In vitro protein synthesis directed by separated transcripts of bacteriophage f1 DNA

RNA was synthesized by purified Escherichia coli RNA polymerase from covalently closed circular replicative form I DNA isolated from E. coli infected with bacteriophage f1. The transcripts were fractionated on the basis of size, and their template activities studied. Both unfractionated and the largest RNA codes for essentially the same products as are made from f1 replicative form I when the DNA is used as a template in a "coupled" system. Other size classes of RNA fail to code for one or more f1-specific products. Hybridization-competition studies suggest that the largest RNA contains sequences common to the smaller RNAs. These data, together with a consideration of the genetic map of f1, support the hypothesis of Sugiura et al. (1969) that filamentous phage DNA contains a number of promoters and one strong terminator. Our data suggest that the terminator is located between the gene VIII and gene III boundaries. Promoter locations are discussed.