Stages in the Replication of Bacteriophage ϕX174 DNA in vivo (original) (raw)

1. Robert L. Sinsheimer,
2. Rolf Knippers, and
3. Tohru Komano
4. Biology Division, California Institute of Technology, Pasadena, California

Excerpt

Research with bacteriophage ϕX174 over the past few years has led to the recognition of three distinct stages in the replication of the viral DNA. An outline of the replicative process is formulated in Fig. 1 (Sinsheimer et al., 1962; Lindqvist and Sinsheimer, 1968; Knippers et al., 1968; Komano et al., 1968).

Upon entry into the cell, the single-stranded DNA of the virus, which is a ring DNA, is quickly converted to a double-stranded DNA ring, the replicative form or RF. Two centrifugal forms of the double-stranded ring are found in the cell: the supercoiled form with both strands covalently closed (RFI), and the open form with one strand open (RFII).

The conversion from single- to double-stranded ring is performed by pre-existent host enzymes. No viral functions are needed for this step. It can occur in the presence of high concentrations of chloramphenicol, or in amino acid auxotrophs starved for...