EcoRI restriction endonuclease cleavage site map of bacteriophage P22 DNA

Abstract

The seven EcoRI restriction endonuclease cleavage sites in bacteriophage P22 DNA have been mapped. The cleavage site map of circularly permuted P22 linear DNA is a circle. The positions of EcoRI sites in the early region of the P22 genome were determined by comparing products of EcoRI digestion of mature linear P22 chromosomes with the EcoRI cleavage fragments of DNA of three λ immP22 hybrid phages and a P22 deletion mutant. An EcoRI site in the late region was mapped by partial digestion of the P22 deletion mutant DNA. Since the P22 genes included in the λ immP22 hybrid phages, and the genetic region missing in the P22 deletion mutant are known, some P22 genes can be positioned on this initial physical map of the P22 genome relative to EcoRI cleavage sites.