Preparation of synthetic human islet amyloid polypeptide (IAPP) in a stable conformation to enable study of conversion to amyloid‐like fibrils

Higham, Claire; Jaikaran, Emma T. A. S.; Fraser, Paul E.; Gross, Michael L.; Clark, Anne

doi:10.1016/s0014-5793(00)01287-4

Cited by 114 publications

(136 citation statements)

References 27 publications

Supporting

Mentioning

122

Contrasting

Order By: Relevance

“…2, A and B, dotted lines). These changes are indicative of a conformational change from an unordered to a ␤-sheet structure and are in agreement with published data on IAPP (12,13).…”

Section: Native Cysteines Are Not Required For Fibril Formation Bysupporting

confidence: 91%

“…Electron microscopy (EM) studies of IAPP deposits revealed the presence of long fibrillar structures (9 -11). Fourier transform infrared and circular dichroism (CD) analysis of IAPP fibrils made from full-length as well as shorter fragments indicates the presence of significant amounts of ␤-sheet structure in the fibrillar form (12,13). X-ray and electron diffraction studies using aligned fibrils have shown that the peptide chains are arranged in a cross-␤-conformation with the individual ␤-strands perpendicular to the fibril axis (14,15).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Identifying Structural Features of Fibrillar Islet Amyloid Polypeptide Using Site-directed Spin Labeling

Jayasinghe

Langen

2004

Journal of Biological Chemistry

143

151

View full text Add to dashboard Cite

Pancreatic amyloid deposits, composed primarily of the 37-residue islet amyloid polypeptide (IAPP), are a characteristic feature found in more than 90% of patients with type II diabetes. Although IAPP amyloid deposits are associated with areas of pancreatic islet ␤-cell dysfunction and depletion and are thought to play a role in disease, their structure is unknown. We used electron paramagnetic resonance spectroscopy to analyze eight spin-labeled derivatives of IAPP in an effort to determine structural features of the peptide. In solution, all eight derivatives gave rise to electron paramagnetic resonance spectra with sharp lines indicative of rapid motion on the sub-nanosecond time scale. These spectra are consistent with a rapidly tumbling and highly dynamic peptide. In contrast, spectra for the fibrillar form exhibit reduced mobility and the presence of strong intermolecular spin-spin interactions. The latter implies that the peptide subunits are ordered and that the same residues from neighboring peptides are in close proximity to one another. Our data are consistent with a parallel arrangement of IAPP peptides within the amyloid fibril. Analysis of spin label mobility indicates a high degree of order throughout the peptide, although the N-terminal region is slightly less ordered. Possible similarities with respect to the domain organization and parallelism of Alzheimer's amyloid ␤ peptide fibrils are discussed.Pancreatic amyloid deposits have been identified as a hallmark of non-insulin-dependent (type II) diabetes mellitus. More than 90% of patients with type II diabetes exhibit amyloid deposits in areas of ␤-cell dysfunction and death (1, 2). The major component of these deposits is the 37-residue islet amyloid polypeptide (IAPP) 1 (3,4), and multiple lines of investigation have provided experimental evidence implicating human IAPP amyloid deposits in type II diabetes (5-8).Although pancreatic amyloid deposits in a diabetic patient were first identified more than a century ago, structural features of these deposits were not described until recently. Electron microscopy (EM) studies of IAPP deposits revealed the presence of long fibrillar structures (9 -11). Fourier transform infrared and circular dichroism (CD) analysis of IAPP fibrils made from full-length as well as shorter fragments indicates the presence of significant amounts of ␤-sheet structure in the fibrillar form (12, 13). X-ray and electron diffraction studies using aligned fibrils have shown that the peptide chains are arranged in a cross-␤-conformation with the individual ␤-strands perpendicular to the fibril axis (14,15). Beyond these observations, little is known about the molecular details of IAPP in the fibrillar form.Amyloid deposits have been identified in a number of human diseases, such as Alzheimer's disease, Parkinson's disease, and familial amyloidotic polyneuropathy (16). Although the primary structure of amyloid forming proteins varies widely, most amyloid deposits appear to share common characteristics, such as the cross-␤-str...

show abstract

“…2, A and B, dotted lines). These changes are indicative of a conformational change from an unordered to a ␤-sheet structure and are in agreement with published data on IAPP (12,13).…”

Section: Native Cysteines Are Not Required For Fibril Formation Bysupporting

confidence: 91%

mentioning

confidence: 99%

Identifying Structural Features of Fibrillar Islet Amyloid Polypeptide Using Site-directed Spin Labeling

Jayasinghe

Langen

2004

Journal of Biological Chemistry

143

151

View full text Add to dashboard Cite

show abstract

“…S1, A and B). Seventeen spin labels were added to every fourth peptides at residues 12,13,14,15,16,17,18,19,24,27,28,29,30,31,32,35, and 36, beginning from the first peptide (supplemental Fig. S1C).…”

Section: Methodsmentioning

confidence: 99%

“…However, the three-dimensional structure of hIAPP fibrils or other misfolded forms remains elusive. FT-IR spectroscopy and circular dichroism show that the fibrils contain ␤-sheet structure (14,15), and x-ray and electron diffraction indicate that the cross-␤-strands are 4.7 Å apart and perpendicular to the fibril axis (16). Site-directed spin labeling and electron paramagnetic resonance (EPR) of hIAPP fibrils show these strands are arranged in a parallel, in-register structure (17).…”

mentioning

confidence: 99%

Fibril Structure of Human Islet Amyloid Polypeptide

Bedrood

Isas

et al. 2012

Journal of Biological Chemistry

143

172

View full text Add to dashboard Cite

Background: Human islet amyloid polypeptide (hIAPP) fibrils of unknown structure are formed in type 2 diabetes. Results: A hIAPP fibril structure was derived from EPR data, electron microscopy, and computer modeling. Conclusion:The fibril is a left-handed helix that contains hIAPP monomers in a staggered conformation. Significance: The results provide the basis for therapeutic prevention of fibril formation and growth.

show abstract

“…Subsequent CD studies demonstrated that the hIAPP monomer adopts primarily a random coil structure. 16,[33][34][35][36][37] Recent NMR studies on human amylin, 38 rat amylin and pramlintide peptides, which have sequences similar to that of amylin, suggest that an α-helical structure is adopted near the N-terminus. 39,40 By interpreting the results of ion mobility mass spectroscopy experiments with a molecular implicit-solvent model, Dupuis et al 29 showed that the hIAPP monomer adopts an α-helical conformation between residues 9-17 on the terminus end, and a short β-hairpin between residues 24-28 and 31-35 on the C-terminus.…”

Section: Introductionmentioning

confidence: 99%

α-helix to β-hairpin transition of human amylin monomer

Singh

Chiu

Reddy

et al. 2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

The human islet amylin polypeptide is produced along with insulin by pancreatic islets. Under some circumstances, amylin can aggregate to form amyloid fibrils, whose presence in pancreatic cells is a common pathological feature of Type II diabetes. A growing body of evidence indicates that small, early stage aggregates of amylin are cytotoxic. A better understanding of the early stages of the amylin aggregation process and, in particular, of the nucleation events leading to fibril growth could help identify therapeutic strategies. Recent studies have shown that, in dilute solution, human amylin can adopt an α-helical conformation, a β-hairpin conformation, or an unstructured coil conformation. While such states have comparable free energies, the β-hairpin state exhibits a large propensity towards aggregation. In this work, we present a detailed computational analysis of the folding pathways that arise between the various conformational states of human amylin in water. A free energy surface for amylin in explicit water is first constructed by resorting to advanced sampling techniques. Extensive transition path sampling simulations are then employed to identify the preferred folding mechanisms between distinct minima on that surface. Our results reveal that the α-helical conformer of amylin undergoes a transformation into the β-hairpin monomer through one of two mechanisms. In the first, misfolding begins through formation of specific contacts near the turn region, and proceeds via a zipping mechanism. In the second, misfolding occurs through an unstructured coil intermediate. The transition states for these processes are identified. Taken together, the findings presented in this work suggest that the inter-conversion of amylin between an α-helix and a β-hairpin is an activated process and could constitute the nucleation event for fibril growth.

show abstract

Preparation of synthetic human islet amyloid polypeptide (IAPP) in a stable conformation to enable study of conversion to amyloid‐like fibrils

Cited by 114 publications

References 27 publications

Identifying Structural Features of Fibrillar Islet Amyloid Polypeptide Using Site-directed Spin Labeling

Identifying Structural Features of Fibrillar Islet Amyloid Polypeptide Using Site-directed Spin Labeling

Fibril Structure of Human Islet Amyloid Polypeptide

α-helix to β-hairpin transition of human amylin monomer

Contact Info

Product

Resources

About