The absence of high-affinity potassium uptake in Candida glabrata, the consequence of the deletion of the TRK1 gene encoding the sole potassium-specific transporter, has a pleiotropic effect. Here, we show that in addition to changes in basic physiological parameters (e.g., membrane potential and intracellular pH) and decreased tolerance to various cell stresses, the loss of high affinity potassium uptake also alters cell-surface properties, such as an increased hydrophobicity and adherence capacity. The loss of an efficient potassium uptake system results in diminished virulence as assessed by two insect host models, Drosophila melanogaster and Galleria mellonella, and experiments with macrophages. Macrophages kill trk1Δ cells more effectively than wild type cells. Consistently, macrophages accrue less damage when co-cultured with trk1Δ mutant cells compared to wild-type cells. We further show that low levels of potassium in the environment increase the adherence of C. glabrata cells to polystyrene and the propensity of C. glabrata cells to form biofilms.

• MeSH
• Biofilms growth & development   MeSH
• Cell Adhesion physiology   MeSH
• Cell Membrane metabolism   MeSH
• Cell Line MeSH
• Candida glabrata genetics   metabolism   pathogenicity   MeSH
• Potassium metabolism   MeSH
• Potassium-Hydrogen Antiporters genetics   MeSH
• Drosophila melanogaster microbiology   MeSH
• Hydrophobic and Hydrophilic Interactions MeSH
• Ion Transport MeSH
• Humans MeSH
• Macrophages immunology   MeSH
• Membrane Potentials physiology   MeSH
• Moths microbiology   MeSH
• Surface Properties MeSH
• Cation Transport Proteins genetics   MeSH
• Gene Expression Regulation, Fungal genetics   MeSH
• THP-1 Cells MeSH
• Virulence genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Potassium MeSH
• Potassium-Hydrogen Antiporters MeSH
• Cation Transport Proteins MeSH
• Trk1 protein, Candida albicans MeSH Browser

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 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