Figure 3.

Broadening the targeting scope of base editors using St1Cas9 variants. (A) K562 cells were transiently transfected with single-vector constructs driving expression of St1BE4max LMD9 and its sgRNA. Genomic DNA was harvested 3 d later, and quantification of base editing was performed on PCR amplified target sites using EditR. The target sequence was defined as the 20 bases upstream of the PAM and are numbered in decreasing order from the PAM. Sequence of the guides and related PAMs are shown with target cytosine highlighted in blue. An expression vector encoding EGFP (−) was used as a negative control. (B–D) Same as A but using St1BE4max LMG18311, CNRZ1066, and TH1477 chimeric proteins. (E) Same as A but using St1ABEmax LMD9. Target adenines are highlighted in red. Most sgRNAs were tested at least twice; only one experiment is shown. See also Supplemental Figure S5.