Solid-state NMR: An emerging technique in structural biology of self-assemblies

- Protein self-assemblies are involved in many biological processes.
- They are insoluble and non-crystalline, limiting X-ray crystallography and solution NMR.
- Magic-angle spinning solid-state NMR can probe atomic structural details.
- Several 3D atomic models of complex assemblies were derived from solid state NMR.
- Hybrid approaches are currently developed to combine solid-state NMR with complementary techniques.

Protein self-assemblies are ubiquitous biological systems involved in many cellular processes, ranging from bacterial and viral infection to the propagation of neurodegenerative disorders. Studying the atomic three-dimensional structures of protein self-assemblies is a particularly demanding task, as these systems are usually insoluble, non-crystalline and of large size. Solid-state NMR (ssNMR) is an emerging method that can provide atomic-level structural data on intact macromolecular assemblies. We here present recent progress in magic-angle spinning ssNMR to study protein assemblies and give an overview on its combination with complementary techniques such as cryo-EM, mass-per-length measurements, SAXS and X-ray diffraction. Applications of ssNMR on its own and in hybrid approaches have revealed precious atomic details and first high-resolution structures of complex biological assemblies, including amyloid fibrils, bacterial filaments, phages or virus capsids.