Cheng Dazhou, Ouyang Zhenlin, He Xiaoyu, Nasu Yusuke, Wen Yurong, Terai Takuya, Campbell Robert E
Department of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Center for Microbiome Research of MedX Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China.
J Am Chem Soc. 2024 Dec 25;146(51):35117-35128. doi: 10.1021/jacs.4c10917. Epub 2024 Nov 27.
Potassium ion (K) is the most abundant metal ion in cells and plays an indispensable role in practically all biological systems. Although there have been reports of both synthetic and genetically encoded fluorescent K indicators, there remains a need for an indicator that is genetically targetable, has high specificity for K versus Na, and has a high fluorescent response in the red to far-red wavelength range. Here, we introduce a series of chemigenetic K indicators, designated as the HaloKbp1 series, based on the bacterial K-binding protein (Kbp) inserted into HaloTag7 self-labeled with environmentally sensitive rhodamine derivatives. This series of high-performance indicators features high brightness in the red to far-red region, large intensiometric fluorescence changes, and a range of values. We demonstrate that they are suitable for the detection of physiologically relevant K concentration changes such as those that result from the Ca-dependent activation of the BK potassium channel.
钾离子（K⁺）是细胞中含量最丰富的金属离子，在几乎所有生物系统中都发挥着不可或缺的作用。尽管已经有关于合成荧光钾指示剂和基因编码荧光钾指示剂的报道，但仍需要一种可进行基因靶向、对钾离子相对于钠离子具有高特异性且在红到远红波长范围内具有高荧光响应的指示剂。在此，我们基于插入用环境敏感罗丹明衍生物进行自标记的HaloTag7的细菌钾结合蛋白（Kbp），引入了一系列化学遗传钾指示剂，命名为HaloKbp1系列。这一系列高性能指示剂的特点是在红到远红区域具有高亮度、较大的强度荧光变化以及一系列解离常数（Kd）值。我们证明它们适用于检测生理相关的钾离子浓度变化，例如由大电导钙激活钾通道的钙依赖性激活所导致的变化。
