Replication of T4 DNA in vitro. II. Assay system for and some properties of gene products required for T4 DNA replication.

[3H]dTTP was not incorporated into T4 DNA in the in vitro system for T4 DNA replication when the system was prepared from cells infected with T4 amber mutants defective in DNA replication. [3H]dTTP incorporation was resumed by adding the missing gene product to the defective system. DNA replication by the reconstituted system proceeded by the discontinuous mode of replication, as observed in the wild-type system. By using this in vitro complementation system, molecular weights of gene 41, 43, 44, 45, and 62 products in the active form were roughly estimated as 60,000, 130,000, 130,000, 60,000, and 130,000, respectively. Complex formation between the products of genes 44 and 62 was detected. Other strong interactions between the gene products tested were not detected by glycerol density gradient sedimentation. Interaction of gene products with denatured DNA was analyzed by using a DNA-agarose column, and the results showed that products of genes 32 and 43 had a strong affinity for DNA.