Amyloid Fibril Formation from Full-Length and Fragments of Amylin

Goldsbury, Claire; Goldie, Kenneth N.; Pellaud, Jérôme; Seelig, Joachim; Frey, Peter; Müller, Shirley A.; Kistler, Joerg; Cooper, Garth J. S.; Aebi, Ueli

doi:10.1006/jsbi.2000.4268

Cited by 306 publications

(368 citation statements)

References 37 publications

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“…The fiber morphologies are similar as measured by TEM (Fig. S4), which provide another check on the aggregation mechanism, because different mechanisms often give rise to different fibril structures (17). Additional experimental data and details on our fitting procedure are given in SI Text.…”

Section: Shown Insupporting

confidence: 55%

Two-dimensional IR spectroscopy and isotope labeling defines the pathway of amyloid formation with residue-specific resolution

Shim

Gupta²,

Ling

et al. 2009

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

278

364

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There is considerable interest in uncovering the pathway of amyloid formation because the toxic properties of amyloid likely stems from prefibril intermediates and not the fully formed fibrils. Using a recently invented method of collecting 2-dimensional infrared spectra and site-specific isotope labeling, we have measured the development of secondary structures for 6 residues during the aggregation process of the 37-residue polypeptide associated with type 2 diabetes, the human islet amyloid polypeptide (hIAPP). By monitoring the kinetics at 6 different labeled sites, we find that the peptides initially develop well-ordered structure in the region of the chain that is close to the ordered loop of the fibrils, followed by formation of the 2 parallel ␤-sheets with the N-terminal ␤-sheet likely forming before the C-terminal sheet. This experimental approach provides a detailed view of the aggregation pathway of hIAPP fibril formation as well as a general methodology for studying other amyloid forming proteins without the use of structure-perturbing labels.aggregation ͉ amylin ͉ fibers ͉ human islet amyloid polypeptide ͉ nucleation M ore than 20 different diseases are associated with proteins that form insoluble amyloid fibers (1). In large quantities, organ function is disrupted by the formation of amyloid deposits, but for several amyloid diseases, there is evidence that the toxic entities are actually prefibril intermediates (2, 3). Although they have been the focus of numerous studies, details about these critical intermediates have been elusive, mostly because it is extraordinarily difficult to obtain structural and kinetic information for amyloid aggregation. The difficulty arises because high-resolution techniques do not have the time resolution required to track the structural changes, nor can they be easily applied to aggregating systems. Optical techniques that do have sufficient time resolution, such as circular dichroism spectroscopy, provide only a low-resolution view of structure. Other techniques, like electron spin resonance and fluorescence spectroscopy, require bulky labels that can perturb the structure and dynamics. Mechanistic information is vital to understand the mechanism of protein misfolding as well as to design inhibitors that subvert the pathway of amyloid formation. What is needed is a technique with sufficient time resolution to observe intermediates, provide residue-level structural information, is nonperturbing, and, ideally, can be used to test molecular dynamics simulations.A technique that satisfies these criteria is 2D infrared (2D IR) spectroscopy when used with site-specific isotope labeling (4). We have recently demonstrated a technological approach for collecting 2D IR spectra that is particularly well-suited for studying amyloid formation (5). Our method uses a mid-IR pulse shaper to automate data collection, much like an NMR spectrometer, so that spectra can be collected quickly enough to monitor fibril kinetics on the fly. In this article, we combine this automated version...

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Section: Shown Insupporting

confidence: 55%

Two-dimensional IR spectroscopy and isotope labeling defines the pathway of amyloid formation with residue-specific resolution

Shim

Gupta²,

Ling

et al. 2009

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

278

364

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“…2B. Although it cannot be directly proven, it is tempting to imply that these later stage assemblies form from protofilaments by either "side-by-side" association or by coiling and twisting, as suggested previously for other systems (35)(36)(37). Most interestingly, in low dose studies at early time points of the 41-, 25-, 8-, or 6-amino acid peptides, no arrays of protofilaments are observed.…”

Section: Table Imentioning

confidence: 74%

“…These polymorphic structural assemblies are reminiscent of those formed from amyloid fibrils of calcitonin and amylin (35)(36)(37). At later stages of assembly, no extended arrays of protofilaments are observed; only multistrand, flat, or twisted ribbons exist in the fields of the same solution deposited on the grid after aging for 13 days, as seen in Fig.…”

Section: Table Imentioning

confidence: 84%

Amyloid Fibril Formation from Sequences of a Natural β-Structured Fibrous Protein, the Adenovirus Fiber

Papanikolopoulou

Schoehn

Forge

et al. 2005

Journal of Biological Chemistry

112

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Amyloid fibrils are fibrous ␤-structures that derive from abnormal folding and assembly of peptides and proteins. Despite a wealth of structural studies on amyloids, the nature of the amyloid structure remains elusive; possible connections to natural, ␤-structured fibrous motifs have been suggested. In this work we focus on understanding amyloid structure and formation from sequences of a natural, ␤-structured fibrous protein. We show that short peptides (25 to 6 amino acids) corresponding to repetitive sequences from the adenovirus fiber shaft have an intrinsic capacity to form amyloid fibrils as judged by electron microscopy, Congo Red binding, infrared spectroscopy, and x-ray fiber diffraction. In the presence of the globular C-terminal domain of the protein that acts as a trimerization motif, the shaft sequences adopt a triple-stranded, ␤-fibrous motif. We discuss the possible structure and arrangement of these sequences within the amyloid fibril, as compared with the one adopted within the native structure. A 6-amino acid peptide, corresponding to the last ␤-strand of the shaft, was found to be sufficient to form amyloid fibrils. Structural analysis of these amyloid fibrils suggests that perpendicular stacking of ␤-strand repeat units is an underlying common feature of amyloid formation.

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“…From the standpoint of molecular structure, the defining feature of an amyloid fibril is the presence of cross-β supramolecular structure, meaning that the β-sheets within the fibril are formed by β-strand segments that run approximately perpendicular to the long axis of the fibril and are linked by hydrogen bonds that run approximately parallel to this axis (11)(12)(13). Although determination of the molecular structures of amyloid fibrils is made difficult by their inherent noncrystallinity and insolubility, techniques such as solid state nuclear magnetic resonance (NMR) (12,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33), electron paramagnetic resonance (EPR) (34-36), electron microscopy (37-43), hydrogen/deuterium exchange (29,(44)(45)(46)(47), scanning mutagenesis (48), chemical crosslinking (27,49,50), and x-ray diffraction of amyloid-like crystals (51,52) have recently shed substantial light on these structures.In vitro, amylin readily forms amyloid fibrils with a variety of morphologies as seen in transmission electron microscope (TEM) and atomic force microscope (AFM) images (40,41), and with typical cross-β diffraction patterns (53). Early solid state NMR studies by Griffiths et al focused on fibrils formed by a peptide representing residues 20-29 of amylin.…”

mentioning

confidence: 99%

Peptide Conformation and Supramolecular Organization in Amylin Fibrils: Constraints from Solid-State NMR

et al. 2007

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The 37-residue amylin peptide, also known as islet amyloid polypeptide, forms fibrils that are the main peptide or protein component of amyloid that develops in the pancreas of type 2 diabetes patients. Amylin also readily forms amyloid fibrils in vitro that are highly polymorphic under typical experimental conditions. We describe a protocol for the preparation of synthetic amylin fibrils that exhibit a single predominant morphology, which we call a striated ribbon, in electron microscope and atomic force microscope images. Solid state nuclear magnetic resonance (NMR) measurements on a series of isotopically labeled samples indicate a single molecular structure within the striated ribbons. We use scanning transmission electron microscopy and several types of one-dimensional and two-dimensional solid state NMR techniques to obtain constraints on the peptide conformation and supramolecular structure in these amylin fibrils, and derive molecular structural models that are consistent with the experimental data. The basic structural unit in amylin striated ribbons, which we call the protofilament, contains four-layers of parallel β-sheets, formed by two symmetric layers of amylin molecules. The molecular structure of amylin protofilaments in striated ribbons closely resembles the protofilament in amyloid fibrils with similar morphology formed by the 40-residue β-amyloid peptide that is associated with Alzheimer's disease. Keywordsislet amyloid polypeptide; type 2 diabetes; amyloid fibril structure; electron microscopy; atomic force microscopy Amylin, also called islet amyloid polypeptide or IAPP, is a 37-residue peptide that is cosecreted with insulin by the β-cells of pancreas. The normal biological effects of amylin secretion include inhibition of glucagon secretion and reduction of the rate of gastric emptying, effects that contribute to the maintenance of postprandial glucose homeostasis (1). Amylin is the major peptide or protein component of the islet amyloid found in the pancreas of approximately 90% of type 2 (or non-insulin-dependent) diabetes patients (2,3). Fibrillar amylin has been shown * Corresponding author: Dr. Robert Tycko, National Institutes of Health, Building 5, Room 112, Bethesda, MD 20892-0520. phone 301-402-8272. fax 301-496-0825. e-mail robertty@mail.nih.gov.Supporting Information Available HPLC chromatograms from the purification of both reduced and oxidized amylin by reverse-phase chromatography ( Figure S1); FPLC chromatograms from the purification of both human and rodent amylin by size-exclusion chromatography ( Figure S2); 1D 13 C spectra of amylin fibrils with various isotopic labeling patterns, in lyophilized and rehydrated conditions ( Figures S3-S5); Table of 13 C NMR chemical shifts in amylin fibrils, TALOS predictions of backbone torsion angles based on these shifts, and torsion angles determined from 15 N fpRFDR-CT measurements (Table S1). This material is freely available on the World Wide Web at http://www.acs.org. to be toxic to cultured β-cells (4), and has been propo...

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Amyloid Fibril Formation from Full-Length and Fragments of Amylin

Cited by 306 publications

References 37 publications

Two-dimensional IR spectroscopy and isotope labeling defines the pathway of amyloid formation with residue-specific resolution

Two-dimensional IR spectroscopy and isotope labeling defines the pathway of amyloid formation with residue-specific resolution

Amyloid Fibril Formation from Sequences of a Natural β-Structured Fibrous Protein, the Adenovirus Fiber

Peptide Conformation and Supramolecular Organization in Amylin Fibrils: Constraints from Solid-State NMR

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