Gene loci fluctuations reveal bacterial chromosome dynamical organization

Chromosomal sites in rod-like bacteria move sub-diffusely, driven by the
out-of-equilibrium nature of the viscoelastic, crowded intracellular
environment. Furthermore, it has been shown that there is a pronounced
dynamical asymmetry between longitudinal (long-axis) and transverse
(radial) motions, manifested in different exponents in the mean square
displacements, and respectively. Here, using polymer simulations and
experimental observations of a locus in Bacillus subtilis, we substantiate
the notion that asymmetric dynamics are a result of the asymmetric
structure of the bacterial chromosome modelled as a bottlebrush polymer in
a poor solvent. Our simulations recapitulate the observed asymmetry as
well as the range of the observed exponent values that are related to
scaling models of polymer dynamics, lending support to the notion that
asymmetric dynamics is a consequence of the bottlebrush structure of the
bacterial chromosome.