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.

• Keywords
• Candida glabrata, Membrane potential, Potassium transport, Saccharomyces cerevisiae, Salt tolerance, Trk1,
• MeSH
• Cell Membrane metabolism   MeSH
• Candida glabrata genetics   metabolism   MeSH
• Potassium metabolism   MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Homeostasis MeSH
• Hydrogen-Ion Concentration MeSH
• Cation Transport Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Fungal MeSH
• Sodium metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Potassium MeSH
• Fungal Proteins MeSH
• Cation Transport Proteins MeSH
• Sodium MeSH

Saccharomyces species, which are mostly used in the food and beverage industries, are known to differ in their fermentation efficiency and tolerance of adverse fermentation conditions. However, the basis of their difference has not been fully elucidated, although their genomes have been sequenced and analyzed. Five strains of four Saccharomyces species (S. cerevisiae, S. kudriavzevii, S. bayanus, and S. paradoxus), when grown in parallel in laboratory conditions, exhibit very similar basic physiological parameters such as membrane potential, intracellular pH, and the degree to which they are able to quickly activate their Pma1 H+-ATPase upon glucose addition. On the other hand, they differ in their ability to proliferate in media with a very low concentration of potassium, in their osmotolerance and tolerance to toxic cations and cationic drugs in a growth-medium specific manner, and in their capacity to survive anhydrobiosis. Overall, S. cerevisiae (T73 more than FL100) and S. paradoxus are the most robust, and S. kudriavzevii the most sensitive species. Our results suggest that the difference in stress survival is based on their ability to quickly accommodate their cell size and metabolism to changing environmental conditions and to adjust their portfolio of available detoxifying transporters.

• Keywords
• Intracellular pH, Membrane potential, Saccharomyces, Stress tolerance,
• MeSH
• Fermentation MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Stress, Physiological MeSH
• Glucose metabolism   MeSH
• Proton-Translocating ATPases genetics   metabolism   MeSH
• Saccharomyces classification   genetics   growth & development   physiology   MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Fungal Proteins MeSH
• Glucose MeSH
• Proton-Translocating ATPases MeSH