The DNA-protein relaxation complex of the plasmid RK2: location of the site-specific nick in the region of the proposed origin of transfer

Mol Gen Genet. 1979 Oct 3;176(2):183-9. doi: 10.1007/BF00273212.


The broad jost range plasmid, RK2, has been isolated as a DNA-protein relaxation complex. Nicking of the plasmid DNA in the relaxation complex occurs at a single specific site (rlx) located approximately 20 kb away from the origin of DNA replication. A cis-acting function required for plasmid transfer, the presumptive origin of transfer, maps in the same region as rlx. The region of RK2 encompassing rlx has been cloned onto pBR322 and shown to promote mobilization of the hybrid plasmid by an RK2 derivative. These results indicate that the RK2 relaxation complex nicks at or near the origin of transfer of the RK2 plasmid.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins / metabolism
  • Chromosome Mapping
  • Cloning, Molecular
  • Conjugation, Genetic*
  • DNA Replication
  • DNA, Superhelical / physiology*
  • Escherichia coli / genetics*
  • Macromolecular Substances
  • Protein Binding
  • R Factors*
  • Transformation, Genetic


  • Bacterial Proteins
  • DNA, Superhelical
  • Macromolecular Substances