Research Highlights

Prof.dr. Bert Poolman

Protein dynamics in the cytoplasm of Escherichia coli. A diffusion map obtained with single-molecule displacement mapping is overlayed with a schematic of the cytoplasm of the cell. The top panel highlights the effect of confinement on the measured diffusion, which leads to lower apparent diffusion coefficients near the boundaries of the cell. The bottom panel shows the effect of the perceived viscosity by diffusing proteins. Since diffusion scales with the complex mass of proteins, bigger particles will be affected more by the crowding of the cytoplasm than smaller molecules, leading to the deviation from the Einstein-Stokes equation. The left panel shows that accumulation of aggregated or misfolded proteins impairs the diffusion in these regions.

Recent breakthroughs by the Poolman group:

Protein diffusion in living cells

We have developed a sensitive single-molecule displacement method for analyzing simulation-based reconstructed diffusion of proteins in small compartments, which we have successfully applied to investigate the relationship between the dynamics of proteins in the cell pole regions and aging of bacterial cells[1]. We use the method to analyze the diffusion of a wide range of proteins in the Escherichia coli cytoplasm to demonstrate that diffusion is fastest in the nucleoid region of the cell and that the newly formed pole of dividing cells exhibits a faster diffusion than the old one; the latter is due to the accumulation of aggregated or damaged proteins.

Last modified:

20 October 2023 2.12 p.m.