Anomalous, non-Gaussian, viscoelastic and age-dependent dynamics of histone-like nucleoid structuring proteins in live Escherichia coli

We report our measurements of the dynamics of H-NS proteins, which interact with both proteins and DNA simultaneously, in live E. coli bacteria. The dynamics turn out to differ significantly from other molecules reported previously. A new power-law distribution was observed for the diffusion coefficients of individual H-NS proteins. In addition, we observed a new distribution of displacements, which does not follow the Gaussian, Cauchy, or Laplace distributions, but the Pearson Type VII distribution. Furthermore, we experimentally measured, for the first time, the time/frequency dependence of the complex modulus of the bacterial cytoplasm, which deviates from the viscoelasticity of homogeneous protein solutions and shows a glass-liquid transition. Lastly, we observed that the dynamics of H-NS protein is cell-length/cell-age dependent. The findings are expected to fundamentally change the current views on bacterial cytoplasm and diffusional dynamics of molecules in bacteria.