Articles de revues : « Amyloid-like assemblie »

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Bochicchio, Brigida, Maria Rosaria Armenante, Maria Antonietta Crudele et Antonietta Pepe. « Molecular Determinants for the Self-Assembly of Elastin Peptides ». Conference Papers in Science 2014 (21 août 2014) : 1–4. http://dx.doi.org/10.1155/2014/214235.

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Elastin and elastin-related peptides have great potential in the biomaterial field, because of their peculiar mechanical properties and spontaneous self-assembling behavior. Depending on their sequences and under appropriate experimental conditions, they are able to self-assemble in different fiber morphologies, including amyloid-like fibers. In this work, we will review recent data on elastin peptides derived from exon 30-coded domain of human tropoelastin. This domain has been shown to be fundamental for the correct assembly of elastin. However, the N-terminal region forms amyloid-like fibers, while the C-terminal fragment forms elastin-like fibers. A rationale for the varied aggregation pattern has been sought in the molecular structure of the peptides. Minimal differences in the sequences, adopting alternative conformations, are shown to be responsible for the observed data.

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Vrancx, Céline, Devkee M. Vadukul, Nuria Suelves, Sabrina Contino, Ludovic D’Auria, Florian Perrin, Vincent van Pesch, Bernard Hanseeuw, Loïc Quinton et Pascal Kienlen-Campard. « Mechanism of Cellular Formation and In Vivo Seeding Effects of Hexameric β-Amyloid Assemblies ». Molecular Neurobiology 58, n^o 12 (4 octobre 2021) : 6647–69. http://dx.doi.org/10.1007/s12035-021-02567-8.

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AbstractThe β-amyloid peptide (Aβ) is found as amyloid fibrils in senile plaques, a typical hallmark of Alzheimer’s disease (AD). However, intermediate soluble oligomers of Aβ are now recognized as initiators of the pathogenic cascade leading to AD. Studies using recombinant Aβ have shown that hexameric Aβ in particular acts as a critical nucleus for Aβ self-assembly. We recently isolated hexameric Aβ assemblies from a cellular model, and demonstrated their ability to enhance Aβ aggregation in vitro. Here, we report the presence of similar hexameric-like Aβ assemblies across several cellular models, including neuronal-like cell lines. In order to better understand how they are produced in a cellular context, we investigated the role of presenilin-1 (PS1) and presenilin-2 (PS2) in their formation. PS1 and PS2 are the catalytic subunits of the γ-secretase complex that generates Aβ. Using CRISPR-Cas9 to knockdown each of the two presenilins in neuronal-like cell lines, we observed a direct link between the PS2-dependent processing pathway and the release of hexameric-like Aβ assemblies in extracellular vesicles. Further, we assessed the contribution of hexameric Aβ to the development of amyloid pathology. We report the early presence of hexameric-like Aβ assemblies in both transgenic mice brains exhibiting human Aβ pathology and in the cerebrospinal fluid of AD patients, suggesting hexameric Aβ as a potential early AD biomarker. Finally, cell-derived hexameric Aβ was found to seed other human Aβ forms, resulting in the aggravation of amyloid deposition in vivo and neuronal toxicity in vitro.

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Vrancx, Céline, Devkee M. Vadukul, Nuria Suelves, Sabrina Contino, Ludovic D’Auria, Florian Perrin, Vincent van Pesch, Bernard Hanseeuw, Loïc Quinton et Pascal Kienlen-Campard. « Mechanism of Cellular Formation and In Vivo Seeding Effects of Hexameric β-Amyloid Assemblies ». Molecular Neurobiology 58, n^o 12 (4 octobre 2021) : 6647–69. http://dx.doi.org/10.1007/s12035-021-02567-8.

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AbstractThe β-amyloid peptide (Aβ) is found as amyloid fibrils in senile plaques, a typical hallmark of Alzheimer’s disease (AD). However, intermediate soluble oligomers of Aβ are now recognized as initiators of the pathogenic cascade leading to AD. Studies using recombinant Aβ have shown that hexameric Aβ in particular acts as a critical nucleus for Aβ self-assembly. We recently isolated hexameric Aβ assemblies from a cellular model, and demonstrated their ability to enhance Aβ aggregation in vitro. Here, we report the presence of similar hexameric-like Aβ assemblies across several cellular models, including neuronal-like cell lines. In order to better understand how they are produced in a cellular context, we investigated the role of presenilin-1 (PS1) and presenilin-2 (PS2) in their formation. PS1 and PS2 are the catalytic subunits of the γ-secretase complex that generates Aβ. Using CRISPR-Cas9 to knockdown each of the two presenilins in neuronal-like cell lines, we observed a direct link between the PS2-dependent processing pathway and the release of hexameric-like Aβ assemblies in extracellular vesicles. Further, we assessed the contribution of hexameric Aβ to the development of amyloid pathology. We report the early presence of hexameric-like Aβ assemblies in both transgenic mice brains exhibiting human Aβ pathology and in the cerebrospinal fluid of AD patients, suggesting hexameric Aβ as a potential early AD biomarker. Finally, cell-derived hexameric Aβ was found to seed other human Aβ forms, resulting in the aggravation of amyloid deposition in vivo and neuronal toxicity in vitro.

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Sade Yazdi, Dorin, Dana Laor Bar-Yosef, Hanaa Adsi, Topaz Kreiser, Shahaf Sigal, Santu Bera, Dor Zaguri et al. « Homocysteine fibrillar assemblies display cross-talk with Alzheimer’s disease β-amyloid polypeptide ». Proceedings of the National Academy of Sciences 118, n^o 24 (7 juin 2021) : e2017575118. http://dx.doi.org/10.1073/pnas.2017575118.

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High levels of homocysteine are reported as a risk factor for Alzheimer’s disease (AD). Correspondingly, inborn hyperhomocysteinemia is associated with an increased predisposition to the development of dementia in later stages of life. Yet, the mechanistic link between homocysteine accumulation and the pathological neurodegenerative processes is still elusive. Furthermore, despite the clear association between protein aggregation and AD, attempts to develop therapy that specifically targets this process have not been successful. It is envisioned that the failure in the development of efficacious therapeutic intervention may lie in the metabolomic state of affected individuals. We recently demonstrated the ability of metabolites to self-assemble and cross-seed the aggregation of pathological proteins, suggesting a role for metabolite structures in the initiation of neurodegenerative diseases. Here, we provide a report of homocysteine crystal structure and self-assembly into amyloid-like toxic fibrils, their inhibition by polyphenols, and their ability to seed the aggregation of the AD-associated β-amyloid polypeptide. A yeast model of hyperhomocysteinemia indicates a toxic effect, correlated with increased intracellular amyloid staining that could be rescued by polyphenol treatment. Analysis of AD mouse model brain sections indicates the presence of homocysteine assemblies and the interplay between β-amyloid and homocysteine. This work implies a molecular basis for the association between homocysteine accumulation and AD pathology, potentially leading to a paradigm shift in the understanding of AD initial pathological processes.

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Shaham-Niv, Shira, Lihi Adler-Abramovich, Lee Schnaider et Ehud Gazit. « Extension of the generic amyloid hypothesis to nonproteinaceous metabolite assemblies ». Science Advances 1, n^o 7 (août 2015) : e1500137. http://dx.doi.org/10.1126/sciadv.1500137.

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The accumulation of amyloid fibrils is the hallmark of several major human diseases. Although the formation of these supramolecular entities has previously been associated with proteins and peptides, it was later demonstrated that even phenylalanine, a single amino acid, can form fibrils that have amyloid-like biophysical, biochemical, and cytotoxic properties. Moreover, the generation of antibodies against these assemblies in phenylketonuria patients and the correlating mice model suggested a pathological role for the assemblies. We determine that several other metabolites that accumulate in metabolic disorders form ordered amyloid-like ultrastructures, which induce apoptotic cell death, as observed for amyloid structures. The formation of amyloid-like assemblies by metabolites implies a general phenomenon of amyloid formation, not limited to proteins and peptides, and offers a new paradigm for metabolic diseases.

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Adsi, Hanaa, Shon A. Levkovich, Elvira Haimov, Topaz Kreiser, Massimiliano Meli, Hamutal Engel, Luba Simhaev et al. « Chemical Chaperones Modulate the Formation of Metabolite Assemblies ». International Journal of Molecular Sciences 22, n^o 17 (25 août 2021) : 9172. http://dx.doi.org/10.3390/ijms22179172.

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The formation of amyloid-like structures by metabolites is associated with several inborn errors of metabolism (IEMs). These structures display most of the biological, chemical and physical properties of protein amyloids. However, the molecular interactions underlying the assembly remain elusive, and so far, no modulating therapeutic agents are available for clinical use. Chemical chaperones are known to inhibit protein and peptide amyloid formation and stabilize misfolded enzymes. Here, we provide an in-depth characterization of the inhibitory effect of osmolytes and hydrophobic chemical chaperones on metabolite assemblies, thus extending their functional repertoire. We applied a combined in vivo-in vitro-in silico approach and show their ability to inhibit metabolite amyloid-induced toxicity and reduce cellular amyloid content in yeast. We further used various biophysical techniques demonstrating direct inhibition of adenine self-assembly and alteration of fibril morphology by chemical chaperones. Using a scaffold-based approach, we analyzed the physiochemical properties of various dimethyl sulfoxide derivatives and their role in inhibiting metabolite self-assembly. Lastly, we employed whole-atom molecular dynamics simulations to elucidate the role of hydrogen bonds in osmolyte inhibition. Our results imply a dual mode of action of chemical chaperones as IEMs therapeutics, that could be implemented in the rational design of novel lead-like molecules.

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Zhang, Jing, Jian Wang, Chengwei Ma et Junxia Lu. « Hydroxyapatite Formation Coexists with Amyloid-like Self-Assembly of Human Amelogenin ». International Journal of Molecular Sciences 21, n^o 8 (22 avril 2020) : 2946. http://dx.doi.org/10.3390/ijms21082946.

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Tooth enamel is formed in an extracellular environment. Amelogenin, the major component in the protein matrix of tooth enamel during the developing stage, could assemble into high molecular weight structures, regulating enamel formation. However, the molecular structure of amelogenin protein assembly at the functional state is still elusive. In this work, we found that amelogenin is able to induce calcium phosphate minerals into hydroxyapatite (HAP) structure in vitro at pH 6.0. Assessed using X-ray diffraction (XRD) and 31P solid-state NMR (SSNMR) evidence, the formed HAP mimics natural enamel closely. The structure of amelogenin protein assembly coexisting with the HAP was also studied using atomic force microscopy (AFM), transmission electron microscopy (TEM) and XRD, indicating the β-amyloid structure of the protein. SSNMR was proven to be an important tool in detecting both the rigid and dynamic components of the protein assembly in the sample, and the core sequence 18EVLTPLKWYQSI29 was identified as the major segment contributing to the β-sheet secondary structure. Our research suggests an amyloid structure may be an important factor in controlling HAP formation at the right pH conditions with the help of other structural components in the protein assembly.

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Sharkey, Lisa M., Nathaniel Safren, Amit S. Pithadia, Julia E. Gerson, Mark Dulchavsky, Svetlana Fischer, Ronak Patel et al. « Mutant UBQLN2 promotes toxicity by modulating intrinsic self-assembly ». Proceedings of the National Academy of Sciences 115, n^o 44 (17 octobre 2018) : E10495—E10504. http://dx.doi.org/10.1073/pnas.1810522115.

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UBQLN2 is one of a family of proteins implicated in ubiquitin-dependent protein quality control and integrally tied to human neurodegenerative disease. Whereas wild-type UBQLN2 accumulates in intraneuronal deposits in several common age-related neurodegenerative diseases, mutations in the gene encoding this protein result in X-linked amyotrophic lateral sclerosis/frontotemporal dementia associated with TDP43 accumulation. Using in vitro protein analysis, longitudinal fluorescence imaging and cellular, neuronal, and transgenic mouse models, we establish that UBQLN2 is intrinsically prone to self-assemble into higher-order complexes, including liquid-like droplets and amyloid aggregates. UBQLN2 self-assembly and solubility are reciprocally modulated by the protein’s ubiquitin-like and ubiquitin-associated domains. Moreover, a pathogenic UBQLN2 missense mutation impairs droplet dynamics and favors amyloid-like aggregation associated with neurotoxicity. These data emphasize the critical link between UBQLN2’s role in ubiquitin-dependent pathways and its propensity to self-assemble and aggregate in neurodegenerative diseases.

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Partouche, David, Valeria Militello, Andrea Gomez-Zavaglia, Frank Wien, Christophe Sandt et Véronique Arluison. « In Situ Characterization of Hfq Bacterial Amyloid : A Fourier-Transform Infrared Spectroscopy Study ». Pathogens 8, n^o 1 (18 mars 2019) : 36. http://dx.doi.org/10.3390/pathogens8010036.

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Hfq is a bacterial protein that regulates gene expression at the post-transcriptional level in Gram-negative bacteria. We have previously shown that Escherichia coli Hfq protein, and more precisely its C-terminal region (CTR), self-assembles into an amyloid-like structure in vitro. In the present work, we present evidence that Hfq unambiguously forms amyloid structures also in vivo. Taking into account the role of this protein in bacterial adaptation and virulence, our work opens possibilities to target Hfq amyloid self-assembly and cell location, with important potential to block bacterial adaptation and treat infections.

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Yarawsky, Alexander E., Stefanie L. Johns, Peter Schuck et Andrew B. Herr. « The biofilm adhesion protein Aap from Staphylococcus epidermidis forms zinc-dependent amyloid fibers ». Journal of Biological Chemistry 295, n^o 14 (26 février 2020) : 4411–27. http://dx.doi.org/10.1074/jbc.ra119.010874.

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The skin-colonizing commensal bacterium Staphylococcus epidermidis is a leading cause of hospital-acquired and device-related infections. Its pathogenicity in humans is largely due to its propensity to form biofilms, surface-adherent bacterial accumulations that are remarkably resistant to chemical and physical stresses. Accumulation-associated protein (Aap) from S. epidermidis has been shown to be necessary and sufficient for mature biofilm formation and catheter infection. Aap contains up to 17 tandem B-repeat domains, capable of zinc-dependent assembly into twisted, rope-like intercellular filaments in the biofilm. Using microscopic and biophysical techniques, we show here that Aap B-repeat constructs assemble further into zinc-dependent functional amyloid fibers. We observed such amyloid fibers by confocal microscopy during both early and late stages of S. epidermidis biofilm formation, and we confirmed that extracellular fibrils from these biofilms contain Aap. Unlike what has been observed for amyloidogenic biofilm proteins from other bacteria, which typically use chaperones or initiator proteins to initiate amyloid assembly, our findings indicate that Aap from S. epidermidis requires Zn2+ as a catalyst that drives amyloid fiber formation, similar to many mammalian amyloid-forming proteins that require metals for assembly. This work provides detailed insights into S. epidermidis biofilm formation and architecture that improve our understanding of persistent staphylococcal infections.

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Terry, Cassandra, Adam Wenborn, Nathalie Gros, Jessica Sells, Susan Joiner, Laszlo L. P. Hosszu, M. Howard Tattum et al. « Ex vivo mammalian prions are formed of paired double helical prion protein fibrils ». Open Biology 6, n^o 5 (mai 2016) : 160035. http://dx.doi.org/10.1098/rsob.160035.

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Mammalian prions are hypothesized to be fibrillar or amyloid forms of prion protein (PrP), but structures observed to date have not been definitively correlated with infectivity and the three-dimensional structure of infectious prions has remained obscure. Recently, we developed novel methods to obtain exceptionally pure preparations of prions from mouse brain and showed that pathogenic PrP in these high-titre preparations is assembled into rod-like assemblies. Here, we have used precise cell culture-based prion infectivity assays to define the physical relationship between the PrP rods and prion infectivity and have used electron tomography to define their architecture. We show that infectious PrP rods isolated from multiple prion strains have a common hierarchical assembly comprising twisted pairs of short fibres with repeating substructure. The architecture of the PrP rods provides a new structural basis for understanding prion infectivity and can explain the inability to systematically generate high-titre synthetic prions from recombinant PrP.

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Carpenter, Kayla, Rachel Brietta Bell, Julius Yunus, Angelika Amon et Luke Edwin Berchowitz. « Phosphorylation-Mediated Clearance of Amyloid-like Assemblies in Meiosis ». Developmental Cell 45, n^o 3 (mai 2018) : 392–405. http://dx.doi.org/10.1016/j.devcel.2018.04.001.

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Shaham-Niv, Shira, Pavel Rehak, Dor Zaguri, Sofiya Kolusheva, Petr Král et Ehud Gazit. « Metabolite amyloid-like fibrils interact with model membranes ». Chemical Communications 54, n^o 36 (2018) : 4561–64. http://dx.doi.org/10.1039/c8cc01423j.

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Zee, Chih-Te, Calina Glynn, Marcus Gallagher-Jones, Jennifer Miao, Carlos G. Santiago, Duilio Cascio, Tamir Gonen, Michael R. Sawaya et Jose A. Rodriguez. « Homochiral and racemic MicroED structures of a peptide repeat from the ice-nucleation protein InaZ ». IUCrJ 6, n^o 2 (24 janvier 2019) : 197–205. http://dx.doi.org/10.1107/s2052252518017621.

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The ice-nucleation protein InaZ from Pseudomonas syringae contains a large number of degenerate repeats that span more than a quarter of its sequence and include the segment GSTSTA. Ab initio structures of this repeat segment, resolved to 1.1 Å by microfocus X-ray crystallography and to 0.9 Å by the cryo-EM method MicroED, were determined from both racemic and homochiral crystals. The benefits of racemic protein crystals for structure determination by MicroED were evaluated and it was confirmed that the phase restriction introduced by crystal centrosymmetry increases the number of successful trials during the ab initio phasing of the electron diffraction data. Both homochiral and racemic GSTSTA form amyloid-like protofibrils with labile, corrugated antiparallel β-sheets that mate face to back. The racemic GSTSTA protofibril represents a new class of amyloid assembly in which all-left-handed sheets mate with their all-right-handed counterparts. This determination of racemic amyloid assemblies by MicroED reveals complex amyloid architectures and illustrates the racemic advantage in macromolecular crystallography, now with submicrometre-sized crystals.

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Marshall, Karen E., et Louise C. Serpell. « Structural integrity of β-sheet assembly ». Biochemical Society Transactions 37, n^o 4 (22 juillet 2009) : 671–76. http://dx.doi.org/10.1042/bst0370671.

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The folding of a protein from a sequence of amino acids to a well-defined tertiary structure is one of the most studied and enigmatic events to take place in biological systems. Relatively recently, it has been established that some proteins and peptides are able to take on conformations other than their native fold to form long fibres known as amyloid. In vivo, these are associated with misfolding diseases, such as Alzheimer's disease, Type 2 diabetes and the amyloidoses. In vitro, peptide assembly leads to amyloid-like fibres that have high stability, resistance to degradation and high tensile strength. Remarkably, despite the lack of any obvious sequence similarity between these fibrillogenic proteins and peptides, all amyloid fibrils share common structural characteristics and their underlying structure is known as ‘cross-β’. Nature is rich in β-sheet protein assemblies such as spider silk and other ‘useful’ amyloids such as curli from Escherichia coli, where the strength of fibrils is fundamental to their function.

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Clark, John I. « Self-assembly of protein aggregates in ageing disorders : the lens and cataract model ». Philosophical Transactions of the Royal Society B : Biological Sciences 368, n^o 1617 (5 mai 2013) : 20120104. http://dx.doi.org/10.1098/rstb.2012.0104.

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Cataract, neurodegenerative disease, macular degeneration and pathologies of ageing are often characterized by the slow progressive destabilization of proteins and their self-assembly to amyloid-like fibrils and aggregates. During normal cell differentiation, protein self-assembly is well established as a dynamic mechanism for cytoskeletal organization. With the increased emphasis on ageing disorders, there is renewed interest in small-molecule regulators of protein self-assembly. Synthetic peptides, mini-chaperones, aptamers, ATP and pantethine reportedly regulate self-assembly mechanisms involving small stress proteins, represented by human αB-crystallin, and their targets. Small molecules are being considered for direct application as molecular therapeutics to protect against amyloid and protein aggregation disorders in ageing cells and tissues in vivo . The identification of specific interactive peptide sites for effective regulation of protein self-assembly is underway using conventional and innovative technologies. The quantification of the functional interactions between small stress proteins and their targets in vivo remains a top research priority. The quantitative parameters controlling protein–protein interactions in vivo need characterization to understand the fundamental biology of self-assembling systems in normal cells and disorders of ageing.

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Tavassoly, Omid, Dorin Sade, Santu Bera, Shira Shaham-Niv, David J. Vocadlo et Ehud Gazit. « Quinolinic Acid Amyloid-like Fibrillar Assemblies Seed α-Synuclein Aggregation ». Journal of Molecular Biology 430, n^o 20 (octobre 2018) : 3847–62. http://dx.doi.org/10.1016/j.jmb.2018.08.002.

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Wolfe, Katie J., Hong Yu Ren, Philipp Trepte et Douglas M. Cyr. « The Hsp70/90 cochaperone, Sti1, suppresses proteotoxicity by regulating spatial quality control of amyloid-like proteins ». Molecular Biology of the Cell 24, n^o 23 (décembre 2013) : 3588–602. http://dx.doi.org/10.1091/mbc.e13-06-0315.

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Conformational diseases are associated with the conversion of normal proteins into aggregation-prone toxic conformers with structures similar to that of β-amyloid. Spatial distribution of amyloid-like proteins into intracellular quality control centers can be beneficial, but cellular mechanisms for protective aggregation remain unclear. We used a high-copy suppressor screen in yeast to identify roles for the Hsp70 system in spatial organization of toxic polyglutamine-expanded Huntingtin (Huntingtin with 103Q glutamine stretch [Htt103Q]) into benign assemblies. Under toxic conditions, Htt103Q accumulates in unassembled states and speckled cytosolic foci. Subtle modulation of Sti1 activity reciprocally affects Htt toxicity and the packaging of Htt103Q into foci. Loss of Sti1 exacerbates Htt toxicity and hinders foci formation, whereas elevation of Sti1 suppresses Htt toxicity while organizing small Htt103Q foci into larger assemblies. Sti1 also suppresses cytotoxicity of the glutamine-rich yeast prion [RNQ+] while reorganizing speckled Rnq1–monomeric red fluorescent protein into distinct foci. Sti1-inducible foci are perinuclear and contain proteins that are bound by the amyloid indicator dye thioflavin-T. Sti1 is an Hsp70 cochaperone that regulates the spatial organization of amyloid-like proteins in the cytosol and thereby buffers proteotoxicity caused by amyloid-like proteins.

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Zhang, Shao-Qing, Hai Huang, Junjiao Yang, Huong T. Kratochvil, Marco Lolicato, Yanxin Liu, Xiaokun Shu, Lijun Liu et William F. DeGrado. « Designed peptides that assemble into cross-α amyloid-like structures ». Nature Chemical Biology 14, n^o 9 (30 juillet 2018) : 870–75. http://dx.doi.org/10.1038/s41589-018-0105-5.

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Al-Garawi, Zahraa S. « Zinc Metal Ion Affected the Structural Stability of Amyloid-Like Nanofibrils ». Al-Mustansiriyah Journal of Science 29, n^o 3 (10 mars 2019) : 50. http://dx.doi.org/10.23851/mjs.v29i3.622.

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Synthetic peptides that self-assemble into well-defined structures with a cross-β arrangement are called amyloid-like fibrils. Amyloids are associated with a list of disorders and neuro-degenerative diseases, such as Alzheimer's and Parkinson`s disease. We previously showed that amyloid-like nanofibrils with a repeating motif “IHIH” were functional fibrils. They were able to bind a metal ion through imidazole moieties and mimic the native carbonic anhydrase enzyme by hydrolysing the CO2 molecule. Thus, these synthetic amyloid fibrils were suggest-ed to be good candidates to moderate and update the modern enzymatic molecules. This study aims to shed a light on the stability of these amyloid nanofibrils over a study period of 25 days, in the presence/absence of a metal ion. The work continued for approximately 7 months in the Biochemistry department, School of Life Sciences at the University of Sussex in the United Kingdom. A set of designed peptides with a repeating motif “IHIH” were ex-plored, based on some structural studies. Short and long peptides with free ends as well as closed ends were investigated. Peptides allowed to self-assemble with and without a metal ion (zinc) were then examined using circular dichroism, fluorimetry and electron microscopy for structural biophysical analysis. Regardless of the metal ion contribution, peptides showed stable secondary structures with a -sheet conformation for the incubation time of 25 days. Their morphologies did not appear to change over time. However, the presence of a zinc ion has an effect on the secondary structure of the mature fibrils. Results indicated that fibrils grown with the zinc ion have a significantly higher propensity to form -sheets secondary structures during incubation time. The presence of a zinc ion also affected the dimensions of the amyloid-like fibrils by the end of the study course, at which point they significantly re-duced. This effect of zinc ion on synthetic amyloid fibrils has not been previously reported. The stabilities of the zinc-nanofibrils point to their potential for use in modifying or updating the enzyme-mimic analytical reactions. The effect of adding zinc on the fibrillation seems to be crucial. Although it apparently improved the -sheet assembly, it affected the width/length of the synthetic amyloids. This effect could be promising toward reducing the generation of amyloid fibrils and ultimately understanding the pathogenesis of Alzheimer disease.

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Theodoridis, Phaedra R., Michael Bokros, Dane Marijan, Nathan C. Balukoff, Dazhi Wang, Chloe C. Kirk, Taylor D. Budine et al. « Local translation in nuclear condensate amyloid bodies ». Proceedings of the National Academy of Sciences 118, n^o 7 (10 février 2021) : e2014457118. http://dx.doi.org/10.1073/pnas.2014457118.

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Biomolecular condensates concentrate molecules to facilitate basic biochemical processes, including transcription and DNA replication. While liquid-like condensates have been ascribed various functions, solid-like condensates are generally thought of as amorphous sites of protein storage. Here, we show that solid-like amyloid bodies coordinate local nuclear protein synthesis (LNPS) during stress. On stimulus, translationally active ribosomes accumulate along fiber-like assemblies that characterize amyloid bodies. Mass spectrometry analysis identified regulatory ribosomal proteins and translation factors that relocalize from the cytoplasm to amyloid bodies to sustain LNPS. These amyloidogenic compartments are enriched in newly transcribed messenger RNA by Heat Shock Factor 1 (HSF1). Depletion of stress-induced ribosomal intergenic spacer noncoding RNA (rIGSRNA) that constructs amyloid bodies prevents recruitment of the nuclear protein synthesis machinery, abolishes LNPS, and impairs the nuclear HSF1 response. We propose that amyloid bodies support local nuclear translation during stress and that solid-like condensates can facilitate complex biochemical reactions as their liquid counterparts can.

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Diaferia, Carlo, Nicole Balasco, Davide Altamura, Teresa Sibillano, Enrico Gallo, Valentina Roviello, Cinzia Giannini, Giancarlo Morelli, Luigi Vitagliano et Antonella Accardo. « Assembly modes of hexaphenylalanine variants as function of the charge states of their terminal ends ». Soft Matter 14, n^o 40 (2018) : 8219–30. http://dx.doi.org/10.1039/c8sm01441h.

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Dean, Dexter N., et Jennifer C. Lee. « Modulating functional amyloid formation via alternative splicing of the premelanosomal protein PMEL17 ». Journal of Biological Chemistry 295, n^o 21 (10 avril 2020) : 7544–53. http://dx.doi.org/10.1074/jbc.ra120.013012.

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The premelanosomal protein (PMEL17) forms functional amyloid fibrils involved in melanin biosynthesis. Multiple PMEL17 isoforms are produced, two of which arise from excision of a cryptic intron within the amyloid-forming repeat (RPT) domain, leading to long (lRPT) and short (sRPT) isoforms with 10 and 7 imperfect repeats, respectively. Both lRPT and sRPT isoforms undergo similar pH-dependent mechanisms of amyloid formation and fibril dissolution. Here, using human PMEL17, we tested the hypothesis that the minor, but more aggregation-prone, sRPT facilitates amyloid formation of lRPT. We observed that cross-seeding by sRPT fibrils accelerates the rate of lRPT aggregation, resulting in propagation of an sRPT-like twisted fibril morphology, unlike the rodlike structure that lRPT normally adopts. This templating was specific, as the reversed reaction inhibited sRPT fibril formation. Despite displaying ultrastructural differences, self- and cross-seeded lRPT fibrils had a similar β-sheet structured core, revealed by Raman spectroscopy, limited-proteolysis, and fibril disaggregation experiments, suggesting the fibril twist is modulated by N-terminal residues outside the amyloid core. Interestingly, bioinformatics analysis of PMEL17 homologs from other mammals uncovered that long and short RPT isoforms are conserved among members of this phylogenetic group. Collectively, our results indicate that the short isoform of RPT serves as a “nucleator” of PMEL17 functional amyloid formation, mirroring how bacterial functional amyloids assemble during biofilm formation. Whereas bacteria regulate amyloid assembly by using individual genes within the same operon, we propose that the modulation of functional amyloid formation in higher organisms can be accomplished through alternative splicing.

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Gazit, Ehud. « Reductionist Approach in Peptide-Based Nanotechnology ». Annual Review of Biochemistry 87, n^o 1 (20 juin 2018) : 533–53. http://dx.doi.org/10.1146/annurev-biochem-062917-012541.

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The formation of ordered nanostructures by molecular self-assembly of proteins and peptides represents one of the principal directions in nanotechnology. Indeed, polyamides provide superior features as materials with diverse physical properties. A reductionist approach allowed the identification of extremely short peptide sequences, as short as dipeptides, which could form well-ordered amyloid-like β-sheet-rich assemblies comparable to supramolecular structures made of much larger proteins. Some of the peptide assemblies show remarkable mechanical, optical, and electrical characteristics. Another direction of reductionism utilized a natural noncoded amino acid, α-aminoisobutryic acid, to form short superhelical assemblies. The use of this exceptional helix inducer motif allowed the fabrication of single heptad repeats used in various biointerfaces, including their use as surfactants and DNA-binding agents. Two additional directions of the reductionist approach include the use of peptide nucleic acids (PNAs) and coassembly techniques. The diversified accomplishments of the reductionist approach, as well as the exciting future advances it bears, are discussed.

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Morris, Kyle L., Alison Rodger, Matthew R. Hicks, Maya Debulpaep, Joost Schymkowitz, Frederic Rousseau et Louise C. Serpell. « Exploring the sequence–structure relationship for amyloid peptides ». Biochemical Journal 450, n^o 2 (15 février 2013) : 275–83. http://dx.doi.org/10.1042/bj20121773.

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Amyloid fibril formation is associated with misfolding diseases, as well as fulfilling a functional role. The cross-β molecular architecture has been reported in increasing numbers of amyloid-like fibrillar systems. The Waltz algorithm is able to predict ordered self-assembly of amyloidogenic peptides by taking into account the residue type and position. This algorithm has expanded the amyloid sequence space, and in the present study we characterize the structures of amyloid-like fibrils formed by three peptides identified by Waltz that form fibrils but not crystals. The structural challenge is met by combining electron microscopy, linear dichroism, CD and X-ray fibre diffraction. We propose structures that reveal a cross-β conformation with ‘steric-zipper’ features, giving insights into the role for side chains in peptide packing and stability within fibrils. The amenity of these peptides to structural characterization makes them compelling model systems to use for understanding the relationship between sequence, self-assembly, stability and structure of amyloid fibrils.

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Singh, Prabhjot, Nishima Wangoo et Rohit K. Sharma. « Phenylalanine dimer assembly structure as the basic building block of an amyloid like photoluminescent nanofibril network ». Soft Matter 16, n^o 17 (2020) : 4105–9. http://dx.doi.org/10.1039/d0sm00387e.

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Guo, Zhen, Zhiwei Shen, Yujiao Wang, Tingyuan Tan et Yi Zhang. « Peptides Co-Assembling into Hydrangea-Like Microstructures ». Journal of Nanoscience and Nanotechnology 20, n^o 5 (1 mai 2020) : 3239–45. http://dx.doi.org/10.1166/jnn.2020.17393.

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Supramolecular assembly in vitro is a simple and effective way to produce multi-level biostructures to mimic the self-assembly of biomolecules in organisms. The study on peptide assembly behaviors would benefit a lot to understand what goes on in life, as well as in the construction of plenty of functional biomaterials that have potential applications in various fields. Since cellular microenvironments are crowded and contain various biomolecules, studying protein and peptide co-assembly is of great interest. Here, we introduced the co-assembly of 5-FAM-ELVFFAE-NH2 (EE-7) and (CY5)-KLVFFAK-NH2 (KK-7), which are sequences derived from the core of the amyloid β (Aβ) peptide, a key protein in Alzheimer’s diseases. Morphologic studies employing atomic force microscopy and scanning electron microscopy indicated that the co-assembled entities had a novel hydrangea-like microstructure, in contrast to micro-sheet structures formed from monocomponent EE-7 or KK-7, respectively. Fluorescence co-localization experiments confirmed that the hydrangealike microstructures were indeed made of both EE-7 and KK-7. We suggest that the formation of the hydrangea-like microstructures is driven by both the electrostatic and hydrophobic interactions between EE-7 and KK-7. A molecular mechanism has been provided to explain the formation of the hydrangea-like microstructures.

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Li, Chen, Lu Xu, Yi Y. Zuo et Peng Yang. « Tuning protein assembly pathways through superfast amyloid-like aggregation ». Biomaterials Science 6, n^o 4 (2018) : 836–41. http://dx.doi.org/10.1039/c8bm00066b.

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Pérez-Chirinos Lallana, Laura, Ivan R. Sasselli et Aitziber L. Cortajarena. « A Multidisciplinary Approach to Design Amyloid-Like Peptides to Form Supramolecular Assemblies ». Biophysical Journal 120, n^o 3 (février 2021) : 209a. http://dx.doi.org/10.1016/j.bpj.2020.11.1418.

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Walker, Lary C., Juliane Schelle et Mathias Jucker. « The Prion-Like Properties of Amyloid-β Assemblies : Implications for Alzheimer's Disease ». Cold Spring Harbor Perspectives in Medicine 6, n^o 7 (7 juin 2016) : a024398. http://dx.doi.org/10.1101/cshperspect.a024398.

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López Deber, María Pilar, David T. Hickman, Deepak Nand, Marc Baldus, Andrea Pfeifer et Andreas Muhs. « Engineering Amyloid-Like Assemblies from Unstructured Peptides via Site-Specific Lipid Conjugation ». PLoS ONE 9, n^o 9 (10 septembre 2014) : e105641. http://dx.doi.org/10.1371/journal.pone.0105641.

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Ray, Sudipta, Apurba K. Das, Michael G. B. Drew et Arindam Banerjee. « A short water-soluble self-assembling peptide forms amyloid-like fibrils ». Chemical Communications, n^o 40 (2006) : 4230. http://dx.doi.org/10.1039/b607657b.

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Scanavachi, Gustavo, Yanis Ricardo Espinosa, Juan Ruso et Rosangela Itri. « Unveiling the Role of Surfactants on Amyloid-Like Protein Self-Assembling ». Biophysical Journal 116, n^o 3 (février 2019) : 483a. http://dx.doi.org/10.1016/j.bpj.2018.11.2608.

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Carcamo-Noriega, Edson N., et Gloria Saab-Rincon. « Identification of fibrillogenic regions in human triosephosphate isomerase ». PeerJ 4 (4 février 2016) : e1676. http://dx.doi.org/10.7717/peerj.1676.

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Background.Amyloid secondary structure relies on the intermolecular assembly of polypeptide chains through main-chain interaction. According to this, all proteins have the potential to form amyloid structure, nevertheless, in nature only few proteins aggregate into toxic or functional amyloids. Structural characteristics differ greatly among amyloid proteins reported, so it has been difficult to link the fibrillogenic propensity with structural topology. However, there are ubiquitous topologies not represented in the amyloidome that could be considered as amyloid-resistant attributable to structural features, such is the case of TIM barrel topology.Methods.This work was aimed to study the fibrillogenic propensity of human triosephosphate isomerase (HsTPI) as a model of TIM barrels. In order to do so, aggregation of HsTPI was evaluated under native-like and destabilizing conditions. Fibrillogenic regions were identified by bioinformatics approaches, protein fragmentation and peptide aggregation.Results.We identified four fibrillogenic regions in the HsTPI corresponding to theβ3,β6,β7y α8 of the TIM barrel. From these, theβ3-strand region (residues 59–66) was highly fibrillogenic. In aggregation assays, HsTPI under native-like conditions led to amorphous assemblies while under partially denaturing conditions (urea 3.2 M) formed more structured aggregates. This slightly structured aggregates exhibited residual cross-βstructure, as demonstrated by the recognition of the WO1 antibody and ATR-FTIR analysis.Discussion.Despite the fibrillogenic regions present in HsTPI, the enzyme maintained under native-favoring conditions displayed low fibrillogenic propensity. This amyloid-resistance can be attributed to the three-dimensional arrangement of the protein, whereβ-strands, susceptible to aggregation, are protected in the core of the molecule. Destabilization of the protein structure may expose inner regions promotingβ-aggregation, as well as the formation of hydrophobic disordered aggregates. Being this last pathway kinetically favored over the thermodynamically more stable fibril aggregation pathway.

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Baker, Max O. D. G., Nirukshan Shanmugam, Chi L. L. Pham, Sarah R. Ball, Emma Sierecki, Yann Gambin, Megan Steain et Margaret Sunde. « The RHIM of the Immune Adaptor Protein TRIF Forms Hybrid Amyloids with Other Necroptosis-Associated Proteins ». Molecules 27, n^o 11 (24 mai 2022) : 3382. http://dx.doi.org/10.3390/molecules27113382.

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TIR-domain-containing adapter-inducing interferon-β (TRIF) is an innate immune protein that serves as an adaptor for multiple cellular signalling outcomes in the context of infection. TRIF is activated via ligation of Toll-like receptors 3 and 4. One outcome of TRIF-directed signalling is the activation of the programmed cell death pathway necroptosis, which is governed by interactions between proteins that contain a RIP Homotypic Interaction Motif (RHIM). TRIF contains a RHIM sequence and can interact with receptor interacting protein kinases 1 (RIPK1) and 3 (RIPK3) to initiate necroptosis. Here, we demonstrate that the RHIM of TRIF is amyloidogenic and supports the formation of homomeric TRIF-containing fibrils. We show that the core tetrad sequence within the RHIM governs the supramolecular organisation of TRIF amyloid assemblies, although the stable amyloid core of TRIF amyloid fibrils comprises a much larger region than the conserved RHIM only. We provide evidence that RHIMs of TRIF, RIPK1 and RIPK3 interact directly to form heteromeric structures and that these TRIF-containing hetero-assemblies display altered and emergent properties that likely underlie necroptosis signalling in response to Toll-like receptor activation.

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Kamada, Ayaka, Nitesh Mittal, L. Daniel Söderberg, Tobias Ingverud, Wiebke Ohm, Stephan V. Roth, Fredrik Lundell et Christofer Lendel. « Flow-assisted assembly of nanostructured protein microfibers ». Proceedings of the National Academy of Sciences 114, n^o 6 (25 janvier 2017) : 1232–37. http://dx.doi.org/10.1073/pnas.1617260114.

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Some of the most remarkable materials in nature are made from proteins. The properties of these materials are closely connected to the hierarchical assembly of the protein building blocks. In this perspective, amyloid-like protein nanofibrils (PNFs) have emerged as a promising foundation for the synthesis of novel bio-based materials for a variety of applications. Whereas recent advances have revealed the molecular structure of PNFs, the mechanisms associated with fibril–fibril interactions and their assembly into macroscale structures remain largely unexplored. Here, we show that whey PNFs can be assembled into microfibers using a flow-focusing approach and without the addition of plasticizers or cross-linkers. Microfocus small-angle X-ray scattering allows us to monitor the fibril orientation in the microchannel and compare the assembly processes of PNFs of distinct morphologies. We find that the strongest fiber is obtained with a sufficient balance between ordered nanostructure and fibril entanglement. The results provide insights in the behavior of protein nanostructures under laminar flow conditions and their assembly mechanism into hierarchical macroscopic structures.

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Koga, Tomoyuki, Kazuhiro Taguchi, Takatoshi Kinoshita et Masahiro Higuchi. « pH-Regulated formation of amyloid-like β-sheet assemblies from polyglutamate grafted polyallylamine ». Chemical Communications, n^o 3 (8 janvier 2002) : 242–43. http://dx.doi.org/10.1039/b109574a.

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Vitagliano, Luigi, Francesca Stanzione, Alfonso De Simone et Luciana Esposito. « Dynamics and stability of amyloid-like steric zipper assemblies with hydrophobic dry interfaces ». Biopolymers 91, n^o 12 (décembre 2009) : 1161–71. http://dx.doi.org/10.1002/bip.21182.

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Han, Zhenlin, Bei Zhang, Yi E. Wang, Yi Y. Zuo et Wei Wen Su. « Self-Assembled Amyloid-Like Oligomeric-Cohesin Scaffoldin for Augmented Protein Display on the Saccharomyces cerevisiae Cell Surface ». Applied and Environmental Microbiology 78, n^o 9 (17 février 2012) : 3249–55. http://dx.doi.org/10.1128/aem.07745-11.

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ABSTRACTIn this study, a molecular self-assembly strategy to develop a novel protein scaffold for amplifying the extent and variety of proteins displayed on the surface ofSaccharomyces cerevisiaeis presented. The cellulosomal scaffolding protein cohesin and its upstream hydrophilic domain (HD) were genetically fused with the yeast Ure2p N-terminal fibrillogenic domain consisting of residues 1 to 80 (Ure2p1-80). The resulting Ure2p1-80-HD-cohesin fusion protein was successfully expressed inEscherichia colito produce self-assembled supramolecular nanofibrils that serve as a novel protein scaffold displaying multiple copies of functional cohesin domains. The amyloid-like property of the nanofibrils was confirmed via thioflavin T staining and atomic force microscopy. These cohesin nanofibrils attached themselves, via a green fluorescent protein (GFP)-dockerin fusion protein, to the cell surface ofS. cerevisiaeengineered to display a GFP-nanobody. The excess cohesin units on the nanofibrils provide ample sites for binding to dockerin fusion proteins, as exemplified using an mCherry-dockerin fusion protein as well as theClostridium cellulolyticumCelA endoglucanase. More than a 24-fold increase in mCherry fluorescence and an 8-fold increase in CelA activity were noted when the cohesin nanofibril scaffold-mediated yeast display was used, compared to using yeast display with GFP-cohesin that contains only a single copy of cohesin. Self-assembled supramolecular cohesin nanofibrils created by fusion with the yeast Ure2p fibrillogenic domain provide a versatile protein scaffold that expands the utility of yeast cell surface display.

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Arya, Shruti, Arpana Kumari, Vijit Dalal, Mily Bhattacharya et Samrat Mukhopadhyay. « Appearance of annular ring-like intermediates during amyloid fibril formation from human serum albumin ». Physical Chemistry Chemical Physics 17, n^o 35 (2015) : 22862–71. http://dx.doi.org/10.1039/c5cp03782d.

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A profound conformational conversion coupled with the temporal evolution of morphologically-distinct ring-like nanoscopic intermediates were monitored during the amyloid assembly of human serum albumin into β-sheet-rich fibrils.

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Bothner, Brian, Yves Aubin et Richard W. Kriwacki. « Peptides Derived from Two Dynamically Disordered Proteins Self-Assemble into Amyloid-like Fibrils ». Journal of the American Chemical Society 125, n^o 11 (mars 2003) : 3200–3201. http://dx.doi.org/10.1021/ja028265w.

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Ottoz, Diana S. M., et Luke E. Berchowitz. « The role of disorder in RNA binding affinity and specificity ». Open Biology 10, n^o 12 (décembre 2020) : 200328. http://dx.doi.org/10.1098/rsob.200328.

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Most RNA-binding modules are small and bind few nucleotides. RNA-binding proteins typically attain the physiological specificity and affinity for their RNA targets by combining several RNA-binding modules. Here, we review how disordered linkers connecting RNA-binding modules govern the specificity and affinity of RNA–protein interactions by regulating the effective concentration of these modules and their relative orientation. RNA-binding proteins also often contain extended intrinsically disordered regions that mediate protein–protein and RNA–protein interactions with multiple partners. We discuss how these regions can connect proteins and RNA resulting in heterogeneous higher-order assemblies such as membrane-less compartments and amyloid-like structures that have the characteristics of multi-modular entities. The assembled state generates additional RNA-binding specificity and affinity properties that contribute to further the function of RNA-binding proteins within the cellular environment.

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Nguyen, Van Duc, Asish Pal, Frank Snijkers, Mathieu Colomb-Delsuc, Giulia Leonetti, Sijbren Otto et Jasper van der Gucht. « Multi-step control over self-assembled hydrogels of peptide-derived building blocks and a polymeric cross-linker ». Soft Matter 12, n^o 2 (2016) : 432–40. http://dx.doi.org/10.1039/c5sm02088c.

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We present a detailed study of self-assembled hydrogels of bundled and cross-linked networks consisting of positively charged amyloid-like nanofibers and a triblock copolymer with negatively charged end blocks as a cross-linker.

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Daskalov, Asen, Birgit Habenstein, Raimon Sabaté, Mélanie Berbon, Denis Martinez, Stéphane Chaignepain, Bénédicte Coulary-Salin, Kay Hofmann, Antoine Loquet et Sven J. Saupe. « Identification of a novel cell death-inducing domain reveals that fungal amyloid-controlled programmed cell death is related to necroptosis ». Proceedings of the National Academy of Sciences 113, n^o 10 (22 février 2016) : 2720–25. http://dx.doi.org/10.1073/pnas.1522361113.

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Recent findings have revealed the role of prion-like mechanisms in the control of host defense and programmed cell death cascades. In fungi, HET-S, a cell death-inducing protein containing a HeLo pore-forming domain, is activated through amyloid templating by a Nod-like receptor (NLR). Here we characterize the HELLP protein behaving analogously to HET-S and bearing a new type of N-terminal cell death-inducing domain termed HeLo-like (HELL) and a C-terminal regulatory amyloid motif known as PP. The gene encoding HELLP is part of a three-gene cluster also encoding a lipase (SBP) and a Nod-like receptor, both of which display the PP motif. The PP motif is similar to the RHIM amyloid motif directing formation of the RIP1/RIP3 necrosome in humans. The C-terminal region of HELLP, HELLP(215-278), encompassing the motif, allows prion propagation and assembles into amyloid fibrils, as demonstrated by X-ray diffraction and FTIR analyses. Solid-state NMR studies reveal a well-ordered local structure of the amyloid core residues and a primary sequence that is almost entirely arranged in a rigid conformation, and confirm a β-sheet structure in an assigned stretch of three amino acids. HELLP is activated by amyloid templating and displays membrane-targeting and cell death-inducing activity. HELLP targets the SBP lipase to the membrane, suggesting a synergy between HELLP and SBP in membrane dismantling. Remarkably, the HeLo-like domain of HELLP is homologous to the pore-forming domain of MLKL, the cell death-execution protein in necroptosis, revealing a transkingdom evolutionary relationship between amyloid-controlled fungal programmed cell death and mammalian necroptosis.

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Klose, Daniel, Sahithya Phani Babu Vemulapalli, Michal Richman, Safra Rudnick, Vered Aisha, Meital Abayev, Marina Chemerovski et al. « Cu²⁺-Induced self-assembly and amyloid formation of a cyclic d,l-α-peptide : structure and function ». Physical Chemistry Chemical Physics 24, n^o 11 (2022) : 6699–715. http://dx.doi.org/10.1039/d1cp05415e.

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The self-assembly of the cyclic d,l-α-peptide generates amyloid-like structures and this process can be arrested at the level of the dimer giving insights into early-stage aggregation and polymorphism.

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Wu, Xialian, Yeyang Ma, Kun Zhao, Jing Zhang, Yunpeng Sun, Yichen Li, Xingqi Dong et al. « The structure of a minimum amyloid fibril core formed by necroptosis-mediating RHIM of human RIPK3 ». Proceedings of the National Academy of Sciences 118, n^o 14 (31 mars 2021) : e2022933118. http://dx.doi.org/10.1073/pnas.2022933118.

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Receptor-interacting protein kinases 3 (RIPK3), a central node in necroptosis, polymerizes in response to the upstream signals and then activates its downstream mediator to induce cell death. The active polymeric form of RIPK3 has been indicated as the form of amyloid fibrils assembled via its RIP homotypic interaction motif (RHIM). In this study, we combine cryogenic electron microscopy and solid-state NMR to determine the amyloid fibril structure of RIPK3 RHIM-containing C-terminal domain (CTD). The structure reveals a single protofilament composed of the RHIM domain. RHIM forms three β-strands (referred to as strands 1 through 3) folding into an S shape, a distinct fold from that in complex with RIPK1. The consensus tetrapeptide VQVG of RHIM forms strand 2, which zips up strands 1 and 3 via heterozipper-like interfaces. Notably, the RIPK3-CTD fibril, as a physiological fibril, exhibits distinctive assembly compared with pathological fibrils. It has an exceptionally small fibril core and twists in both handedness with the smallest pitch known so far. These traits may contribute to a favorable spatial arrangement of RIPK3 kinase domain for efficient phosphorylation.

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Li, Yaping, Na Li, Lei Wang, Qinhua Lu, Xiang Ji et Feng Zhang. « A Comparative Study on the Self-Assembly of Peptide TGV-9 by In Situ Atomic Force Microscopy ». Microscopy and Microanalysis 26, n^o 2 (13 février 2020) : 319–25. http://dx.doi.org/10.1017/s1431927620000082.

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AbstractPrevious studies of amyloid diseases reported that the aggregating proteins share a similar conserved peptide sequence which can form the cross-β-sheet-containing nanostructures like nanofilaments. The template-assisted self-assembly (TASA) of peptides on inorganic substrates with different hydrophilicity could be an alternative approach to shed light on the fibrillization mechanism of proteins/peptides in vivo. To figure out the effect of interfaces on amyloid aggregation, we herein employed in situ atomic force microscopy (AFM) to investigate the self-assembling of a Parkinson disease-related core peptide sequence (TGV-9) on a hydrophobic liquid–solid interface via real-time observation of the dynamic fibrillization process. The results show that TGV-9 forms one-dimensional nanostructures on the surface of highly ordered pyrolytic graphite (HOPG) with three preferred growth orientations, which are consistent with the atomic lattice of HOPG, indicating an epitaxial growth or TASA. Conversely, the nanostructures formed in bulk solution can be free-standing nanofilaments, and the fibrillization mechanism is different from that on HOPG. These results could not only deepen the understanding of the protein/peptide aggregation mechanism but also benefit for the early diagnosis and clinic treatment of related diseases.

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Gour, Nidhi, Chandra Kanth P., Bharti Koshti, Vivekshinh Kshtriya, Dhruvi Shah, Sunita Patel, Reena Agrawal-Rajput et Manoj K. Pandey. « Amyloid-like Structures Formed by Single Amino Acid Self-Assemblies of Cysteine and Methionine ». ACS Chemical Neuroscience 10, n^o 3 (novembre 2018) : 1230–39. http://dx.doi.org/10.1021/acschemneuro.8b00310.

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Ganesh, S., et R. Jayakumar. « Structural transitions involved in a novel amyloid-like ?-sheet assemblage of tripeptide derivatives ». Biopolymers 70, n^o 3 (21 octobre 2003) : 336–45. http://dx.doi.org/10.1002/bip.10474.

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McIntosh, Pauline B., Stephen R. Martin, Deborah J. Jackson, Jameela Khan, Erin R. Isaacson, Lesley Calder, Kenneth Raj et al. « Structural Analysis Reveals an Amyloid Form of the Human Papillomavirus Type 16 E1∧E4 Protein and Provides a Molecular Basis for Its Accumulation ». Journal of Virology 82, n^o 16 (18 juin 2008) : 8196–203. http://dx.doi.org/10.1128/jvi.00509-08.

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ABSTRACT The abundant human papillomavirus (HPV) type 16 E4 protein exists as two distinct structural forms in differentiating epithelial cells. Monomeric full-length 16E1∧E4 contains a limited tertiary fold constrained by the N and C termini. N-terminal deletions facilitate the assembly of E1∧E4 into amyloid-like fibrils, which bind to thioflavin T. The C-terminal region is highly amyloidogenic, and its deletion abolishes amyloid staining and prevents E1∧E4 accumulation. Amyloid-imaging probes can detect 16E1∧E4 in biopsy material, as well as 18E1∧E4 and 33E1∧E4 in monolayer cells, indicating structural conservation. Our results suggest a role for fibril formation in facilitating the accumulation of E1∧E4 during HPV infection.

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