FIG. 8.

Structures of three IS elements. A total four copies of IS elements were identified on the pC2C203U28 plasmid, but only two copies (c2p086-c2p087 and c2p117-c2p118) seemed to be functional. The regions including c2p086-c2p087 and c2p117-c2p118 were designated ISCbt5 (or ISCbt5-a) and ISCbt6 (or ISCbt6-a), respectively. An IS element similar to ISCbt5-a was found in the c-st phage genome, and it was designated ISCbt5-c; C2P087 of ISCbt5-a was similar to CST045 of ISCbt5-c, although ISCbt5-c had a deletion in its 5′-terminal region. These IS elements had the special target sites (TTTAA). The total DNA of the D-1873 strain contained both these IS elements (designated ISCbt5-b and ISCbt6-b) with the TTTAA target site, but the DNAs of C-ST, C-203, and C-468 strains contained only the IS target site.