Exposed Hsp70-binding site impacts yeast Sup35 prion disaggregation and propagation

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Amyloid fibril formation and disaggregation are central to neurodegenerative diseases.
• Chaperones modulate amyloid propagation and cellular effects, but their site-specific interactions are unclear.
• Understanding chaperone-amyloid binding is crucial for disease mechanisms and therapeutic strategies.

Purpose of the Study:

• To identify specific chaperone binding sites on amyloid fibrils.
• To investigate how these binding sites influence amyloid disaggregation and propagation in vivo.
• To explore the role of chaperone-amyloid interactions in prion strain phenotypes.

Main Methods:

• Identified binding sites of Ssa1, Sis1, and Hsp104 chaperones for the yeast prion protein Sup35.
• Conducted biophysical and genetic analyses using Sup35 deletion mutants and various amyloid conformations.
• Developed a reconstitution system with Ssa1-binding tags and hybrid chaperones (HAP/ClpP).

Main Results:

• Ssa1 binding outside the amyloid core significantly facilitates Sup35 amyloid disaggregation and yeast prion propagation.
• The reconstitution system demonstrated successful degradation of distinct prion strain conformations.
• Specific positioning and exposure of chaperone-binding regions on amyloid fibrils impact disaggregation efficiency.

Conclusions:

• The Ssa1-binding region's location on amyloid fibrils is critical for efficient disaggregation and prion propagation.
• Findings provide molecular insights into prion propagation and offer strategies for amyloid deposit elimination.
• This study elucidates the role of site-specific chaperone binding in modulating amyloid-related disease phenotypes.