一种基于荧光RNA的基因编码Mg2+传感器，可实现对活细胞中Mg2+的稳定检测。

Abstract

Magnesium plays crucial roles in many biological processes and the stabilization of biomolecules, including DNA, RNA, and proteins. Despite significant progress, however, our understanding of how cells regulate Mg 2+ homeostasis and transport remains incomplete. One of the goals is to develop approaches for detecting Mg 2+ dynamics with high spatial and temporal resolution. Herein, we describe the development of MagFR, a ratiometric Mg 2+ sensor based on Pepper and Clivia fluorescent RNAs. In this sensor, Pepper fluorescence is highly Mg 2+ dependent, and Clivia fluorescence acts as the normalizer. MagFR has favourable properties, including a large dynamic range, pH insensitivity, and high selectivity, allowing robust detection of Mg 2+ in both live bacterial and mammalian cells. By targeting MagFR to distinct subcellular compartments in mammalian cells, we observed that the free cytoplasmic Mg 2+ concentration is slightly higher than that in the nucleoplasm. We demonstrated that mammalian cells maintain Mg 2+ homeostasis even under conditions of elevated extracellular Mg 2+ , revealing the robustness of intracellular regulatory mechanisms governing Mg 2+ balance. MagFR also enabled real-time detection of cellular Mg 2+ dynamics following ATP depletion. Overall, this study offers a robust and versatile tool for imaging Mg 2+ dynamics in cells, which will be useful for elucidating the functionality and mechanism of Mg 2+ homeostasis underlying diverse cellular processes.