Trk1, the sole potassium-specific transporter in Candida glabrata, contributes to the proper functioning of various...

Candida glabrata is a haploid yeast that is considered to be an emergent pathogen since it is the second most prevalent cause of candidiasis. Contrary to most yeasts, this species carries only one plasma membrane potassium transporter named CgTrk1. We show in this work that the activity of this transporter is regulated at the posttranslational level, and thus Trk1 contributes to potassium uptake under very different external cation concentrations. In addition to its function in potassium uptake, we report a diversity of physiological effects related to this transporter. CgTRK1 contributes to proper cell size, intracellular pH and membrane-potential homeostasis when expressed in Saccharomyces cerevisiae. Moreover, lithium influx experiments performed both in C. glabrata and S. cerevisiae indicate that the salt tolerance phenotype linked to CgTrk1 can be related to a high capacity to discriminate between potassium and lithium (or sodium) during the transport process. In summary, we show that CgTRK1 exerts a diversity of pleiotropic physiological roles and we propose that the corresponding protein may be an attractive pharmacological target for the development of new antifungal drugs.