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The Hsp70 Chaperone System Stabilizes a Thermo-sensitive Subproteome in E. coli.
Liang Zhao1, Giulia Vecchi2, Michele Vendruscolo2
1Department of Cellular Biochemistry, Group Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany.
Cell Reports
|August 1, 2019
Summary
The Hsp70 chaperone system stabilizes many proteins, revealing a previously unknown role in maintaining proteome stability under heat stress. This highlights its crucial function beyond typical chaperone activity.
Area of Science:
- Molecular Biology
- Proteomics
- Biochemistry
Background:
- Molecular chaperones, like the DnaK (Hsp70) system, are vital for protein homeostasis.
- The full impact of chaperones on overall proteome stability, especially under stress, is not well understood.
Purpose of the Study:
- To investigate the role of the DnaK (Hsp70) system in maintaining protein stability in Escherichia coli.
- To quantify the effects of heat stress and Hsp70 overexpression on the proteome.
Main Methods:
- Utilized pulse proteolysis coupled with quantitative proteomics.
- Analyzed approximately 1,500 soluble proteins in E. coli.
Main Results:
- Identified around 500 soluble proteins as protease-sensitive under normal conditions, indicating a metastable subproteome.
- Observed unfolding of an additional ~200 proteins upon acute heat stress.
- Demonstrated that DnaK (Hsp70) overexpression significantly stabilizes numerous thermolabile proteins, including ribosomal and large hetero-oligomeric proteins.
Conclusions:
- The Hsp70 system plays a critical role in stabilizing proteins against denaturing conditions.
- Beyond its known chaperone functions, Hsp70 actively maintains protein folded states under stress.
- A significant portion of the proteome exists in a metastable state, reliant on chaperone systems for stability.
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