Department of Membrane Transport, Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague, Czech Republic.
Microbiology (Reading). 2014 Aug;160(Pt 8):1705-1713. doi: 10.1099/mic.0.078600-0. Epub 2014 Jun 9.
Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells.
光滑念珠菌是一种耐盐和氟康唑（FLC）的酵母物种。在这里，我们分析了质膜碱金属阳离子外排蛋白、阳离子/质子反向转运蛋白和阳离子 ATP 酶对阳离子稳态和膜电位（ΔΨ）维持的贡献。使用一系列缺乏 CNH1 和/或 ENA1 基因的单突变体和双突变体，我们表明钾和有毒碱金属阳离子的外排能力丧失导致光滑念珠菌细胞的质膜轻微超极化；这种超极化促使更多的阳离子进入细胞并影响阳离子稳态。令人惊讶的是，用亚抑制浓度的 FLC 孵育细胞会导致光滑念珠菌质膜产生更高的超极化。FLC 处理会导致细胞对各种阳离子药物和毒性阳离子的敏感性显著增加，这些阳离子是由质膜负内电位驱动进入细胞的。碱金属阳离子转运蛋白的功能障碍会增强 FLC 加阳离子药物处理的效果，这些转运蛋白有助于调节膜电位和阳离子稳态。总之，我们表明，亚抑制浓度的 FLC 和阳离子药物的联合使用会强烈影响光滑念珠菌细胞的生长。
