Figure 7. Mutations to Conserved APOBEC Residues Increase CBE Product Purity.
(A-H) Characterization of EA-BE4 compared to BE4 (A-D) and eA3A-BE5 compared to eA3A-BE4 (EH). (A and E) Comparison of transversion frequency by base editor variants with mutations at conserved deaminase residues in BE4 and eA3A-BE4. Error bars depict standard error of the mean. In (A), * P < 0.02; ** P = 2.0×10−6, N = 3,636 and 1,208 substrate nucleotides. 95% CI: 18-35% reduction. In (E), * P < 0.07; ** P = 2.5×10−5, Welch’s T-test, N = 1,837 and 685 substrate nucleotides. 95% CI: 17-36% reduction. (B and F) Base editor mutation activity profiles in HEK293T cells, depicted as in Figure 1. (C and G) Sequence motif for base editing efficiency in HEK293T cells. (D and h) Comparison of base editing efficiency between BE4 and EA-BE4, and between eA3A-BE4 and eA3A-BE5. Error bars depict the standard error of the mean. (I) Pareto frontier showing the tradeoff between cytosine transversion purity and editing window size by base editor. Scatter plot densities show bootstrap samples of the mean. Single-nucleotide base editing precision was simulated by choosing the substrate nucleotide closest to the position with maximum base editing efficiency as the target substrate. The distribution plot shows the position of target nucleotides used in the simulated precision task.