Fig. 5

Hybrid plasmid formation via two rounds of single-strand exchanges. a Sequence alignments of pOX38-Gen, the hybrid plasmid in XL10-pF-pV-hybrid-1 and pRJF293HA. The figure was constructed using Easyfig. The black inverted triangle denotes the specific 28-bp fusion site where the whole sequence of pOX38-Gen was inserted into RJF293HA. Green, virulence genes. Red, tra genes. Yellow, IS elements. b Putative mechanism underlying the formation of the hybrid plasmid pF-pV-hybrid-1. This hybrid plasmid possibly emerged from two rounds of chain cleavages and exchanges between pOX38-Gen and pRJF293HA within the 28-bp homologous region, which consists of 10-bp inverted repeat sequences (underlined) and an 8-bp internal spacer region (bold). The arrowheads represent the supposed cleavage sites for recombination. The shared sequence is shown in black, the sequence specific to pOX38-Gen is shown in red and the sequence specific to pRJF293HA is shown in blue