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Osmolytes Can Destabilize Proteins in Cells by Modulating Electrostatics and Quinary Interactions
Xiangfei Song1, Liaoyuan An1, Mengting Wang1
1University of Chinese Academy of Sciences, Beijing, 100049, China.
ACS Chemical Biology
|April 12, 2021
Summary
Osmolytes like glycerol stabilize proteins in E. coli cells, but betaine and taurine destabilize them by altering folding rates and weakening salt bridges. This in vivo effect differs from in vitro findings.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- In vitro studies demonstrate osmolyte-induced protein stabilization.
- The in vivo effects of osmolytes on protein folding remain less understood.
Purpose of the Study:
- To investigate the in vivo effects of glycerol, sorbitol, betaine, and taurine on protein folding in E. coli.
- To elucidate the mechanisms underlying osmolyte-induced protein stabilization or destabilization within a cellular environment.
Main Methods:
- Utilized NMR spectroscopy to monitor protein folding in E. coli cells.
- Introduced 400 mM concentrations of various osmolytes (glycerol, sorbitol, betaine, taurine) into E. coli.
- Analyzed changes in protein folding and unfolding rates.
Main Results:
- Glycerol was the only osmolyte that stabilized the folded protein in E. coli.
- Betaine and taurine significantly destabilized the protein by modulating folding/unfolding rates.
- Betaine and taurine were found to enhance protein-environment quinary interactions and weaken protein salt bridges.
Conclusions:
- In vivo, glycerol stabilizes proteins, while betaine and taurine destabilize them, contrary to some in vitro expectations.
- Destabilization by betaine and taurine is attributed to enhanced quinary interactions and weakened salt bridges.
- These cellular mechanisms counteract the typical preferential exclusion mechanism of osmolyte action.
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