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.
Literature 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