TY - JOUR
T1 - Membrane association of the Arabidopsis ARF exchange factor GNOM involves interaction of conserved domains
AU - Anders, Nadine
AU - Nielsen, Michael M.
AU - Keicher, Jutta
AU - Stierhof, York-Dieter
AU - Furutani, Masahiko
AU - Jürgens, Gerd
AU - Tasaka, Masao
AU - Skriver, Karen
N1 - Keywords: ADP-Ribosylation Factors; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Catalysis; Cell Membrane; Conserved Sequence; Dimerization; Guanine Nucleotide Exchange Factors; Immunophilins; Molecular Sequence Data; Mutant Proteins; Protein Binding; Protein Structure, Tertiary
PY - 2008
Y1 - 2008
N2 - The GNOM protein plays a fundamental role in Arabidopsis thaliana development by regulating endosome-to-plasma membrane trafficking required for polar localization of the auxin efflux carrier PIN1. GNOM is a family member of large ARF guanine nucleotide exchange factors (ARF-GEFs), which regulate vesicle formation by activating ARF GTPases on specific membranes in animals, plants, and fungi. However, apart from the catalytic exchange activity of the SEC7 domain, the functional significance of other conserved domains is virtually unknown. Here, we show that a distinct N-terminal domain of GNOM mediates dimerization and in addition interacts heterotypically with two other conserved domains in vivo. In contrast with N-terminal dimerization, the heterotypic interaction is essential for GNOM function, as mutations abolishing this interaction inactivate the GNOM protein and compromise its membrane association. Our results suggest a general model of large ARF-GEF function in which regulated changes in protein conformation control membrane association of the exchange factor and, thus, activation of ARFs.
AB - The GNOM protein plays a fundamental role in Arabidopsis thaliana development by regulating endosome-to-plasma membrane trafficking required for polar localization of the auxin efflux carrier PIN1. GNOM is a family member of large ARF guanine nucleotide exchange factors (ARF-GEFs), which regulate vesicle formation by activating ARF GTPases on specific membranes in animals, plants, and fungi. However, apart from the catalytic exchange activity of the SEC7 domain, the functional significance of other conserved domains is virtually unknown. Here, we show that a distinct N-terminal domain of GNOM mediates dimerization and in addition interacts heterotypically with two other conserved domains in vivo. In contrast with N-terminal dimerization, the heterotypic interaction is essential for GNOM function, as mutations abolishing this interaction inactivate the GNOM protein and compromise its membrane association. Our results suggest a general model of large ARF-GEF function in which regulated changes in protein conformation control membrane association of the exchange factor and, thus, activation of ARFs.
U2 - 10.1105/tpc.107.056515
DO - 10.1105/tpc.107.056515
M3 - Journal article
C2 - 18203920
SN - 1040-4651
VL - 20
SP - 142
EP - 151
JO - The Plant Cell
JF - The Plant Cell
IS - 1
ER -