Drittes Physikalisches Institut-Biophysik, Georg-August-Universität, 37077 Göttingen, Germany.
Department of Chemical and Biomolecular Engineering, Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX 77005, USA.
Science. 2014 May 30;344(6187):1031-5. doi: 10.1126/science.1250170.
Cells are active systems with molecular force generation that drives complex dynamics at the supramolecular scale. We present a quantitative study of molecular motions in cells over times from milliseconds to hours. Noninvasive tracking was accomplished by imaging highly stable near-infrared luminescence of single-walled carbon nanotubes targeted to kinesin-1 motor proteins in COS-7 cells. We observed a regime of active random "stirring" that constitutes an intermediate mode of transport, different from both thermal diffusion and directed motor activity. High-frequency motion was found to be thermally driven. At times greater than 100 milliseconds, nonequilibrium dynamics dominated. In addition to directed transport along microtubules, we observed strong random dynamics driven by myosins that result in enhanced nonspecific transport. We present a quantitative model connecting molecular mechanisms to mesoscopic fluctuations.
细胞是具有分子力产生的活跃系统，可在超分子尺度上驱动复杂的动力学。我们对细胞内的分子运动进行了从毫秒到小时的时间尺度的定量研究。通过对靶向 COS-7 细胞中的驱动蛋白-1 运动蛋白的单壁碳纳米管的近红外发光进行高稳定性的成像，实现了非侵入性的追踪。我们观察到一种活跃的随机“搅拌”状态，它构成了一种不同于热扩散和定向马达活动的中间运输模式。发现高频运动是由热驱动的。在大于 100 毫秒的时间内，非平衡动力学占主导地位。除了沿着微管的定向运输，我们还观察到由肌球蛋白驱动的强烈的随机动力学，这导致了增强的非特异性运输。我们提出了一个定量模型，将分子机制与介观涨落联系起来。
