Self-transmissible plasmids possess the necessary genes to mediate their transfer from one bacterial cell to another without requiring any additional mobile genetic element. Usually, such plasmids encode a complete type IV secretion system (T4SS), the components required to synthesize a pilus, and the proteins needed to process and transfer the plasmid DNA from the donor to the recipient cell. The F plasmid of Escherichia coli is a typical example of a self-transmissible plasmid, and it contains a cluster of genes that are required for its own transmission, known as the tra genes (transfer genes). These genes encode proteins that are involved in the formation of conjugative pili, the recognition of recipient cells, the transfer of the plasmid DNA, and the regulation of the mating process.