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Updated: Feb 19, 2026
Inducible and Reversible Dominant-negative DN Protein Inhibition
Published on: January 7, 2019
A dominant-negative mutant inhibits multiple prion variants through a common mechanism
Fen Pei1, Susanne DiSalvo2, Suzanne S Sindi3
1The University of Arizona, Department of Molecular and Cellular Biology, Tucson, Arizona, United States of America.
Abstract:
Prions adopt alternative, self-replicating protein conformations and thereby determine novel phenotypes that are often irreversible. Nevertheless, dominant-negative prion mutants can revert phenotypes associated with some conformations. These observations suggest that, while intervention is possible, distinct inhibitors must be developed to overcome the conformational plasticity of prions. To understand the basis of this specificity, we determined the impact of the G58D mutant of the Sup35 prion on three of its conformational variants, which form amyloids in S. cerevisiae. G58D had been previously proposed to have unique effects on these variants, but our studies suggest a common mechanism. All variants, including those reported to be resistant, are inhibited by G58D but at distinct doses. G58D lowers the kinetic stability of the associated amyloid, enhancing its fragmentation by molecular chaperones, promoting Sup35 resolubilization, and leading to amyloid clearance particularly in daughter cells. Reducing the availability or activity of the chaperone Hsp104, even transiently, reverses curing. Thus, the specificity of inhibition is determined by the sensitivity of variants to the mutant dosage rather than mode of action, challenging the view that a unique inhibitor must be developed to combat each variant.
Insights
Prion protein conformations can be reversed by specific mutants. The G58D mutant inhibits various Sup35 prion variants by destabilizing amyloids, challenging the need for unique inhibitors for each variant.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Science
Background:
- Prions are self-replicating protein conformations causing irreversible phenotypes.
- Dominant-negative prion mutants offer potential therapeutic intervention.
- Prion conformational plasticity necessitates specific inhibitors.
Purpose of the Study:
- To investigate the impact of the G58D mutant on Sup35 prion variants.
- To elucidate the mechanism of prion variant inhibition by G58D.
- To challenge the notion of variant-specific inhibitor development.
Main Methods:
- Studied three amyloid conformational variants of the Sup35 prion in S. cerevisiae.
- Assessed the inhibitory effects of the G58D mutant on these variants.
- Investigated the role of molecular chaperones, particularly Hsp104, in prion clearance.
Main Results:
- G58D inhibited all tested Sup35 prion variants, including resistant ones, albeit at different concentrations.
- G58D reduced amyloid kinetic stability, promoting fragmentation and clearance.
- Hsp104 chaperone activity was crucial for G58D-mediated prion curing, with its reduction reversing the effect.
Conclusions:
- Inhibition specificity is determined by variant sensitivity to G58D dosage, not a unique mechanism of action.
- A common inhibitory mechanism exists for different prion variants.
- This challenges the paradigm requiring distinct inhibitors for each prion variant.
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