Enzyme-mediated tagging of RNA.

RNA molecules can play diverse roles in the cell owing to their secondary structure dynamics and various binding modes. Studying localization and dynamics of RNA in vitro or in cells requires tagging with suitable reporter molecules-fluorophores being the most prominent ones. Enzymatic RNA labeling approaches are currently emerging as valuable alternatives to purely chemical synthesis and to binding- or hybridization-based RNA-imaging approaches. Different classes of enzymes allow for cotranscriptional or posttranscriptional installation of small functional groups in RNA. The enzymatic step is typically combined with a second chemical step, providing flexibility regarding the reporter. The flourishing field of bioorthogonal chemistry propels this approach. We will present latest achievements and remaining challenges in the field of enzyme-mediated RNA tagging and emphasize efforts to achieve site-specificity and intracellular labeling.