Fig. 5

Hypothesized Mechanism of Plasmid Formation through Two Rounds of Homologous Recombination. The formation of pJTGC-02-p1 and pJTGC-02-p2 plasmids occurred through two rounds of homologous recombination. a The first-round homologous recombination, driven by IS26, resulted in the fusion of pTGC-02-tmex and pTGC-02-mcr8, creating a giant fusion plasmid. b The second-round homologous recombination, involving an identical sequence downstream of tmexCD1-toprJ1 and Tet(A) regions, led to the dissociation of the fusion plasmid into the two novel plasmids, pJTGC-02-p1 and pJTGC-02-p2. This process replaced the Tet(A) region with the tmexCD1-toprJ1 region, giving rise to pJTGC-02-p1, which co-harbors mcr-8 and tmexCD1-toprJ1. pTGC-02-tmex is represented in yellow, pTGC-02-mcr8 in blue, IS26 in purple double strands, X-H-YafZ-H in green double strands, and antibiotic resistance genes in red rectangles