Single-Molecule Force Spectroscopy of Deoxyribonucleic Acid and Deoxyribonucleic Acid Polymerase Activity Impacted by Alkylating Agents

DNA alkylating agents are widely used in anticancer pharmacology.Although shown to induce cross-linking and/or methylation of DNA,how they affect the mechanical properties of DNA and activity of DNAenzymes remains to be elucidated. Here, we perform single-moleculeoptical tweezer experiments on DNA treated with alkylating agents,including melphalan, cisplatin, and dacarbazine. While all three drugsinduce a significant increase of overstretching force and a reductionof hysteresis, suggesting stabilization of DNA against shearing forces,their effects on elasticity of DNA were quite different, with thelargest change in persistence length induced by cisplatin. Furthermore,we find that these alkylating-agent-induced changes on DNA have differenteffects on processivity of DNA polymerase, with melphalan and cisplatinshowing significantly reduced activity and dacarbazine showing littleeffect. Overall, our results provide new insights into the effectsfor these alkylating agents, which could potentially facilitate abetter design of related drugs.

Automated summary

DNA alkylating agents, including melphalan, cisplatin, and dacarbazine, were found to induce changes in the mechanical properties of DNA and the activity of DNA enzymes, as revealed by single-molecule optical tweezer experiments. These agents stabilized DNA against shearing forces and increased its overstretching force, but had different effects on the elasticity of DNA, with cisplatin inducing the largest change in persistence length. Furthermore, these agents showed varying effects on the processivity of DNA polymerase, with melphalan and cisplatin significantly reducing activity and dacarbazine showing little effect.