Rice Na+/H+-antiporter Nhx1 partially complements the alkali-metal- cation sensitivity of yeast strains lacking three sodium transporters

摘要

A triple mutant strain of Saccharomyces cerevisiae lacking its own Na+-ATPases and Na+/H+ antiporters (enal-4DELTA nha1DELTA nhx1DELTA) was used for the expression of the Oryza saliva NHX1 gene encoding a putative vacuolar Na+/H+ exchanger. Upon expression in yeast cells, the OsNhx1p is not a transport system specific only for sodium cations but it has a broad substrate specificity for at least four alkali metal cations (Na+, Li+, K+ and Rb+) and is able to substitute for the endogenous yeast ScNhx1 antiporter. Its activity contributes to sequestration of alkali metal cations in intracellular vesicles.