Elucidation of Primary Structure Elements Controlling Early Amyloid β-Protein Oligomerization

Bitan, Gal; Vollers, Sabrina S.; Teplow, David B.

doi:10.1074/jbc.m300825200

Cited by 280 publications

(406 citation statements)

References 63 publications

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“…Substitution of Ile-41 by Gly, eliminating both the side chain and the stereocenter of the C R group, yielded a distribution that was qualitatively similar to that of A -(1-40) ( Figure 4B). 36 When Ile-41 was substituted by Ala, the oligomer size distribution was a composite of the distributions characteristic of A (1-40) and A (1-42) ( Figure 4B), whereas substitution of Ile-41 by Val or Leu yielded distributions that were similar to WT A (1-42) in the amount of paranuclei formed but displayed substantially fewer high order oligomers. 36 These data indicated that a minimal alkyl side-chain in position 41, such as the methyl group of Ala, was essential for paranucleus formation.…”

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 98%

“…36 When Ile-41 was substituted by Ala, the oligomer size distribution was a composite of the distributions characteristic of A (1-40) and A (1-42) ( Figure 4B), whereas substitution of Ile-41 by Val or Leu yielded distributions that were similar to WT A (1-42) in the amount of paranuclei formed but displayed substantially fewer high order oligomers. 36 These data indicated that a minimal alkyl side-chain in position 41, such as the methyl group of Ala, was essential for paranucleus formation. Moreover, whereas the propyl and iso-butyl side chains of Val and Leu, respectively, supported paranucleus formation, the sec-butyl side chain of Ile-41 was important for paranucleus self-association ( Figure 4B).…”

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 98%

“…Similarly, truncation of the N-terminal 2 or 4 residues of A (1-40) yielded distributions characterized by formation of higher order oligomers ( Figure 5C), whereas equivalent truncations of A (1-42) did not affect the oligomer size distributions ( Figure 5D). 36 In contrast, substitution of Ala-21 by Gly (Flemish mutation), or of Phe-19 by Pro (a modification known to abolish fibril formation), altered the oligomer size distribution of A -(1-42) ( Figure 5B) but had little effect on the distribution of A (1-40) oligomers ( Figure 5A) (a full discussion of the effects of the structural modifications described here is given in ref 36).…”

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 99%

“…Substitution of Glu-22 by Gln (Dutch mutation), Gly (Arctic mutation), or Lys (Italian mutation), or substitution of Asp-23 by Asn (Iowa mutation) led to formation of A (1-40) oligomers of higher order than those observed for WT A (1-40) ( Figure 5A). 36 The same substitutions had essentially no effect on the oligomer size distributions of A (1-42) analogues (Figure . 5B).…”

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 99%

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Rapid Photochemical Cross‐Linking — A New Tool for Studies of Metastable, Amyloidogenic Protein Assemblies

Bitan¹,

Teplow²

2004

ChemInform

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104

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Amyloidoses comprise a class of diseases characterized pathologically by the presence of deposits of fibrillar, aberrantly folded proteins, known as amyloids. Historically, these deposits were considered the key factors causing disease. However, recent evidence suggests that soluble protein oligomers, which are precursors for amyloid fibrils, are the primary toxic effectors responsible for the disease process. Understanding the mechanism by which these oligomers exert their toxicity requires knowledge of the structure, kinetics, and thermodynamics of their formation and conversion into larger assemblies. Such studies have been difficult due to the metastable nature of the oligomers. For the amyloid -protein (A ), a consensus about the size and relative abundance of small oligomers has not been achieved. We describe here the application of the method Photoinduced Cross-Linking of Unmodified Proteins (PICUP) to the study of A oligomerization. This approach distinguishes oligomerization patterns of amyloidogenic and nonamyloidogenic proteins, allows quantification of each component in oligomer mixtures, and provides a means of correlating primary structure modifications with assembly characteristics. PICUP thus is a powerful tool for the investigation of small, metastable protein oligomers. The method provides essential insights into the factors that control the assembly of pathogenic protein oligomers, facilitating efforts toward the development of therapeutic agents.

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Section: Picup As a Tool For Structural Studiesmentioning

confidence: 98%

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 98%

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 99%

Section: Picup As a Tool For Structural Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Rapid Photochemical Cross‐Linking — A New Tool for Studies of Metastable, Amyloidogenic Protein Assemblies

Bitan¹,

Teplow²

2004

ChemInform

Self Cite

104

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“…During PICUP coupled with sizeexclusion chromatography, A␤40 and A␤42 display distinct oligomer size distributions: A␤40 displays a rapid equilibrium among monomers, dimers, trimers, and tetramers, whereas A␤42 preferentially forms pentamer͞hexamer units (paranuclei), which further assemble into beaded superstructures similar to early protofibrils (15). Additional studies of primary structure elements controlling early oligomerization demonstrate that Ile-41 is critical for paranucleus formation by A␤42 and that Ala-42 is necessary for further assembly of A␤42 into larger oligomers (16). In addition, oxidation of Met-35 blocks paranucleus formation but does not alter the A␤40 oligomer size distribution (17).…”

mentioning

confidence: 99%

In silico study of amyloid β-protein folding and oligomerization

Urbanc

Cruz

Yun

et al. 2004

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

327

478

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Experimental findings suggest that oligomeric forms of the amyloid ␤ protein (A␤) play a critical role in Alzheimer's disease. Thus, elucidating their structure and the mechanisms of their formation is critical for developing therapeutic agents. We use discrete molecular dynamics simulations and a four-bead protein model to study oligomerization of two predominant alloforms, A␤40 and A␤42, at the atomic level. The four-bead model incorporates backbone hydrogen-bond interactions and amino acid-specific interactions mediated through hydrophobic and hydrophilic elements of the side chains. During the simulations we observe monomer folding and aggregation of monomers into oligomers of variable sizes. A␤40 forms significantly more dimers than A␤42, whereas pentamers are significantly more abundant in A␤42 relative to A␤40. Structure analysis reveals a turn centered at Gly-37-Gly-38 that is present in a folded A␤42 monomer but not in a folded A␤40 monomer and is associated with the first contacts that form during monomer folding. Our results suggest that this turn plays an important role in A␤42 pentamer formation. A␤ pentamers have a globular structure comprising hydrophobic residues within the pentamer's core and hydrophilic N-terminal residues at the surface of the pentamer. The N termini of A␤40 pentamers are more spatially restricted than A␤42 pentamers. A␤40 pentamers form a ␤-strand structure involving Ala-2-Phe-4, which is absent in A␤42 pentamers. These structural differences imply a different degree of hydrophobic core exposure between pentamers of the two alloforms, with the hydrophobic core of the A␤42 pentamer being more exposed and thus more prone to form larger oligomers.Alzheimer's disease ͉ discrete molecular dynamics ͉ four-bead protein model ͉ oligomer formation T he amyloid ␤-protein (A␤) has been strongly linked to the etiology and pathogenesis of Alzheimer's disease (AD). A␤ assembles into amyloid fibrils and smaller, oligomeric assemblies. Experimental and clinical findings suggest that protofibrillar intermediates (1-3) and oligomeric forms (4-13) of A␤ may be particularly important. If so, elucidating the structures of these A␤ oligomers and the mechanisms of their formation is critical for developing therapeutic agents. Unlike proteins with stable folds, A␤ oligomers are metastable. They cannot be crystallized for x-ray diffraction studies nor can they be easily studied by using solutionphase NMR. Monomers and oligomers are also in dynamic equilibrium, which makes the study of pure populations of conformers using classical biophysical techniques difficult.A␤ exists in two predominant forms, 40 (A␤40) or 42 (A␤42) amino acids in length. Of the two, A␤42 is associated most strongly with an increased risk for AD, is more neurotoxic, and forms fibrils significantly faster. Recent experiments demonstrated that A␤ oligomers can be covalently cross-linked, and therefore stabilized, by using the technique of photo-induced cross-linking of unmodified proteins (PICUP) (14). During PICUP coupled with si...

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Internalisation and toxicity of amyloid‐β 1‐42 are influenced by its conformation and assembly state rather than size

et al. 2020

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Amyloid fibrils found in plaques in Alzheimer’s disease (AD) brains are composed of amyloid‐β peptides. Oligomeric amyloid‐β 1‐42 (Aβ42) is thought to play a critical role in neurodegeneration in AD. Here, we determine how size and conformation affect neurotoxicity and internalisation of Aβ42 assemblies using biophysical methods, immunoblotting, toxicity assays and live‐cell imaging. We report significant cytotoxicity of Aβ42 oligomers and their internalisation into neurons. In contrast, Aβ42 fibrils show reduced internalisation and no toxicity. Sonicating Aβ42 fibrils generates species similar in size to oligomers but remains nontoxic. The results suggest that Aβ42 oligomers have unique properties that underlie their neurotoxic potential. Furthermore, we show that incubating cells with Aβ42 oligomers for 24 h is sufficient to trigger irreversible neurotoxicity.

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Elucidation of Primary Structure Elements Controlling Early Amyloid β-Protein Oligomerization

Cited by 280 publications

References 63 publications

Rapid Photochemical Cross‐Linking — A New Tool for Studies of Metastable, Amyloidogenic Protein Assemblies

Rapid Photochemical Cross‐Linking — A New Tool for Studies of Metastable, Amyloidogenic Protein Assemblies

In silico study of amyloid β-protein folding and oligomerization

Internalisation and toxicity of amyloid‐β 1‐42 are influenced by its conformation and assembly state rather than size

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