Dye disaggregation light-up aptamer for super-resolution RNA imaging

Abstract

Genetically encoded light-up RNA aptamers have become powerful tools for visualizing RNAs in cells. However, fluorogenic dye/aptamer pairs used for super-resolution RNA imaging are still rare. Herein, we reported an environment-sensitive dye Nap which can light up its target RNA aptamer NapRA for aptamer-based RNA imaging with confocal and structured illumination microscopy (SIM). Nap was designed to be amphiphilic to assemble into nano-particles in water associated with the quenched fluorescence by the aggregation effects. NapRA was obtained from SELEX technology with a 12-round Nap-based selection and has a high binding affinity to Nap of Kd = 3.142 nM. The super affinity disintegrated the dye aggregate and resulted in a turn-on fluorescent signal. The light-up feature combined with high photostability made Nap/NapRA a useful system capable of super-resolution imaging of the expression of RNA in bacteria. This work represents the first application of dye aggregation-disaggregation for aptamer-based RNA imaging.