Fig. 2

Schematic strategy of the marker-free deletion. a Positional relationship among the target deletion and regions A, B, and C contained in the PCR fragments used for construction of the pop-in construct. b Recombinant PCR pop-in construct ligating the fragments A, B, C, and the mazF cassette. c Integrant of the mazF cassette at the target region via a double crossover at regions A and C. An intrachromosomal crossover event between the directly repeated sequences corresponding to the region B resulted in elimination of the mazF cassette together with the target deletion. d Final structure of the marker-free deletion