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Infrared nanospectroscopy characterization of oligomeric and fibrillar aggregates during amyloid formation.

Ruggeri FS, Longo G, Faggiano S, Lipiec E, Pastore A, Dietler G - Nat Commun (2015)

Bottom Line: We describe their secondary structure, monitoring at the nanoscale an α-to-β transition, and couple these studies with an independent measurement of the evolution of their intrinsic stiffness.These results suggest that the aggregation of Josephin proceeds from the monomer state to the formation of spheroidal intermediates with a native structure.Only successively, these intermediates evolve into misfolded aggregates and into the final fibrils.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Physique de la Matière Vivante, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.

ABSTRACT
Amyloids are insoluble protein fibrillar aggregates. The importance of characterizing their aggregation has steadily increased because of their link to human diseases and material science applications. In particular, misfolding and aggregation of the Josephin domain of ataxin-3 is implicated in spinocerebellar ataxia-3. Infrared nanospectroscopy, simultaneously exploiting atomic force microscopy and infrared spectroscopy, can characterize at the nanoscale the conformational rearrangements of proteins during their aggregation. Here we demonstrate that we can individually characterize the oligomeric and fibrillar species formed along the amyloid aggregation. We describe their secondary structure, monitoring at the nanoscale an α-to-β transition, and couple these studies with an independent measurement of the evolution of their intrinsic stiffness. These results suggest that the aggregation of Josephin proceeds from the monomer state to the formation of spheroidal intermediates with a native structure. Only successively, these intermediates evolve into misfolded aggregates and into the final fibrils.

No MeSH data available.


Related in: MedlinePlus

AFM-infrared chemical maps and spectra of fibrils and oligomers after 7-day incubation.(a) AFM height. Infrared absorption at (b) 1,700 cm−1 (amide I), (c) 1,655 cm−1 (amide I) and (d) 1,430 cm−1. Scale bar, 1 μm. Spectra of amyloid structures: (e) misfolded oligomer (labelled 1, 2 and 3 in a) and (f) fibrils (labelled a–f in a).
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f5: AFM-infrared chemical maps and spectra of fibrils and oligomers after 7-day incubation.(a) AFM height. Infrared absorption at (b) 1,700 cm−1 (amide I), (c) 1,655 cm−1 (amide I) and (d) 1,430 cm−1. Scale bar, 1 μm. Spectra of amyloid structures: (e) misfolded oligomer (labelled 1, 2 and 3 in a) and (f) fibrils (labelled a–f in a).

Mentions: After 7-day incubation, both oligomers and fibrils were present in the AFM images (Fig. 5a) with typical average heights of 100–150 nm (Supplementary Fig. 6). Comparison of the absorption maps collected at the amide I band (Fig. 5b,c) and at the band around 1,430 cm−1 (Fig. 5d) showed a clear difference between oligomers and fibrils. The first species had higher absorption in the α-helix component of the amide I band (1,655 cm−1). The latter had higher absorption close to the β-sheet and β-turn components (1,700–1,680 cm−1) and at 1,430 cm−1. In other words, by performing absorption maps at different wavenumbers, we could clearly distinguish the structure of oligomers from that of fibrils through their different secondary structure content, which was causing differential response to infrared light exposure.


Infrared nanospectroscopy characterization of oligomeric and fibrillar aggregates during amyloid formation.

Ruggeri FS, Longo G, Faggiano S, Lipiec E, Pastore A, Dietler G - Nat Commun (2015)

AFM-infrared chemical maps and spectra of fibrils and oligomers after 7-day incubation.(a) AFM height. Infrared absorption at (b) 1,700 cm−1 (amide I), (c) 1,655 cm−1 (amide I) and (d) 1,430 cm−1. Scale bar, 1 μm. Spectra of amyloid structures: (e) misfolded oligomer (labelled 1, 2 and 3 in a) and (f) fibrils (labelled a–f in a).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525161&req=5

f5: AFM-infrared chemical maps and spectra of fibrils and oligomers after 7-day incubation.(a) AFM height. Infrared absorption at (b) 1,700 cm−1 (amide I), (c) 1,655 cm−1 (amide I) and (d) 1,430 cm−1. Scale bar, 1 μm. Spectra of amyloid structures: (e) misfolded oligomer (labelled 1, 2 and 3 in a) and (f) fibrils (labelled a–f in a).
Mentions: After 7-day incubation, both oligomers and fibrils were present in the AFM images (Fig. 5a) with typical average heights of 100–150 nm (Supplementary Fig. 6). Comparison of the absorption maps collected at the amide I band (Fig. 5b,c) and at the band around 1,430 cm−1 (Fig. 5d) showed a clear difference between oligomers and fibrils. The first species had higher absorption in the α-helix component of the amide I band (1,655 cm−1). The latter had higher absorption close to the β-sheet and β-turn components (1,700–1,680 cm−1) and at 1,430 cm−1. In other words, by performing absorption maps at different wavenumbers, we could clearly distinguish the structure of oligomers from that of fibrils through their different secondary structure content, which was causing differential response to infrared light exposure.

Bottom Line: We describe their secondary structure, monitoring at the nanoscale an α-to-β transition, and couple these studies with an independent measurement of the evolution of their intrinsic stiffness.These results suggest that the aggregation of Josephin proceeds from the monomer state to the formation of spheroidal intermediates with a native structure.Only successively, these intermediates evolve into misfolded aggregates and into the final fibrils.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Physique de la Matière Vivante, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.

ABSTRACT
Amyloids are insoluble protein fibrillar aggregates. The importance of characterizing their aggregation has steadily increased because of their link to human diseases and material science applications. In particular, misfolding and aggregation of the Josephin domain of ataxin-3 is implicated in spinocerebellar ataxia-3. Infrared nanospectroscopy, simultaneously exploiting atomic force microscopy and infrared spectroscopy, can characterize at the nanoscale the conformational rearrangements of proteins during their aggregation. Here we demonstrate that we can individually characterize the oligomeric and fibrillar species formed along the amyloid aggregation. We describe their secondary structure, monitoring at the nanoscale an α-to-β transition, and couple these studies with an independent measurement of the evolution of their intrinsic stiffness. These results suggest that the aggregation of Josephin proceeds from the monomer state to the formation of spheroidal intermediates with a native structure. Only successively, these intermediates evolve into misfolded aggregates and into the final fibrils.

No MeSH data available.


Related in: MedlinePlus