Nucleic Acid Synthesis in Bacillus subtilis Infected with Bacteriophage β22

ABSTRACT

Changes in the synthesis of host and phage nucleic acid after infection of Bacillus subtilis with virulent bacteriophage β22 were analyzed by deoxyribonucleic acid (DNA)-DNA and ribonucleic acid (RNA)-DNA hybridization. Host DNA replication continued during the first third of the 55-min latent period and then ceased at approximately the time replication of the phage genome was initiated. Host-specific RNA was synthesized concurrently with phage RNA during the first half of the latent period but was repressed late in the infection. For much of the latent period, the population of phage-specific RNA changed continually as new species were transcribed and earlier species were repressed; detectable changes ceased coincidentally with the appearance of intracellular phage. Control over transcription of phage DNA was to some degree an intrinsic property of the interaction of B. subtilis DNA-dependent RNA polymerase and the phage genome, since only the early species of phage RNA were synthesized in vitro by B. subtilis polymerase and pure β22 DNA. In vitro transcription of late functions was demonstrated by using the endogenous RNA polymerase activity of the nucleoprotein complex (nuclear fraction) from infected cells.