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Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis
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Normal cellular prion protein with a methionine at position 129 has a more exposed helix 1 and is more prone to

Nancy Pham1, Shaoman Yin, Shuiliang Yu

  • 1Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic Research Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.

Biochemical and Biophysical Research Communications
|February 16, 2008
PubMed

Insights

The methionine form of human prion protein (PrP) aggregates faster due to an exposed helix 1 region, influencing prion disease pathogenesis. This finding clarifies the role of the PRNP codon 129 polymorphism in disease mechanisms.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Genetics

Background:

  • The human prion gene (PRNP) exhibits a common polymorphism at codon 129, with either methionine (M) or valine (V) alleles.
  • This PRNP codon 129 polymorphism significantly impacts prion disease susceptibility and clinical presentation.
  • The precise molecular mechanisms by which this polymorphism influences prion disease pathogenesis remain incompletely understood.

Purpose of the Study:

  • To investigate the conformational differences between wild-type human prion protein (PrP) variants with methionine (rPrP(C(129M))) or valine (rPrP(C(129V))) at codon 129.
  • To elucidate how these conformational differences affect prion protein aggregation propensity and kinetics.
  • To explore the influence of the codon 129 polymorphism on prion seeding and propagation.

Main Methods:

  • Utilized a panel of monoclonal antibodies to compare the epitopes of rPrP(C(129M)) and rPrP(C(129V)).
  • Assessed the aggregation rates and aggregate formation of the two PrP variants.
  • Employed a seeded aggregation assay using a pathogenic mutant PrP (rPrP((129M)/10OR)) to compare seeding efficiency with rPrP(C(129M)) and rPrP(C(129V)).

Main Results:

  • rPrP(C(129M)) exhibits a more exposed helix 1 region compared to rPrP(C(129V)).
  • rPrP(C(129M)) demonstrates a significantly faster aggregation rate and forms larger aggregates than rPrP(C(129V)).
  • The pathogenic rPrP((129M)/10OR) seed more efficiently promoted the aggregation of rPrP(C(129M)) than rPrP(C(129V)).

Conclusions:

  • The exposed helix 1 region in rPrP(C(129M)) likely underlies its increased aggregation propensity.
  • These findings provide a mechanistic explanation for how the PRNP codon 129 polymorphism influences prion disease pathogenesis.
  • The differential aggregation and seeding efficiencies highlight the critical role of residue 129 in prion protein misfolding and disease.

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