Minimalist model for force-dependent DNA replication.

In experiments using optical or magnetic tweezers, investigators have monitored the rate at which polymerase enzymes catalyze DNA replication when the template strand is subjected to a stretching force. For T7, Klenow, and Sequenase polymerases, the replication rate increases modestly at low tension and then decreases markedly at higher tension. Molecular-dynamics (MD) simulations using x-ray structure data for the open and closed complexes of the Taq enzyme with DNA revealed that the dependence of replication rate on tension could be accounted for in terms of the induced enthalpy changes for the two DNA segments adjacent to the site of the added nucleotide.