Synthesis and maturation of phage P22 DNA : II. Properties of temperature-sensitive phage mutants defective in DNA metabolism

Abstract

Three temperature-sensitive mutants of phage P22 have been isolated which are defective in phage DNA metabolism. After infection at restrictive temperature, one mutant (ts 12.1) fails to synthesize measurable quantities of phage DNA; nevertheless, parental phage DNA is recovered in a fast-sedimenting form similar to the first intermediate form observed after infection with normal phage. Another mutant (ts 5.1) synthesizes normal amounts of phage DNA, but neither this DNA nor parental DNA is converted from the first, fast-sedimenting intermediate form into the second, more slowly sedimenting intermediate observed in normal infections. The third mutant (ts 10.1), produces both intermediate forms in sequence, but fails to produce DNA having the sedimentation properties of mature phage DNA. None of the mutants encapsulates any DNA.The properties of these mutants are interpreted as supporting a scheme of sequential intermediates in P22 phage DNA synthesis and maturation.