Functional characterization of a wheat plasma membrane Na+/H+ antiporter in yeast

The functional analysis of the sodium exchanger SOS1 from wheat, TaSOS1, was undertaken using Saccharomyces cerevisiae as a heterologous expression system. The TaSOS1 protein, with significant sequence homology to SOS1 sodium exchangers from Arabidopsis and rice, is abundant in roots and leaves, and is induced by salt treatment. TaSOS1 suppressed the salt sensitivity of a yeast strain lacking the major Na⁺ efflux systems by decreasing the cellular Na⁺ content while increasing K⁺ content. Na⁺/H⁺ exchange activity of purified plasma membrane from yeast cells expressing TaSOS1 was higher than controls transformed with empty vector. These results demonstrate that TaSOS1 contributes to plasma membrane Na⁺/H⁺ exchange.