Modifying the 5′-Cap for Click Reactions of Eukaryotic mRNA and To Tune Translation Efficiency in Living Cells

Holstein J., Anhäuser L., Rentmeister A.

Abstract

The 5′-cap is a hallmark of eukaryotic mRNAs and plays fundamental roles in RNA metabolism, ranging from quality control to export and translation. Modifying the 5′-cap may thus enable modulation of the underlying processes and investigation or tuning of several biological functions. A straightforward approach is presented for the efficient production of a range of N7-modified caps based on the highly promiscuous methyltransferase Ecm1. We show that these, as well as N2-modified 5′-caps, can be used to tune translation of the respective mRNAs both in vitro and in cells. Appropriate modifications allow subsequent bioorthogonal chemistry, as demonstrated by intracellular live-cell labeling of a target mRNA. The efficient and versatile N7 manipulation of the mRNA cap makes mRNAs amenable to both modulation of their biological function and intracellular labeling, and represents a valuable addition to the chemical biology toolbox.