Wild-type cells of Candida albicans, the most common human fungal pathogen, are able to grow at very low micromolar concentrations of potassium in the external milieu. One of the reasons behind that behaviour is the existence of three different types of K⁺ transporters in their plasma membrane: Trk1, Acu1 and Hak1. This work shows that the transporters are very differently regulated at the transcriptional level upon exposure to saline stress, pH alterations or K⁺ starvation. We propose that different transporters take the lead in the diverse environmental conditions, Trk1 being the “house-keeping” one, and Acu1/Hak1 dominating upon K⁺ limiting conditions. Heterologous expression of the genes coding for the three transporters in a Saccharomyces cerevisiae strain lacking its endogenous potassium transporters showed that all of them mediated cation transport but with very different efficiencies. Moreover, expression of the transporters in S. cerevisiae also affected other physiological characteristics such as sodium and lithium tolerance, membrane potential or intracellular pH, being, in general, CaTrk1 the most effective in keeping these parameters close to the usual wild-type physiological levels.

最常见的人类真菌病原体白色念珠菌的野生型细胞能够在外部环境中以非常低的微摩尔浓度钾生长。该行为背后的原因之一是它们的质膜中存在三种不同类型的K ⁺转运蛋白：Trk1，Acu1和Hak1。这项工作表明，转运蛋白在暴露于盐胁迫，pH值变化或K ⁺饥饿时，在转录水平上的调控差异很大。我们建议在不同的环境条件下由不同的运输者带头，Trk1是“家务”，而Acu1 / Hak1在K ⁺限制条件下占主导地位。编码三个转运蛋白的基因在大肠杆菌中的异源表达。缺乏其内源钾转运蛋白的酿酒酵母菌株显示它们全部都介导阳离子转运，但是效率非常不同。此外，转运蛋白在S中的表达。酿酒酵母还影响其他生理特性，例如耐钠和锂，膜电位或细胞内pH值，因此，Ca Trk1通常最有效地将这些参数保持在通常的野生型生理水平附近。