TY - JOUR
T1 - Stress-regulated Arabidopsis GAT2 is a low affinity γ-aminobutyric acid transporter
AU - Meier, Stefan
AU - Bautzmann, Robin
AU - Komarova, Nataliya Y.
AU - Ernst, Viona
AU - Grotemeyer, Marianne Suter
AU - Schröder, Kirsten
AU - Haindrich, Alexander C.
AU - Fernández, Adriana Vega
AU - Robert, Christelle A.M.
AU - Ward, John M.
AU - Rentsch, Doris
N1 - Publisher Copyright:
© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.
PY - 2024/10/1
Y1 - 2024/10/1
N2 - The four-carbon non-proteinogenic amino acid γ-aminobutyric acid (GABA) accumulates to high levels in plants in response to various abiotic and biotic stress stimuli, and plays a role in C:N balance, signaling, and as a transport regulator. Expression in Xenopus oocytes and voltage-clamping allowed the characterization of Arabidopsis GAT2 (At5g41800) as a low affinity GABA transporter with a K0.5GABA ~8 mM. l-Alanine and butylamine represented additional substrates. GABA-induced currents were strongly dependent on the membrane potential, reaching the highest affinity and highest transport rates at strongly negative membrane potentials. Mutation of Ser17, previously reported to be phosphorylated in planta, did not result in altered affinity. In a short-term stress experiment, AtGAT2 mRNA levels were up-regulated at low water potential and under osmotic stress (polyethylene glycol and mannitol). Furthermore, AtGAT2 promoter activity was detected in vascular tissues, maturating pollen, and the phloem unloading region of young seeds. Even though this suggested a role for AtGAT2 in long-distance transport and loading of sink organs, under the conditions tested neither AtGAT2-overexpressing plants, atgat2 or atgat1 T-DNA insertion lines, nor atgat1 atgat2 doubleknockout mutants differed from wild-type plants in growth on GABA, amino acid levels, or resistance to salt and osmotic stress.
AB - The four-carbon non-proteinogenic amino acid γ-aminobutyric acid (GABA) accumulates to high levels in plants in response to various abiotic and biotic stress stimuli, and plays a role in C:N balance, signaling, and as a transport regulator. Expression in Xenopus oocytes and voltage-clamping allowed the characterization of Arabidopsis GAT2 (At5g41800) as a low affinity GABA transporter with a K0.5GABA ~8 mM. l-Alanine and butylamine represented additional substrates. GABA-induced currents were strongly dependent on the membrane potential, reaching the highest affinity and highest transport rates at strongly negative membrane potentials. Mutation of Ser17, previously reported to be phosphorylated in planta, did not result in altered affinity. In a short-term stress experiment, AtGAT2 mRNA levels were up-regulated at low water potential and under osmotic stress (polyethylene glycol and mannitol). Furthermore, AtGAT2 promoter activity was detected in vascular tissues, maturating pollen, and the phloem unloading region of young seeds. Even though this suggested a role for AtGAT2 in long-distance transport and loading of sink organs, under the conditions tested neither AtGAT2-overexpressing plants, atgat2 or atgat1 T-DNA insertion lines, nor atgat1 atgat2 doubleknockout mutants differed from wild-type plants in growth on GABA, amino acid levels, or resistance to salt and osmotic stress.
KW - Arabidopsis
KW - GABA
KW - low water potential
KW - oocyte
KW - osmotic stress
KW - phosphorylation
KW - transporter
KW - γ‐Aminobutyric acid
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U2 - 10.1093/jxb/erae321
DO - 10.1093/jxb/erae321
M3 - Article
C2 - 39058302
AN - SCOPUS:85207815288
SN - 0022-0957
VL - 75
SP - 6295
EP - 6311
JO - Journal of experimental botany
JF - Journal of experimental botany
IS - 20
ER -