How Does Hyperphopsphorylation Promote Tau Aggregation and Modulate Filament Structure and Stability?

Liang Xu, Jie Zheng, Martin Margittai, Ruth Nussinov, Buyong Ma*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Tau proteins are hyperphosphorylated at common sites in their N- and C-terminal domains in at least three neurodegenerative diseases, Parkinson, dementia with Lewy bodies, and Alzheimer's, suggesting specific pathology but general mechanism. Full-length human tau filament comprises a rigid core and a two-layered fuzzy coat. Tau is categorized into two groups of isoforms, with either four repeats (R1-R4) or three repeats (R1, R3, and R4); their truncated constructs are respectively called K18 and K19. Using multiscale molecular dynamics simulations, we explored the conformational consequences of hyperhposphorylation on tau's repeats. Our lower conformational energy filament models suggest a rigid filament core with a radius of ∼30 to 40 Å and an outer layer with a thickness of ∼140 Å consisting of a double-layered polyelectrolyte. The presence of the phosphorylated terminal domains alters the relative stabilities in the K18 ensemble, thus shifting the populations of the full-length filaments. However, the structure with the straight repeats in the core region is still the most stable, similar to the truncated K18 peptide species without the N- and C-terminus. Our simulations across different scales of resolution consistently reveal that hyperphosphorylation of the two terminal domains decreases the attractive interactions among the N- and C-terminus and repeat domain. To date, the relationship on the conformational level between phosphorylation and aggregation has not been understood. Our results suggest that the exposure of the repeat domain upon hyperphosphorylation could enhance tau filament aggregation. Thus, we discovered that even though these neurodegenerative diseases vary and their associated tau filaments are phosphorylated to different extents, remarkably, the three pathologies appear to share a common tau aggregation mechanism.

Original languageEnglish
Pages (from-to)565-575
Number of pages11
JournalACS Chemical Neuroscience
Volume7
Issue number5
DOIs
StatePublished - 18 May 2016

Funding

FundersFunder number
National Science FoundationCBET-0952624, CBET-1510099
National Institutes of HealthHHSN261200800001E
National Cancer InstituteZIABC010441
National Institute of Neurological Disorders and StrokeR01NS076619
Alzheimer's Association2015-NIRG-341372
China Scholarship CouncilCSC201306065001

    Keywords

    • Alzheimer's disease
    • Tau
    • amyloid
    • hyperphosphorylation
    • paired helical filaments

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