Expanding the Nucleoside Recoding Toolkit: Revealing RNA Population Dynamics with 6-Thioguanosine.

RNA-sequencing (RNA-seq) measures RNA abundance in a biological sample but does not provide temporal information about the sequenced RNAs. Metabolic labeling can be used to distinguish newly made RNAs from pre-existing RNAs. Mutations induced from chemical recoding of the hydrogen bonding pattern of the metabolic label can reveal which RNAs are new in the context of a sequencing experiment. These nucleotide recoding strategies have been developed for a single uridine analogue, 4-thiouridine (sU), limiting the scope of these experiments. Here we report the first use of nucleoside recoding with a guanosine analogue, 6-thioguanosine (sG). Using TimeLapse sequencing (TimeLapse-seq), sG can be recoded under RNA-friendly oxidative nucleophilic-aromatic substitution conditions to produce adenine analogues (substituted 2-aminoadenosines). We demonstrate the first use of sG recoding experiments to reveal transcriptome-wide RNA population dynamics.