Aggregation and fibril morphology of the Arctic mutation of Alzheimer's Aβ peptide by CD, TEM, STEM and in situ AFM
2012 (English)In: Journal of Structural Biology, ISSN 1047-8477, E-ISSN 1095-8657, Vol. 180, no 1, 174-189 p.Article in journal (Refereed) Published
Morphology of aggregation intermediates, polymorphism of amyloid fibrils and aggregation kinetics of the "Arctic" mutant of the Alzheimer's amyloid β-peptide, Aβ((1-40))(E22G), in a physiologically relevant Tris buffer (pH 7.4) were thoroughly explored in comparison with the human wild type Alzheimer's amyloid peptide, wt-Aβ((1-40)), using both in situ atomic force and electron microscopy, circular dichroism and thioflavin T fluorescence assays. For arc-Aβ((1-40)) at the end of the 'lag'-period of fibrillization an abrupt appearance of ∼3nm size 'spherical aggregates' with a homogeneous morphology, was identified. Then, the aggregation proceeds with a rapid growth of amyloid fibrils with a variety of morphologies, while the spherical aggregates eventually disappeared during in situ measurements. Arc-Aβ((1-40)) was also shown to form fibrils at much lower concentrations than wt-Aβ((1-40)): ⩽2.5μM and 12.5μM, respectively. Moreover, at the same concentration, 50μM, the aggregation process proceeds more rapidly for arc-Aβ((1-40)): the first amyloid fibrils were observed after c.a. 72h from the onset of incubation as compared to approximately 7days for wt-Aβ((1-40)). Amyloid fibrils of arc-Aβ((1-40)) exhibit a large variety of polymorphs, at least five, both coiled and non-coiled distinct fibril structures were recognized by AFM, while at least four types of arc-Aβ((1-40)) fibrils were identified by TEM and STEM and their mass-per-length statistics were collected suggesting supramolecular structures with two, four and six β-sheet laminae. Our results suggest a pathway of fibrillogenesis for full-length Alzheimer's peptides with small and structurally ordered transient spherical aggregates as on-pathway immediate precursors of amyloid fibrils.
Place, publisher, year, edition, pages
San Diego, CA, USA: Academic Press, 2012. Vol. 180, no 1, 174-189 p.
Amyloid β-peptide, Arctic mutation, Spherical aggregates, Polymorphism of amyloid fibrils, AFM, TEM, STEM, Mass-per-length measurements, Real time growth, CD, ThT assay
IdentifiersURN: urn:nbn:se:umu:diva-58029DOI: 10.1016/j.jsb.2012.06.010PubMedID: 22750418OAI: oai:DiVA.org:umu-58029DiVA: diva2:546522