Bacteriophage T7 DNA Replication In Vivo and In Vitro

Abstract

The genome of bacteriophage T7 is a linear double stranded DNA molecule (molecular weight: 25×106) with terminal redundancies of about 250 base pairs. The genetic information is sequentially ex-pressed after infection: (l) An E. coli RN polymerase transcribes the “pre-early” genes of T7 occupying the leftmost 17% of the genetic map. These genes (among others) code for a viral specific RNA polymerase (product of gene 1; Chamberlin, McGrath and Waskell, 1970) and for a virus induced ATP-dependent polynucleotide ligase (product of gene 1.3; Masamune, Frenkel and Richardson, 1971), (2) The, T7 MA polymerase transcribes the remaining 80% of the genetic map. “Early” genes contain the information for enzymes of DNA metabolism, (3) “Late” genes (genes 7 through 19) are coding for components of the viral envelope (Review: Studier, 1972). A list of the gene products involved in DNA replication is given in Table 1.