Temperature-Dependent Structural Changes of Parkinson's Alpha-Synuclein Reveal the Role of Pre-Existing Oligomers in Alpha-Synuclein Fibrillization (original) (raw)
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Characterization of fibrillation process of α-synuclein at the initial stage
Biochemical and Biophysical Research Communications, 2008
a b s t r a c t a-Synuclein is the major component of the filamentous Lewy bodies and Lewy-related neurites, neuropathological hallmarks of Parkinson's disease. Although numerous studies on a-synuclein fibrillation have been reported, the molecular mechanisms of aggregation and fibrillation at the initial stage are still unclear. In the present study, structural properties and propensities to form fibrils of a-synuclein at the initial stage were investigated using 2D 1 H-15 N NMR spectroscopy, electron microscope, and small angle X-ray scattering (SAXS). Observation of the 2D 1 H-15 N HSQC spectra indicated significant attenuation of many cross peak intensities in the regions of KTKEGV-type repeats and the non-Ab component of Alzheimer's disease amyloid (NAC), suggesting that these regions contributed fibril formation. Oligomerization comprising heptamer was successfully monitored at the initial stage using the time-dependent SAXS measurements.
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The major component of neural inclusions that are the pathological hallmark of Parkinson's disease are amyloid fibrils of the protein a-synuclein (aS). Here we investigated if the disease-related mutation A30P not only modulates the kinetics of aS aggregation, but also alters the structure of amyloid fibrils. To this end we optimized the method of quenched hydrogen/deuterium exchange coupled to NMR spectroscopy and performed two-dimensional proton-detected highresolution magic angle spinning experiments. The combined data indicate that the A30P mutation does not cause changes in the number, location and overall arrangement of b-strands in amyloid fibrils of aS. At the same time, several residues within the fibrillar core retain nano-second dynamics. We conclude that the increased pathogenicity related to the familial A30P mutation is unlikely to be caused by a mutation-induced change in the conformation of aS aggregates.
Structural heterogeneity of α-synuclein fibrils amplified from patient brain extracts
Nature Communications
Parkinson’s disease (PD) and Multiple System Atrophy (MSA) are clinically distinctive diseases that feature a common neuropathological hallmark of aggregated α-synuclein. Little is known about how differences in α-synuclein aggregate structure affect disease phenotype. Here, we amplified α-synuclein aggregates from PD and MSA brain extracts and analyzed the conformational properties using fluorescent probes, NMR spectroscopy and electron paramagnetic resonance. We also generated and analyzed several in vitro α-synuclein polymorphs. We found that brain-derived α-synuclein fibrils were structurally different to all of the in vitro polymorphs analyzed. Importantly, there was a greater structural heterogeneity among α-synuclein fibrils from the PD brain compared to those from the MSA brain, possibly reflecting on the greater variability of disease phenotypes evident in PD. Our findings have significant ramifications for the use of non-brain-derived α-synuclein fibrils in PD and MSA stud...
Proceedings of the National Academy of Sciences, 2005
The 140-residue protein ␣-synuclein (AS) is able to form amyloid fibrils and as such is the main component of protein inclusions involved in Parkinson's disease. We have investigated the structure and dynamics of full-length AS fibrils by high-resolution solid-state NMR spectroscopy. Homonuclear and heteronuclear 2D and 3D spectra of fibrils grown from uniformly 13 C͞ 15 N-labeled AS and AS reverse-labeled for two of the most abundant amino acids, K and V, were analyzed. 13 C and 15 N signals exhibited linewidths of <0.7 ppm. Sequential assignments were obtained for 48 residues in the hydrophobic core region. We identified two different types of fibrils displaying chemical-shift differences of up to 13 ppm in the 15 N dimension and up to 5 ppm for backbone and side-chain 13 C chemical shifts. EM studies suggested that molecular structure is correlated with fibril morphology. Investigation of the secondary structure revealed that most amino acids of the core region belong to -strands with similar torsion angles in both conformations. Selection of regions with different mobility indicated the existence of monomers in the sample and allowed the identification of mobile segments of the protein within the fibril in the presence of monomeric protein. At least 35 C-terminal residues were mobile and lacked a defined secondary structure, whereas the N terminus was rigid starting from residue 22. Our findings agree well with the overall picture obtained with other methods and provide insight into the amyloid fibril structure and dynamics with residue-specific resolution.
Cryo-EM structure of alpha-synuclein fibrils
eLife, 2018
Parkinson's disease is a progressive neuropathological disorder that belongs to the class of synucleinopathies, in which the protein alpha-synuclein is found at abnormally high concentrations in affected neurons. Its hallmark are intracellular inclusions called Lewy bodies and Lewy neurites. We here report the structure of cytotoxic alpha-synuclein fibrils (residues 1-121), determined by cryo-electron microscopy at a resolution of 3.4 Å. Two protofilaments form a polar fibril composed of staggered β-strands. The backbone of residues 38 to 95, including the fibril core and the non-amyloid component region, are well resolved in the EM map. Residues 50-57, containing three of the mutation sites associated with familial synucleinopathies, form the interface between the two protofilaments and contribute to fibril stability. A hydrophobic cleft at one end of the fibril may have implications for fibril elongation, and invites for the design of molecules for diagnosis and treatment of s...
Structural Comparison of Mouse and Human α-Synuclein Amyloid Fibrils by Solid-State NMR
Journal of Molecular Biology, 2012
Fibrillar α-synuclein (AS) is the major component of Lewy bodies, the pathological hallmark of Parkinson's disease. Mouse AS (mAS) aggregates much faster than human AS (hAS), although mAS differs from hAS at only seven positions in its primary sequence. Currently, little is known about the site-specific structural differences between mAS and hAS fibrils. Here, we applied state-of-the-art solid-state nuclear magnetic resonance (ssNMR) methods to structurally characterize mAS fibrils. The assignment strategy employed a set of high-resolution 2D and 3D ssNMR spectra recorded on uniformly [ 13 C, 15 N], [1-13 C]glucose, and [2-13 C]glucose labeled mAS fibrils. An almost complete resonance assignment (96% of backbone amide 15 N and 93% of all 13 C nuclei) was obtained for residues from Gly41 to Val95, which form the core of mAS fibrils. Six β-strands were identified to be within the fibril core of mAS based on a secondary chemical shift and NHHC analysis. Intermolecular 13 C: 15 N labeled restraints obtained from mixed 1:1 13 C/ 15 Nlabeled mAS fibrils reveal a parallel, in-register supramolecular β-sheet arrangement. The results were compared in detail to recent structural studies on hAS fibrils and indicate the presence of a structurally conserved motif comprising residues Glu61-Lys80.
Structural and Biophysical Characterization of Stable Alpha-Synuclein Oligomers
International Journal of Molecular Sciences
The aggregation of α-synuclein (α-syn) into neurotoxic oligomers and fibrils is an important pathogenic feature of synucleinopatheis, including Parkinson’s disease (PD). A further characteristic of PD is the oxidative stress that results in the formation of aldehydes by lipid peroxidation. It has been reported that the brains of deceased patients with PD contain high levels of protein oligomers that are cross-linked to these aldehydes. Increasing evidence also suggests that prefibrillar oligomeric species are more toxic than the mature amyloid fibrils. However, due to the heterogenous and metastable nature, characterization of the α-syn oligomeric species has been challenging. Here, we generated and characterized distinct α-syn oligomers in vitro in the presence of DA and lipid peroxidation products 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE). HNE and ONE oligomer were stable towards the treatment with SDS, urea, and temperature. The secondary structure analysis revealed tha...
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Structural conversion of the presynaptic, intrinsically disordered protein a-synuclein into amyloid fibrils underlies neurotoxicity in Parkinson's disease. The detailed mechanism by which this conversion occurs is largely unknown. Here, we identify a discrete pattern of transient tertiary interactions in monomeric a-synuclein involving amino acid residues that are, in the fibrillar state, part of b-strands. Importantly, this pattern of pairwise interactions does not correspond to that found in the amyloid state. A redistribution of this network of fibril-like contacts must precede aggregation into the amyloid structure.
Journal of fluorescence, 2016
The etiology of Parkinson's disease involves the interplay between the environmental and genetic factors. Here in this study human α-synuclein upon exposure to 100 μM pendimethalin for 12 h in vitro passes through a partially folded state which proceeds to the aggregated state and terminally ends in the fibrillar phase. Variations in the ANS fluorescence intensities led to the detection of intermediate and aggregated states at 6 and 10 h respectively. Far-UV CD analysis depicted significant α-helical content for intermediate state at 6 h in presence of 100 μM pendimethalin. Further increasing the incubation time to 12 h resulted in a predominant β-sheet content which was confirmed to be fibrillar by TEM. Turbidity, Rayleigh scattering analysis, Congo red assay and ThT measurements supported the TEM data i.e. the formation of fibrillar structure of human α-synuclein upon 12 h incubation. Thus, our observation could suggest a possible underlying molecular basis for Parkinson's...