Methods to study the structure of misfolded protein states in systemic amyloidosis

2021 ◽  
Vol 49 (2) ◽  
pp. 977-985
Author(s):  
Marcus Fändrich ◽  
Matthias Schmidt
Keyword(s):  
Protein Misfolding ◽  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Systemic Amyloidosis ◽  
Structural Basis ◽  
Amyloid A ◽  
Serum Amyloid A Protein ◽  
Proteolytic Stability

Systemic amyloidosis is defined as a protein misfolding disease in which the amyloid is not necessarily deposited within the same organ that produces the fibril precursor protein. There are different types of systemic amyloidosis, depending on the protein constructing the fibrils. This review will focus on recent advances made in the understanding of the structural basis of three major forms of systemic amyloidosis: systemic AA, AL and ATTR amyloidosis. The three diseases arise from the misfolding of serum amyloid A protein, immunoglobulin light chains or transthyretin. The presented advances in understanding were enabled by recent progress in the methodology available to study amyloid structures and protein misfolding, in particular concerning cryo-electron microscopy (cryo-EM) and nuclear magnetic resonance (NMR) spectroscopy. An important observation made with these techniques is that the structures of previously described in vitro formed amyloid fibrils did not correlate with the structures of amyloid fibrils extracted from diseased tissue, and that in vitro fibrils were typically more protease sensitive. It is thus possible that ex vivo fibrils were selected in vivo by their proteolytic stability.

scholarly journals Cryo-EM demonstrates the in vitro proliferation of an ex vivo amyloid fibril morphology by seeding

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Thomas Heerde ◽  
Matthies Rennegarbe ◽  
Alexander Biedermann ◽  
Dilan Savran ◽  
Peter B. Pfeiffer ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Proteinase K ◽  
Seed Structure ◽  
In Vitro Proliferation ◽  
Amyloid A ◽  
Fibril Structure ◽  
Proteolytic Stability ◽  
Fibril Morphology

AbstractSeveral studies showed that seeding of solutions of monomeric fibril proteins with ex vivo amyloid fibrils accelerated the kinetics of fibril formation in vitro but did not necessarily replicate the seed structure. In this research we use cryo-electron microscopy and other methods to analyze the ability of serum amyloid A (SAA)1.1-derived amyloid fibrils, purified from systemic AA amyloidosis tissue, to seed solutions of recombinant SAA1.1 protein. We show that 98% of the seeded fibrils remodel the full fibril structure of the main ex vivo fibril morphology, which we used for seeding, while they are notably different from unseeded in vitro fibrils. The seeded fibrils show a similar proteinase K resistance as ex vivo fibrils and are substantially more stable to proteolytic digestion than unseeded in vitro fibrils. Our data support the view that the fibril morphology contributes to determining proteolytic stability and that pathogenic amyloid fibrils arise from proteolytic selection.

scholarly journals AA amyloid fibrils from diseased tissue are structurally different from in vitro formed SAA fibrils

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Akanksha Bansal ◽  
Matthias Schmidt ◽  
Matthies Rennegarbe ◽  
Christian Haupt ◽  
Falk Liberta ◽  
...  
Keyword(s):  
Protein Misfolding ◽  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Surrounding Tissue ◽  
Amyloid A ◽  
Cryo Electron Microscopy ◽  
Β Sheet ◽  
Misfolding Disease

AbstractSystemic AA amyloidosis is a world-wide occurring protein misfolding disease of humans and animals. It arises from the formation of amyloid fibrils from serum amyloid A (SAA) protein. Using cryo electron microscopy we here show that amyloid fibrils which were purified from AA amyloidotic mice are structurally different from fibrils formed from recombinant SAA protein in vitro. Ex vivo amyloid fibrils consist of fibril proteins that contain more residues within their ordered parts and possess a higher β-sheet content than in vitro fibril proteins. They are also more resistant to proteolysis than their in vitro formed counterparts. These data suggest that pathogenic amyloid fibrils may originate from proteolytic selection, allowing specific fibril morphologies to proliferate and to cause damage to the surrounding tissue.

scholarly journals Biological and Structural Basis for Aha1 Regulation of Hsp90 ATPase Activity in Maintaining Proteostasis in the Human Disease Cystic Fibrosis

2010 ◽  
Vol 21 (6) ◽  
pp. 871-884 ◽  
Author(s):  
Atanas V. Koulov ◽  
Paul LaPointe ◽  
Bingwen Lu ◽  
Abbas Razvi ◽  
Judith Coppinger ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Atpase Activity ◽  
Protein Misfolding ◽  
Atp Hydrolysis ◽  
Structural Basis ◽  
Inherited Disease ◽  
Hsp90 Chaperone ◽  
Terminal Domains

The activator of Hsp90 ATPase 1, Aha1, has been shown to participate in the Hsp90 chaperone cycle by stimulating the low intrinsic ATPase activity of Hsp90. To elucidate the structural basis for ATPase stimulation of human Hsp90 by human Aha1, we have developed novel mass spectrometry approaches that demonstrate that the N- and C-terminal domains of Aha1 cooperatively bind across the dimer interface of Hsp90 to modulate the ATP hydrolysis cycle and client activity in vivo. Mutations in both the N- and C-terminal domains of Aha1 impair its ability to bind Hsp90 and stimulate its ATPase activity in vitro and impair in vivo the ability of the Hsp90 system to modulate the folding and trafficking of wild-type and variant (ΔF508) cystic fibrosis transmembrane conductance regulator (CFTR) responsible for the inherited disease cystic fibrosis (CF). We now propose a general model for the role of Aha1 in the Hsp90 ATPase cycle in proteostasis whereby Aha1 regulates the dwell time of Hsp90 with client. We suggest that Aha1 activity integrates chaperone function with client folding energetics by modulating ATPase sensitive N-terminal dimer structural transitions, thereby protecting transient folding intermediates in vivo that could contribute to protein misfolding systems disorders such as CF when destabilized.

scholarly journals Comparative study of the stabilities of synthetic in vitro and natural ex vivo transthyretin amyloid fibrils

2020 ◽  
Vol 295 (33) ◽  
pp. 11379-11387 ◽  
Author(s):  
Sara Raimondi ◽  
P. Patrizia Mangione ◽  
Guglielmo Verona ◽  
Diana Canetti ◽  
Paola Nocerino ◽  
...  
Keyword(s):  
Thermodynamic Stability ◽  
Amyloid Fibrils ◽  
Current Knowledge ◽  
Ex Vivo ◽  
Biochemical Properties ◽  
Amyloid Formation ◽  
Free Energies

Systemic amyloidosis caused by extracellular deposition of insoluble fibrils derived from the pathological aggregation of circulating proteins, such as transthyretin, is a severe and usually fatal condition. Elucidation of the molecular pathogenic mechanism of the disease and discovery of effective therapies still represents a challenging medical issue. The in vitro preparation of amyloid fibrils that exhibit structural and biochemical properties closely similar to those of natural fibrils is central to improving our understanding of the biophysical basis of amyloid formation in vivo and may offer an important tool for drug discovery. Here, we compared the morphology and thermodynamic stability of natural transthyretin fibrils with those of fibrils generated in vitro either using the common acidification procedure or primed by limited selective cleavage by plasmin. The free energies for fibril formation were −12.36, −8.10, and −10.61 kcal mol−1, respectively. The fibrils generated via plasmin cleavage were more stable than those prepared at low pH and were thermodynamically and morphologically similar to natural fibrils extracted from human amyloidotic tissue. Determination of thermodynamic stability is an important tool that is complementary to other methods of structural comparison between ex vivo fibrils and fibrils generated in vitro. Our finding that fibrils created via an in vitro amyloidogenic pathway are structurally similar to ex vivo human amyloid fibrils does not necessarily establish that the fibrillogenic pathway is the same for both, but it narrows the current knowledge gap between in vitro models and in vivo pathophysiology.

scholarly journals Microcin Amyloid Fibrils A Are Reservoir of Toxic Oligomeric Species

2012 ◽  
Vol 287 (15) ◽  
pp. 11665-11676 ◽  
Author(s):  
Mohammad Shahnawaz ◽  
Claudio Soto
Keyword(s):  
Environmental Conditions ◽  
Protein Misfolding ◽  
Amyloid Fibrils ◽  
Target Cells ◽  
Low Molecular Weight ◽  
Toxic Species ◽  
Soluble Species ◽  
Misfolding Diseases

Microcin E492 (Mcc), a low molecular weight bacteriocin produced by Klebsiella pneumoniae RYC492, has been shown to exist in two forms: soluble forms that are believed to be toxic to the bacterial cell by forming pores and non-toxic fibrillar forms that share similar biochemical and biophysical properties with amyloids associated with several human diseases. Here we report that fibrils polymerized in vitro from soluble forms sequester toxic species that can be released upon changing environmental conditions such as pH, ionic strength, and upon dilution. Our results indicate that basic pH (≥8.5), low NaCl concentrations (≤50 mm), and dilution (>10-fold) destabilize Mcc fibrils into more soluble species that are found to be toxic to the target cells. Additionally, we also found a similar conversion of non-toxic fibrils into highly toxic oligomers using Mcc aggregates produced in vivo. Moreover, the soluble protein released from fibrils is able to rapidly polymerize into amyloid fibrils under fibril-forming conditions and to efficiently seed aggregation of monomeric Mcc. Our findings indicate that fibrillar forms of Mcc constitute a reservoir of toxic oligomeric species that is released into the medium upon changing the environmental conditions. These findings may have substantial implications to understand the dynamic process of interconversion between toxic and non-toxic aggregated species implicated in protein misfolding diseases.

scholarly journals Global Proteotoxicity Caused by Human β2 Microglobulin Variants Impairs the Unfolded Protein Response in C. elegans

2021 ◽  
Vol 22 (19) ◽  
pp. 10752
Author(s):  
Sarah C. Good ◽  
Katherine M. Dewison ◽  
Sheena E. Radford ◽  
Patricija van Oosten-Hawle
Keyword(s):  
Er Stress ◽  
Molecular Mechanisms ◽  
Amyloid Fibrils ◽  
Signal Sequence ◽  
Systemic Amyloidosis ◽  
Wild Type ◽  
Β2 Microglobulin ◽  
C Elegans

Aggregation of β2 microglobulin (β2m) into amyloid fibrils is associated with systemic amyloidosis, caused by the deposition of amyloid fibrils containing the wild-type protein and its truncated variant, ΔN6 β2m, in haemo-dialysed patients. A second form of familial systemic amyloidosis caused by the β2m variant, D76N, results in amyloid deposits in the viscera, without renal dysfunction. Although the folding and misfolding mechanisms of β2 microglobulin have been widely studied in vitro and in vivo, we lack a comparable understanding of the molecular mechanisms underlying toxicity in a cellular and organismal environment. Here, we established transgenic C. elegans lines expressing wild-type (WT) human β2m, or the two highly amyloidogenic naturally occurring variants, D76N β2m and ΔN6 β2m, in the C. elegans bodywall muscle. Nematodes expressing the D76N β2m and ΔN6 β2m variants exhibit increased age-dependent and cell nonautonomous proteotoxicity associated with reduced motility, delayed development and shortened lifespan. Both β2m variants cause widespread endogenous protein aggregation contributing to the increased toxicity in aged animals. We show that expression of β2m reduces the capacity of C. elegans to cope with heat and endoplasmic reticulum (ER) stress, correlating with a deficiency to upregulate BiP/hsp-4 transcripts in response to ER stress in young adult animals. Interestingly, protein secretion in all β2m variants is reduced, despite the presence of the natural signal sequence, suggesting a possible link between organismal β2m toxicity and a disrupted ER secretory metabolism.

scholarly journals Cryo-EM structure of an amyloid fibril from systemic amyloidosis

2018 ◽  
Author(s):  
Falk Liberta ◽  
Sarah Loerch ◽  
Matthies Rennegarbe ◽  
Angelika Schierhorn ◽  
Per Westermark ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Serum Amyloid A ◽  
Amyloid Fibril ◽  
Ex Vivo ◽  
Serum Amyloid ◽  
Aa Amyloidosis ◽  
Amyloid A ◽  
Serum Amyloid A Protein ◽  
N Terminus

AbstractSystemic AA amyloidosis is a worldwide occurring disease of humans and animals that arises from the misfolding of serum amyloid A protein. To provide insights into the molecular basis of this disease we used electron cryo-microscopy and determined the structure of an ex vivo amyloid fibril purified from AA amyloidotic mice at 3.0 Å resolution. The fibril consists of C-terminally truncated serum amyloid A protein arranged into a compactly folded all-β conformation. The structure identifies the protein N-terminus as central for the assembly of this fibril and provides a mechanism for its prion-like replication. Our data further explain how amino acid substitutions within the tightly packed fibril core can lead to amyloid resistance in vivo.

scholarly journals Protease Resistance of ex vivo Amyloid Fibrils implies the proteolytic Selection of disease-associated Fibril Morphologies

2021 ◽  
Author(s):  
Jonathan Schoenfelder ◽  
Peter Benedikt Pfeiffer ◽  
Tejaswini Pradhan ◽  
Johan Bijzet ◽  
Bouke P.C. Hazenberg ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Amino Acid Sequences ◽  
The Body ◽  
Amyloid A ◽  
Chain Analysis ◽  
Polypeptide Chains ◽  
Amyloid Diseases ◽  
Selection Of

Several studies recently showed that ex vivo fibrils from patient or animal tissue were structurally different from in vitro formed fibrils from the same polypeptide chain. Analysis of serum amyloid A (SAA) and Aβ-derived amyloid fibrils additionally revealed that ex vivo fibrils were more protease stable than in vitro fibrils. These observations gave rise to the proteolytic selection hypothesis that suggested that disease-associated amyloid fibrils were selected inside the body by their ability to resist endogenous clearance mechanisms. We here show, for more than twenty different fibril samples, that ex vivo fibrils are more protease stable than in vitro fibrils. These data support the idea of a proteolytic selection of pathogenic amyloid fibril morphologies and help to explain why only few amino acid sequences lead to amyloid diseases, although many, if not all, polypeptide chains can form amyloid fibrils in vitro.

scholarly journals Bifunctional amyloid-reactive peptide promotes binding of antibody 11-1F4 to diverse amyloid types and enhances therapeutic efficacy

2018 ◽  
Vol 115 (46) ◽  
pp. E10839-E10848 ◽  
Author(s):  
Jonathan S. Wall ◽  
Angela D. Williams ◽  
James S. Foster ◽  
Tina Richey ◽  
Alan Stuckey ◽  
...  
Keyword(s):  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
Serum Amyloid ◽  
Al Amyloidosis ◽  
Peptide Epitope ◽  
Amyloid A ◽  
Affinity Peptide ◽  
The Many

Amyloidosis is a malignant pathology associated with the formation of proteinaceous amyloid fibrils that deposit in organs and tissues, leading to dysfunction and severe morbidity. More than 25 proteins have been identified as components of amyloid, but the most common form of systemic amyloidosis is associated with the deposition of amyloid composed of Ig light chains (AL). Clinical management of amyloidosis focuses on reducing synthesis of the amyloid precursor protein. However, recently, passive immunotherapy using amyloid fibril-reactive antibodies, such as 11-1F4, to remove amyloid from organs has been shown to be effective at restoring organ function in patients with AL amyloidosis. However, 11-1F4 does not bind amyloid in all AL patients, as evidenced by PET/CT imaging, nor does it efficiently bind the many other forms of amyloid. To enhance the reactivity and expand the utility of the 11-1F4 mAb as an amyloid immunotherapeutic, we have developed a pretargeting “peptope” comprising a multiamyloid-reactive peptide, p5+14, fused to a high-affinity peptide epitope recognized by 11-1F4. The peptope, known as p66, bound the 11-1F4 mAb in vitro with subnanomolar efficiency, exhibited multiamyloid reactivity in vitro and, using tissue biodistribution and SPECT imaging, colocalized with amyloid deposits in a mouse model of systemic serum amyloid A amyloidosis. Pretreatment with the peptope induced 11-1F4 mAb accumulation in serum amyloid A deposits in vivo and enhanced 11-1F4–mediated dissolution of a human AL amyloid extract implanted in mice.

scholarly journals Doxycycline reduces fibril formation in a transgenic mouse model of AL amyloidosis

Blood ◽  
2011 ◽  
Vol 118 (25) ◽  
pp. 6610-6617 ◽  
Author(s):  
Jennifer Ellis Ward ◽  
Ruiyi Ren ◽  
Gianluca Toraldo ◽  
Pam SooHoo ◽  
Jian Guan ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Amyloid Fibrils ◽  
Cell Clone ◽  
Ex Vivo ◽  
Organ Damage ◽  
Fibril Formation ◽  
Al Amyloidosis ◽  
Cmv Promoter

AbstractSystemic AL amyloidosis results from the aggregation of an amyloidogenic immunoglobulin (Ig) light chain (LC) usually produced by a plasma cell clone in the bone marrow. AL is the most rapidly fatal of the systemic amyloidoses, as amyloid fibrils can rapidly accumulate in tissues including the heart, kidneys, autonomic or peripheral nervous systems, gastrointestinal tract, and liver. Chemotherapy is used to eradicate the cellular source of the amyloidogenic precursor. Currently, there are no therapies that target the process of LC aggregation, fibril formation, or organ damage. We developed transgenic mice expressing an amyloidogenic λ6 LC using the cytomegalovirus (CMV) promoter to circumvent the disruption of B cell development by premature expression of recombined LC. The CMV-λ6 transgenic mice develop neurologic dysfunction and Congophilic amyloid deposits in the stomach. Amyloid deposition was inhibited in vivo by the antibiotic doxycycline. In vitro studies demonstrated that doxycycline directly disrupted the formation of recombinant LC fibrils. Furthermore, treatment of ex vivo LC amyloid fibrils with doxycycline reduced the number of intact fibrils and led to the formation of large disordered aggregates. The CMV-λ6 transgenic model replicates the process of AL amyloidosis and is useful for testing the antifibril potential of orally available agents.

Sign in / Sign up

Export Citation Format

Share Document