Arabidopsis thaliana CHX17 gene complements the kha1 deletion phenotypes in Saccharomyces cerevisiae.

AtChx17p is a putative K(+)/H(+) exchanger from Arabidopsis thaliana, expressed in the roots and probably involved in K(+) acquisition and homeostasis. AtCHX17 cDNA complements the phenotypes of the kha1Delta mutation in S. cerevisiae cells: a growth defect at increased pH and hygromycin sensitivity. The localization of GFP-tagged AtChx17 protein in yeast cells is similar to that of ScKha1p: a bold dotted pattern inside the cells resembling the Golgi fluorescence markers. These results show that (a) the proteins AtChx17 and ScKha1 could have similar functions and (b) S. cerevisiae kha1 deletion mutants could serve for the heterologous expression and characterization of plant transporters. The results of this work are evidence that a S. cerevisiae strain with deletions of genes encoding alkali-metal-cation/H(+) antiporters (i.e. Nha1p, Nhx1p, Kha1p) could be an ideal tool for expression and functional analysis of any type of similar plant antiporters (plasma membrane, endosomal/prevacuolar and Golgi). Copyright 2006 John Wiley & Sons, Ltd.