A series of precise and controllable base editors with split-TadA-8e

Sep 8, 2025Molecular therapy. Nucleic acids

A set of precise and adjustable DNA base editors using split TadA-8e enzyme

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CRISPR Gene Editing on OpenScience ↗PubMed ↗DOI ↗

Abstract

sABE8e shows comparable on-target adenine editing activity to ABE8e while reducing off-target effects.

Adenine base editors are tools for converting A to G in genomic DNA.
ABE8e is associated with a higher incidence of off-target events in both DNA and RNA.
sABE8e is designed to enable controlled adenine base editing through rapamycin-induced dimerization.
Controllable versions of base editors, such as sAYBE and seA&C-BEmax, were developed from sABE8e.
sAYBE and seA&C-BEmax exhibit similar or slightly lower base editing efficiency with fewer off-target effects.

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Adenine base editors (ABEs) enable efficient A-to-G base conversions in genomic DNA, serving as powerful tools for basic research and clinical disease treatment. TadA-8e with high processive and compatibility makes ABE8e to be the most widely used adenine base editor and has also facilitated the creation of more elegant base editors based on TadA-8e fusion, such as AYBE and eA&C-BEmax. However, ABE8e has more off-target events including DNA off-target and RNA off-target, which raises safety concerns for precision gene editing. Here, we split the TadA-8e of ABE8e (sABE8e) to enable controlled adenine base editing through rapamycin-induced dimerization between FRB and FKBP12. sABE8e has comparable on-target adenine editing activity to ABE8e while maintaining reduced DNA and RNA off-target effects. Harnessing this site of split TadA-8e, we have also developed controllable AYBE (sAYBE) and eA&C-BEmax (seA&C-BEmax), which both offer similar or slightly low base editing efficiency with decreased off-targets compared to AYBE or eA&C-BEmax. These precise and controllable base editing tools will advance the future application of base editors in basic research and clinical disease treatment.