[Effect of Escherichia coli mutation affecting the RNA polymerase sigma factor on phage T4 development]

The bacterial RNA polymerase sigma factor is necessary throughout T4 development. T4 can develop in the E. coli RpoD800 mutant cells only at permissive temperature. RNA synthesis in T4-infected mutant cells remains temperature-sensitive throughout infection as in uninfected mutant bacteria. This shows that bacterial sigma factor is necessary for all types of RNA synthesis in infected E. coli. The data obtained suggest also that active sigma factor is necessary for early, but not for late T4 DNA replication.