Fig. 1

The IPTG-inducible CBEs enabled efficient C-T mutation. a The diagrammatic sketch of main components in CBEs. b The western blot of dCBE and nCBE, each with 0 mM or 0.5 mM IPTG induction, respectively. c The sgRNA appA1 target sequence (20 bp spacer) was located in the non-template strand of gene appA, 5′ upstream from the PAM “TGG”. The position of each nucleotide (1–20) was defined as follows: the 3′ end closest to the PAM nominated as 1, while the 5′ end farthest nominated as 20. The red colored Cs meant the editable Cs in this target, and the underlined Cs were the key nucleotides that could be mutated to produce stop codon. d Two PYG agar plates (left with 0 mM IPTG, right with 0.5 mM IPTG) were displayed, where the majorities of colonies were red and white, respectively. e Four typical genotypes (C, T<C, T≥C, and T) were listed with the increase of IPTG. Black arrows indicated the position where the mutation peaks of T appeared. f, g After the plasmid dCBE-appA1 or nCBE-appA1 was electroporated, the efficiencies of C-T at position 16, 18, and 19 in appA1 target sequence were individually calculated for dCBE-appA1 and nCBE-appA1, with the IPTG induction of constant concentration 0.5 mM in phase 1 and various concentration ranging from 0 to 0.5 mM in phase 2