Restriction endonuclease Hin dIII cleavage site map of bacteriophage P22.

The 14 Hind111 cleavage sites on P22 DNA have been mapped. Hind111 cleavage sites were located relative to EcoRI sites by determining the molecular weights and map order of fragments produced by HindIII, or Hind111 and EcoRI digestion. Molecular weights were estimated from the electrophoretic mobility of fragments. The Hind111 fragment order was established by Hind111 cleavage of segments of the P22 genome obtained as isolated EcoRI fragments or as overlapping genetic substitutions in bacteriophage A chromosomes. The resulting HindIIIIEcoRI cleavage site map defines physical markers in all regions of the P22 genome and defines the locations of a number of P22 genes on this physical map of the P22 chromosome. Three Hind111 sites and two HpaI sites have been mapped in imm1, one of two P22 gene clusters controlling lysogeny. Two of these Hind111 sites lie within the structural gene ant specifying one of the regulatory proteins of the imm1 region. Assignment of the ant gene to specific Hind111 fragments utilized the insertion element Tnl, which was shown to contain no Hind111 cleavage sites.