Fig. 4: Minimization of RNA off-target effects for TadA ortholog-derived base editors.

a, b Deaminase mutagenesis screening to minimize RNA off-target edits of representative TadA ortholog-derived base editors. Heatmap format showing the on-target editing activity at sgRNA-1, with adenine editing activity in blue and cytosine editing activity in pink (a) and histogram showing RNA A-to-I conversion frequency at a specific site within mRNA transcript (b). NC, negative control. VN, FA, Rdel, VG, and VW, amino acid substitutions corresponding to A106V&D108N, F148A, R153 deletion, or V82G/W of ecTadA, respectively. RNA A-to-I conversion frequency of base editors containing Q13XZ4, B3PCY2, E8WVH3, Q57LE3, and Q9951 were depicted in orange, pink, blue, purple, and gray, respectively. Data shown here represent means of results from n = 3 biologically independent experiments. Data were presented as mean values ± SEM. c, d Box plots showing the number of RNA A-to-I (c) and C-to-U edits (d) induced by engineered TadA ortholog-derived base editors or nCas9 control. Box plots here are defined by whiskers in terms of minima and maxima, and the center and bounds of the box by quartiles (Q1–Q3). n = 4 biologically independent experiments. ** represents P < 0.01 and *** represents P < 0.001 with two-tailed unpaired t-test. Exact P values were as follows, P = 0.000241, 0.002087, 4.24e-05, and 6.33e-06, respectively. Source data are provided as a Source Data file.