Docking sites inside Cas9 for adenine base editing diversification and RNA off-target elimination

Nat Commun. 2020 Nov 17;11(1):5827. doi: 10.1038/s41467-020-19730-9.

Abstract

Base editing tools with diversified editing scopes and minimized RNA off-target activities are required for broad applications. Nevertheless, current Streptococcus pyogenes Cas9 (SpCas9)-based adenine base editors (ABEs) with minimized RNA off-target activities display constrained editing scopes with efficient editing activities at positions 4-8. Here, functional ABE variants with diversified editing scopes and reduced RNA off-target activities are identified using domain insertion profiling inside SpCas9 and with different combinations of TadA variants. Engineered ABE variants in this study display narrowed, expanded or shifted editing scopes with efficient editing activities across protospacer positions 2-16. And when combined with deaminase engineering, the RNA off-target activities of engineered ABE variants are further minimized. Thus, domain insertion profiling provides a framework to improve and expand ABE toolkits, and its combination with other strategies for ABE engineering deserves comprehensive explorations in the future.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine*
  • Binding Sites
  • CRISPR-Associated Protein 9 / genetics*
  • CRISPR-Associated Protein 9 / metabolism*
  • Cytosine / metabolism
  • Deoxyribonuclease I / genetics
  • Deoxyribonuclease I / metabolism
  • Gene Editing
  • HEK293 Cells
  • Humans
  • Loss of Function Mutation
  • Protein Domains
  • Protein Engineering / methods*
  • RNA / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism*

Substances

  • Recombinant Proteins
  • RNA
  • Cytosine
  • CRISPR-Associated Protein 9
  • Cas9 endonuclease Streptococcus pyogenes
  • Deoxyribonuclease I
  • Adenine