Replication of Bacteriophage M‐13: Template Specific Inhibition of DNA Synthesis by Nalidixic Acid

Nalidixic acid, a specific inhibitor of bacterial DNA synthesis, has no effect on the conversion of M‐13 parental or progeny single strands into double‐stranded replicative form molecules. However, the double strand to double strand replication of the replicative forms as well as the synthesis of single‐stranded M‐13 DNA are completely inhibited. As in the case of M‐13, the formation of the parental replicative form of ΨX 174 is also insensitive to nalidixic acid. It is concluded that nalidixic acid (or some metabolic product thereof) interferes with DNA replication only if a double‐stranded template is involved, but has no effect on the synthesis of a complementary strand on various single‐stranded templates.