Probing amyloid-beta fibril stability by increasing ionic strengths

Area of Science:

• Biochemistry
• Biophysics
• Computational Biology

Background:

• Amyloid-beta (Aβ) protein aggregation is central to neurodegenerative diseases.
• Previous studies indicate ionic strength influences Aβ fibril morphology.
• The precise mechanisms of ionic strength-dependent Aβ aggregation remain incompletely understood.

Purpose of the Study:

• To elucidate the effects of ionic strength on the structure and dynamics of a model Aβ fibril.
• To investigate how varying NaCl concentrations alter Aβ fibril properties.
• To provide molecular-level insights into ionic strength-dependent aggregation mechanisms.

Main Methods:

• All-atom molecular dynamics simulations of a model Aβ fibril.
• Simulations conducted over 40 nanoseconds at varying NaCl concentrations.
• Analysis of vibrational spectra and calculation of stretching force constants.

Main Results:

• Increasing ionic strength leads to a stiffer Aβ fibril structure.
• Fibril elongation at low ionic strength is promoted by N-terminal hydrogen bonding.
• Aggregation at higher ionic strength is suggested to be driven by hydrophobic interactions.

Conclusions:

• Ionic strength is a critical factor modulating Aβ fibril mechanics and aggregation pathways.
• Molecular dynamics simulations offer a powerful tool to study these ionic effects.
• Understanding these mechanisms can inform therapeutic strategies for amyloid-related diseases.