New approaches for sensing metabolites and proteins in live cells using RNA.

Tools to study the abundance, distribution, and flux of intracellular molecules are crucial for understanding cellular signaling and physiology. Although powerful, the current FRET-based technology for imaging cellular metabolites is not easily generalizable. Thus, new platforms for generating genetically encoded sensors are needed. We recently developed a new class of biosensors on the basis of Spinach, an RNA mimic of GFP. In this case, RNA aptamers against a target ligand are modularly fused to Spinach that substantially induce Spinach fluorescence in the presence of ligand. We have used this approach to detect metabolites and proteins both in vitro and in living bacteria, thus providing an alternative to FRET-based sensors and a generalizable approach for generating fluorescent sensors to any ligand of interest.