Expanding the Repertoire of Amyloid Polymorphs by Co-polymerization of Related Protein Precursors

Sarell, Claire J.; Woods, Lucy A.; Su, Yongchao; Debelouchina, Galia T.; Ashcroft, Alison E.; Griffin, Robert G.; Stockley, Peter G.; Radford, Sheena E.

doi:10.1074/jbc.m112.447524

Cited by 39 publications

(75 citation statements)

References 62 publications

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“…For example, WT β2m forms amyloids of different morphology and stability from solvent mixtures containing varying amounts of trifluoroethanol (37). Coprecipitation of WT β2m and the truncated ΔN6 variant was also shown to produce a distinct polymorph (38). Here, substitution of one or two hydrogens in Pro32 by fluorine elicits a similar effect.…”

Section: Discussionmentioning

confidence: 51%

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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Section: Discussionmentioning

confidence: 51%

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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“…Perhaps unsurprisingly then, the heteropolymeric fibrils formed from β 2 m and ΔN6 do not resemble those formed from β 2 m alone at acidic pH or from ∆N6 alone at neutral pH. Instead biophysical experiments have shown that the heteropolymeric fibrils of β 2 m/ΔN6 form a unique polymorph that is thermodynamically less stable than both β 2 m and ∆N6 homopolymeric fibrils 30 . These findings show that the heteropolymorphic fibrils do not possess “average” structural or thermodynamic characteristics resulting from mixing of the two precursors.…”

Section: Condition 2: Co-aggregation Occurs By One Partner Protein Afmentioning

confidence: 97%

“…β 2 m forms amyloid fibrils in vivo resulting in the disease dialysis-related amyloidosis (DRA) 27 . However, in the absence of other co-factors or co-solvents human β 2 m will not form fibrils in vitro at neutral pH within an experimentally tractable timescale, 28 , 29 while ΔN6 is highly aggregation prone 20 , 30 . Surprisingly, when monomeric human β 2 m is mixed with monomeric ΔN6 fibril formation from both proteins occurs, resulting in heteropolymeric fibrils, even at neutral pH (Row 7 of Table 1).…”

Section: Condition 2: Co-aggregation Occurs By One Partner Protein Afmentioning

confidence: 99%

Assessing the causes and consequences of co-polymerization in amyloid formation

Sarell

Stockley

Radford

2013

Prion

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How, and why, different proteins form amyloid fibrils is most often studied in vitro using a single purified protein sequence. However, many amyloid diseases involve co-aggregation of different protein species, including proteins with/without post-translational modifications (e.g., different strains of PrP), proteins of different length (e.g., β2-microglobulin and ΔN6, Aβ40, and Aβ42), sequence variants (e.g., Aβ and AβARC), and proteins from different organisms (e.g., bovine PrP and human PrP). The consequences of co-aggregation of different proteins upon the structure, stability, species transmission and toxicity of the resulting amyloid aggregates is discussed here, including the role of co-aggregation in expanding the repertoire of oligomeric and fibrillar structures and how this can affect their biological and biophysical properties.

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“…The fibril architecture can contain complicated structural features (Figure 1g-k), which likely form the basis of the pathological assembly and, therefore, are critical for understanding the folding and self-assembly pathway. In addition, amyloid fibrils can be polymorphic (17,45) and consist of mixtures of different proteins (46). Although amyloid fibrils are an important category of insoluble and noncrystalline proteins, their atomic-resolution structures are essentially inaccessible by solution NMR and X-ray diffraction; therefore, MAS NMR is the method of choice for characterizing these systems.…”

Section: Magic Angle Spinning Nmr Of Membrane Proteins and Amyloid Fimentioning

confidence: 99%

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

Andreas²,

Griffin

2015

Annu. Rev. Biochem.

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137

100

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Magic angle spinning (MAS) NMR studies of amyloid and membrane proteins and large macromolecular complexes are an important new approach to structural biology. However, the applicability of these experiments, which are based on (13)C- and (15)N-detected spectra, would be enhanced if the sensitivity were improved. Here we discuss two advances that address this problem: high-frequency dynamic nuclear polarization (DNP) and (1)H-detected MAS techniques. DNP is a sensitivity enhancement technique that transfers the high polarization of exogenous unpaired electrons to nuclear spins via microwave irradiation of electron-nuclear transitions. DNP boosts NMR signal intensities by factors of 10(2) to 10(3), thereby overcoming NMR's inherent low sensitivity. Alternatively, it permits structural investigations at the nanomolar scale. In addition, (1)H detection is feasible primarily because of the development of MAS rotors that spin at frequencies of 40 to 60 kHz or higher and the preparation of extensively (2)H-labeled proteins.

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Expanding the Repertoire of Amyloid Polymorphs by Co-polymerization of Related Protein Precursors

Cited by 39 publications

References 62 publications

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

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

Assessing the causes and consequences of co-polymerization in amyloid formation

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection

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Expanding the Repertoire of Amyloid Polymorphs by Co-polymerization of Related Protein Precursors

Cited by 39 publications

References 62 publications

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

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

Assessing the causes and consequences of co-polymerization in amyloid formation

Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and 1H Detection

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Magic Angle Spinning NMR of Proteins: High-Frequency Dynamic Nuclear Polarization and ¹H Detection