S. aureus ABE8e V106W Adenine Base Editor

SaABE8e variant with V106W mutation in TadA* domain, reducing off-target RNA editing while maintaining DNA editing efficiency.

Length: 3850 bp (1283 aa)

Type: Adenine Base Editor

Conversion: A-to-G

Origin: TadA8e-V106W evolved adenine deaminase variant fused to S. aureus Cas9 D10A nickase

Characteristics

Contains V106W mutation in TadA* deaminase domain that reduces off-target RNA editing 7.2-fold compared to parent SaABE8e. V106W sterically blocks accommodation of RNA 2'-hydroxyl groups, decoupling DNA and RNA editing activities. Maintains robust on-target DNA editing while providing 2.7-fold improvement in off-target DNA specificity and 3.7-fold reduction in indel formation. Single-AAV compatible with NNGRRT PAM recognition.

Applications

Single-AAV adenine base editing for applications requiring minimal off-target RNA editing. Preferred for therapeutic development where transcriptome perturbation must be minimized. Validated for reducing aberrant A-to-I RNA editing from ~15,000 transcriptome-wide edits to near-background levels. Suitable for long-term expression applications and hard-to-transduce tissues.

Limitations

NNGRRT PAM more restrictive than SpCas9 NGG. May show slightly reduced on-target editing efficiency compared to parent SaABE8e at some sites. Requires empirical validation for each target. RNA editing reduction most effective when combined with TadA E59A mutation (as in ABEmaxAW).

Literature References

  1. Gaudelli NM, Komor AC, Rees HA, et al. (2017). Programmable base editing of A•T to G•C in genomic DNA without DNA cleavage. Nature 551:464-471 - Gaudelli 2017 Adenine Base Editor
  2. Richter et al. (2020). Phage-assisted evolution of an adenine base editor with improved Cas domain compatibility and activity. Nat Biotechnol - Richter 2020 ABE8e
  3. Rees et al. (2019). Analysis and minimization of cellular RNA editing by DNA adenine base editors. Sci Adv - Rees 2019 RNA Editing Minimization