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Diffusion NMR and Rheology of a Model Polymer in Bacterial Cell Lysate Crowders
Yanitza Trosel1, Liam P Gregory2, Valerie K Booth1,2
1Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada.
Biomacromolecules
|May 22, 2023
Summary
Macromolecular crowding in bacterial cell lysates affects polymer diffusion modestly. Unlike artificial crowders, biological lysates exhibit non-Newtonian fluid behavior, crucial for understanding intracellular environments.
Area of Science:
- Biophysics
- Cell Biology
- Polymer Science
Background:
- The intracellular environment is crowded and heterogeneous, impacting biomolecule dynamics and kinetics.
- Macromolecular crowding is often studied using artificial agents like Ficoll, but their effects may differ from biological crowding.
Purpose of the Study:
- To investigate the effects of bacterial cell lysate crowding on polymer diffusivity.
- To compare the behavior of biological crowders with traditional artificial crowders.
Main Methods:
- Diffusion Nuclear Magnetic Resonance (NMR) was used to measure the translational diffusivity of polyethylene glycol (PEG).
- PEG diffusivity was assessed in bacterial cell lysates with different pretreatments (unmanipulated, ultracentrifuged, anion exchanged) and in artificial Ficoll crowders.
- Rheological properties of biological and artificial crowders were compared.
Main Results:
- A small test polymer (PEG) showed a modest decrease in self-diffusivity with increasing crowder concentration in all bacterial lysate treatments.
- The decrease in self-diffusivity was significantly less pronounced in bacterial lysates compared to artificial Ficoll crowders.
- Bacterial cell lysates exhibited non-Newtonian, shear-thinning behavior with a yield stress, contrasting with the Newtonian response of Ficoll.
Conclusions:
- Bacterial cell lysate crowding has a less pronounced effect on small polymer diffusivity than artificial crowders.
- Biological crowders display complex rheological properties (non-Newtonian) distinct from artificial crowders.
- Understanding these differences is vital for accurately modeling intracellular environments and biochemical processes.
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