Bioorthogonal in-cell Labeling and Profiling of N6-isopentenyladenosine (i6A) Modified RNA

Abstract

Chemical modifications in RNAs play critical roles in structural diversification and functional regulation of many vital biochemical processes. Several hydrophobic prenyl-modifications have been discovered in a variety of RNA species since the 1990s. Prenyl groups are the feedstocks of terpene and many other biological molecules and the processes of prenylation in different macromolecules have been widely studied. We present here a new chemical biology technique to identify and label i6A, a prenyl-modified RNA residue, based on the unique reactivity of the prenyl group. We also found that iodine-mediated cycloaddition reactions of the prenyl group occurs in a superfast manner, and converts i6A from a hydrogen-bond acceptor into a donor. Based on this reactivity, we developed an iodine-mediated oxidation and reverse transcription (IMORT) method to profile cellular i6A residues with a single-base resolution, allowing for the transcriptome-wide detection and analysis of various i6A-containing RNA species.