Cytoplasmic RNA-Protein Particles Exhibit Non-Gaussian Subdiffusive Behavior

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• 作者：Thomas J. Lampo¹ ; Stella Stylianidou⁶ ; Mikael P. Backlund² ; Paul A. Wiggins⁶ ; ⁷ ; ⁸ ; Andrew J. Spakowitz¹ ; ³ ; ⁴ ; ⁵ ; ^{ajspakow@stanford.edu}
• 刊名：Biophysical Journal
• 出版年：2017
• 出版时间：7 February 2017
• 年：2017
• 卷：112
• 期：3
• 页码：532-542
• 全文大小：843 K
• 卷排序：112

文摘

The cellular cytoplasm is a complex, heterogeneous environment (both spatially and temporally) that exhibits viscoelastic behavior. To further develop our quantitative insight into cellular transport, we analyze data sets of mRNA molecules fluorescently labeled with MS2-GFP tracked in real time in live Escherichia coli and Saccharomyces cerevisiae cells. As shown previously, these RNA-protein particles exhibit subdiffusive behavior that is viscoelastic in its origin. Examining the ensemble of particle displacements reveals a Laplace distribution at all observed timescales rather than the Gaussian distribution predicted by the central limit theorem. This ensemble non-Gaussian behavior is caused by a combination of an exponential distribution in the time-averaged diffusivities and non-Gaussian behavior of individual trajectories. We show that the non-Gaussian behavior is a consequence of significant heterogeneity between trajectories and dynamic heterogeneity along single trajectories. Informed by theory and simulation, our work provides an in-depth analysis of the complex diffusive behavior of RNA-protein particles in live cells.