Fig. 2

Integration rate improvement by LE/RE strategy. a LE/RE strategy was used to improve the integration efficiency. The functional domains of a recombination site are divided as a spacer region and two palindromic regions. The recombination between LE and RE mutation site generates a LE:RE double-mutant site and a wild-type loxP site. For in vitro application, a genetic Element of Interest (EoI) flanked by two LE sites is first excised out, and then integrates into an RE site, finally being flanked by a LE/RE site and a loxP site. b Excision rate quantification of palindromic mutant site pairs (LE–LE or RE–RE) and double-mutant site and loxP site (LE:RE-loxP). LE includes lox71, loxJT15, loxJT510, loxJTZ17LE; RE includes lox66, loxJT15RE, loxJT510 RE, loxJTZ17. Error bar represents the standard deviation, n = 3. c Excision rate comparison between same pair recombination group and LE:RE–WT pair recombination group. Center value represents the mean of the excision rates. t test was performed for difference evaluation between the two groups. d Integration rate quantification of selected LE- and RE-mutant sites. The integration rate between loxJT15 and loxJTZ17 is three-fold of that between loxP site. Error bar represents the standard deviation and P value was generated by t test, n = 3. LE, left element with mutation in left palindromic region, RE, right element with mutation in right palindromic region