(266h) The Impact of Biological Fluctuations On Transport Processes within Live Bacterial Cells

The environment inside live bacterial cells is crowded by the cell's chromosome and a host of proteins that are constantly burning ATP in performing their biological functions. Our tracking experiments of fluorescently labeled chromosomal loci in live E. coli cells reveals a robust scaling of the mean square displacement (MSD) as $\tau^{0.39}$. Treating these cells with a range of drug treatments that suppress specific biological activities (e.g. transcription, translation, topoisomerase activity, and ATP synthesis) alters the subdiffusion coefficient but does not alter the power-law scaling of the MSD. The subdiffusion coefficient for live E. coli cells exhibits a temperature dependence that is best modeled using an Arrhenius equation, indicative of the enzymatic activity playing a critical role in the intracellular dynamics. In contrast, cells that are treated to block ATP synthesis have a linear temperature dependence for their subdiffusion coefficient, which is more consistent with the Stokes-Einstein relationship. The temperature dependence of the subdiffusion coefficient suggests a critical role that biological fluctuations play in the transport behavior within live bacterial cells. We develop a theoretical model for intracellular transport, accounting for viscoelasticity using a fractional Langevin approach. Within this formulation, we consider several models for biological fluctuations to specifically address the observed experimental behavior, focusing on both particle motion and chromosomal motion within the cell. We then proceed to discuss the potential impact of biological fluctuations on regulatory activity in the cell.