Patterns of Ribonucleic Acid Synthesis in TS-infected Escherichia coli

The role of DNA replication in the synthesis of RNA and proteins during the “late” period of the infective cycle of T!%nfected Escherichia coli F has been examined. Inhibition of DNA synthesis was achieved by addition of chloramphenicol to TS-infected cultures or by use of a mutant of T5 (T5 am I), which is unable to cause the synthesis of an active DNA polymerase upon infection of the nonpermissive host, E. coli F. The synthesis of late or Class III RNA and lysozyme, a presumed late protein, was measured. In the absence of DNA synthesis a small amount of late or Class III RNA species is formed by 9 to 12 min after infection, but much greater quantities are produced under conditions allowing concurrent DNA replication. The synthesis of T5 lysozyme occurs normally in both the permissive and nonpermissive hosts.