Characterization of bacteriophage φ42 DNA

The DNA isolated from streptococcal phage φ42 is a linear, double-stranded molecule with a mass of 24.1 × 10 6 daltons. The DNA has been characterized by sucrose gradient centrifugation and by agarose gel electrophoresis after cleavage with restriction enzymes Hin dIII, Pvu II, Sal I, and Xba I. Analysis of restriction enzyme digests of DNA which has been digested with exonuclease III demonstrates that the molecules are circularly permuted. The permutation appears to cover sequences present throughout the genome of phage φ42.