By Rita Strack from Nature Methods
Metal ions are ubiquitous in living systems and are important in cell homeostasis, signaling, and beyond. Despite the importance and diversity of metal ions, useful tools for visualizing and quantifying their dynamic regulation at the subcellular level are still needed.
Two studies by Yamuna Krishnan at the University of Chicago and colleagues report tools that make the subcellular sensing of sodium and potassium ion levels a reality. Both tools are ratiometric DNA nanodevices that can be targeted to specific regions of a cell for dynamic, quantitative measurements of ion abundance.
“I wondered why a cell had so many different kinds of membrane-bound compartments and then learned that each compartment was making very different kinds of molecules for the cell. Yet enzymes that were active in one organelle turned off when they were transported to another and vice versa. So I wondered whether the ionic environment inside different organelles was different,” says Krishnan about her inspiration for her lab’s work. “But at the time I started my lab in 2005, other than pH, very little was known about the levels of the various ions within organelles. So curiosity drove me to develop a way to measure ion levels inside organelles, and I developed a DNA-based technology to do it.”