Recombinant PrPSc shares structural features with brain-derived PrPSc: Insights from limited proteolysis

Area of Science:

• Structural Biology
• Prion Biology
• Biochemistry

Background:

• Prion protein scrapie (PrPSc) forms amyloid fibers, with evidence suggesting a core 4-rung β-solenoid structure.
• Previous studies mapped proteinase K (PK) cleavage sites in brain-derived PrPSc to predict β-solenoid threading.

Purpose of the Study:

• To investigate the structural architecture of recombinant PrPSc (recPrPSc) using limited proteolysis.
• To compare the structural features and PK cleavage sites of recPrPSc with those of brain-derived PrPSc.

Main Methods:

• Limited proteolysis of mouse and bank vole recPrPSc.
• High-resolution SDS-PAGE, epitope analysis, and mass spectrometry to identify PK cleavage sites.
• Analysis of N-terminally and doubly truncated PK-resistant fragments.

Main Results:

• recPrPSc exhibited N-terminally truncated PK-resistant fragments similar to brain-derived PrPSc.
• Doubly truncated fragments (~89/97-152) were detected in some recPrPSc, characteristic of atypical prion strains.
• Shared PK cleavage sites suggest a conserved β-solenoid architecture between recPrPSc and brain PrPSc.

Conclusions:

• recPrPSc and brain PrPSc share a common structural architecture, indicated by similar PK cleavage sites and fragment patterns.
• Differences in fragment yields suggest variations in threading and biochemical properties between recPrPSc and brain PrPSc.
• recPrPSc provides a valuable platform for structural studies of prions, overcoming limitations associated with brain-derived material.