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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Structural characterization of polyglutamine fibrils by solid-state NMR spectroscopy.
Robert Schneider1, Miria C Schumacher, Henrik Mueller
1Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Journal of Molecular Biology
|July 19, 2011
Summary
Polyglutamine (PolyQ) protein aggregates in neurodegenerative diseases like Huntington's disease. Our study reveals a consistent fibril structure across varying PolyQ lengths, suggesting a common aggregation mechanism.
Area of Science:
- Biochemistry
- Structural Biology
- Neuroscience
Background:
- Polyglutamine (PolyQ) expansions are implicated in severe neurodegenerative diseases, including Huntington's disease.
- The precise structural basis of PolyQ aggregation and its correlation with toxicity remain incompletely understood.
Purpose of the Study:
- To investigate the fibrillar structure of polyglutamine peptides with varying lengths (below, at, and above the toxicity threshold).
- To elucidate the molecular arrangement and conformational states within these aggregates.
Main Methods:
- Solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy, specifically dipolar correlation experiments.
- Electron Microscopy (EM) for structural visualization.
Main Results:
- Consistent dry fibril core width (70-80 Å) observed across all polyglutamine lengths.
- Predominantly β-strand secondary structure with tight interdigitation of glutamine side chains.
- Identification of two distinct glutamine residue populations, suggesting conformational heterogeneity.
- Shorter peptides (15 glutamines) form single β-strands, while longer constructs adopt a superpleated arrangement.
Conclusions:
- Polyglutamine fibril formation exhibits a conserved structural core regardless of length.
- The superpleated model provides a framework for understanding the assembly of longer polyglutamine aggregates.
- Structural insights may inform therapeutic strategies targeting polyglutamine-mediated neurodegeneration.
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