Journal article
In vitro 0N4R tau fibrils contain a monomorphic β-sheet core enclosed by dynamically heterogeneous fuzzy coat segments
Proceedings of the National Academy of Sciences - PNAS, Vol.116(33), pp.16357-16366
08/13/2019
DOI: 10.1073/pnas.1906839116
PMCID: PMC6697781
PMID: 31358628
Abstract
SignificanceThe microtubule-binding protein tau misfolds into filamentous aggregates in many neurodegenerative diseases. Understanding the structure and dynamics of tau fibrils is important for designing anti-tau inhibitors. Patient-brain-derived tau fibrils have been shown to adopt disease-specific molecular conformations, but in vitro heparin-fibrillized tau was recently proposed to exhibit significant structural polymorphism. Using solid-state NMR, we show that the β-sheet core of heparin-fibrillized 0N4R tau adopts a single molecular conformation that encompasses the second and third microtubule-binding repeats, and both cysteine residues in the protein are involved in side-chain packing with other β-sheet residues. Extensive characterization of the protein dynamics indicates that these tau fibrils are heterogeneously dynamic, and the first and fourth microtubule-binding repeats are semirigid while retaining β-sheet character.
Misfolding of the microtubule-binding protein tau into filamentous aggregates is characteristic of many neurodegenerative diseases such as Alzheimer’s disease and progressive supranuclear palsy. Determining the structures and dynamics of these tau fibrils is important for designing inhibitors against tau aggregation. Tau fibrils obtained from patient brains have been found by cryo-electron microscopy to adopt disease-specific molecular conformations. However, in vitro heparin-fibrillized 2N4R tau, which contains all four microtubule-binding repeats (4R), was recently found to adopt polymorphic structures. Here we use solid-state NMR spectroscopy to investigate the global fold and dynamics of heparin-fibrillized 0N4R tau. A single set of 13C and 15N chemical shifts was observed for residues in the four repeats, indicating a single β-sheet conformation for the fibril core. This rigid core spans the R2 and R3 repeats and adopts a hairpin-like fold that has similarities to but also clear differences from any of the polymorphic 2N4R folds. Obtaining a homogeneous fibril sample required careful purification of the protein and removal of any proteolytic fragments. A variety of experiments and polarization transfer from water and mobile side chains indicate that 0N4R tau fibrils exhibit heterogeneous dynamics: Outside the rigid R2–R3 core, the R1 and R4 repeats are semirigid even though they exhibit β-strand character and the proline-rich domains undergo large-amplitude anisotropic motions, whereas the two termini are nearly isotropically flexible. These results have significant implications for the structure and dynamics of 4R tau fibrils in vivo.
Details
- Title: Subtitle
- In vitro 0N4R tau fibrils contain a monomorphic β-sheet core enclosed by dynamically heterogeneous fuzzy coat segments
- Creators
- Aurelio J. Dregni - Massachusetts Institute of TechnologyVenkata S. Mandala - Massachusetts Institute of TechnologyHaifan Wu - University of California, San FranciscoMatthew R. Elkins - Massachusetts Institute of TechnologyHarrison K. Wang - Massachusetts Institute of TechnologyIvan Hung - National High Magnetic Field LaboratoryWilliam F. DeGrado - University of California, San FranciscoMei Hong - Massachusetts Institute of Technology
- Resource Type
- Journal article
- Publication Details
- Proceedings of the National Academy of Sciences - PNAS, Vol.116(33), pp.16357-16366
- DOI
- 10.1073/pnas.1906839116
- PMID
- 31358628
- PMCID
- PMC6697781
- NLM abbreviation
- Proc Natl Acad Sci U S A
- ISSN
- 0027-8424
- eISSN
- 1091-6490
- Publisher
- National Academy of Sciences
- Number of pages
- 10
- Language
- English
- Date published
- 08/13/2019
- Academic Unit
- Biochemistry and Molecular Biology
- Record Identifier
- 9985112880302771
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