Endonuclease R-EcoRII restriction of bacteriophage f1 DNA in vitro: ordering of genes V and VII, location of an RNA promotor for gene VIII.

Replicative form DNA of bacteriophage f1 was found to be sensitive in vitro to restriction by endonuclease R-EcoRII if the DNA was isolated from an Escherichia coli strain deficient in cytosine methylase activity. A similar observation was previously made with DNA from the closely related bacteriophage fd (S. Schlagman, S. Hattman, M. S. May, and L. Berger, submitted for publication). The two DNA fragments produced by the endo R-EcoRII digestion of f1 DNA were localized on the f1 cleavage map and their genetic content was determined. The polypeptides synthesized in a "coupled" transcription-translation system under the direction of each RII fragment were examined. The results of such experiments allow the ordering of genes V and VII and indicate the location of a RNA promotor for gene VIII.