Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity

We recently developed base editing, the programmable conversion of target C:G base pairs to T:A without inducing double-stranded DNA breaks (DSBs) or requiring homology-directed repair using engineered fusions of Cas9 variants and cytidine deaminases. Over the past year, the third-generation base editor (BE3) and related technologies have been successfully used by many researchers in a wide range of organisms. The product distribution of base editing-the frequency with which the target C:G is converted to mixtures of undesired by-products, along with the desired T:A product-varies in a target site-dependent manner. We characterize determinants of base editing outcomes in human cells and establish that the…

• HH
  Howard Hughes Medical Institute

  Award: award341256
• NI
  National Institute of General Medical Sciences

  Awards: award341258, R35 GM118062
• NI
  National Institute of Biomedical Imaging and Bioengineering

  Awards: R01 EB022376, award341257
• DS
  Defense Sciences Office, DARPA

  Awards: HR0011-17-2-0049, award341255