The origin of plasmid DNA transfer, oriT, has been localized on RK2, a conjugative drug-resistance plasmid of the IncP group with a very broad host range in gram-negative bacteria. The transfer origin is contained in a 760-base-pair Hae II restriction fragment that maps in the same region as the singlestrand nick made by the RK2 relaxation complex. The functional oriT was subcloned as a 112-bas...
