Single-Molecule DNA Stretching Using Optical Tweezers

Abstract The advent of techniques to mechanically manipulate single (bio)molecules has sparked large efforts to precisely study the mechanical and elastic properties of proteins, protein fibers, DNA, RNA, etc. Two widely used techniques in this area are atomic force microscopy (AFM) and optical tweezers. Optical tweezers complement AFM at the lower end of the force regime: forces of typically a few hundred picoNewtons down to fractions of a picoNewton can be assessed using optical tweezers. This has allowed for, among other things, the precise measurement of forces and displacements exerted by individual motor proteins. In this report, we focus on the use of optical tweezers for force spectroscopy on single DNA molecules, and on the range of applications that this technique offers to learn not only about DNA itself, but also about the mechanics and thermodynamics of protein-DNA interaction.