Protein Interactions and Misfolding Analyzed by AFM Force Spectroscopy

McAllister, Chad; Karymov, Mikhail A.; Kawano, Yoshiko; Lushnikov, Alexander Y.; Mikheikin, Andrew; Uversky, Vladimir N.; Lyubchenko, Yuri L.

doi:10.1016/j.jmb.2005.10.012

Cited by 120 publications

(151 citation statements)

References 65 publications

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“…In this context, we have recently demonstrated that force spectroscopy is capable of probing misfolded protein conformations (13). To measure single molecule interactions proteins were anchored on the mica surface and the AFM probe, and the interaction between the tethered molecules was measured after bringing them together by approaching the tip to the surface.…”

Section: Introductionmentioning

confidence: 99%

Nanomedicine and protein misfolding diseases

Kransnoslobodtsev

Shlyakhtenko

Ukraintsev

et al. 2005

Nanomedicine: Nanotechnology, Biology and Medicine

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Misfolding and self assembly of proteins in nano-aggregates of different sizes and morphologies (nano-ensembles, primarily nanofilaments and nano-rings) is a complex phenomenon that can be facilitated, impeded, or prevented, by interactions with various intracellular metabolites, intracellular nanomachines controlling protein folding and interactions with other proteins. A fundamental understanding of molecular processes leading to misfolding and self-aggregation of proteins involved in various neurodegenerative diseases will provide critical information to help identify appropriate therapeutic routes to control these processes. An elevated propensity of misfolded protein conformation in solution to aggregate with the formation of various morphologies impedes the use of traditional physical chemical approaches for studies of misfolded conformations of proteins. In our recent alternative approach, the protein molecules were tethered to surfaces to prevent aggregation and AFM force spectroscopy was used to probe the interaction between protein molecules depending on their conformations. It was shown that formation of filamentous aggregates is facilitated at pH values corresponding to the maximum of rupture forces. In this paper, a novel surface chemistry was developed for anchoring of amyloid β (Aβ) peptides at their N-terminal moieties. The use of the site specific immobilization procedure allowed to measure the rupture of Aβ -Aβ contacts at single molecule level. The rupture of these contacts is accompanied by the extension of the peptide chain detected by a characteristic elasto-mechanical component of the forcedistance curves. Potential applications of the nanomechanical studies to understanding the mechanisms of development of protein misfolding diseases are discussed.

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Section: Introductionmentioning

confidence: 99%

Nanomedicine and protein misfolding diseases

Kransnoslobodtsev

Shlyakhtenko

Ukraintsev

et al. 2005

Nanomedicine: Nanotechnology, Biology and Medicine

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“…Therefore, we suggested that an increase of the attractive forces between two Aβ proteins measured by the AFM at the acidic pH is due to increasing the number of the inter-protein hydrophobic contacts at this pH compared to the ones at the basic pH. In other words, the increase of the attractive forces between two Aβ proteins measured by AFM at the acidic pH compared to basic pH 40,42 reflects the difference in the inter-protein hydrophobic interactions at these pHs.…”

Section: Resultsmentioning

confidence: 88%

“…40,42 These experiments have shown a non-linear, sigmoidal functional relationship between the attractive forces and pH magnitudes. These forces were found to be minimal in the wide range of the basic pH and increased significantly at the acidic pH.…”

Section: Resultsmentioning

confidence: 98%

“…13,[35][36][37][38][39] It was demonstrated 13,38,39 that the aggregation rate of the Aβ fibril formation is much faster at the acidic pH compared to the neutral and basic pHs. Data obtained by solid state NMR spectroscopy 9 and atomic force microscopy experiments [40][41][42] also showed pH-dependent structural alterations of the Aβ monomers. On the other hand, pH values determine protonated and deprotonated states of the amino acid residues having ionogenic groups.…”

Section: Introductionmentioning

confidence: 85%

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Dynamic properties of pH-dependent structural organization of the amyloidogenic β-protein (1-40)

Rubinstein

Lyubchenko

Sherman

2009

Prion

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The structural organization of the amyloidogenic β-protein containing 40 amino acid residues (Aβ40) was studied by the high temperature molecular dynamics simulations in the acidic (pH ~ 3) and basic (pH ~ 8) pH regions. The obtained data suggest that the central Ala21-Gly29 segment of Aβ40 can adopt folded and partially unfolded structures. At the basic pH, this segment forms folded structures stabilized by electrostatic interactions and hydrogen bonds. At the acidic pH, it forms partially unfolded structures. Two other segments flanking to the central segment exhibit the propensity to adopt unstable interconverting α-helical, 3 10 -helical and turn-like structures. One of these segments is comprised of the Ala30-Val36 residues at both of the considered pHs. The second segment is comprised of the Glu11-Phe20 at the basic pH and of the Glu11-Val24 residues at the acidic pHs. The revealed pH-dependent structuration of the Aβ40 allowed us to suggest a possible scenario for initial Aβ aggregation. According to this scenario, the occurrence of the partially unfolded states of the Ala21-Gly29 segment plays main role in the Aβ oligomerization process.

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“…AFM has been utilized to characterize the size, shape, kinetics and intermolecular forces of aggregating peptides on a surface in situ. [13,[43][44][45][46][47] In this work, we applied time-lapse lateral force microscopy (LFM) to study the nucleation mechanisms of SELP on mica surface in contact mode AFM. For higher temporal resolution, the slow scan axis was disabled and a single line was continuously scanned to observe nucleation in real time.…”

Section: Silk-elastin-like Peptide (Selp)mentioning

confidence: 99%

Direct Observation of Amyloid Nucleation under Nanomechanical Stretching

et al. 2013

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Self-assembly of amyloid nanofiber is associated with functional and pathological processes such as in neurodegenerative diseases. Despite intensive studies, stochastic nature of the process has made it difficult to elucidate molecular mechanisms for the key amyloid nucleation. Here, we investigated the amyloid nucleation of silk-elastinlike peptide (SELP) using time-lapse lateral force microscopy (LFM). By repeated scanning a single line on a SELP-coated mica surface, we observed sudden stepwise height increases, corresponds to nucleation of an amyloid fiber. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction, serves as the template for further selfassembly perpendicular to the scan direction. Such mechanically induced nucleation of amyloid fibrils allows positional and directional control of amyloid assembly in vitro, which we demonstrate by generating single nanofibers at predetermined nucleation sites.

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Protein Interactions and Misfolding Analyzed by AFM Force Spectroscopy

Cited by 120 publications

References 65 publications

Nanomedicine and protein misfolding diseases

Nanomedicine and protein misfolding diseases

Dynamic properties of pH-dependent structural organization of the amyloidogenic β-protein (1-40)

Direct Observation of Amyloid Nucleation under Nanomechanical Stretching

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