Bacillus subtilis DNA polymerase III is required for the replication of the virulent bacteriophage phi e

Action of 6-(p-hydroxyphenylazo)-uracil on bacteriophage IG 1

IG 1, a temperate phage of Bacillus subtilis, is strongly induced from its lysogens by 6-(p-hydroxyphenylazo)-uracil, an azopyrimidine known as selectively inhibiting the B. subtilis DNA polymerase III. IG 1 phages originated either by induction or infection multiply, abundantly, in the presence of that azopyrimidine, in spite of the drastic decline of cell viability. Chloramphenicol completely suppresses the induction effect and also blocks the formation of spontaneously induced phage particles.

Relationship of Bacillus subtilis DNA polymerase III to bacteriophage PBS2-induced DNA polymerase and to the replication of uracil-containing DNA

In vivo studies of PBS2 phage replication in a temperature-sensitive Bacillus subtilis DNA polymerase III (Pol III) mutant and a temperature-resistant revertant of this mutant have suggested the possible involvement of Pol III in PBS2 DNA synthesis. Previous results with 6-(p-hydroxyphenylazo)-uracil (HPUra), a specific inhibitor of Pol III and DNA replication in uninfected cells, suggest that Pol III is not involved in phage DNA replication, due to its resistance to this drug. Experiments were designed to examine possible explanations for this apparent contradiction. First, assays of the host Pol III and the phage-induced DNA polymerase activities in extracts indicated that a labile Pol III did not result in a labile phage-induced enzyme, suggesting that this new polymerase is not a modified HPUra-resistant form of Pol III. Indeed the purified phage-induced enzyme was resistant to the active, reduced form of HPUra under all assay conditions tested. Since in vitro Pol III was capable of replicating the uracil-containing DNA found in this phage, the sensitivity of the purified enzyme to reduced HPUra was examined using phage DNA as template-primer and dUTP as substrate; these new substrates did not affect the sensitivity of the host enzyme to the drug.

Bacillus subtilis DNA polymerase III is required for the replication of DNA of bacteriophages SPP-1 and phi 105

The replication of the Bacillus subtilis bacteriophages SPP-1 and phi 105 is sensitive to 6-(p-hydroxyphenylazo)-uracil (HPUra), a selective inhibitor of replicative DNA synthesis of B. subtilis which acts specifically at the levels of a replication-specific polymerase, DNA polymerase III (pol III). The origin of the HPUra-sensitive polymerase required for phage replication was examined by comparison of the drug sensitivity of phage development in a normosensitive host with that in a host carrying azp-12, a polC mutation that specifies production of an HPUra-resistant pol III. azp-12 specified HPUra-resistant phage host pol III. The host polIII requirement for SPP-1 replication also was confirmed by the demonstration that phage development was temperature sensitive in a host mutant carrying the polC mutation mut-1 (ts). Examination of the pol III activity of crude and purified cell-free preparations derived from phage-infected cells did not indicate any detectable changes in the specific activity, purification behavior, or drug sensitivity of the enzyme.

Induction of mutations in B. subtilis phage SPP1 by growth on host cells carrying a mutator DNA polymerase III

Phage SPP1 infecting a mutator strain of B. subtilis (BD337) which carries a defective DNA polymerase III is mutagenized. This effect is absent in phages SPO2, SP82G and øe. The results confirm previous observations that SPP1 uses host DNA polymerase III for its DNA synthesis.

Bacteriophages of Bacillus subtilis

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