Cellular RNA adenosines susceptible to TadA-8e-mediated deamination (TadA-8e RNA off-targets)

Cellular RNA adenosines susceptible to low-level TadA-8e-mediated deamination refers to the collection of adenosine residues within the transcriptome that undergo unintended adenosine-to-inosine (A-to-I) conversion by the TadA-8e enzyme. TadA-8e is a highly active, laboratory-evolved variant of the Escherichia coli tRNA adenosine deaminase (TadA) used in CRISPR-based Adenine Base Editors (ABEs) to convert A•T base pairs to G•C in DNA (Richter et al., 2020, Nature Biotechnology). While TadA-8e significantly improves DNA editing efficiency, its high affinity for nucleic acids results in widespread, guide-independent RNA editing (Lapinaite et al., 2020, Science). These off-target RNA modifications can lead to the production of mutant proteins, altered RNA stability, or disrupted splicing patterns, posing potential safety risks for therapeutic applications (Grünewald et al., 2019, Nature). Because these edits occur across the transcriptome rather than at a single therapeutic locus, they are characterized as a systemic off-target effect rather than a traditional drug target. Researchers have developed refined variants, such as TadA-8e-V106W, to mitigate these transcriptome-wide effects while preserving high-efficiency DNA editing (Kim et al., 2019, Nature Biotechnology). Monitoring these susceptible RNA sites is a critical component of the safety assessment for any ABE-based gene therapy.

Other names

RNA off-target editingTadA-8e-mediated RNA deaminationTranscriptome-wide A-to-I editingABE-mediated RNA off-targets

Hydrolytic deamination of adenosine to inosine in RNA molecules, catalyzed by the TadA-8e enzyme component of a base editor.