S. aureus CBE-KKH C-terminal Fragment

SaCas9-KKH variant base editor with altered PAM recognition (NNNRRT). Enables broader targeting when combined with compact AAV packaging.

Length: 1000 bp (333 aa)

Type: Cytosine Base Editor

Conversion: C-to-T

Origin: Rat APOBEC1 fused to S. aureus Cas9-KKH D10A nickase (E782K/N968K/R1015H), split at Lys534/Cys535

Characteristics

KKH mutations (E782K/N968K/R1015H) in SaCas9 alter PAM recognition from NNGRRT to NNNRRT, expanding targeting scope. Maintains editing window positions 4-8. Split-intein architecture enables dual-AAV delivery with improved targeting flexibility.

Applications

Expands targetable sites compared to wild-type saCBE through relaxed PAM (NNNRRT vs NNGRRT). Enables C-to-T editing at loci inaccessible to standard SaCas9 editors. Validated for multi-organ AAV delivery in mouse models.

Limitations

Dual-AAV co-transduction required. KKH mutations may slightly reduce on-target activity compared to wild-type SaCas9. Still more restrictive PAM than SpCas9-NG or SpRY variants.

Literature References

  1. Komor et al. (2016). Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage. Nature - Komor 2016 BE3
  2. Levy et al. (2020). Cytosine and adenine base editing of the brain, liver, retina, heart and skeletal muscle of mice via adeno-associated viruses. Nat Biomed Eng - Levy 2020 BE3.9max