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Protein Misfolding Cyclic Amplification of Prions
10:12

Protein Misfolding Cyclic Amplification of Prions

Published on: November 7, 2012

Amyloid formation by recombinant full-length prion proteins in phospholipid bicelle solutions

Thorsten Lührs1, Ralph Zahn, Kurt Wüthrich

  • 1Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland.

Journal of Molecular Biology
|February 10, 2006
PubMed

Insights

Researchers created a beta-sheet-rich prion protein variant (PrP beta) that forms amyloid fibrils (PrP betaf) mimicking pathogenic forms. This in vitro conversion assay characterizes prion protein conformational changes relevant to transmissible spongiform encephalopathies.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Neuroscience

Background:

  • Prion diseases involve misfolded prion proteins (PrP Sc).
  • Understanding PrP C to PrP Sc conversion is crucial for transmissible spongiform encephalopathies (TSEs).

Purpose of the Study:

  • To generate and characterize a recombinant prion protein beta-sheet variant (PrP beta) and its amyloid fibrils (PrP betaf).
  • To investigate the conditions and molecular requirements for PrP C to PrP beta conformational transition.
  • To establish an in vitro assay for studying prion protein misfolding relevant to TSEs.

Main Methods:

  • Generation of recombinant full-length prion protein variants.
  • Induction of conformational transition in bicellar solutions at pH 5.0.
  • Characterization of amyloid fibrils using proteinase K digestion and Congo red birefringence.
  • Analysis of N-terminally truncated PrP fragments to identify essential regions.
  • Determination of activation enthalpy for PrP C dimerization.

Main Results:

  • PrP beta aggregates into amyloid fibrils (PrP betaf) with properties similar to pathogenic PrP Sc.
  • The conformational transition from PrP C to PrP beta is facilitated by specific bicellar conditions (pH 5.0, lipid mixtures).
  • The flexible peptide segment 105-120 is essential for PrP beta generation.
  • PrP C dimerization is the rate-limiting step, with sequence-dependent activation enthalpy.
  • The protocol is applicable across multiple species (human, cow, elk, pig, dog, mouse).

Conclusions:

  • An in vitro assay successfully generated PrP beta amyloid fibrils mimicking pathogenic PrP Sc.
  • The study identifies key structural (peptide segment 105-120) and mechanistic (dimerization) factors in prion protein conformational transitions.
  • This assay provides a valuable tool for molecular characterization of prion protein misfolding in TSEs.

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