Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL , 1015 Lausanne, Switzerland.
Institute of Physics , Bijenicka cesta 46, HR-10000 Zagreb, Croatia.
Nano Lett. 2015 Oct 14;15(10):7118-25. doi: 10.1021/acs.nanolett.5b03264. Epub 2015 Sep 28.
Combination of glass nanocapillaries with optical tweezers allowed us to detect DNA-protein complexes in physiological conditions. In this system, a protein bound to DNA is characterized by a simultaneous change of the force and ionic current signals from the level observed for the bare DNA. Controlled displacement of the protein away from the nanocapillary opening revealed decay in the values of the force and ionic current. Negatively charged proteins EcoRI, RecA, and RNA polymerase formed complexes with DNA that experienced electrophoretic force lower than the bare DNA inside nanocapillaries. Force profiles obtained for DNA-RecA in our system were different than those in the system with nanopores in membranes and optical tweezers. We suggest that such behavior is due to the dominant impact of the drag force comparing to the electrostatic force acting on a DNA-protein complex inside nanocapillaries. We explained our results using a stochastic model taking into account the conical shape of glass nanocapillaries.
玻璃纳米毛细管与光学镊子的组合使我们能够在生理条件下检测 DNA-蛋白质复合物。在这个系统中，与 DNA 结合的蛋白质的特征是同时改变力和离子电流信号，其变化幅度超过裸 DNA 观察到的水平。控制蛋白质从纳米毛细管开口处的位移会导致力和离子电流值衰减。带负电荷的 EcoRI、RecA 和 RNA 聚合酶等蛋白质与 DNA 形成复合物，在纳米毛细管内经历的电泳力低于裸 DNA。在我们的系统中获得的 DNA-RecA 力谱与在具有膜纳米孔和光学镊子的系统中的力谱不同。我们认为这种行为是由于与作用在纳米毛细管内 DNA-蛋白质复合物上的静电力相比，阻力的主导影响造成的。我们使用考虑到玻璃纳米毛细管的锥形形状的随机模型来解释我们的结果。
