DNA Synthesis in Temperature Sensitive Mutants of Escherichia coli

One of the characteristics of the control mechanism of the DNA replication in Escherichia coli is that the replication proceeds from a fixed locus by a single growing point in a sequential way (Lark, Repko, and Hoffman, 1963; Cairns, 1963). This control mechanism may be closely related to the fact that the initiation of DNA replication requires the synthesis of certain proteins (Hanawalt, Maaløe, Cummings, and Schaechter, 1961). One possible function of these proteins might be to catalyze the priming reaction necessary for the action of DNA polymerase (Jacob, Brenner, and Cuzin, 1963). In fact, a temperature sensitive mutant has been isolated whose DNA synthesis at 41°C shows the same kinetics as those of wild type in the absence of protein synthesis (Kohiyama, Lanfrom, Brenner, and Jacob, 1963). Preliminary experiments suggested that the function of the DNA polymerase in crude extracts of this temperature sensitive mutant is normal even at...