A SAXS Study of Glucagon Fibrillation

Oliveira, Cristiano L. P.; Behrens, Manja A.; Pedersen, Jens Oluf; Erlacher, Kurt; Otzen, Daniel E.; Pedersen, Jan Skov

doi:10.1016/j.jmb.2009.01.020

Cited by 151 publications

(161 citation statements)

References 35 publications

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“…This is possible with small angle X-ray scattering (SAXS), a noninvasive technique that allows the study of fibrillation in solution under physiologically relevant conditions. Due to signal additivity SAXS can provide low-to-medium-resolution structural information from relatively simple polydisperse solutions as recently illustrated for fibrillation (13)(14)(15). Here we use SAXS to obtain structural information about the species present during the fibrillation of αSN at neutral pH and 37°C.…”

mentioning

confidence: 99%

Low-resolution structure of a vesicle disrupting α-synuclein oligomer that accumulates during fibrillation

Giehm

Svergun

Otzen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

226

264

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One of the major hallmarks of Parkinson disease is aggregation of the protein α-synuclein (αSN). Aggregate cytotoxicity has been linked to an oligomeric species formed at early stages in the aggregation process. Here we follow the fibrillation process of αSN in solution over time using small angle X-ray scattering and resolve four major coexisting species in the fibrillation process, namely monomer, dimer, fibril and an oligomer. By ab initio modeling to fit the data, we obtain a low-resolution structure of a symmetrical and slender αSN fibril in solution, consisting of a repeating unit with a maximal distance of 900 Å and a diameter of ∼180 Å. The same approach shows the oligomer to be shaped like a wreath, with a central channel and with dimensions corresponding to the width of the fibril. The structure, accumulation and decay of this oligomer is consistent with an on-pathway role for the oligomer in the fibrillation process. We propose an oligomer-driven αSN fibril formation mechanism, where the fibril is built from the oligomers. The wreath-shaped structure of the oligomer highlights its potential cytotoxicity by simple membrane permeabilization. This is confirmed by the ability of the purified oligomer to disrupt liposomes. Our results provide the first structural description in solution of a potentially cytotoxic oligomer, which accumulates during the fibrillation of αSN.alpha-synuclein | amyloid | structral nucleus | solution structure P arkinson Disease (PD) is a common neurodegenerative disorder of the brain. Hallmarks of PD are massive death of dopaminergic neurons and formation of intracellular Lewy bodies (LBs). LBs mainly consist of large fibrillar inclusions of α-synuclein (αSN), a 140-residue natively unfolded protein (1). Numerous in vitro studies of αSN fibrillation have shown that fibril formation is a nucleated polymerization and that oligomers form transiently in the lag phase (1-5). Such oligomers, rather than fibrils or monomers, have been suggested to be the neurotoxic species (4, 6), however whether the oligomers are on-or offpathway in fibril formation and whether the cytotoxic species corresponds to the nucleus of fibrillation remain unclear. Neurotoxicity is proposed to arise from a pore-like membrane permeabilization (6) or by destabilization of the membrane allowing nonspecific ion-transport (7). Unambiguous structural information of the cytotoxic species is difficult to obtain due to sample coexistence of different species, sensitivity to sample handling and potential surface-binding artifacts. The morphology of purified oligomers from wildtype and mutant αSN have been studied by atomic force microscopy (AFM) and electron microscopy (EM) (4, 5), but purified oligomers may be structurally and functionally distinct from those in equilibrium with monomers and fibrils. Different conditions can lead to different oligomers (4, 5, 8) with varying ability to disrupt artificial cell membranes (9-12). Ideally, structural studies should be conducted on an unperturbed ensemble of all potential ...

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mentioning

confidence: 99%

Low-resolution structure of a vesicle disrupting α-synuclein oligomer that accumulates during fibrillation

Giehm

Svergun

Otzen

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

226

264

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“…The presence of smaller aggregates such as oligomers and protofibrils formed during the nucleation process has recently been revealed experimentally for several proteins. Various techniques such as solid-state NMR (7), small angle x-ray scattering (12,13), site-directed labeling of fluorescence probes (8), hydrogen/deuterium (H/D) exchange experiments (14), and immunological assays (6) have revealed the structural details of the prefibrillar oligomers involved in fibrillation. However, quantifying and characterizing their physico-chemical properties are often hampered due to their unstable and heterogeneous properties; therefore, it is very difficult to clarify how these species contribute to the formation of mature fibrils with a rigid ␤-sheet core.…”

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confidence: 99%

Stepwise Organization of the β-Structure Identifies Key Regions Essential for the Propagation and Cytotoxicity of Insulin Amyloid Fibrils

Chatani

Imamura

Yamamoto

et al. 2014

Journal of Biological Chemistry

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“…A closer characterization of the experimental data was made by indirect Fourier transformation (IFT), using the method developed by Glatter (48) in a modified implementation (49,50). From the IFT transformations, indicated with solid black lines in Fig.…”

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confidence: 99%

The Role of Nanometer-Scaled Ligand Patterns in Polyvalent Binding by Large Mannan-Binding Lectin Oligomers

Gjelstrup

Kaspersen

Behrens

et al. 2012

The Journal of Immunology

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Mannan-binding lectin (MBL) is an important protein of the innate immune system and protects the body against infection through opsonization and activation of the complement system on surfaces with an appropriate presentation of carbohydrate ligands. The quaternary structure of human MBL is built from oligomerization of structural units into polydisperse complexes typically with three to eight structural units, each containing three lectin domains. Insight into the connection between the structure and ligand-binding properties of these oligomers has been lacking. In this article, we present an analysis of the binding to neoglycoprotein-coated surfaces by size-fractionated human MBL oligomers studied with small-angle x-ray scattering and surface plasmon resonance spectroscopy. The MBL oligomers bound to these surfaces mainly in two modes, with dissociation constants in the micro to nanomolar order. The binding kinetics were markedly influenced by both the density of ligands and the number of ligand-binding domains in the oligomers. These findings demonstrated that the MBL-binding kinetics are critically dependent on structural characteristics on the nanometer scale, both with regard to the dimensions of the oligomer, as well as the ligand presentation on surfaces. Therefore, our work suggested that the surface binding of MBL involves recognition of patterns with dimensions on the order of 10–20 nm. The recent understanding that the surfaces of many microbes are organized with structural features on the nanometer scale suggests that these properties of MBL ligand recognition potentially constitute an important part of the pattern-recognition ability of these polyvalent oligomers.

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A SAXS Study of Glucagon Fibrillation

Cited by 151 publications

References 35 publications

Low-resolution structure of a vesicle disrupting α-synuclein oligomer that accumulates during fibrillation

Low-resolution structure of a vesicle disrupting α-synuclein oligomer that accumulates during fibrillation

Stepwise Organization of the β-Structure Identifies Key Regions Essential for the Propagation and Cytotoxicity of Insulin Amyloid Fibrils

The Role of Nanometer-Scaled Ligand Patterns in Polyvalent Binding by Large Mannan-Binding Lectin Oligomers

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