A domain-based approach for analyzing the function of aluminum-activated malate transporters from wheat (Triticum aestivum) and arabidopsis thaliana in xenopus oocytes

Takayuki Sasaki, Yoshiyuki Tsuchiya, Michiyo Ariyoshi, Peter R. Ryan, Takuya Furuichi, Yoko Yamamoto

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Wheat and Arabidopsis plants respond to aluminum (Al) ions by releasing malate from their root apices via Al-activated malate transporter. Malate anions bind with the toxic Al ions and contribute to the Al tolerance of these species. The genes encoding the transporters in wheat and Arabidopsis, TaALMT1 and AtALMT1, respectively, were expressed in Xenopus laevis oocytes and characterized electrophysiologically using the two-electrode voltage clamp system. The Al-activated currents generated by malate efflux were detected for TaALMT1 but not for AtALMT1. Chimeric proteins were generated by swapping the N- and C-terminal halves of TaALMT1 and AtALMT1 (Ta::At and At::Ta). When these chimeras were characterized in oocytes, Al-activated malate efflux was detected for the Ta::At chimera but not for At::Ta, suggesting that the N-terminal half of TaALMT1 is necessary for function in oocytes. An additional chimera, Ta(48)::At, generated by swapping 17 residues from the N-terminus of AtALMT1 with the equivalent 48 residues from TaALMT1, was sufficient to support transport activity. This 48 residue region includes a helical region with a putative transmembrane domain which is absent in AtALMT1. The deletion of this domain from Ta(48)::At led to the complete loss of transport activity. Furthermore, truncations and a deletion at the C-terminal end of TaALMT1 indicated that a putative helical structure in this region was also required for transport function. This study provides insights into the structure-function relationships of Al-activated ALMT proteins by identifying specific domains on the N- and C-termini of TaALMT1 that are critical for basal transport function and Al responsiveness in oocytes.

Original languageEnglish
Pages (from-to)2126-2138
Number of pages13
JournalPlant and Cell Physiology
Volume55
Issue number12
DOIs
Publication statusPublished - Sep 11 2014

    Fingerprint

Keywords

  • Aluminum-activated malate transporter
  • Arabidopsis thaliana
  • Domain structure
  • Electrophysiology
  • Wheat (Triticum aestivum)
  • Xenopus laevis oocyte

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

Cite this