S. aureus ABE8e Adenine Base Editor

Compact adenine base editor using S. aureus Cas9 (NNGRRT PAM). TadA8e deaminase provides 590-fold faster deamination than ABE7.10 with editing window at positions 4-9.

Length: 3900 bp (1300 aa)

Type: Adenine Base Editor

Conversion: A-to-G

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

Characteristics

Compact all-in-one ABE using SaCas9 (~1 kb smaller than SpCas9), enabling complete editor packaging in single AAV vector. Contains TadA8e for 590-fold faster deamination kinetics versus TadA7.10. NNGRRT PAM recognition. Achieves 2.5-fold higher editing efficiency than dual-AAV split-intein systems at matched doses. Demonstrates 66% liver, 33% heart, and 22% muscle editing in mice.

Applications

Single-AAV adenine base editing for cardiovascular, liver, and muscle gene therapy. Validated for PCSK9 editing with 93% protein knockdown and substantial plasma cholesterol reduction. Suitable for hard-to-transduce tissues where dual-AAV co-transduction efficiency is limiting. Compatible with various AAV serotypes for tissue-specific targeting.

Limitations

NNGRRT PAM more restrictive than SpCas9 NGG, reducing targetable sites. Still approaches single-AAV packaging limits (~4.5 kb), leaving limited space for additional regulatory elements. Lower editing efficiency than SaKKH-ABE8e variant with expanded PAM.

Sequence

atgaaacggacagccgacggaagcgagttcgagtcaccaaagaagaagcggaaagtctctgaggtggagttttcccacgagtactggatgagacatgccctgaccctggccaagagggcacgggatgagagggaggtgcctgtgggagccgtgctggtgctgaacaatagagtgatcggcgagggctggaacagagccatcggcctgcacgacccaacagcccatgccgaaattatggccctgagacagggcggcctggtcatgcagaactacagactgattgacgccaccctgtacgtgacattcgagccttgcgtgatgtgcgccggcgccatgatccactctaggatcggccgcgtggtgtttggcgtgaggaactcaaaaagaggcgccgcaggctccctgatgaacgtgctgaactaccccggcatgaatcaccgcgtcgaaattaccgagggaatcctggcagatgaatgtgccgccctgctgtgcgatttctatcggatgcctagacaggtgttcaatgctcagaagaaggcccagagctccatcaactccggaggatctagcggaggctcctctggctctgagacacctggcacaagcgagagcgcaacacctgaaagcagcgggggcagcagcggggggtcaatgcaggagaaccagcagaagcaaaattacatcctgggcctggccatcggcatcaccagcgtgggctatggcctgatcgacagcaagaccagagaagtgattgacgccggcgtgcggctattcccagaggccgactctgaaaacaacagcaatagaagatctaagcggggcgcccggagactgaaaagacgaagaatccacagactgaacagagtgaaagacctcctggctgactaccagatgatcgacttaaacaacgtgcccaagtctaccgacccctacaccatccgggtgaagggactgcgggaacctctgaccaaggaagagtttgccatcgctctgctgcatatcgccaagagaagaggcctgcacaacatctccgtgagcatgggcgatgaggaacaggacaacgagctgtccaccaagcagcagctgcagaagaacgctcagcagctgcaggacaaatacgtgtgcgagctgcaactggaaagactgaccaacatcaacaaggtcagaggcgagaagaaccggttcaagaccgaagatttcgtgaaggaagtgaagcagctgtgcgagacccagcggcagtaccacaacatcgacgatcagttcatccagcagtacatcgacctggtgagcacccggagagaatacttcgagggccctggcaacggctctccatatggctgggatggagatctgctgaagtggtatgagaagctgatgggcagatgcacctacttccctgaggagctgagaagcgtgaagtacgcctacagcgccgatctgtttaacgccctgaacgatctgaacaacctggttgtgacccgcgacgacaaccctaagctggaatactacgagaaataccacattatcgagaacgtgttcaagcagaagaaaaatccaactctgaagcaaatcgccaaagagatcggcgtgcaggattacgacatcagaggatacagaattaccaagtccggtaagcctcagttcaccagcttcaaactctaccacgacctgaaaaacatctttgaacaggccaaatacctggaagatgtggagatgctggatgagatagctaaaatcctgacaatctaccaagacgagatcagcatcaagaaagccctggaccagctgcctgagctgctgaccgagagcgaaaaaagccagatcgctcagctgaccggctacaccggtacacatagactgtctctgaagtgcatccacatcgtgatcgacgagctgtgggagagccccgaaaaccagatggaaatcttcaccagactgaacctcaagccaaagaaggtggaaatgagcgagatcgacagcatccctaccacactggtggatgagttcatcctgagccctgtggtgaagcgggccttcatccagtccatcaaggtgatcaacgctgtgatcaacagattcggcctgcccgaggacatcattatcgagctggccagagagaagaacagcaaggacagaaggaagttcatcaacaagctgcagaaacagaatgaggccacccggaaaaaaatcgagcagctgctggccaagtacggcaataccaatgccaagtacatgatcgaaaagatcaagctgcatgacatgcaggagggcaagtgtctgtacagcctggaagctatccccctggaagacctgctgtctaatcctacacactacgaggtggaccacatcatccctagaagcgtgtccttcgacaacagcctgaacaacaaggttctggtgaagcaaagcgagaacagcaagaagggcaataggaccccttaccagtacctgagcagcaacgagtccaagatctcttacaaccagttcaagcagcacattctgaacctgtctaaggccaaagatagaatcagcaagaagaaacgagatatgctgctggaagaacgggacatcaacaaattcgaggtgcagaaggaattcatcaacagaaaccttgtggacacccggtacgccactcgggagctgagcaacctgctgaagacctacttcagcacacacgactacgccgtgaaagtgaagaccatcaacggcggcttcacaaaccacctgaggaaggtgtgggacttcaagaagcaccggaaccacggctacaagcaccacgccgaggatgccctggtcatcgccaacgccgactttctgttcaaaacccacaaggccctgagacggacagacaagatcctggaacagcctggactggaagtcaacgacaccaccgtgaaggtggacacagaggagaagtaccaggagttattcgagacaccgaaacaagtgaagaacatcaagcagtttagagatttcaagtattctcacagagttgacaagaagcccaaccggcagctgatcaatgataccctgtacagtaccagagagatcgatggcgaaacctacgtggtccaaacactgaaagacctgtacgccaaggacaatgaaaaggtgaaaaagctctttacagaacggcctcaaaagatactgatgtaccagcacgatcctaagacctttgagaaactgatgaccattctgaatcagtacgctgaggcaaagaatcctctggccgcttattacgaggataagggcgaatacgtgaccaagtacgccaagaagggcaacggccctgccatccacaagatcaaatacatcgacaagaaactgggcagctacctggacgtgagtaacaaatatcctgagacacagaacaagctggtgaaactgtctctgaagagctttagattcgacatctacaaatgtgaacagggctacaagatggtgtccattggctacctcgacgtactgaagaaggacaactactactacatccccaaagataagtacgaggccgagaagcagaaaaagaagatcaaggaaagcgacctcttcgtgggcagcttctactacaacgacctgatcatgtacgaggacgaactcttccgggtgatcggagtgaactccgatatcaacaacctggttgagctgaatatggtcgacatcacctacaaggatttctgcgaggtgaacaacgtgacaggcgagaagagaatcaagaaaaccatcggaaagagagtggtgctgatcgagaagtatacgaccgacatcctgggaaatctgtataaaacgcccctgcctaagaagccccagctcattttcaagagaggcgagctgtctggcggctcaaaaagaaccgccgacggcagcgaattcgagcccaagaagaagaggaaagtcta

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. Gaudelli et al. (2020). Directed evolution of adenine base editors with increased activity and therapeutic application. Nat Biotechnol - Gaudelli 2020 ABE8 Variants
  4. 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