Acceleration of DNA Replication of Klenow Fragment by Small Resisting ForceSupported by the National Natural Science Foundation of China (Grant Nos. 11674381, 21991133, 11774407, 11874415, 11874414, and 31770812), the Key Research Program on Frontier Science (Grant No. QYZDB-SSWSLH045), the National Key Research and Development Program of China (Grant No. 2016YFA0301500), the CAS Strategic Priority Research Program (Grant No. XDB37010100), and

Abstract

DNA polymerases are an essential class of enzymes or molecular motors that catalyze processive DNA syntheses during DNA replications. A critical issue for DNA polymerases is their molecular mechanism of processive DNA replication. We have proposed a model for chemomechanical coupling of DNA polymerases before, based on which the predicted results have been provided about the dependence of DNA replication velocity upon the external force on Klenow fragment of DNA polymerase I. Here, we performed single molecule measurements of the replication velocity of Klenow fragment under the external force by using magnetic tweezers. The single molecule data verified quantitatively the previous theoretical predictions, which is critical to the chemomechanical coupling mechanism of DNA polymerases. A prominent characteristic for the Klenow fragment is that the replication velocity is independent of the assisting force whereas the velocity increases largely with the increase of the resisting force, attains the maximum velocity at about 3.8 pN and then decreases with the further increase of the resisting force.