Prion aggregates are typically composed of which structural motif?

Prion aggregates are typically composed of which structural motif?

• A. Alpha helices.
• B. Beta sheets.
• C. Triple helices.
• D. Random coils.

Answer: (B)

Prion aggregates are formed by beta-sheet rich structures. The disease-associated form of the prion protein (PrPSc) has increased beta-sheet content and stacks into insoluble amyloid fibrils through extensive beta-sheet interactions, giving that cross-beta architecture. The normal prion protein is largely alpha-helical, so it’s the shift toward beta sheets that drives aggregation. Alpha helices alone wouldn’t produce the long, ordered amyloid fibers, and random coils are disordered rather than the stable structure seen in aggregates; triple helices aren’t a typical feature of prion amyloids. So, beta sheets best explain the composition of prion aggregates.

Prion aggregates are formed by beta-sheet rich structures. The disease-associated form of the prion protein (PrPSc) has increased beta-sheet content and stacks into insoluble amyloid fibrils through extensive beta-sheet interactions, giving that cross-beta architecture. The normal prion protein is largely alpha-helical, so it’s the shift toward beta sheets that drives aggregation. Alpha helices alone wouldn’t produce the long, ordered amyloid fibers, and random coils are disordered rather than the stable structure seen in aggregates; triple helices aren’t a typical feature of prion amyloids. So, beta sheets best explain the composition of prion aggregates.