Extended Data Fig. 6: Additional data showing that SECURE BE3 variants induce substantially reduced numbers of RNA edits but possess comparable and more-precise DNA editing activities in HEK293T cells.

a, Initial screen of transcriptome-wide RNA editing activities of six BE3 variants containing various rAPOBEC1 mutations and expressed at high levels in HEK293T cells (sorting cells with top 5% of GFP signal). Jitter plots of single replicate RNA-seq experiments showing RNA cytosines modified by expression of wild-type BE3, BE3-E63Q (rAPOBEC1 catalytic site mutant), BE3-P29F, BE3-P29T, BE3-L182A, BE3-R33A, BE3-K34A and BE3-R33A/K34A variants. n, total number of modified cytosines identified in each sample. b, Heat map of on-target DNA base-editing efficiencies of nCas9–UGI–NLS (control), wild-type BE3, BE3-R33A and BE3-R33A/K34A in HEK293T cells with the RNF2 gRNA (cells from experiment shown in Fig. 2a). Bases within the editing window of the on-target spacer sequence are numbered as previously described. Note the inclusion of C12, which is inefficiently edited by wild-type BE3 in these samples but not edited by the SECURE BE3 variants, even with higher expression. c, Dot plot for HEK293T on-target data displayed in b, expanded to include all cytosines across the spacer sequence.