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Updated: Apr 3, 2026
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Sequence-specific solid-state NMR assignments of the mouse ASC PYRIN domain in its filament form
Francesco Ravotti1, Lorenzo Sborgi2, Riccardo Cadalbert1
1Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland.
Abstract:
The apoptosis-associated speck-like protein (ASC protein) plays a central role in eukaryotic innate immune response. Upon infection, multiple ASC molecules assemble into long filaments, which are fundamental for triggering the cellular defense mechanism by starting an inflammatory cascade with the activation of caspase-1. ASC is composed of two domains, the C-terminal caspase-recruitment domain, which is involved in the recruitment of the caspase, and the N-terminal PYRIN domain (PYD), which is responsible for the formation of the filament. Here we present the (13)C and (15)N chemical shift assignment for filaments formed by the PYD of mouse ASC, a 91-residue protein. The backbone between residues 4 and 84 is assigned without interruption. Also, 86 % of the sidechain resonances for this stretch are assigned. Residues 1-3 and 85-91 show unfavorable dynamics and are not observed. Secondary chemical-shift analysis shows the presence of six α-helices.
Insights
The apoptosis-associated speck-like protein (ASC) PYRIN domain forms filaments crucial for innate immunity. This study provides key chemical shift assignments for these mouse ASC PYD filaments, revealing their structural properties.
Area of Science:
- Biochemistry
- Immunology
- Structural Biology
Background:
- The apoptosis-associated speck-like protein (ASC) is vital for innate immunity, initiating inflammatory responses via caspase-1 activation.
- ASC functions through filament formation mediated by its PYRIN domain (PYD).
Purpose of the Study:
- To determine the (13)C and (15)N chemical shift assignments for filaments formed by the mouse ASC PYD.
- To elucidate the structural characteristics of ASC PYD filaments.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was used to obtain (13)C and (15)N chemical shift assignments.
- Secondary chemical shift analysis was employed to identify secondary structures.
Main Results:
- Complete backbone and 86% sidechain assignments were achieved for residues 4-84 of the mouse ASC PYD filament.
- Residues 1-3 and 85-91 exhibited unfavorable dynamics and were not observed.
- Secondary chemical shift analysis indicated the presence of six α-helices.
Conclusions:
- This study provides foundational NMR data for the mouse ASC PYD filament.
- The assigned chemical shifts will facilitate further structural and dynamic studies of ASC-mediated immune signaling.
