β 2‐microglobulin can be refolded into a native state from <i>ex vivo</i> amyloid fibrils

Bellotti, Vittorio; Stoppini, Monica; Mangione, Palma; Sunde, Margaret; Robinson, Carol; Asti, Annalia; Brancaccio, Diego; Ferri, Giuseppina

doi:10.1046/j.1432-1327.1998.2580061.x

Cited by 110 publications

(107 citation statements)

References 23 publications

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“…This model might also represent a system for the evaluation of events, such as proteolysis, that could remodel, stabilize, or dissolve amyloid fibrils. We have clearly established that in natural amyloid fibrils, the full-length protein is the predominant species, but a form lacking the first six N-terminal residues (⌬N6␤ 2 -m) also exists (25,36). The remarkable amyloidogenic propensity of this species, in comparison with the full-length protein, and its ability to form fibrils at neutral pH is well documented (20,27).…”

Section: Discussionmentioning

confidence: 79%

Heparin Strongly Enhances the Formation of β2-Microglobulin Amyloid Fibrils in the Presence of Type I Collagen

Relini

Stefano

Torrassa

et al. 2008

Journal of Biological Chemistry

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111

104

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The tissue specificity of fibrillar deposition in dialysis-related amyloidosis is most likely associated with the peculiar interaction of ␤ 2 -microglobulin (␤ 2 -m) with collagen fibers. However, other co-factors such as glycosaminoglycans might facilitate amyloid formation. In this study we have investigated the role of heparin in the process of collagen-driven amyloidogenesis. In fact, heparin is a well known positive effector of fibrillogenesis, and the elucidation of its potential effect in this type of amyloidosis is particularly relevant because heparin is regularly given to patients subject to hemodialysis to prevent blood clotting. We have monitored by atomic force microscopy the formation of ␤ 2 -m amyloid fibrils in the presence of collagen fibers, and we have discovered that heparin strongly accelerates amyloid deposition. The mechanism of this effect is still largely unexplained. Using dynamic light scattering, we have found that heparin promotes ␤ 2 -m aggregation in solution at pH 6.4. Morphology and structure of fibrils obtained in the presence of collagen and heparin are highly similar to those of natural fibrils. The fibril surface topology, investigated by limited proteolysis, suggests that the general assembly of amyloid fibrils grown under these conditions and in vitro at low pH is similar. The exposure of these fibrils to trypsin generates a cleavage at the C-terminal of lysine 6 and creates the 7-99 truncated form of ␤ 2 -m (⌬N6␤ 2 -m) that is a ubiquitous constituent of the natural ␤ 2 -m fibrils. The formation of this ␤ 2 -m species, which has a strong propensity to aggregate, might play an important role in the acceleration of local amyloid deposition. Dialysis-related amyloidosis (DRA),2 a severe disease arising as a complication of long term hemodialysis, involves the deposition of ␤ 2 -microglobulin (␤ 2 -m) amyloid fibrils in bones and ligaments. ␤ 2 -m constitutes the light chain of the major histocompatibility complex class I and CD1 (1), and in normal catabolism, it is continuously released in the serum and cleared from the circulation by the kidney. The replacement of renal function by hemodialysis does not efficiently remove ␤ 2 -m. The persistent increase of its plasma concentration is associated with ␤ 2 -m deposition in the osteotendineous system, which is the specific target tissue of this type of amyloidosis. Among extra-cerebral amyloidoses, DRA represents the most striking case of tissue-specific targeting. Although other organs can be involved, bones and ligaments never escape amyloid deposition. Homma (2) first pointed out that collagen might be involved in determining this tissue specificity and demonstrated a collagen/␤ 2 -m interaction.We have recently determined the binding properties governing the collagen/␤ 2 -m interaction, and we found that the latter is quite weak but is enhanced when ␤ 2 -m is truncated at the N-terminal end, and the pH is reduced from 7.4 to 6.4 (3). We subsequently demonstrated that fibrillar collagen (type I), which is abundant in skeletal...

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Section: Discussionmentioning

confidence: 79%

Heparin Strongly Enhances the Formation of β2-Microglobulin Amyloid Fibrils in the Presence of Type I Collagen

Relini

Stefano

Torrassa

et al. 2008

Journal of Biological Chemistry

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111

104

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“…Aggregates can form from the association of transient, partially folded intermediates during refolding experiments and during the production of recombinant proteins in heterologous expression systems (27) (28). For ␤ 2 -microglobulin, one of a group of 20 or so proteins associated with the formation amyloid fibrils in vivo (29), MS was used to identify N-terminally truncated forms of the protein present in high concentrations in ex vivo deposits (30). The H/D exchange properties of a mixture of wild-type and the major N-terminal truncation of ␤ 2 -microglobulin showed that the modified protein was significantly less protected from exchange than the wild-type protein (31).…”

Section: Protein Misfolding and Aggregationmentioning

confidence: 99%

Dynamic Protein Complexes: Insights from Mass Spectrometry

Hernández¹,

Robinson²

2001

Journal of Biological Chemistry

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The recent sequencing of the human genome has revealed that the human cell contains only twice the number of genes as the worm or fly (1). This implies that the regulation of gene products as well as their interactions accounts for the increased biological complexity of higher organisms. Consequently to exploit the wealth of information provided by genome sequencing it is essential to be able to study both stable and transient macromolecular complexes. Although the yeast two-hybrid system (2) and cross-linking combined with mass spectrometry (MS) 1 (3) are exceptionally powerful approaches to defining stable complexes within the proteasome, MS has the additional potential to describe transient, dynamic complexes through two major developments. These are (i) the ability to probe molecular dynamics through the coupling of MS with hydrogen deuterium (H/D) exchange technologies and (ii) the control of the conditions within the mass spectrometer such that non-covalent interactions between proteins and cofactors can be examined.Over the last decade H/D exchange in conjunction with MS has developed to an extent whereby it can probe the exchange behavior of regions of secondary structure in macromolecular complexes (4) and even individual residues in smaller proteins (5). In parallel with these developments major advances have been made in the ability to study non-covalent complexes in the gas phase. Specifically the coupling of time-of-flight methods with electrospray and the refinement of this process to a nanoflow technique have enabled applications from simple dimeric complexes (6) through to homo-(7) and hetero-oligomeric complexes (8) and even small particles (9 -11). Consequently the ability to probe both non-covalent interactions as well as H/D exchange enables not only the definition of the stoichiometry of interacting subunits but also their conformational dynamics and subunit interfaces to be investigated.Early applications of mass spectrometry to examine non-covalent protein ligand interactions present in the solution phase led to conflicting results in which specific interactions were not necessarily reproduced in the gas phase of the mass spectrometer. It is now widely accepted that the nature of the interactions, either hydrophobic or ionic, plays a major role in determining the outcome of small protein ligand interactions (12). Specifically, if the dominant interactions are ionic, greater gas phase stability of the complex is observed than for hydrophobically driven ligand binding. With the increasing size of multiprotein complexes generated in the gas phase, however, involving a much greater number of interactions, the net effect is a closer agreement between the gas and solution phase data (13). The fact that these complexes can be observed in the mass spectrometer enables their stability and folding to be probed in the presence of a wide range of ligands and cofactors as well as in response to thermal and chemical denaturation. It is the recent applications of MS to study dynamic protein complexes t...

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“…Free ␤ 2 m then associates to form amyloid fibrils that typically accumulate in the musculoskeletal system and result in the development of the disorder dialysis-related amyloidosis. The majority of ex vivo ␤ 2 m amyloid is comprised of full-length wild-type ␤ 2 m, although small amounts (Ͻ30%) of modified or truncated forms are found (2)(3)(4).…”

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confidence: 99%

Crystal structure of monomeric human β-2-microglobulin reveals clues to its amyloidogenic properties

Trinh

Smith

Kalverda

et al. 2002

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

177

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Dissociation of human ␤-2-microglobulin (␤2m) from the heavy chain of the class I HLA complex is a critical first step in the formation of amyloid fibrils from this protein. As a consequence of renal failure, the concentration of circulating monomeric ␤2m increases, ultimately leading to deposition of the protein into amyloid fibrils and development of the disorder, dialysis-related amyloidosis. Here we present the crystal structure of a monomeric form of human ␤2m determined at 1.8-Å resolution that reveals remarkable structural changes relative to the HLA-bound protein.These involve the restructuring of a ␤ bulge that separates two short ␤ strands to form a new six-residue ␤ strand at one edge of this ␤ sandwich protein. Beta-2-microglobulin (␤ 2 m) constitutes the noncovalently bound light chain of the class I human leukocyte antigen (HLA class I). The protein is 99 residues in length and has a seven-stranded ␤ sandwich fold typical of the Ig superfamily (1). In vivo, ␤ 2 m is continuously shed from the surface of cells displaying HLA class 1 molecules into the serum, where it is transported to the kidneys to be degraded and excreted. As a consequence of renal failure, the concentration of ␤ 2 m circulating in the serum increases up to 60-fold (2). Free ␤ 2 m then associates to form amyloid fibrils that typically accumulate in the musculoskeletal system and result in the development of the disorder dialysis-related amyloidosis. The majority of ex vivo ␤ 2 m amyloid is comprised of full-length wild-type ␤ 2 m, although small amounts (Ͻ30%) of modified or truncated forms are found (2-4).As for other amyloidogenic proteins (5-7), mild acidification has been shown to promote formation of amyloid fibrils in vitro from pure ␤ 2 m, both de novo (8-10) and by extension of ex vivo material (11). Under acidic conditions, high yields of amyloidlike fibrils displaying a variety of morphologies form spontaneously in vitro (8-10). Incubation of ␤ 2 m at pH 3.6 results in the formation of a partially unfolded species that assembles into short curly fibrils Ϸ10 nm wide and Ͻ200 nm in length. By contrast, fibrils with a long straight morphology, more reminiscent of ex vivo amyloid, are generated by incubation of aciddenatured forms of the protein at low ionic strengths at pH 2.5 and below, either alone (10) or in the presence of fibrillar seeds (11). Amyloid fibrils of ␤ 2 m have also been generated in vitro at neutral pH by deletion of the N-terminal 6 residues (12); incubation of the full length protein in the presence of Cu 2ϩ ions (13); dialysis of the protein at neutral pH into H 2 O followed by its concentration by drying onto the membrane surface (14); and by the extension of ex vivo material, believed to proceed by the assembly of a rarely populated intermediate onto the ends of existing fibrillar seeds (11, 15). The common theme to emerge from these studies is that conformational rearrangements of the normally highly soluble native protein are required for amyloid fibrils to form.More than 80 crystal structures of h...

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β 2‐microglobulin can be refolded into a native state from ex vivo amyloid fibrils

Cited by 110 publications

References 23 publications

Heparin Strongly Enhances the Formation of β2-Microglobulin Amyloid Fibrils in the Presence of Type I Collagen

Heparin Strongly Enhances the Formation of β2-Microglobulin Amyloid Fibrils in the Presence of Type I Collagen

Dynamic Protein Complexes: Insights from Mass Spectrometry

Crystal structure of monomeric human β-2-microglobulin reveals clues to its amyloidogenic properties

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