High-Performance Chemigenetic Potassium Ion Indicator.

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.

Maximizing the performance of protein-based fluorescent biosensors.

Fluorescent protein (FP)-based biosensors are genetically encoded tools that enable the imaging of biological processes in the context of cells, tissues, or live animals. Though widely used in biological research, practically all existing biosensors are far from ideal in terms of their performance, properties, and applicability for multiplexed imaging. These limitations have inspired researchers to explore an increasing number of innovative and creative ways to improve and maximize biosensor performance.