Restriction endonuclease HindIII cleavage site map of bacteriophage P22

Abstract

The 14 HindIII cleavage sites on P22 DNA have been mapped. HindIII cleavage sites were located relative to EcoRI sites by determining the molecular weights and map order of fragments produced by HindIII, or HindIII and EcoRI digestion. Molecular weights were estimated from the electrophoretic mobility of fragments. The HindIII fragment order was established by HindIII cleavage of segments of the P22 genome obtained as isolated EcoRI fragments or as overlapping genetic substitutions in bacteriophage λ chromosomes. The resulting HindIII/ EcoRI 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 HindIII sites and two HpaI sites have been mapped in immI, one of two P22 gene clusters controlling lysogeny. Two of these HindIII sites lie within the structural gene ant specifying one of the regulatory proteins of the immI region. Assignment of the ant gene to specific HindIII fragments utilized the insertion element Tnl, which was shown to contain no HindIII cleavage sites.