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1.
Nat Commun ; 10(1): 2493, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31175300

RESUMO

Tauopathies are neurodegenerative diseases characterized by intracellular amyloid deposits of tau protein. Missense mutations in the tau gene (MAPT) correlate with aggregation propensity and cause dominantly inherited tauopathies, but their biophysical mechanism driving amyloid formation is poorly understood. Many disease-associated mutations localize within tau's repeat domain at inter-repeat interfaces proximal to amyloidogenic sequences, such as 306VQIVYK311. We use cross-linking mass spectrometry, recombinant protein and synthetic peptide systems, in silico modeling, and cell models to conclude that the aggregation-prone 306VQIVYK311 motif forms metastable compact structures with its upstream sequence that modulates aggregation propensity. We report that disease-associated mutations, isomerization of a critical proline, or alternative splicing are all sufficient to destabilize this local structure and trigger spontaneous aggregation. These findings provide a biophysical framework to explain the basis of early conformational changes that may underlie genetic and sporadic tau pathogenesis.


Assuntos
Agregação Patológica de Proteínas/genética , Tauopatias/genética , Proteínas tau/genética , Motivos de Aminoácidos/genética , Simulação por Computador , Células HEK293 , Humanos , Espectrometria de Massas , Microscopia Eletrônica de Transmissão , Mutação de Sentido Incorreto , Agregação Patológica de Proteínas/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Proteínas tau/metabolismo , Proteínas tau/ultraestrutura
2.
Elife ; 72018 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-29988016

RESUMO

Tauopathies feature progressive accumulation of tau amyloids. Pathology may begin when these amplify from a protein template, or seed, whose structure is unknown. We have purified and characterized distinct forms of tau monomer-inert (Mi) and seed-competent (Ms). Recombinant Ms triggered intracellular tau aggregation, induced tau fibrillization in vitro, and self-assembled. Ms from Alzheimer's disease also seeded aggregation and self-assembled in vitro to form seed-competent multimers. We used crosslinking with mass spectrometry to probe structural differences in Mi vs. Ms. Crosslinks informed models of local peptide structure within the repeat domain which suggest relative inaccessibility of residues that drive aggregation (VQIINK/VQIVYK) in Mi, and exposure in Ms. Limited proteolysis supported this idea. Although tau monomer has been considered to be natively unstructured, our findings belie this assumption and suggest that initiation of pathological aggregation could begin with conversion of tau monomer from an inert to a seed-competent form.

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