C. jejuni ABE8e Adenine Base Editor
Ultra-compact adenine base editor using Campylobacter jejuni Cas9. Smallest ABE architecture (~3.8 kb) with 22-nt protospacer and editing window at positions 3-11.
Origin: TadA8e deaminase fused to Campylobacter jejuni CjCas9 D8A nickase
Characteristics
Smallest base editor architecture (~3.8 kb) using ultra-compact CjCas9, leaving maximum cargo space for regulatory elements and reporters in single AAV. Uses 22-nucleotide protospacer. Editing window spans positions 3-11, providing broad positional flexibility. Part of three-editor suite collectively targeting ~82% of genomic adenines. Enables complex vector designs with multiple expression cassettes.
Applications: Single-AAV base editing where minimal editor size is critical for incorporating additional cargo (reporters, tissue-specific promoters, safety switches). Complementary to SaCas9 and Nme2Cas9 editors for comprehensive genome coverage. Suitable for applications requiring complex vector architectures within AAV packaging constraints.
Limitations: Specific PAM requirements limit targeting scope when considered individually. 22-nucleotide protospacer may have different specificity profile compared to standard 20-nt guides. Requires optimization of guide design parameters specific to CjCas9.
Architecture: All-in-one (single vector)
References
- Davis et al. (2022). Efficient in vivo base editing via single adeno-associated viruses with size-optimized genomes encoding compact adenine base editors. Nat Biomed Eng - Davis 2022 Single-AAV ABEs
- Richter et al. (2020). Phage-assisted evolution of an adenine base editor with improved Cas domain compatibility and activity. Nat Biotechnol - Richter 2020 ABE8e
- 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