Department of Chemistry, Oregon Center for Optics, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
Proc Natl Acad Sci U S A. 2010 Jan 12;107(2):721-5. doi: 10.1073/pnas.0908338107. Epub 2009 Dec 22.
The dynamic microenvironment of cells depends on macromolecular architecture, equilibrium fluctuations, and nonequilibrium forces generated by cytoskeletal proteins. We studied the influence of these factors on the motions of mitochondria in mating S. cerevisiae using Fourier imaging correlation spectroscopy (FICS). Our measurements provide detailed length-scale dependent information about the dynamic behavior of mitochondria. We investigate the influence of the actin cytoskeleton on mitochondrial motion and make comparisons between conditions in which actin network assembly and disassembly is varied either by using disruptive pharmacological agents or mutations that alter the rates of actin polymerization. Under physiological conditions, nonequilibrium dynamics of the actin cytoskeleton leads to 1.5-fold enhancement of the long-time mitochondrial diffusion coefficient and a transient subdiffusive temporal scaling of the mean-square displacement (MSD proportional, variant tau (alpha), with alpha = 2/3). We find that nonequilibrium forces associated with actin polymerization are a predominant factor in driving mitochondrial transport. Moreover, our results lend support to an existing model in which these forces are directly coupled to mitochondrial membrane surfaces.
细胞的动态微环境取决于大分子结构、平衡波动和细胞骨架蛋白产生的非平衡力。我们使用傅里叶相关光谱成像技术（FICS）研究了这些因素对交配酿酒酵母中线粒体运动的影响。我们的测量结果提供了关于线粒体动态行为的详细的长度尺度相关信息。我们研究了肌动蛋白细胞骨架对线粒体运动的影响，并比较了使用破坏药理学制剂或改变肌动蛋白聚合速率的突变来改变肌动蛋白网络组装和拆卸的条件。在生理条件下，肌动蛋白细胞骨架的非平衡动力学导致长时间线粒体扩散系数增加 1.5 倍，平均平方位移（MSD）的瞬态亚扩散时间标度（MSD 与 tau（alpha）成正比，alpha = 2/3）。我们发现与肌动蛋白聚合相关的非平衡力是驱动线粒体运输的主要因素。此外，我们的结果支持了一个现有的模型，即这些力直接与线粒体膜表面耦合。
