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Distinct dimerization for various alloforms of the amyloid-beta protein: Aβ(1-40), Aβ(1-42), and Aβ(1-40)(D23N)

Sébastien Côté1, Rozita Laghaei, Philippe Derreumaux

  • 1Département de Physique and Groupe de recherche sur les protéines membranaires (GEPROM), Université de Montréal, Montréal, Québec, Canada.

The Journal of Physical Chemistry. B
|March 14, 2012
PubMed

Insights

Amyloid-beta (Aβ) dimers, crucial in Alzheimer's disease, show distinct folding behaviors. Aβ(1-42) dimers form more beta-strands than Aβ(1-40) dimers, influencing oligomerization and disease progression.

Area of Science:

  • Biochemistry and Molecular Biology
  • Neuroscience
  • Computational Chemistry

Background:

  • Amyloid-beta (Aβ) protein oligomers, particularly dimers, are implicated in Alzheimer's disease pathogenesis.
  • Distinct alloforms, Aβ(1-40) and Aβ(1-42), exhibit different oligomer distributions, potentially due to structural variations in their dimers.
  • Limited structural data exists for Aβ dimers, hindering a full understanding of their role in Alzheimer's disease.

Purpose of the Study:

  • To investigate the structural differences and folding propensities of wild-type Aβ(1-40), Aβ(1-42), and mutated Aβ(1-40)(D23N) dimers.
  • To elucidate how specific amino acid residues and salt bridges influence Aβ dimer structure and fibrillation.
  • To complement experimental findings with molecular dynamics simulations of Aβ dimer folding.

Main Methods:

  • Utilized Hamiltonian-temperature replica exchange molecular dynamics simulations.
  • Employed an accurate coarse-grained force field for simulating Aβ dimer folding.
  • Analyzed the free energy landscape and β-strand propensity of different Aβ dimer variants.

Main Results:

  • The Aβ(1-42) dimer exhibits a higher propensity for β-strand formation in key regions (central hydrophobic core and C-terminus) compared to Aβ(1-40).
  • Aβ(1-42) dimer displays a broader and more complex free energy landscape than Aβ(1-40) dimer.
  • The D23N mutation disrupts the D23-K28 salt bridge, increasing β-strand propensity in Aβ(1-40)(D23N) dimers, similar to Aβ(1-42).

Conclusions:

  • The specific amino acids Ile41-Ala42 and the D23-K28 salt bridge significantly impact Aβ dimer folding and structural properties.
  • Structural differences in Aβ dimers, particularly β-strand formation propensity, are critical for understanding varying oligomerization pathways.
  • Computational simulations provide valuable insights into the molecular mechanisms underlying Aβ aggregation in Alzheimer's disease.

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