Saccharomyces cerevisiae has been frequently used to study biogenesis, functionality, and intracellular transport of various renal proteins, including ion channels, solute transporters, and aquaporins. Specific mutations in genes encoding most of these renal proteins affect kidney function in such a way that various disease phenotypes ultimately occur. In this context, human kidney anion exchanger 1 (kAE1) represents an important bicarbonate/chloride exchanger which maintains the acid-base homeostasis in the human body. Malfunctions in kAE1 lead to a pathological phenotype known as distal renal tubular acidosis (dRTA). Here, we evaluated the potential of baker's yeast as a model system to investigate different cellular aspects of kAE1 physiology. For the first time, we successfully expressed yeast codon-optimized full-length versions of tagged and untagged wild-type kAE1 and demonstrated their partial localization at the yeast plasma membrane (PM). Finally, pH and chloride measurements further suggest biological activity of full-length kAE1, emphasizing the potential of S. cerevisiae as a model system for studying trafficking, activity, and/or degradation of mammalian ion channels and transporters such as kAE1 in the future. IMPORTANCE Distal renal tubular acidosis (dRTA) is a common kidney dysfunction characterized by impaired acid secretion via urine. Previous studies revealed that α-intercalated cells of dRTA patients express mutated forms of human kidney anion exchanger 1 (kAE1) which result in inefficient plasma membrane targeting or diminished expression levels of kAE1. However, the precise dRTA-causing processes are inadequately understood, and alternative model systems are helpful tools to address kAE1-related questions in a fast and inexpensive way. In contrast to a previous study, we successfully expressed full-length kAE1 in Saccharomyces cerevisiae. Using advanced microscopy techniques as well as different biochemical and functionality assays, plasma membrane localization and biological activity were confirmed for the heterologously expressed anion transporter. These findings represent first important steps to use the potential of yeast as a model organism for studying trafficking, activity, and degradation of kAE1 and its mutant variants in the future.

中文翻译：

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酿酒酵母：研究人类肾脏阴离子交换剂1的功能和细胞内转运的合适模型系统的第一步

酿酒酵母（Saccharomyces cerevisiae）经常用于研究各种肾脏蛋白的生物发生，功能和细胞内转运，包括离子通道，溶质转运蛋白和水通道蛋白。编码大多数这些肾脏蛋白的基因中的特定突变会影响肾脏功能，从而最终出现各种疾病表型。在此背景下，人肾阴离子交换剂1（kAE1）代表了一种重要的碳酸氢盐/氯化物交换剂，可维持人体中的酸碱稳态。kAE1的功能异常会导致一种病理表型，称为远端肾小管性酸中毒（dRTA）。在这里，我们评估了面包酵母作为模型系统研究kAE1生理学不同细胞方面的潜力。首次，我们成功表达了标记和未标记的野生型kAE1的酵母密码子优化全长版本，并证明了它们在酵母质膜（PM）上的部分定位。最后，pH和氯化物的测量结果进一步表明了全长kAE1的生物活性，强调了酿酒酵母作为未来研究哺乳动物离子通道和转运蛋白（例如kAE1）的运输，活性和/或降解的模型系统的潜力。重要事项远端肾小管性酸中毒（dRTA）是常见的肾功能不全，其特征是尿液酸分泌受损。先前的研究表明，dRTA患者的α插入细胞表达人类肾脏阴离子交换剂1（kAE1）的突变形式，这导致质膜靶向效率低下或kAE1表达水平降低。然而，导致dRTA的精确过程还没有得到足够的了解，替代模型系统是快速，廉价地解决与kAE1相关问题的有用工具。与先前的研究相反，我们成功地在酿酒酵母中表达了全长kAE1。使用先进的显微镜技术以及不同的生化和功能测定，证实了异源表达的阴离子转运蛋白的质膜定位和生物活性。这些发现代表了重要的第一步，即利用酵母作为模型生物的潜力来研究未来kAE1及其突变体的运输，活性和降解。与先前的研究相反，我们成功地在酿酒酵母中表达了全长kAE1。使用先进的显微镜技术以及不同的生化和功能测定，证实了异源表达的阴离子转运蛋白的质膜定位和生物活性。这些发现代表了重要的第一步，即利用酵母作为模型生物的潜力来研究未来kAE1及其突变体的运输，活性和降解。与先前的研究相反，我们成功地在酿酒酵母中表达了全长kAE1。使用先进的显微镜技术以及不同的生化和功能测定，证实了异源表达的阴离子转运蛋白的质膜定位和生物活性。这些发现代表了重要的第一步，即利用酵母作为模型生物的潜力来研究未来kAE1及其突变体的运输，活性和降解。