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Concealment of epitope by reduction and alkylation in prion protein

Jue Yuan1, Michael Kinter, John McGeehan

  • 1Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, OH 44106, USA.

Biochemical and Biophysical Research Communications
|December 15, 2004
PubMed

Insights

Reducing and alkylating the prion protein (PrP) conceals a key epitope, inhibiting its conversion to the pathological form (PrPSc). This structural change offers potential therapeutic strategies for prion diseases.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Molecular Biology

Background:

  • Prion diseases involve the conversion of cellular prion protein (PrPC) to a pathological isoform (PrPSc).
  • This conversion is characterized by a conformational change from alpha-helix to beta-sheet structures, particularly in the alpha1 domain (residues 144-154).
  • In vitro studies show that reducing and alkylating PrPC can inhibit PrPSc formation.

Purpose of the Study:

  • To investigate the structural effects of reduction and alkylation on PrPC.
  • To determine how these modifications impact the accessibility of specific epitopes, including those targeted by therapeutic antibodies.
  • To explore the implications for prion disease pathogenesis and treatment.

Main Methods:

  • Chemical modification of recombinant PrP through reduction and alkylation.
  • Assessment of antibody epitope accessibility using antibody binding assays.
  • Mass spectrometry to analyze alkylation sites.
  • Evaluation of structural changes in both liquid and solid phases.

Main Results:

  • Reduction and alkylation concealed a critical epitope within the alpha1 domain recognized by the therapeutic antibody 6H4.
  • Antibody affinity for epitopes in the N- and C-terminal domains remained unaffected.
  • Mass spectrometry confirmed alkylation occurred at cysteine residues without modifying the cryptic epitope.
  • Structural rearrangements were observed in both liquid and solid states.

Conclusions:

  • Reduction and alkylation induce significant tertiary structural rearrangements in PrP.
  • These modifications effectively mask a therapeutically relevant epitope, potentially blocking PrPSc conversion.
  • The findings suggest novel therapeutic avenues for prion diseases by targeting PrP structure.

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