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Direct observation of secondary nucleation along the fibril surface of the amyloid β 42 peptide

Thacker, Dev LU ; Barghouth, Mohammad LU ; Bless, Mara LU ; Zhang, Enming LU and Linse, Sara LU (2023) In Proceedings of the National Academy of Sciences of the United States of America 120(25).
Abstract

Alzheimer's disease is a neurodegenerative condition which involves heavy neuronal cell death linked to oligomers formed during the aggregation process of the amyloid β peptide 42 (Aβ42). The aggregation of Aβ42 involves both primary and secondary nucleation. Secondary nucleation dominates the generation of oligomers and involves the formation of new aggregates from monomers on catalytic fibril surfaces. Understanding the molecular mechanism of secondary nucleation may be crucial in developing a targeted cure. Here, the self-seeded aggregation of WT Aβ42 is studied using direct stochastic optical reconstruction microscopy (dSTORM) with separate fluorophores in seed fibrils and monomers. Seeded aggregation proceeds faster than nonseeded... (More)

Alzheimer's disease is a neurodegenerative condition which involves heavy neuronal cell death linked to oligomers formed during the aggregation process of the amyloid β peptide 42 (Aβ42). The aggregation of Aβ42 involves both primary and secondary nucleation. Secondary nucleation dominates the generation of oligomers and involves the formation of new aggregates from monomers on catalytic fibril surfaces. Understanding the molecular mechanism of secondary nucleation may be crucial in developing a targeted cure. Here, the self-seeded aggregation of WT Aβ42 is studied using direct stochastic optical reconstruction microscopy (dSTORM) with separate fluorophores in seed fibrils and monomers. Seeded aggregation proceeds faster than nonseeded reactions because the fibrils act as catalysts. The dSTORM experiments show that monomers grow into relatively large aggregates on fibril surfaces along the length of fibrils before detaching, thus providing a direct observation of secondary nucleation and growth along the sides of fibrils. The experiments were repeated for cross-seeded reactions of the WT Aβ42 monomer with mutant Aβ42 fibrils that do not catalyze the nucleation of WT monomers. While the monomers are observed by dSTORM to interact with noncognate fibril surfaces, we fail to notice any growth along such fibril surfaces. This implies that the failure to nucleate on the cognate seeds is not a lack of monomer association but more likely a lack of structural conversion. Our findings support a templating role for secondary nucleation, which can only take place if the monomers can copy the underlying parent structure without steric clashes or other repulsive interactions between nucleating monomers.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Amyloid aggregation, dSTORM, secondary nucleation
in
Proceedings of the National Academy of Sciences of the United States of America
volume
120
issue
25
article number
e2220664120
publisher
National Academy of Sciences
external identifiers
  • pmid:37307445
  • scopus:85163171752
ISSN
0027-8424
DOI
10.1073/pnas.2220664120
language
English
LU publication?
yes
id
ae4578df-560f-4b51-9704-f2489de3585f
date added to LUP
2023-09-13 08:36:38
date last changed
2024-04-20 04:18:10
@article{ae4578df-560f-4b51-9704-f2489de3585f,
  abstract     = {{<p>Alzheimer's disease is a neurodegenerative condition which involves heavy neuronal cell death linked to oligomers formed during the aggregation process of the amyloid β peptide 42 (Aβ42). The aggregation of Aβ42 involves both primary and secondary nucleation. Secondary nucleation dominates the generation of oligomers and involves the formation of new aggregates from monomers on catalytic fibril surfaces. Understanding the molecular mechanism of secondary nucleation may be crucial in developing a targeted cure. Here, the self-seeded aggregation of WT Aβ42 is studied using direct stochastic optical reconstruction microscopy (dSTORM) with separate fluorophores in seed fibrils and monomers. Seeded aggregation proceeds faster than nonseeded reactions because the fibrils act as catalysts. The dSTORM experiments show that monomers grow into relatively large aggregates on fibril surfaces along the length of fibrils before detaching, thus providing a direct observation of secondary nucleation and growth along the sides of fibrils. The experiments were repeated for cross-seeded reactions of the WT Aβ42 monomer with mutant Aβ42 fibrils that do not catalyze the nucleation of WT monomers. While the monomers are observed by dSTORM to interact with noncognate fibril surfaces, we fail to notice any growth along such fibril surfaces. This implies that the failure to nucleate on the cognate seeds is not a lack of monomer association but more likely a lack of structural conversion. Our findings support a templating role for secondary nucleation, which can only take place if the monomers can copy the underlying parent structure without steric clashes or other repulsive interactions between nucleating monomers.</p>}},
  author       = {{Thacker, Dev and Barghouth, Mohammad and Bless, Mara and Zhang, Enming and Linse, Sara}},
  issn         = {{0027-8424}},
  keywords     = {{Amyloid aggregation; dSTORM; secondary nucleation}},
  language     = {{eng}},
  number       = {{25}},
  publisher    = {{National Academy of Sciences}},
  series       = {{Proceedings of the National Academy of Sciences of the United States of America}},
  title        = {{Direct observation of secondary nucleation along the fibril surface of the amyloid β 42 peptide}},
  url          = {{http://dx.doi.org/10.1073/pnas.2220664120}},
  doi          = {{10.1073/pnas.2220664120}},
  volume       = {{120}},
  year         = {{2023}},
}