The role of shear forces in primary and secondary nucleation of amyloid fibrils

Emil Axell, Jing Hu, Max Lindberg, Alexander J. Dear, Lei Ortigosa-Pascual, Ewa A. Andrzejewska, Greta Šneiderienė, Dev Thacker, Tuomas P. J. Knowles, Emma Sparr, Sara Linse

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review

Sammanfattning

Shear forces affect self-assembly processes ranging from crystallization to fiber formation. Here, the effect of mild agitation on amyloid fibril formation was explored for four peptides and investigated in detail for Aβ42, which is associated with Alzheimer's disease. To gain mechanistic insights into the effect of mild agitation, nonseeded and seeded aggregation reactions were set up at various peptide concentrations with and without an inhibitor. First, an effect on fibril fragmentation was excluded by comparing the monomer-concentration dependence of aggregation kinetics under idle and agitated conditions. Second, using a secondary nucleation inhibitor, Brichos, the agitation effect on primary nucleation was decoupled from secondary nucleation. Third, an effect on secondary nucleation was established in the absence of inhibitor. Fourth, an effect on elongation was excluded by comparing the seeding potency of fibrils formed under idle or agitated conditions. We find that both primary and secondary nucleation steps are accelerated by gentle agitation. The increased shear forces facilitate both the detachment of newly formed aggregates from catalytic surfaces and the rate at which molecules are transported in the bulk solution to encounter nucleation sites on the fibril and other surfaces. Ultrastructural evidence obtained with cryogenic transmission electron microscopy and free-flow electrophoresis in microfluidics devices imply that agitation speeds up the detachment of nucleated species from the fibril surface. Our findings shed light on the aggregation mechanism and the role of detachment for efficient secondary nucleation. The results inform on how to modulate the relative importance of different microscopic steps in drug discovery and investigations.

Originalspråkengelska
Sidor (från-till)e2322572121
Antal sidor10
TidskriftProceedings of the National Academy of Sciences of the United States of America
Volym121
Nummer25
DOI
StatusPublished - 2024 juni 18

Ämnesklassifikation (UKÄ)

  • Fysikalisk kemi
  • Biofysik
  • Biokemi och molekylärbiologi

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