THE SAL1 GENE OF ARABIDOPSIS, ENCODING AN ENZYME WITH 3'(2'),5'-BISPHOSPHATE NUCLEOTIDASE AND INOSITOL POLYPHOSPHATE 1-PHOSPHATASE ACTIVITIES, INCREASES SALT TOLERANCE IN YEAST
Fj. Quintero et al., THE SAL1 GENE OF ARABIDOPSIS, ENCODING AN ENZYME WITH 3'(2'),5'-BISPHOSPHATE NUCLEOTIDASE AND INOSITOL POLYPHOSPHATE 1-PHOSPHATASE ACTIVITIES, INCREASES SALT TOLERANCE IN YEAST, The Plant cell, 8(3), 1996, pp. 529-537
A cDNA library in a yeast expression vector was prepared from roots of
Arabidopsis exposed to salt and was used to select Li+-tolerant yeast
transformants. The cDNA SAL1 isolated from one of these transformants
encodes a polypeptide of 353 amino acid residues. This protein is hom
ologous to the HAL2 and CysQ phosphatases of yeast and Escherichia col
i, respectively. Partial cDNA sequences in the data bases indicate tha
t rice produces a phosphatase highly homologous to SAL1 and that a sec
ond gene homologous to SAL1 exists in Arabidopsis. The SAL1 protein ex
pressed in E. coli showed 3'(2',5'-bisphosphate nucleotidase and inosi
tol polyphosphate 1-phosphatase activities. In yeast, SAL1 restored th
e ability of a hal2/met22 mutant to grow on sulfate as a sole sulfur s
ource, increased the intracellular Li+ tolerance, and modified Na+ and
Li+ effluxes. We propose that the product of SAL1 participates in the
sulfur assimilation pathway as well as in the phosphoinositide signal
ing pathway and that changes in the latter may affect Na+ and Li+ flux
es.