Infection by choleraphage Φ 138: bacteriophage DNA and replicative intermediates

Abstract

Choleraphage Φ 138 contains a linear, double-stranded, circularly permuted DNA molecule of 30 × 10⁶ daltons or 45 kilobase pairs. Upon infection, the host DNA is degraded, and synthesis of phage-specific DNA is detectable 20 min after infection. The phage utilizes primarily the host DNA degradation products for its own DNA synthesis. A physical map of Φ138 DNA was constructed with the restriction endonucleases Bg/II, HindIII, and PstI. A concatemeric replicative DNA intermediate equivalent to eight mature genome lengths was identified. The concatemer was shown to be the precursor for the synthesis of mature bacteriophage DNA which is subsequently packaged by a headful mechanism.