The Arabidopsis thaliana SOS2 gene encodes a protein kinase that is required for salt tolerance.
In Arabidopsis thaliana, the Salt Overly Sensitive 2 (SOS2) gene is required for intracellular Na(+) and K(+) homeostasis. Mutations in SOS2 cause Na(+) and K(+) imbalance and render plants more sensitive toward growth inhibition by high Na(+) and low K(+) environments. We isolated the SOS2 gene through positional cloning. SOS2 is predicted to encode a serine/threonine type protein kinase with an N-terminal catalytic domain similar to that of the yeast SNF1 kinase. Sequence analyses of sos2 mutant alleles reveal that both the N-terminal catalytic domain and the C-terminal regulatory domain of SOS2 are functionally essential. The steady-state level of SOS2 transcript is up-regulated by salt stress in the root. Autophosphorylation assays show that SOS2 is an active protein kinase. In the recessive sos2-5 allele, a conserved glycine residue in the kinase catalytic domain is changed to glutamate. This mutation abolishes SOS2 autophosphorylation, indicating that SOS2 protein kinase activity is required for salt tolerance.
Liu
J
J
Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA.
Ishitani
M
M
Halfter
U
U
Kim
C S
CS
Zhu
J K
JK
D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D018744:DNA, Plant; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D018517:Plant Roots / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012492:Salts; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D012492:Salts; C406738:SOS2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases