Figure 2. Efficiency and mutation rates of the hetereologous non-homologous end-joining (NHEJ) pathway in E. coli.

(a) Efficiency of the NHEJ system in re-circularizing the in vitro HindIII- or SmaI-digested pUC19 plasmid and the in vivo CRISPR-Cas9 cleaved pUC-lacZ plasmid. The error bars represent standard deviations from three replicate experiments. The results are expressed as colony-forming units (CFU) per μg of plasmid DNA. mku and ligd, derived from M. tuberculosis H37Rv and involved in the NHEJ pathway, are hetereologously expressed in E. coli using a strong constitutive P_J23119 promoter. (b) The mutation rates of the NHEJ system with different artificially created DSBs. The mutation rates are statistically determined based on the proportion of white colonies on the X-gal plate. The error bars represent standard deviations from three replicate experiments.