The maintenance of potassium homeostasis is crucial for all types of cells, including Candida glabrata. Three types of plasma-membrane systems mediating potassium influx with different transport mechanisms have been described in yeasts: the Trk1 uniporter, the Hak cation-proton symporter and the Acu ATPase. The C. glabrata genome contains only one gene encoding putative system for potassium uptake, the Trk1 uniporter. Therefore, its importance in maintaining adequate levels of intracellular potassium appears to be critical for C. glabrata cells. In this study, we first confirmed the potassium-uptake activity of the identified gene's product by heterologous expression in a suitable S. cerevisiae mutant, further we generated a corresponding deletion mutant in C. glabrata and analysed its phenotype in detail. The obtained results show a pleiotropic effect on the cell physiology when CgTRK1 is deleted, affecting not only the ability of trk1Δ to grow at low potassium concentrations, but also the tolerance to toxic alkali-metal cations and cationic drugs, as well as the membrane potential and intracellular pH. Taken together, our results find the sole potassium uptake system in C. glabrata cells to be a promising target in the search for its specific inhibitors and in developing new antifungal drugs.

• MeSH
• Cell Membrane metabolism   MeSH
• Candida glabrata metabolism   physiology   MeSH
• Potassium metabolism   MeSH
• Homeostasis physiology   MeSH
• Ion Transport physiology   MeSH
• Cations metabolism   MeSH
• Membrane Potentials physiology   MeSH
• Cation Transport Proteins metabolism   MeSH
• Gene Expression Regulation, Fungal physiology   MeSH
• Saccharomyces cerevisiae metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Potassium MeSH
• Cations MeSH
• Cation Transport Proteins MeSH
• Trk1 protein, Candida albicans MeSH Browser

The virulence of Candida species depends on many environmental conditions, including extracellular pH and concentration of alkali metal cations. Tests of the tolerance/sensitivity of four pathogenic Candida species (C. albicans, C. dubliniensis, C. glabrata, and C. parapsilosis) to alkali metal cations under various growth conditions revealed significant differences among these species. Though all of them can be classified as rather osmotolerant yeast species, they exhibit different levels of tolerance to different salts. C. parapsilosis and C. albicans are the most salt-tolerant in general; C. dubliniensis is the least tolerant on rich YPD media and C. glabrata on acidic (pH 3.5) minimal YNB medium. C. dubliniensis is relatively salt-sensitive in spite of its ability to maintain as high intracellular K(+)/Na(+) ratio as its highly salt-tolerant relative C. albicans. On the other hand, C. parapsilosis can grow in the presence of very high external NaCl concentrations in spite of its high intracellular Na(+) concentrations (and thus lower K(+)/Na(+) ratio) and thus resembles salt-tolerant (halophilic) Debaryomyces hansenii.

• MeSH
• Candida albicans pathogenicity   physiology   MeSH
• Candida glabrata pathogenicity   physiology   MeSH
• Candida metabolism   pathogenicity   physiology   MeSH
• Potassium Chloride analysis   pharmacology   MeSH
• Lithium Chloride analysis   pharmacology   MeSH
• Sodium Chloride analysis   pharmacology   MeSH
• Species Specificity MeSH
• Salts MeSH
• Salt Tolerance physiology   MeSH
• Virulence MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Potassium Chloride MeSH
• Lithium Chloride MeSH
• Sodium Chloride MeSH
• Salts MeSH

The transport activity and substrate specificity of two chimeras consisting of S. cerevisiae Nha1p's N-terminal regions (either first 125 or 184 AA) and the rest of the C. glabrata Cnh1p (up to the total protein length of 946 AA) were compared with those of the two native antiporters. Both chimeric transporters were functional upon expression in S. cerevisiae cells, their presence improved the ability of cells to grow in the presence of high external concentration of K(+), Na(+) or Rb(+) (as chlorides), but not in the presence of the smallest cation (Li(+)). Cation efflux confirmed the ability of chimeras to export cations and showed their significantly reduced transport capacity compared to the wild-type proteins. Despite the very high level of primary sequence identity (87 %) between the S. cerevisiae and C. glabrata plasma-membrane Na(+)/H(+) antiporters, various parts of these proteins are not exchangeable without affecting the antiporter's transport capacity.

• MeSH
• Candida glabrata drug effects   genetics   growth & development   metabolism   MeSH
• Potassium Chloride pharmacology   MeSH
• Sodium Chloride pharmacology   MeSH
• Fungal Proteins chemistry   genetics   metabolism   MeSH
• Molecular Sequence Data MeSH
• Sodium-Hydrogen Exchangers chemistry   genetics   metabolism   MeSH
• Cation Transport Proteins chemistry   genetics   metabolism   MeSH
• Recombinant Fusion Proteins chemistry   genetics   metabolism   MeSH
• Saccharomyces cerevisiae Proteins chemistry   genetics   metabolism   MeSH
• Saccharomyces cerevisiae drug effects   genetics   growth & development   metabolism   MeSH
• Amino Acid Sequence MeSH
• Sequence Analysis, DNA MeSH
• Sequence Alignment MeSH
• Salt Tolerance * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Potassium Chloride MeSH
• Sodium Chloride MeSH
• CNH1 protein, Candida albicans MeSH Browser
• Fungal Proteins MeSH
• Sodium-Hydrogen Exchangers MeSH
• NHA1 protein, S cerevisiae MeSH Browser
• Cation Transport Proteins MeSH
• Recombinant Fusion Proteins MeSH
• Saccharomyces cerevisiae Proteins MeSH