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

VL - 20

SP - 142

EP - 151

JO - The Plant Cell

JF - The Plant Cell

SN - 1040-4651

IS - 1

ER -