Using RNA sensors to guide mutations in adenine base editors for reducing toxicity

RNA off-target editing of classical adenine base editors (ABEs) is associated with substantial toxicity in vitro and in vivo.

• The extent of RNA editing-related toxicity in ABEs remains unclear.
• A novel fluorescent RNA inosine sensor was developed to evaluate RNA off-target editing efficiently.
• Deep mutation scanning identified various TadA8e mutants with reduced RNA editing activity.
• The H52L/D53R mutant is compatible with both SpCas9 and IscB nickase.
• Engineered ABEs demonstrated the ability to target clinically relevant sites with improved precision.

Simplified