Human Tau isoforms assemble into ribbon-like fibrils that display polymorphic structure and stability.
Fibrous aggregates of Tau protein are characteristic features of Alzheimer disease. We applied high resolution atomic force and EM microscopy to study fibrils assembled from different human Tau isoforms and domains. All fibrils reveal structural polymorphism; the "thin twisted" and "thin smooth" fibrils resemble flat ribbons (cross-section approximately 10 x 15 nm) with diverse twist periodicities. "Thick fibrils" show periodicities of approximately 65-70 nm and thicknesses of approximately 9-18 nm such as routinely reported for "paired helical filaments" but structurally resemble heavily twisted ribbons. Therefore, thin and thick fibrils assembled from different human Tau isoforms challenge current structural models of paired helical filaments. Furthermore, all Tau fibrils reveal axial subperiodicities of approximately 17-19 nm and, upon exposure to mechanical stress or hydrophobic surfaces, disassemble into uniform fragments that remain connected by thin thread-like structures ( approximately 2 nm). This hydrophobically induced disassembly is inhibited at enhanced electrolyte concentrations, indicating that the fragments resemble structural building blocks and the fibril integrity depends largely on hydrophobic and electrostatic interactions. Because full-length Tau and repeat domain constructs assemble into fibrils of similar thickness, the "fuzzy coat" of Tau protein termini surrounding the fibril axis is nearly invisible for atomic force microscopy and EM, presumably because of its high flexibility.
Wegmann
Susanne
S
Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland.
Jung
Yu Jin
YJ
Biotechnology Center, University of Technology, 01307 Dresden, Germany.
Chinnathambi
Subashchandrabose
S
Max-Planck-Unit for Structural Molecular Biology, c/o DESY, 22607 Hamburg, Germany and the German Center for Neurodegenerative Diseases, c/o CAESAR, 53175 Bonn, Germany.
Mandelkow
Eva-Maria
EM
Max-Planck-Unit for Structural Molecular Biology, c/o DESY, 22607 Hamburg, Germany and the German Center for Neurodegenerative Diseases, c/o CAESAR, 53175 Bonn, Germany.
Mandelkow
Eckhard
E
Max-Planck-Unit for Structural Molecular Biology, c/o DESY, 22607 Hamburg, Germany and the German Center for Neurodegenerative Diseases, c/o CAESAR, 53175 Bonn, Germany. Electronic address: mand@mpasmb.desy.de.
Muller
Daniel J
DJ
Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland. Electronic address: daniel.mueller@bsse.ethz.ch.
D000544:Alzheimer Disease / Q000378:metabolism; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000648:ultrastructure*; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D016875:tau Proteins / Q000737:chemistry* / Q000378:metabolism
C054369:MAPT protein, human; D046912:Multiprotein Complexes; D020033:Protein Isoforms; D016875:tau Proteins