Bacterial Chromosomal Loci Move Subdiffusively through a Viscoelastic Cytoplasm

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Bacterial Chromosomal Loci Move Subdiffusively through a Viscoelastic Cytoplasm

Stephanie C. Weber, Andrew J. Spakowitz, and Julie A. Theriot

Phys. Rev. Lett. 104, 238102 – Published 8 June 2010

See Synopsis: Scenes from a cytoplasm

Abstract

Tracking of fluorescently labeled chromosomal loci in live bacterial cells reveals a robust scaling of the mean square displacement (MSD) as $τ^{0.39}$ . We propose that the observed motion arises from relaxation of the Rouse modes of the DNA polymer within the viscoelastic environment of the cytoplasm. The time-averaged and ensemble-averaged MSD of chromosomal loci exhibit ergodicity, and the velocity autocorrelation function is negative at short time lags. These observations are most consistent with fractional Langevin motion and rule out a continuous time random walk model as an explanation for anomalous motion in vivo.

Received 6 December 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.238102

Synopsis

Scenes from a cytoplasm

Published 18 June 2010

Time-lapse images of DNA molecules in a bacterial cell reveal the forces that can inhibit diffusion.

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Authors & Affiliations

Stephanie C. Weber^1,2, Andrew J. Spakowitz^3,4, and Julie A. Theriot^1,2,4,5

¹Department of Biochemistry, Stanford University, Stanford, California 94305, USA
²Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
³Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
⁴Biophysics Program, Stanford University, Stanford, California 94305, USA
⁵Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA

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Issue

Vol. 104, Iss. 23 — 11 June 2010

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