Mechanistic Studies of Peptide Self-Assembly: Transient α-Helices to Stable β-Sheets

Liu, Gai; Prabhakar, A.; Aucoin, Darryl; Simon, Miranda; Sparks, Samuel; Robbins, Kevin J.; Sheen, Andrew; Petty, Sarah A.; Lazo, Noel D.

doi:10.1021/ja1069882

Cited by 82 publications

(139 citation statements)

References 89 publications

Supporting

Mentioning

116

Contrasting

Order By: Relevance

“…8). This sort of self-assembly based on transient a-helices has been demonstrated also for model peptides (48,63), islet amyloid polypeptide (64), and a-synuclein (44), and also in vivo for the assembly of silk into its cross-b structure (65).…”

Section: The Very N-terminus Of Ab Affects Its Fibrillization Kineticsmentioning

confidence: 73%

Pyroglutamate-Modified Amyloid-β(3–42) Shows α-Helical Intermediates before Amyloid Formation

Dammers

Reiß

Gremer

et al. 2017

Biophysical Journal

View full text Add to dashboard Cite

Pyroglutamate-modified amyloid-b (pEAb) has been described as a relevant Ab species in Alzheimer's-diseaseaffected brains, with pEAb (3-42) as a dominant isoform. Ab (1-40) and Ab (1-42) have been well characterized under various solution conditions, including aqueous solutions containing trifluoroethanol (TFE). To characterize structural properties of pEAb (3-42) possibly underlying its drastically increased aggregation propensity compared to Ab (1-42), we started our studies in various TFE-water mixtures and found striking differences between the two Ab species. Soluble pEAb (3-42) has an increased tendency to form b-sheet-rich structures compared to Ab (1-42), as indicated by circular dichroism spectroscopy data. Kinetic assays monitored by thioflavin-T show drastically accelerated aggregation leading to large fibrils visualized by electron microscopy of pEAb (3-42) in contrast to Ab (1-42). NMR spectroscopy was performed for backbone and side-chain chemical-shift assignments of monomeric pEAb (3-42) in 40% TFE solution. Although the difference between pEAb (3-42) and Ab (1-42) is purely N-terminal, it has a significant impact on the chemical environment of >20% of the total amino acid residues, as revealed by their NMR chemical-shift differences. Freshly dissolved pEAb (3-42) contains two a-helical regions connected by a flexible linker, whereas the N-terminus remains unstructured. We found that these a-helices act as a transient intermediate to b-sheet and fibril formation of pEAb (3-42).

show abstract

Section: The Very N-terminus Of Ab Affects Its Fibrillization Kineticsmentioning

confidence: 73%

Pyroglutamate-Modified Amyloid-β(3–42) Shows α-Helical Intermediates before Amyloid Formation

Dammers

Reiß

Gremer

et al. 2017

Biophysical Journal

View full text Add to dashboard Cite

show abstract

“…Similarly, it also is possible that domain swapping occurs prior to nucleation, resulting in the assembly of native-like but transient oligomeric aggregates. Note that various oligomeric assemblies of amyloidogenic proteins feature ␣-helical or native-like structures (66,67) that typically, but not always (68), are lost during fibril maturation.…”

Section: Discussionmentioning

confidence: 99%

Amyloid-like Fibrils from a Domain-swapping Protein Feature a Parallel, in-Register Conformation without Native-like Interactions

Hoop

Kodali

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

The formation of amyloid-like fibrils is characteristic of various diseases, but the underlying mechanism and the factors that determine whether, when, and how proteins form amyloid, remain uncertain. Certain mechanisms have been proposed based on the three-dimensional or runaway domain swapping, inspired by the fact that some proteins show an apparent correlation between the ability to form domain-swapped dimers and a tendency to form fibrillar aggregates. Intramolecular ␤-sheet contacts present in the monomeric state could constitute intermolecular ␤-sheets in the dimeric and fibrillar states. One example is an amyloid-forming mutant of the immunoglobulin binding domain B1 of streptococcal protein G, which in its native conformation consists of a four-stranded ␤-sheet and one ␣-helix. Under native conditions this mutant adopts a domainswapped dimer, and it also forms amyloid-like fibrils, seemingly in correlation to its domain-swapping ability. We employ magic angle spinning solid-state NMR and other methods to examine key structural features of these fibrils. Our results reveal a highly rigid fibril structure that lacks mobile domains and indicate a parallel in-register ␤-sheet structure and a general loss of native conformation within the mature fibrils. This observation contrasts with predictions that native structure, and in particular intermolecular ␤-strand interactions seen in the dimeric state, may be preserved in "domain-swapping" fibrils. We discuss these observations in light of recent work on related amyloidforming proteins that have been argued to follow similar mechanisms and how this may have implications for the role of domain-swapping propensities for amyloid formation.Amyloid fibril formation is characteristic of a variety of human disorders, including Huntington and Alzheimer diseases (1, 2). In amyloid-related diseases, one or more proteins are found in fibrillar aggregates, in a non-native, highly ␤-sheetrich conformation. Depending on the disease context, the propensity for amyloid formation may be traced to mutations and cleavage events, combined with poorly understood external triggers. Many proteins can also be made to form amyloid fibrils in vitro. Intriguingly, there are many accounts of proteins that form amyloid-like fibrils that are not associated with pathologies (2). Whether disease-related or not, amyloid fibrils share key biochemical and biophysical characteristics, suggesting common structural features. Understanding the fibril formation pathway is of interest not only as there may be a correlation between disease onset and protein aggregation, but also because transient oligomeric precursors may act as toxic species. However, a lack of high resolution structures of most fibrils and their precursors limits our knowledge of the mechanism of formation.One seemingly common structural motif for amyloid fibrils is an in-register parallel (IP) 3 assembly into pleated ␤-sheets, stabilized by backbone-to-backbone hydrogen bonding, combined with favorable side-chain interactions (e....

show abstract

“…This is especially interesting in view of the NMR work of Lazo and coworkers, who reported that IAPP 11−25 structures with an induced kink in the central region were not aggregation prone. 51 Thus, stabilization of the kink in IAPP 1−37 by CLR01 provides a plausible structural explanation for the inhibition of aggregation by the molecular tweezer.…”

Section: Acs Chemical Biologymentioning

confidence: 96%

Molecular Tweezers Inhibit Islet Amyloid Polypeptide Assembly and Toxicity by a New Mechanism

Lopes¹,

Attar²,

Nair³

et al. 2015

ACS Chem. Biol.

View full text Add to dashboard Cite

In type-2 diabetes (T2D), islet amyloid polypeptide (IAPP) self-associates into toxic assemblies causing islet β-cell death. Therefore, preventing IAPP toxicity is a promising therapeutic strategy for T2D. The molecular tweezer CLR01 is a supramolecular tool for selective complexation of K residues in (poly)peptides. Surprisingly, it inhibits IAPP aggregation at substoichiometric concentrations even though IAPP has only one K residue at position 1, whereas efficient inhibition of IAPP toxicity requires excess CLR01. The basis for this peculiar behavior is not clear. Here, a combination of biochemical, biophysical, spectroscopic, and computational methods reveals a detailed mechanistic picture of the unique dual inhibition mechanism for CLR01. At low concentrations, CLR01 binds to K1, presumably nucleating nonamyloidogenic, yet toxic, structures, whereas excess CLR01 binds also to R11, leading to nontoxic structures. Encouragingly, the CLR01 concentrations needed for inhibition of IAPP toxicity are safe in vivo, supporting its development toward diseasemodifying therapy for T2D.

show abstract

Mechanistic Studies of Peptide Self-Assembly: Transient α-Helices to Stable β-Sheets

Cited by 82 publications

References 89 publications

Pyroglutamate-Modified Amyloid-β(3–42) Shows α-Helical Intermediates before Amyloid Formation

Pyroglutamate-Modified Amyloid-β(3–42) Shows α-Helical Intermediates before Amyloid Formation

Amyloid-like Fibrils from a Domain-swapping Protein Feature a Parallel, in-Register Conformation without Native-like Interactions

Molecular Tweezers Inhibit Islet Amyloid Polypeptide Assembly and Toxicity by a New Mechanism

Contact Info

Product

Resources

About