Role of the origin of transfer in termination of strand transfer during bacterial conjugation

The termination of conjugal transfer of the broad-host-range plasmid R1162 DNA was examined. The results indicate that the inverted repeat within the origin of transfer (oriT) is essential for efficient termination in vivo. However, the inverted repeat is not required for specific cleavage in vitro of single-stranded DNA within oriT. It was proposed that during transfer, the inverted repeat acts to initiate termination by trapping the protein required for ligation of the transferring strand.