Human cell based directed evolution of adenine base editors with improved efficiency

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• Adenine base editors (ABE) enable precise A•T to G•C conversions for genome editing.
• Low activity at certain genomic sites limits the efficacy of current ABE systems.

Purpose of the Study:

• To develop a screening system for evolving ABE deaminase components.
• To identify and engineer high-activity ABE variants for improved genome editing.

Main Methods:

• A directional screening system was developed in human cells.
• The deaminase component of ABE was evolved to create new variants.
• Engineered variants were tested for editing activity in human cells and mouse models.

Main Results:

• Three high-activity NG-ABEmax variants (NG-ABEmax-SGK, NG-ABEmax-R, NG-ABEmax-K) were identified.
• A consolidated variant, NG-ABEmax-KR, demonstrated superior editing activity compared to the original NG-ABEmax.
• NG-ABEmax-KR significantly increased editing activity for natural mutations in gamma globin gene promoters.

Conclusions:

• The developed screening platform is broadly applicable for evolving base editors.
• NG-ABEmax-KR represents a significant advancement in ABE efficiency and applicability.
• This work provides a method to enhance base editor traits beyond increased editing activity.