# Harnessing Molecular Recognition for Small‐Molecule‐Mediated Reversible Photochemical Control Over mRNA Translation

## TL;DR

A small molecule can be used with light to control mRNA translation in cells, offering a new way to study gene expression.

## Contribution

This is the first demonstration of using aptamer-based molecular recognition for reversible, photochemical control of mRNA translation in cells.

## Key findings

- A small molecule ligand selectively photocrosslinks to PreQ1 RNA aptamers in a traceless and reversible manner.
- Caged mRNA constructs with PreQ1 aptamers remain translationally repressed until irradiated with 302 nm light.
- This method enables precise photochemical activation of translation for both reporter and wild-type genes in cells.

## Abstract

Chemical probes that control the function of complex RNA molecules offer unique opportunities to interrogate biological systems. In this study, we demonstrate that a small molecule ligand selectively recognizes and undergoes traceless, reversible photocrosslinking to PreQ1 RNA aptamers. This effect is selective and dependent on both the chemical structure and RNA sequence/structure. A homogeneously modified, caged mRNA construct containing a PreQ1 aptamer and an eGFP or wild type p53 coding sequence displayed repressed translation in vitro or in cells until irradiated with 302 nm light, resulting in cleavage of the photocage and restoration of translation. This method demonstrates for the first time that aptamer‐based molecular recognition of a small molecule ligand can be used to precisely and photochemically activate the translation of a complex mRNA in cells.

A small molecule ligand undergoes traceless, reversible photocrosslinking to PreQ1 RNA aptamer in a selective manner, dependent on both the RNA sequence/structure and ligand chemical structure. A caged mRNA construct incorporating the PreQ1 aptamer and an eGFP or p53 coding sequence remained translationally repressed until exposure to 302 nm light, which cleaved the photocage and restored translation in vitro and in cells, enabling precise photochemical control of both wild type and reporter gene expression.