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Phosphoglycerate Kinase Can Adopt a Topologically Misfolded Form that is More Stable than its Native State
Yingzi Xia1, Barbara Amann2, Richard E Gillilan3
1Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
Biorxiv : the Preprint Server for Biology
|July 16, 2025
Summary
Globular proteins usually refold to their most stable native state. However, E. coli phosphoglycerate kinase (PGK) forms a more kinetically stable misfolded state, challenging the Thermodynamic Hypothesis.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Folding
Background:
- The Thermodynamic Hypothesis posits that native protein states are the most stable.
- This explains reversible protein refolding after denaturation.
- However, exceptions to this paradigm are being discovered.
Purpose of the Study:
- To investigate the refolding behavior of E. coli phosphoglycerate kinase (PGK) upon dilution from denaturant.
- To characterize an unusual, kinetically stable misfolded form of PGK.
- To elucidate the structural basis for the stabilization of this misfolded state.
Main Methods:
- Protein refolding experiments involving dilution from denaturant.
- Kinetic stability assays measuring resistance to thermal and detergent-induced denaturation.
- Circularization of PGK to investigate topological effects on misfolding.
Main Results:
- E. coli PGK refolded into a monomeric, native-like misfolded form, not the native state.
- This misfolded form exhibited greater kinetic stability than the native state.
- Circularization of PGK prevented the formation of these kinetically stable misfolded forms, indicating a topological basis.
Conclusions:
- Misfolded proteins can achieve kinetic stability without aggregation or amyloid formation.
- Topological features, such as protein termini threading, can stabilize misfolded states.
- Topologically misfolded proteins represent a potential vulnerability in cellular proteostasis networks.
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