensitive ARF-GEF that is required for the proper polar localization of PIN1, a candidate transporter of the plant hormone auxin. Mutations in GNOM lead to developmental defects that resemble those caused by interfering with auxin transport. Both PIN1 localization and auxin transport are also sensitive to BFA. In this paper, we show that GNOM localizes to endosomes and is required for their structural integrity. We engineered a BFA-resistant version of GNOM. In plants harboring this fully functional GNOM variant, PIN1 localization and auxin transport are no longer sensitive to BFA, while trafficking of other proteins is still affected by the drug. Our results demonstrate that GNOM is required for the recycling of auxin transport components and suggest that ARF-GEFs regulate specific endosomal trafficking pathways.
Geldner
Niko
N
ZMBP, Entwicklungsgenetik, Universität Tübingen, Auf der Morgenstelle 3, D-72076, Tübingen, Germany.
Anders
Nadine
N
Wolters
Hanno
H
Keicher
Jutta
J
Kornberger
Wolfgang
W
Muller
Philippe
P
Delbarre
Alain
A
Ueda
Takashi
T
Nakano
Akihiko
A
Jürgens
Gerd
G
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D004351:Drug Resistance / Q000235:genetics; D011992:Endosomes / Q000378:metabolism*; D005818:Genetic Engineering; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; C088087:GNOM protein, Arabidopsis; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D010937:Plant Growth Regulators; D020126:Brefeldin A