Hollow core of Alzheimer's Aβ42 amyloid observed by cryoEM is relevant at physiological pH

Yifat Miller, Buyong Ma, Chung Jung Tsai, Ruth Nussinov

Research output: Contribution to journalArticlepeer-review

Abstract

Recent cryoEM density maps of Aβ42 fibrils obtained at low pH revealed two protofilaments winding around a hollow core raising the question if such tubular structures also exist at physiological pH. Based on the cryoEM measurements and on NMR data, we probe amyloid fibril organizations corresponding to the observed cryoEM density map. Our study demonstrates that the tubular Aβ42 fibril models exist at both acidic and physiological pH; however, the relative populations of the polymorphic models shift with pH. At acidic pH, the hollow core model exhibits higher population than the other models; at physiological pH, although it is less populated compared to the other models, structurally, it is stable and represents 8% of the population. We observe that only models with C termini facing the external surface of the fibril retain the hollow core under acidic and physiological conditions with dimensions similar to those observed by cryoEM; on the other hand, the hydrophobic effect shrinks the tubular cavity in the alternative organization. The existence of the hollow core fibril at physiological pH emphasizes the need to examine toxic effects of minor oligomeric species with unique organizations.

Original languageEnglish
Pages (from-to)14128-14133
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number32
DOIs
StatePublished - 10 Aug 2010

Keywords

  • Amyloid fibril structures
  • Polymorphism
  • Self-assembly

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