Supplementary Figure 2: Screening for DNA methylation-resistant base editors.

(a) Characteristics of the APOBEC/AID deaminases used to construct BEs. (b) Schematic diagram illustrating the in vitro CpG methylation of plasmid vectors. (c) BstUI restriction of unmethylated, partially methylated and fully methylated plasmid vectors. Plasmids were treated with different amounts of CpG methyltransferase M.SssI for in vitro methylation and then digested with methylation-sensitive enzyme BstUI. The methylation of cytidines in plasmid DNA used in (d) and Fig. 1c,d reached almost 100% (arrow head), as the methylated plasmid was almost completely resistant to BstUI restriction. In contrast, decreased amount of CpG methyltransferase resulted in partially methylated plasmid DNAs, which were partially digested accordingly. Gel images are representative of three independent experiments and uncropped gel images are shown in Supplementary Fig. 11. (d) Immunoblots of the BEs co-transfected with unmethylated or methylated vectors. Tubulin was used as a loading control and immunoblot images are representative of three independent experiments. Uncropped blot images are shown in Supplementary Fig. 11.