TRANSFER REGION OF INCI1 PLASMID R64 AND ROLE OF SHUFFLON IN R64 TRANSFER

To locate the transfer region of the 122-kiloase plasmid R64drd-11 belonging to incompatibility group I1, a series of deletion derivatives was constructed by in vitro recombinant DNA techniques followed by double homologous recombination in vivo. A plasmid designated pKK609 and bearing a 56.7-kilobase R64 sequence was the smallest transferable plasmid. A plasmid designated pKK610 and no longer possessing the 44-base-pair sequence from one end of pKK609 essential for the R64 oriT function failed to transfer, indicating that the oriT sequence of the R64 transfer system is located at one end. The other end of the R64 transfer region comprises a DNA segment of about 19 kilobases responsible for pilus formation. Shufflon, DNA with a novel rearrangement in R64, was found to be involved in pilus formation.