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Portrait of Sara Snogerup Linse

Sara Linse


Portrait of Sara Snogerup Linse

The role of fibril structure and surface hydrophobicity in secondary nucleation of amyloid fibrils


  • Dev Thacker
  • Kalyani Sanagavarapu
  • Birgitta Frohm
  • Georg Meisl
  • Tuomas P.J. Knowles
  • Sara Linse

Summary, in English

Crystals, nanoparticles, and fibrils catalyze the generation of new aggregates on their surface from the same type of monomeric building blocks as the parent assemblies. This secondary nucleation process can be many orders of magnitude faster than primary nucleation. In the case of amyloid fibrils associated with Alzheimer's disease, this process leads to the multiplication and propagation of aggregates, whereby short-lived oligomeric intermediates cause neurotoxicity. Understanding the catalytic activity is a fundamental goal in elucidating the molecular mechanisms of Alzheimer's and associated diseases. Here we explore the role of fibril structure and hydrophobicity by asking whether the V18, A21, V40, and A42 side chains which are exposed on the Aβ42 fibril surface as continuous hydrophobic patches play a role in secondary nucleation. Single, double, and quadruple serine substitutions were made. Kinetic analyses of aggregation data at multiple monomer concentrations reveal that all seven mutants retain the dominance of secondary nucleation as the main mechanism of fibril proliferation. This finding highlights the generality of secondary nucleation and its independence of the detailed molecular structure. Cryo-electron micrographs reveal that the V18S substitution causes fibrils to adopt a distinct morphology with longer twist distance than variants lacking this substitution. Self- and cross-seeding data show that surface catalysis is only efficient between peptides of identical morphology, indicating a templating role of secondary nucleation with structural conversion at the fibril surface. Our findings thus provide clear evidence that the propagation of amyloid fibril strains is possible even in systems dominated by secondary nucleation rather than fragmentation.


  • Biochemistry and Structural Biology
  • NanoLund: Center for Nanoscience
  • MultiPark: Multidisciplinary research focused on Parkinson´s disease

Publishing year







Proceedings of the National Academy of Sciences of the United States of America





Document type

Journal article


National Academy of Sciences


  • Cell and Molecular Biology


  • Amyloid
  • Secondary nucleation
  • Strain propagation
  • Surface catalysis




  • ISSN: 0027-8424