The microtubule-associated protein Tau plays a central role in the pathogenesis of Alzheimer’s disease. Although Tau interaction with membranes is thought to affect some of its physiological functions and its aggregation properties, the sequence determinants and the structural and functional consequences of such interactions remain poorly understood. Here, we report that the interaction of Tau with vesicles results in the formation of highly stable protein/phospholipid complexes. These complexes are toxic to primary hippocampal cultures and are detected by MC-1, an antibody recognizing pathological Tau conformations. The core of these complexes is comprised of the PHF6* and PHF6 hexapeptide motifs, the latter in a β-strand conformation. Studies using Tau-derived peptides enabled the design of mutants that disrupt Tau interactions with phospholipids without interfering with its ability to form fibrils, thus providing powerful tools for uncoupling these processes and investigating the role of membrane interactions in regulating Tau function, aggregation and toxicity.

A strategy for simplified and complete resonance assignment of insoluble and noncrystalline proteins by solid-state NMR (ssNMR) spectroscopy is presented. Proteins produced with [1-13 C]-or [2-13 C]glucose are very sparsely labeled, and the resulting 2D ssNMR spectra exhibit smaller line widths (by a factor of ∼2 relative to uniformly labeled proteins) and contain a reduced number of crosspeaks. This allows for an accelerated and straightforward resonance assignment without the necessity of time-consuming 3D spectroscopy or sophisticated pulse sequences. The strategy aims at complete backbone and side-chain resonance assignments based on bidirectional sequential walks. The approach was successfully demonstrated with the de novo assignment of the Type Three Secretion System PrgI needle protein. Using a limited set of simple 2D experiments, we report a 97% complete resonance assignment of the backbone and side-chain 13 C atoms.R ecent developments in magic-angle-spinning (MAS) solidstate NMR (ssNMR) methodology, 1À4 isotope labeling schemes, 5,6 structure calculation protocols, 7,8 and access to highfield instrumentation have allowed details at atomic resolution and, in the most favorable cases, high-resolution structures of microcrystalline proteins, 6À11 fibrillar aggregates, 12À17 oligomeric complexes, 18À22 and membrane proteins in nativelike environments 23À26 to be obtained. However, achieving a sufficient (and if possible, nearly complete) assignment of the NMR signals still remains as a major obstacle in obtaining site-specific structural information. The lack of resolution and the spectral overlap observed in uniformly ([U-13 C]glucose) labeled proteins requires the use of several 2D experiments 27 and, in the case of remaining assignment ambiguities, 3D or 4D spectroscopy. This renders the assignment step extremely time-consuming and demanding in terms of instrument performance and access to high-field spectrometers. An alternative to uniform labeling is the use of 13 C alternate labeling schemes, 5,28,29 which reduce spectral crowding and facilitate the assignment and the collection of distance restraints, as previously demonstrated 5,6 with glycerolbased labeling schemes.We recently reported 30 the use of mixtures of [1-13 C]-5 and [2-13 C]glucose (Glc) 29 for ssNMR studies of supramolecular protein interfaces. The high spectral quality observed for [1-13 C]-and [2-13 C]Glc-labeled R-synuclein already suggested that this labeling scheme could be useful for resonance assignments. Here we demonstrate that [1-13

The aggregation of α-synuclein (α-syn) is considered the key pathogenic event in many neurological disorders such as Parkinson's disease (PD), dementia with Lewy bodies and multiple system atrophy, giving rise to a whole category of neurodegenerative diseases known as synucleinopathies. Although the molecular basis of α-syn toxicity has not been precisely elucidated, a great deal of effort has been put into identifying compounds that could inhibit or even reverse the aggregation process. Previous reports indicated that many phenolic compounds are potent inhibitors of α-syn aggregation. The aim of the present study was to assess the anti-aggregating effect of gallic acid (GA) (3,4,5-trihydroxybenzoic acid), a benzoic acid derivative that belongs to a group of phenolic compounds known as phenolic acids. By employing an array of biophysical and biochemical techniques and a cell-viability assay, GA was shown not only to inhibit α-syn fibrillation and toxicity but also to disaggregate preformed α-syn amyloid fibrils. Interestingly, GA was found to bind to soluble, non-toxic oligomers with no β-sheet content, and to stabilize their structure. The binding of GA to the oligomers may represent a potential mechanism of action. Additionally, by using structure activity relationship data obtained from fourteen structurally similar benzoic acid derivatives, it was determined that the inhibition of α-syn fibrillation by GA is related to the number of hydroxyl moieties and their position on the phenyl ring. GA may represent the starting point for designing new molecules that could be used for the treatment of PD and related disorders.

A single amyloidogenic protein is implicated in multiple neurological diseases and capable of generating a number of aggregate “strains” with distinct structures. Among the amyloidogenic proteins, α-synuclein generates multiple patterns of proteinopathies in a group of diseases, such as Parkinson disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). However, the link between specific conformations and distinct pathologies, the key concept of the strain hypothesis, remains elusive. Here we show that in the presence of bacterial endotoxin, lipopolysaccharide (LPS), α-synuclein generated a self-renewable, structurally distinct fibril strain that consistently induced specific patterns of synucleinopathies in mice. These results suggest that amyloid fibrils with self-renewable structures cause distinct types of proteinopathies despite the identical primary structure and that exposure to exogenous pathogens may contribute to the diversity of synucleinopathies.