Stress-regulated Arabidopsis GAT2 is a low affinity γ-aminobutyric acid transporter

Stefan Meier, Robin Bautzmann, Nataliya Y. Komarova, Viona Ernst, Marianne Suter Grotemeyer, Kirsten Schröder, Alexander C. Haindrich, Adriana Vega Fernández, Christelle A.M. Robert, John M. Ward, Doris Rentsch

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)6295-6311
Number of pages17
JournalJournal of experimental botany
Volume75
Issue number20
DOIs
StatePublished - Oct 1 2024

Bibliographical note

Publisher Copyright:
© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.

Keywords

  • Arabidopsis
  • GABA
  • low water potential
  • oocyte
  • osmotic stress
  • phosphorylation
  • transporter
  • γ‐Aminobutyric acid

PubMed: MeSH publication types

  • Journal Article

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