Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210, USA.
Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
Nucleic Acids Res. 2021 Sep 7;49(15):8987-8999. doi: 10.1093/nar/gkab656.
Single molecule force spectroscopy is a powerful approach to probe the structure, conformational changes, and kinetic properties of biological and synthetic macromolecules. However, common approaches to apply forces to biomolecules require expensive and cumbersome equipment and relatively large probes such as beads or cantilevers, which limits their use for many environments and makes integrating with other methods challenging. Furthermore, existing methods have key limitations such as an inability to apply compressive forces on single molecules. We report a nanoscale DNA force spectrometer (nDFS), which is based on a DNA origami hinge with tunable mechanical and dynamic properties. The angular free energy landscape of the nDFS can be engineered across a wide range through substitution of less than 5% of the strand components. We further incorporate a removable strut that enables reversible toggling of the nDFS between open and closed states to allow for actuated application of tensile and compressive forces. We demonstrate the ability to apply compressive forces by inducing a large bend in a 249bp DNA molecule, and tensile forces by inducing DNA unwrapping of a nucleosome sample. These results establish a versatile tool for force spectroscopy and robust methods for designing nanoscale mechanical devices with tunable force application.
单分子力谱学是一种强大的方法，可以探测生物和合成大分子的结构、构象变化和动力学特性。然而，常用的施加力的方法需要昂贵且繁琐的设备和相对较大的探针，如珠子或悬臂梁，这限制了它们在许多环境中的使用，并使与其他方法的集成具有挑战性。此外，现有的方法存在关键的局限性，例如无法对单分子施加压缩力。我们报告了一种基于 DNA 折纸铰链的纳米级 DNA 力谱仪（nDFS），该铰链具有可调节的机械和动态特性。nDFS 的角自由能景观可以通过替换少于 5%的链成分在很宽的范围内进行工程设计。我们进一步引入了一个可移动的支柱，能够使 nDFS 在打开和关闭状态之间进行可逆切换，从而实现对拉伸和压缩力的驱动施加。我们通过在 249bp DNA 分子中诱导大弯曲来证明施加压缩力的能力，并通过诱导核小体样品的 DNA 解旋来证明施加拉伸力的能力。这些结果为力谱学建立了一种通用的工具，并为设计具有可调力施加的纳米级机械装置提供了稳健的方法。
