The elastic property of a single DNA molecule cross-linked by cisplatin: A magnetic tweezers study

We observed that the elastic property of a DNA molecule was dramatically changed when the molecule reacted with an anticancer drug, cisplatin. It has been known from bulk assays that cisplatin induces the formation of intra- and inter-strand crosslinks, especially at two neighboring purine sites. From micromanipulation of a single DNA molecule with a magnetic tweezers apparatus, we obtained kinetic information on the interaction between a single DNA molecule and cisplatin, and on the conformation and elastic property of a cisplatin-bound DNA molecule: a single DNA molecule under a constant force was gradually shortened as it interacted with cisplatin, and the elasticity of the DNA molecule revealed by the force vs. extension data was dramatically altered, which indicates that DNA crosslinking by cisplatin is responsible for the changes in the conformation and elasticity. We demonstrated that magnetic tweezers are a versatile tool in studying the mechanical properties of an individual DNA molecule, which have a significant impact on the function of DNA and, therefore, on the anti-cancer effect of cisplatin.