TY - JOUR
T1 - Regulation of durum wheat Na+/H+ exchanger TdSOS1 by phosphorylation
AU - Feki, Kaouthar
AU - Quintero, Francisco J.
AU - Pardo, Jose M.
AU - Masmoudi, Khaled
N1 - Funding Information:
Acknowledgments This study was supported by a grant from Ministry of Higher Education Scientific Research and Technology of Tunisia and the grants A/8077/07 from the Spanish Agency for International Development Cooperation (AECID) and BIO2009-08641 from the Ministry of Science and Innovation (MICINN), co-financed by Fondo Europeo de Desarrollo Regional (FEDER). K. F. is the holder of a grant from the Spanish Ministry of Foreign Affairs and Cooperation (MAEC). The TdSOS1 cDNA sequence has been deposited in the GenBank database with Accession No. EU552490.
PY - 2011/8
Y1 - 2011/8
N2 - 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.
AB - 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.
KW - Auto-inhibitory domain
KW - Na/H antiporter SOS1
KW - Phosphorylation
KW - SOS2
KW - Salt stress
KW - Triticum durum
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U2 - 10.1007/s11103-011-9787-8
DO - 10.1007/s11103-011-9787-8
M3 - Article
C2 - 21573979
AN - SCOPUS:79960615547
SN - 0167-4412
VL - 76
SP - 545
EP - 556
JO - Plant Molecular Biology
JF - Plant Molecular Biology
IS - 6
ER -