Schematic comparison of plasmids pO157-2, pO157, and pSFO157. Genes are shown in blocks; shaded blocks share less similarity with other genes. (A to E) Comparative analysis of gene contents for all three plasmids (pO157, pO157-2, and pSFO157) divided by regions according to pSFO157 (1). Block coloring indicates type of region: insertion sequences are represented by red blocks, transposons are dark orange, hly genes are dark green, etp genes are blue, tra genes are light green, and toxB is light orange. Areas not present in the plasmids are shown with dotted lines. tr, truncated; hp, genes coding for a hypothetical protein.