A dominant-negative mutant inhibits multiple prion variants through a common mechanism

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.