Figure 5: Describing the β₂-sliding clamp recycling process during replication.

(a) A Monte Carlo simulation of the β₂-clamp assembly and disassembly reaction. For illustrative purposes, we perform a Monte Carlo simulation of the proposed model, utilizing the experimentally determined primer formation and unloading rate, as well as the replication time, and under the assumption that primer formation is rate limiting. We show the simulation results for five individual traces (coloured lines). The black curve is the analytical solution for the average number of loaded β₂-clamps. Here we divide the total trace into three time regions, namely initiation (red), steady state (green) and termination (blue). (b) A zoom of the different sections from a. (left) A build-up of loaded β₂-clamps on the DNA proceeds for ~10 min. (middle) After the gradual accumulation of loaded β₂-clamps, a steady state plateau of 46 DNA-bound β₂-clamps is maintained for ~2/3 of the replication process. (right) After termination, all DNA-bound β₂-clamps are unloaded in ~5 min. (c) A cartoon illustrating the DNA-bound β₂-clamp build-up during replication. As the rate at which β₂-clamps are loaded (one every 4 s) is much faster than the unloading rate of individual β₂-clamps (once every 195 s) during replication, there will be a dynamic reservoir of β₂-clamps that have not yet been unloaded left on the lagging strand.