Role of genes 46 and 47 in bacteriophage T4 reproduction: III. Formation of joint molecules in biparental recombination

The role of bacteriophage T4 gene 46 in recombination between non-replicating chromosomes was examined. DNA was extracted from Escherichia coli B infected with a mixture of ³H]thymidine-labeled and (¹³C, ¹⁵N)-labeled T4 multiple mutants under non-permissive conditions. The densities of extracted, purified DNAs were determined by neutral cesium sulfate density-gradient centrifugation. When the phage was a double mutant defective in both DNA ligase and DNA polymerase genes, a considerable portion of the ³H label was found at a hybrid density. By contrast, when phage had a third mutation in gene 46, the amount of ³H label found at the hybrid position was greatly reduced. These findings indicate that hybrid molecule formation requires the function of gene 46.