Fig. 1.
Replication is disrupted by UV-induced damage or following inactivation of the DNA polymerase, τ complex, or helicase–primase complex. (A) A diagram of the replisome, indicating the subunits of each protein complex. (B) Thermosensitive mutants that inactivate the polymerase core, τ complex, or helicase complex are viable at 30 °C but fail to grow at the restrictive temperature of 42 °C following overnight incubation. (C) The rate of DNA synthesis is inhibited following UV-induced damage or inactivation of the replisome’s essential subunits. Wild-type or mutant cultures, grown at 30 °C were pulse-labeled with 1 µCi per 10 µg/mL [3H]thymidine for 2 min at the indicated times following mock treatment (open symbols), 50 J/m2 UV irradiation (filled symbols), or a shift to 42 °C (filled symbols). The amount of radioactivity incorporated into the DNA, relative to pretreated cultures is plotted. Error bars represent SE of two experiments.