The Monomer–Seed Interaction Mechanism in the Formation of the β2-Microglobulin Amyloid Fibril Clarified by Solution NMR Techniques

Yanagi, Kotaro; Sakurai, Kazumasa; Yoshimura, Yuichi; Konuma, Tsuyoshi; Lee, Young-Ho; Sugase, Kenji; Ikegami, Takahisa; Naiki, Hironobu; Goto, Yuji

doi:10.1016/j.jmb.2012.05.034

Cited by 34 publications

(37 citation statements)

References 58 publications

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“…3B). This type of two-step model has been proposed by various authors on the basis of nuclear magnetic resonance 46 , atomic force microscopy 47, 48 , fluorescence microscopy experiments 49, 50 . This is the analog of the Michaelis–Menten scheme in enzyme kinetics 51 , and the initial rate under steady-state approximation iswhere K m is the Michaelis constant and is equal to (k −1 + k + 2 )/k + 1 .…”

Section: Resultsmentioning

confidence: 99%

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

Honda

Kuwata

2017

Sci Rep

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The conversion of globular proteins into amyloid fibrils is associated with a wide variety of human diseases. One example is the prion protein (PrP), which adopts an α-helical structure in the native state but its amyloid form is implicated in the pathogenesis of prion diseases. Previous evidence has suggested that destabilization of the native state promotes amyloid formation, but the underlying mechanism remains unknown. In this study, we report that the native state of PrP serves as a potent inhibitor in the formation of PrP amyloid fibrils. By monitoring the time courses of thioflavin T fluorescence, the kinetics of amyloid formation was studied in vitro under various concentrations of pre-formed amyloid, monomer, and denaturant. Quantitative analysis of the kinetic data using various models of enzyme kinetics suggested that the native state of PrP is either an uncompetitive or noncompetitive inhibitor of amyloid formation. This study highlights the significant role of the native state in inhibiting amyloid formation, which provides new insights into the pathogenesis of misfolding diseases.

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Section: Resultsmentioning

confidence: 99%

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

Honda

Kuwata

2017

Sci Rep

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“…When the effects of salts on amyloid fibrillation were examined, several studies indicated the importance of anion binding and coupled conformational transition to trigger fibrillation . Raman et al examined the effects of various salts on the fibrillation of β2m under acidic conditions.…”

Section: Discussionmentioning

confidence: 99%

Heparin‐induced amyloid fibrillation of β₂‐microglobulin explained by solubility and a supersaturation‐dependent conformational phase diagram

Hata

Naiki

et al. 2017

Protein Science

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Amyloid fibrils are fibrillar deposits of denatured proteins associated with amyloidosis and are formed by a nucleation and growth mechanism. We revisited an alternative and classical view of amyloid fibrillation: amyloid fibrils are crystal-like precipitates of denatured proteins formed above solubility upon breaking supersaturation. Various additives accelerate and then inhibit amyloid fibrillation in a concentration-dependent manner, suggesting that the combined effects of stabilizing and destabilizing forces affect fibrillation. Heparin, a glycosaminoglycan and anticoagulant, is an accelerator of fibrillation for various amyloidogenic proteins. By using β -microglobulin, a protein responsible for dialysis-related amyloidosis, we herein examined the effects of various concentrations of heparin on fibrillation at pH 2. In contrast to previous studies that focused on accelerating effects, higher concentrations of heparin inhibited fibrillation, and this was accompanied by amorphous aggregation. The two-step effects of acceleration and inhibition were similar to those observed for various salts. The results indicate that the anion effects caused by sulfate groups are one of the dominant factors influencing heparin-dependent fibrillation, although the exact structures of fibrils and amorphous aggregates might differ between those formed by simple salts and matrix-forming heparin. We propose that a conformational phase diagram, accommodating crystal-like amyloid fibrils and glass-like amorphous aggregates, is important for understanding the effects of various additives.

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“…S20B) also suggests that their structural properties approximate those of WT fibrils. At pH 2.5, β2m exists as a mixture of partially structured and extensively unfolded conformers (32). Because the BC loop that maintains Pro32 in the cis conformation will be (partially) denatured under these conditions, the average trans-cis amide bond ratio for an equimolar mixture of 4R-Fpr (6.7:1) and 4S-fpr (2.5:1) effectively mimics that of unmodified proline (4.6:1) (20).…”

Section: Polymorphism Of β2m Amyloids Regulated By Cis-trans Pro32mentioning

confidence: 99%

Both the cis - trans equilibrium and isomerization dynamics of a single proline amide modulate β2-microglobulin amyloid assembly

Torbeev

Hilvert

2013

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

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The human protein β2-microglobulin (β2m) aggregates as amyloid fibrils in patients undergoing long-term hemodialysis. Isomerization of Pro32 from its native cis to a nonnative trans conformation is thought to trigger β2m misfolding and subsequent amyloid assembly. To examine this hypothesis, we systematically varied the free-energy profile of proline cis-trans isomerization by replacing Pro32 with a series of 4-fluoroprolines via total chemical synthesis. We show that β2m's stability, (un)folding, and aggregation properties are all influenced by the rate and equilibrium of Pro32 cistrans isomerization. As anticipated, the β2m monomer was either stabilized or destabilized by respective incorporation of (2S,4S)-fluoroproline, which favors the native cis amide bond, or the stereoisomeric (2S,4R)-fluoroproline, which disfavors this conformation. However, substitution of Pro32 with 4,4-difluoroproline, which has nearly the same cis-trans preference as proline but an enhanced isomerization rate, caused pronounced destabilization of the protein and increased oligomerization at neutral pH. More remarkably, these subtle alterations in chemical compositionincorporation of one or two fluorine atoms into a single proline residue in the 99 amino acid long protein-modulated the aggregation properties of β2m, inducing the formation of polymorphically distinct amyloid fibrils. These results highlight the importance of conformational dynamics for molecular assembly of an amyloid cross-β structure and provide insights into mechanistic aspects of Pro32 cis-trans isomerism in β2m aggregation.protein conformation | polymorphism | amyloidogenesis | native chemical ligation

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The Monomer–Seed Interaction Mechanism in the Formation of the β2-Microglobulin Amyloid Fibril Clarified by Solution NMR Techniques

Cited by 34 publications

References 58 publications

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

Heparin‐induced amyloid fibrillation of β₂‐microglobulin explained by solubility and a supersaturation‐dependent conformational phase diagram

Both the cis - trans equilibrium and isomerization dynamics of a single proline amide modulate β2-microglobulin amyloid assembly

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The Monomer–Seed Interaction Mechanism in the Formation of the β2-Microglobulin Amyloid Fibril Clarified by Solution NMR Techniques

Cited by 34 publications

References 58 publications

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

The native state of prion protein (PrP) directly inhibits formation of PrP-amyloid fibrils in vitro

Heparin‐induced amyloid fibrillation of β2‐microglobulin explained by solubility and a supersaturation‐dependent conformational phase diagram

Both the cis - trans equilibrium and isomerization dynamics of a single proline amide modulate β2-microglobulin amyloid assembly

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Heparin‐induced amyloid fibrillation of β₂‐microglobulin explained by solubility and a supersaturation‐dependent conformational phase diagram