Location of the 5-Methylcytosine Group on the Bacteriophage φX174 Genome

Abstract

Bacteriophage φX174 DNA was labeled in vivo with [methyl-^(3)H]methionine. The methyl-labeled progeny DNA was extracted from purified bacteriophage φX174 particles and was used as template for in vitro synthesis of the complementary strand in the presence of the nucleoside triphosphates and Escherichia coli polymerase I. The resultant replicative form DNA was then cleaved, in separate experiments, with restriction endonucleases from Haemophilus influenzae and H. aegyptius. The DNA fragments were analyzed by polyacrylamide gel electrophoresis. It is concluded that the single methylcytosine in the viral DNA is located in a specific region of the φX174 genome, very likely in gene H.