Fig. 1.

Modular structure of the plasmid genome. An example of the IncP-1 plasmid genome is shown. The replication module is the only element essential for plasmid maintenance. The other modules assist in plasmid maintenance. IncP-1β and IncP-1α are lineages of IncP-1 plasmids. Horizontal arrows indicate the direction of transcription. Each functional module is regulated by a transcriptional regulator encoded in the module block or global regulators encoded in the central control region [188,189].