Structure of the toxic core of α-synuclein from invisible crystals

Abstract

Summary The protein α-synuclein is the main component of Lewy bodies, the neuron-associated aggregates seen in Parkinson’s disease and other neurodegenerative pathologies. An 11-residue segment, which we term NACore, appears responsible for amyloid formation and cytotoxicity of α-synuclein. Here we report crystals of NACore having dimensions smaller than the wavelength of visible light and thus invisible by optical microscopy. Thousands of times too small for structure determination by synchrotron x-ray diffraction, these crystals have yielded an atomic resolution structure by the frontier method of Micro-Electron Diffraction. The 1.4 Å resolution structure demonstrates for the first time that this method can determine previously unknown protein structures and here yields the highest resolution achieved by any cryo-electron microscopy method to date. The structure reveals protofibrils built of pairs of face-to-face β-sheets. X-ray fiber diffraction patterns show the similarity of NACore to toxic fibrils of full-length α-synuclein. The NACore structure, together with that of a second segment, inspires a model for most of the ordered portion of the toxic, full-length α-synuclein fibril, opening opportunities for design of inhibitors of α-synuclein fibrils.

Familial Parkinson’s point mutation abolishes multiple system atrophy prion replication

“…***P < 0.001, ****P < 0.0001. not feasible to generate, and only recently has cryo-electron microscopy (cryo-EM) enabled structural biologists to ascertain the structure of tau prions from an Alzheimer's disease patient (12). A handful of α-synuclein structures have been reported using synthetic fibrils, although many are based on highly ordered protein fragments (13)(14)(15)(16). Comparing our finding that the E46K mutation blocks MSA prion replication with the published α-synuclein structures, we noted that the Greek key motif proposed by Tuttle et al (13), which is based on a solid-state NMR structure of full-length fibrils, suggests that residue E46 forms an important salt bridge with K80 to stabilize the conformation.…”

Optical Structural Analysis of Individual α‐Synuclein Oligomers

“…Genetic and pathological evidence suggests that the protein α‐synuclein is central to neurodegeneration in PD 4. Specifically, the transition from an intrinsically disordered α‐synuclein monomer through a series of oligomeric intermediates (with varying structures and size) to a highly structured filament5, 6 is recognised to drive pathogenesis in α‐synucleinopathies. Furthermore, aggregates of α‐synuclein exhibit cell–cell transfer, leading to seeding and recruitment of more protein molecules to form additional aggregates that can generate new seeds in an exponential way,7 leading to the region–region spread of disease.…”

Analysis of Diffracted Intensities from Finite Protein Crystals with Incomplete Unit Cells

“…SXC experiments on finite protein crystals require the merging of diffraction data from large quantities of crystals to address experimental limitations imposed by radiation damage and for the collection of three-dimensional structural information. Diffraction data collected in microED experiments have also been reported to be merged from multiple crystals in some instances [24,25]. As derived by Kirian et al [13], the diffracted intensity distribution averaged from n finite crystals can be expressed as…”