Regulation of durum wheat Na+/H+ exchanger TdSOS1 by phosphorylation

Kaouthar Feki, Francisco J. Quintero, Jose M. Pardo, Khaled Masmoudi

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

We have identified a plasma membrane Na+/H+ exchanger from durum wheat, designated TdSOS1. Heterologous expression of TdSOS1 in a yeast strain lacking endogenous Na+ efflux proteins showed complementation of the Na+- and Li+-sensitive phenotype by a mechanism involving cation efflux. Salt tolerance conferred by TdSOS1 was maximal when co-expressed with the Arabidopsis protein kinase complex SOS2/SOS3. In vitro phosphorylation of TdSOS1 with a hyperactive form of the Arabidopsis SOS2 kinase (T/DSOS2Δ308) showed the importance of two essential serine residues at the C-terminal hydrophilic tail (S1126, S1128). Mutation of these two serine residues to alanine decreased the phosphorylation of TdSOS1 by T/DSOS2Δ308 and prevented the activation of TdSOS1. In addition, deletion of the C-terminal domain of TdSOS1 encompassing serine residues at position 1126 and 1128 generated a hyperactive form that had maximal sodium exclusion activity independent from the regulatory SOS2/SOS3 complex. These results are consistent with the presence of an auto-inhibitory domain at the C-terminus of TdSOS1 that mediates the activation of TdSOS1 by the protein kinase SOS2. Expression of TdSOS1 mRNA in young seedlings of the durum wheat variety Om Rabia3, using different abiotic stresses (ionic and oxidative stress) at different times of exposure, was monitored by RT-PCR.

Original languageEnglish
Pages (from-to)545-556
Number of pages12
JournalPlant Molecular Biology
Volume76
Issue number6
DOIs
Publication statusPublished - Aug 2011
Externally publishedYes

Keywords

  • Auto-inhibitory domain
  • Na/H antiporter SOS1
  • Phosphorylation
  • SOS2
  • Salt stress
  • Triticum durum

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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