Dependence of diffusion in Escherichia coli cytoplasm on protein size, environmental conditions and cell growth
- Max Planck Institute for Terrestrial Microbiology, Germany
- Max Planck Institute for Dynamics and Self-Organization, Germany
Abstract
Inside prokaryotic cells, passive translational diffusion typically limits the rates with which cytoplasmic proteins can reach their locations. Diffusion is thus fundamental to most cellular processes, but the understanding of protein mobility in the highly crowded and non-homogeneous environment of a bacterial cell is still limited. Here we investigated the mobility of a large set of proteins in the cytoplasm of Escherichia coli, by employing fluorescence correlation spectroscopy (FCS) combined with simulations and theoretical modeling. We conclude that cytoplasmic protein mobility could be well described by Brownian diffusion in the confined geometry of the bacterial cell and at the high viscosity imposed by macromolecular crowding. We observed similar size dependence of protein diffusion for the majority of tested proteins, whether native or foreign to E. coli. For the faster-diffusing proteins, this size dependence is well consistent with the Stokes-Einstein relation once taking into account the specific dumbbell shape of protein fusions. Pronounced subdiffusion and hindered mobility are only observed for proteins with extensive interactions within the cytoplasm. Finally, while protein diffusion becomes markedly faster in actively growing cells, at high temperature, or upon treatment with rifampicin, and slower at high osmolarity, all of these perturbations affect proteins of different sizes in the same proportions, which could thus be described as changes of a well-defined cytoplasmic viscosity.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting file; Source Data files have been provided for all figures.
Article and author information
Author details
Jaime Agudo-Canalejo
Funding
Max-Planck-Gesellschaft
- Nicola Bellotto
- Jaime Agudo-Canalejo
- Remy Colin
- Ramin Golestanian
- Gabriele Malengo
- Victor Sourjik
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Bellotto et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Dependence of diffusion in Escherichia coli cytoplasm on protein size, environmental conditions and cell growth
eLife 11:e82654.
https://doi.org/10.7554/eLife.82654
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