Enzymatic Modification of 5'-Capped RNA and Subsequent Labeling by Click Chemistry

The combination of enzymatic modification and bioorthogonal click chemistry provides a powerful approach for site-specific labeling of different classes of biomolecules in vitro and even in cellular environments. Herein, we describe a chemoenzymatic method to site specifically label 5'-capped model mRNAs independent of their sequence. A trimethylguanosine synthase was engineered to introduce alkyne, azido, or 4-vinylbenzyl moieties to the 5'-cap. These functional groups were then used for labeling using typical click reactions, such as the azide-alkyne cycloaddition or the tetrazine ligation.