Replication of Bacteriophage T7 DNA by Purified Proteins

Bacteriophage T7 provides a system for understanding the enzymatic and molecular mechanisms involved in the replication of a linear, duplex DNA molecule. Each T7 particle contains an entirely double-stranded DNA molecule, each strand consisting of an uninterrupted sequence of 40,000 nucleotides (Fig. 1a). The DNA molecules isolated from T7, like those from T-even phages, contain a terminal repetition but, unlike the circularly permuted collection isolated from T-even phages, they form a unique collection of sequences (for reviews, see Thomas 1966; Studier 1972).