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Matiiv AB, Trubitsina NP, Matveenko AG, Barbitoff YA, Zhouravleva GA, Bondarev SA. Amyloid and Amyloid-Like Aggregates: Diversity and the Term Crisis. BIOCHEMISTRY (MOSCOW) 2021; 85:1011-1034. [PMID: 33050849 DOI: 10.1134/s0006297920090035] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Active accumulation of the data on new amyloids continuing nowadays dissolves boundaries of the term "amyloid". Currently, it is most often used to designate aggregates with cross-β structure. At the same time, amyloids also exhibit a number of other unusual properties, such as: detergent and protease resistance, interaction with specific dyes, and ability to induce transition of some proteins from a soluble form to an aggregated one. The same features have been also demonstrated for the aggregates lacking cross-β structure, which are commonly called "amyloid-like" and combined into one group, although they are very diverse. We have collected and systematized information on the properties of more than two hundred known amyloids and amyloid-like proteins with emphasis on conflicting examples. In particular, a number of proteins in membraneless organelles form aggregates with cross-β structure that are morphologically indistinguishable from the other amyloids, but they can be dissolved in the presence of detergents, which is not typical for amyloids. Such paradoxes signify the need to clarify the existing definition of the term amyloid. On the other hand, the demonstrated structural diversity of the amyloid-like aggregates shows the necessity of their classification.
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Affiliation(s)
- A B Matiiv
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia
| | - N P Trubitsina
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia
| | - A G Matveenko
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia
| | - Y A Barbitoff
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia.,Bioinformatics Institute, St. Petersburg, 197342, Russia
| | - G A Zhouravleva
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia.,Laboratory of Amyloid Biology, St. Petersburg State University, St. Petersburg, 199034, Russia
| | - S A Bondarev
- Department of Genetics and Biotechnology, Faculty of Biology, St. Petersburg State University, St. Petersburg, 199034, Russia. .,Laboratory of Amyloid Biology, St. Petersburg State University, St. Petersburg, 199034, Russia
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2
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Tikhodeyev ON. The mechanisms of epigenetic inheritance: how diverse are they? Biol Rev Camb Philos Soc 2018; 93:1987-2005. [PMID: 29790249 DOI: 10.1111/brv.12429] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/22/2018] [Accepted: 04/27/2018] [Indexed: 12/18/2022]
Abstract
Although epigenetic inheritance (EI) is a rapidly growing field of modern biology, it still has no clear place in fundamental genetic concepts which are traditionally based on the hereditary role of DNA. Moreover, not all mechanisms of EI attract the same attention, with most studies focused on DNA methylation, histone modification, RNA interference and amyloid prionization, but relatively few considering other mechanisms such as stable inhibition of plastid translation. Herein, we discuss all known and some hypothetical mechanisms that can underlie the stable inheritance of phenotypically distinct hereditary factors that lack differences in DNA sequence. These mechanisms include (i) regulation of transcription by DNA methylation, histone modifications, and transcription factors, (ii) RNA splicing, (iii) RNA-mediated post-transcriptional silencing, (iv) organellar translation, (v) protein processing by truncation, (vi) post-translational chemical modifications, (vii) protein folding, and (viii) homologous and non-homologous protein interactions. The breadth of this list suggests that any or almost any regulatory mechanism that participates in gene expression or gene-product functioning, under certain circumstances, may produce EI. Although the modes of EI are highly variable, in many epigenetic systems, stable allelic variants can be distinguished. Irrespective of their nature, all such alleles have an underlying similarity: each is a bimodular hereditary unit, whose features depend on (i) a certain epigenetic mark (epigenetic determinant) in the DNA sequence or its product, and (ii) the DNA sequence itself (DNA determinant; if this is absent, the epigenetic allele fails to perpetuate). Thus, stable allelic epigenetic inheritance (SAEI) does not contradict the hereditary role of DNA, but involves additional molecular mechanisms with no or almost no limitations to their variety.
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Affiliation(s)
- Oleg N Tikhodeyev
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg 199034, Russia
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3
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Flores-Fernández JM, Rathod V, Wille H. Comparing the Folds of Prions and Other Pathogenic Amyloids. Pathogens 2018; 7:E50. [PMID: 29734684 PMCID: PMC6027354 DOI: 10.3390/pathogens7020050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 04/29/2018] [Accepted: 05/02/2018] [Indexed: 01/13/2023] Open
Abstract
Pathogenic amyloids are the main feature of several neurodegenerative disorders, such as Creutzfeldt⁻Jakob disease, Alzheimer’s disease, and Parkinson’s disease. High resolution structures of tau paired helical filaments (PHFs), amyloid-β(1-42) (Aβ(1-42)) fibrils, and α-synuclein fibrils were recently reported using cryo-electron microscopy. A high-resolution structure for the infectious prion protein, PrPSc, is not yet available due to its insolubility and its propensity to aggregate, but cryo-electron microscopy, X-ray fiber diffraction, and other approaches have defined the overall architecture of PrPSc as a 4-rung β-solenoid. Thus, the structure of PrPSc must have a high similarity to that of the fungal prion HET-s, which is part of the fungal heterokaryon incompatibility system and contains a 2-rung β-solenoid. This review compares the structures of tau PHFs, Aβ(1-42), and α-synuclein fibrils, where the β-strands of each molecule stack on top of each other in a parallel in-register arrangement, with the β-solenoid folds of HET-s and PrPSc.
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Affiliation(s)
- José Miguel Flores-Fernández
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, 204 Brain and Aging Research Building, Edmonton, AB T6G 2M8, Canada.
| | - Vineet Rathod
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, 204 Brain and Aging Research Building, Edmonton, AB T6G 2M8, Canada.
| | - Holger Wille
- Department of Biochemistry & Centre for Prions and Protein Folding Diseases, University of Alberta, 204 Brain and Aging Research Building, Edmonton, AB T6G 2M8, Canada.
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4
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3D structure determination of amyloid fibrils using solid-state NMR spectroscopy. Methods 2018; 138-139:26-38. [DOI: 10.1016/j.ymeth.2018.03.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/28/2018] [Accepted: 03/30/2018] [Indexed: 01/08/2023] Open
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Tikhodeyev ON, Tarasov OV, Bondarev SA. Allelic variants of hereditary prions: The bimodularity principle. Prion 2017; 11:4-24. [PMID: 28281926 PMCID: PMC5360123 DOI: 10.1080/19336896.2017.1283463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/04/2017] [Accepted: 01/10/2017] [Indexed: 12/26/2022] Open
Abstract
Modern biology requires modern genetic concepts equally valid for all discovered mechanisms of inheritance, either "canonical" (mediated by DNA sequences) or epigenetic. Applying basic genetic terms such as "gene" and "allele" to protein hereditary factors is one of the necessary steps toward these concepts. The basic idea that different variants of the same prion protein can be considered as alleles has been previously proposed by Chernoff and Tuite. In this paper, the notion of prion allele is further developed. We propose the idea that any prion allele is a bimodular hereditary system that depends on a certain DNA sequence (DNA determinant) and a certain epigenetic mark (epigenetic determinant). Alteration of any of these 2 determinants may lead to establishment of a new prion allele. The bimodularity principle is valid not only for hereditary prions; it seems to be universal for any epigenetic hereditary factor.
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Affiliation(s)
- Oleg N. Tikhodeyev
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
| | - Oleg V. Tarasov
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
- Saint-Petersburg Scientific Center of RAS, Saint-Petersburg, Russia
| | - Stanislav A. Bondarev
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
- The Laboratory of Amyloid Biology, Saint-Petersburg State University, Saint-Petersburg, Russia
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Wear MP, Kryndushkin D, O’Meally R, Sonnenberg JL, Cole RN, Shewmaker FP. Proteins with Intrinsically Disordered Domains Are Preferentially Recruited to Polyglutamine Aggregates. PLoS One 2015; 10:e0136362. [PMID: 26317359 PMCID: PMC4552826 DOI: 10.1371/journal.pone.0136362] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/31/2015] [Indexed: 12/12/2022] Open
Abstract
Intracellular protein aggregation is the hallmark of several neurodegenerative diseases. Aggregates formed by polyglutamine (polyQ)-expanded proteins, such as Huntingtin, adopt amyloid-like structures that are resistant to denaturation. We used a novel purification strategy to isolate aggregates formed by human Huntingtin N-terminal fragments with expanded polyQ tracts from both yeast and mammalian (PC-12) cells. Using mass spectrometry we identified the protein species that are trapped within these polyQ aggregates. We found that proteins with very long intrinsically-disordered (ID) domains (≥100 amino acids) and RNA-binding proteins were disproportionately recruited into aggregates. The removal of the ID domains from selected proteins was sufficient to eliminate their recruitment into polyQ aggregates. We also observed that several neurodegenerative disease-linked proteins were reproducibly trapped within the polyQ aggregates purified from mammalian cells. Many of these proteins have large ID domains and are found in neuronal inclusions in their respective diseases. Our study indicates that neurodegenerative disease-associated proteins are particularly vulnerable to recruitment into polyQ aggregates via their ID domains. Also, the high frequency of ID domains in RNA-binding proteins may explain why RNA-binding proteins are frequently found in pathological inclusions in various neurodegenerative diseases.
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Affiliation(s)
- Maggie P. Wear
- Department of Pharmacology, Uniformed Services University of the Heath Sciences, Bethesda, Maryland, 20814, United States of America
| | - Dmitry Kryndushkin
- Department of Pharmacology, Uniformed Services University of the Heath Sciences, Bethesda, Maryland, 20814, United States of America
| | - Robert O’Meally
- Johns Hopkins Mass Spectrometry and Proteomic Facility, Johns Hopkins University, Baltimore, Maryland, 21218, United States of America
| | - Jason L. Sonnenberg
- Chemistry department, School of Sciences, Stevenson University, Stevenson, Maryland, 21153, United States of America
| | - Robert N. Cole
- Johns Hopkins Mass Spectrometry and Proteomic Facility, Johns Hopkins University, Baltimore, Maryland, 21218, United States of America
| | - Frank P. Shewmaker
- Department of Pharmacology, Uniformed Services University of the Heath Sciences, Bethesda, Maryland, 20814, United States of America
- * E-mail:
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Cestari TF, Dantas LP, Boza JC. Acquired hyperpigmentations. An Bras Dermatol 2014; 89:11-25. [PMID: 24626644 PMCID: PMC3938350 DOI: 10.1590/abd1806-4841.20142353] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 03/25/2013] [Indexed: 01/15/2023] Open
Abstract
Cutaneous hyperpigmentations are frequent complaints, motivating around 8.5% of all
dermatological consultations in our country. They can be congenital, with different
patterns of inheritance, or acquired in consequence of skin problems, systemic
diseases or secondary to environmental factors. The vast majority of them are linked
to alterations on the pigment melanin, induced by different mechanisms. This review
will focus on the major acquired hyperpigmentations associated with increased
melanin, reviewing their mechanisms of action and possible preventive measures.
Particularly prominent aspects of diagnosis and therapy will be emphasized, with
focus on melasma, post-inflammatory hyperpigmentation, periorbital pigmentation,
dermatosis papulosa nigra, phytophotodermatoses, flagellate dermatosis, erythema
dyschromicum perstans, cervical poikiloderma (Poikiloderma of Civatte), acanthosis
nigricans, cutaneous amyloidosis and reticulated confluent dermatitis
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Affiliation(s)
- Tania Ferreira Cestari
- Rio Grande do Sul Federal University, Internal Medicine Department, Porto Alegre(RS), Brazil, PhD - Associate Professor at the Internal Medicine Department, at Rio Grande do Sul Federal University (UFRGS). Teaching Professor at the Child and Adolescent Health Sciences and the Surgical Post-Graduation Programs at Rio Grande do Sul Federal University (UFRGS). Chief of the Dermatology Department at Porto Alegre Clinics Hospital - Rio Grande do Sul Federal University (HCPA-UFRGS) - Porto Alegre (RS), Brazil
| | - Lia Pinheiro Dantas
- Rio Grande do Sul Federal University, Medical Sciences Post Graduation program, Porto AlegreRS, Brazil, MD, Dermatologist, MSc (in course) at the Medical Sciences Post Graduation program at Rio Grande do Sul Federal University (UFRGS) - Porto Alegre (RS), Brazil
| | - Juliana Catucci Boza
- Rio Grande do Sul Federal University, Child and Adolescent Health Sciences Post Graduation Program, Porto AlegreRS, Brazil, MD, Dermatologist, PhD (in course) at the Child and Adolescent Health Sciences Post Graduation Program at Rio Grande do Sul Federal University (UFRGS) - Porto Alegre (RS), Brazil
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Dehsorkhi A, Castelletto V, Hamley IW. Self-assembling amphiphilic peptides. J Pept Sci 2014; 20:453-67. [PMID: 24729276 PMCID: PMC4237179 DOI: 10.1002/psc.2633] [Citation(s) in RCA: 266] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/27/2014] [Accepted: 03/04/2014] [Indexed: 01/08/2023]
Abstract
The self-assembly of several classes of amphiphilic peptides is reviewed, and selected applications are discussed. We discuss recent work on the self-assembly of lipopeptides, surfactant-like peptides and amyloid peptides derived from the amyloid-β peptide. The influence of environmental variables such as pH and temperature on aggregate nanostructure is discussed. Enzyme-induced remodelling due to peptide cleavage and nanostructure control through photocleavage or photo-cross-linking are also considered. Lastly, selected applications of amphiphilic peptides in biomedicine and materials science are outlined.
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Affiliation(s)
- Ashkan Dehsorkhi
- Department of Chemistry, University of ReadingWhiteknights, Reading, RG6 6AD, UK
| | - Valeria Castelletto
- Department of Chemistry, University of ReadingWhiteknights, Reading, RG6 6AD, UK
| | - Ian W Hamley
- Department of Chemistry, University of ReadingWhiteknights, Reading, RG6 6AD, UK
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9
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Hall D, Edskes H. Computational modeling of the relationship between amyloid and disease. Biophys Rev 2012; 4:205-222. [PMID: 23495357 PMCID: PMC3595053 DOI: 10.1007/s12551-012-0091-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 06/21/2012] [Indexed: 01/29/2023] Open
Abstract
Amyloid is a title conferred upon a special type of linear protein aggregate that exhibits a common set of structural features and dye binding capabilities. The formation of amyloid is associated with over twenty-seven distinct human diseases which are collectively referred to as the amyloidoses. Although there is great diversity amongst the amyloidoses with regard to the polypeptide monomeric precursor, targeted tissues and the nature and time course of disease development, the common underlying link of a structurally similar amyloid aggregate has prompted the search for a unified theory of disease progression in which amyloid production is the central element. Computational modeling has allowed the formulation and testing of scientific hypotheses for exploring this relationship. However, the majority of computational studies on amyloid aggregation are pitched at the atomistic level of description, in simple ideal solution environments, with simulation time scales of the order of microseconds and system sizes limited to a hundred monomers (or less). The experimental reality is that disease related amyloid aggregation processes occur in extremely complex reaction environments (i.e. the human body), over time-scales of months to years with monitoring of the reaction achieved using extremely coarse or indirect experimental markers that yield little or no atomistic insight. Clearly a substantial gap exists between computational and experimental communities with a deficit of 'useful' computational methodology that can be directly related to available markers of disease progression. This Review will place its focus on the development of these latter types of computational models and discuss them in relation to disease onset and progression.
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Affiliation(s)
- Damien Hall
- Institute of Basic Medical Science, University of Tsukuba, Lab 225-B, Building D. 1-1-1 Tennodai, Tsukuba-shi, Ibaraki-ken 305-8577 Japan
| | - Herman Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830 USA
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10
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On the use of size exclusion chromatography for the resolution of mixed amyloid aggregate distributions: I. Equilibrium partition models. Anal Biochem 2012; 426:69-85. [DOI: 10.1016/j.ab.2012.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/30/2012] [Accepted: 04/01/2012] [Indexed: 11/24/2022]
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11
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Hall D. Semi-automated methods for simulation and measurement of amyloid fiber distributions obtained from transmission electron microscopy experiments. Anal Biochem 2012; 421:262-77. [DOI: 10.1016/j.ab.2011.10.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/04/2011] [Accepted: 10/04/2011] [Indexed: 11/27/2022]
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12
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Ingerson-Mahar M, Gitai Z. A growing family: the expanding universe of the bacterial cytoskeleton. FEMS Microbiol Rev 2011; 36:256-66. [PMID: 22092065 DOI: 10.1111/j.1574-6976.2011.00316.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/02/2011] [Accepted: 11/10/2011] [Indexed: 12/16/2022] Open
Abstract
Cytoskeletal proteins are important mediators of cellular organization in both eukaryotes and bacteria. In the past, cytoskeletal studies have largely focused on three major cytoskeletal families, namely the eukaryotic actin, tubulin, and intermediate filament (IF) proteins and their bacterial homologs MreB, FtsZ, and crescentin. However, mounting evidence suggests that these proteins represent only the tip of the iceberg, as the cellular cytoskeletal network is far more complex. In bacteria, each of MreB, FtsZ, and crescentin represents only one member of large families of diverse homologs. There are also newly identified bacterial cytoskeletal proteins with no eukaryotic homologs, such as WACA proteins and bactofilins. Furthermore, there are universally conserved proteins, such as the metabolic enzyme CtpS, that assemble into filamentous structures that can be repurposed for structural cytoskeletal functions. Recent studies have also identified an increasing number of eukaryotic cytoskeletal proteins that are unrelated to actin, tubulin, and IFs, such that expanding our understanding of cytoskeletal proteins is advancing the understanding of the cell biology of all organisms. Here, we summarize the recent explosion in the identification of new members of the bacterial cytoskeleton and describe a hypothesis for the evolution of the cytoskeleton from self-assembling enzymes.
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Goldsbury C, Baxa U, Simon MN, Steven AC, Engel A, Wall JS, Aebi U, Müller SA. Amyloid structure and assembly: insights from scanning transmission electron microscopy. J Struct Biol 2010; 173:1-13. [PMID: 20868754 DOI: 10.1016/j.jsb.2010.09.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 09/14/2010] [Accepted: 09/16/2010] [Indexed: 10/19/2022]
Abstract
Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).
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Affiliation(s)
- Claire Goldsbury
- The Brain and Mind Research Institute, University of Sydney, NSW 2006, Australia
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14
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Bolognesi ML, Ai Tran HN, Staderini M, Monaco A, López-Cobeñas A, Bongarzone S, Biarnés X, López-Alvarado P, Cabezas N, Caramelli M, Carloni P, Menéndez J, Legname G. Discovery of a Class of Diketopiperazines as Antiprion Compounds. ChemMedChem 2010; 5:1324-34. [DOI: 10.1002/cmdc.201000133] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Fei L, Perrett S. New insights into the molecular mechanism of amyloid formation from cysteine scanning. Prion 2010; 4:9-12. [PMID: 20083897 DOI: 10.4161/pri.4.1.10670] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Our laboratory recently reported the identification of a peptide region, QVNI, within the prion domain of the yeast protein Ure2 that may act as an initiation point for fibril formation.(1) This potential amyloid-forming region, which corresponds to residues 18-21 of Ure2, was initially identified by systematic cysteine scanning of the Ure2 prion domain. The point mutant R17C, and the corresponding octapeptide CQVNIGNR, were found to form fibrils rapidly under oxidative conditions due to the formation of a disulfide bond. Deletions within the QVNI sequence cause the fibril formation ability of R17C Ure2 to be inhibited. The aggregation propensity of this region is strongly modulated by its preceding residue: replacement of R17 with a hydrophobic residue promotes fibril formation in both full-length Ure2 and in the corresponding octapeptides. The wild-type octapeptide, RQVNIGNR, also forms fibrils, and is the shortest amyloid-forming peptide found for Ure2 to date. Interestingly, the wild-type octapeptide crystallizes readily and so provides a starting point towards obtaining high resolution structural information for the amyloid core of Ure2 fibrils.
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Affiliation(s)
- Li Fei
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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16
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Structural insights into alternate aggregated prion protein forms. J Mol Biol 2009; 393:1033-42. [PMID: 19720066 DOI: 10.1016/j.jmb.2009.08.056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 08/11/2009] [Accepted: 08/22/2009] [Indexed: 11/21/2022]
Abstract
The conversion of the cellular form of the prion protein (PrP(C)) to an abnormal, alternatively folded isoform (PrP(Sc)) is the central event in prion diseases or transmissible spongiform encephalopathies. Recent studies have demonstrated de novo generation of murine prions from recombinant prion protein (recPrP) after inoculation into transgenic and wild-type mice. These so-called synthetic prions lead to novel prion diseases with unique neuropathological and biochemical features. Moreover, the use of recPrP in an amyloid seeding assay can specifically detect and amplify various strains of prions. We employed this assay in our experiments and analyzed in detail the morphology of aggregate structures produced under defined chemical constraints. Our results suggest that changes in the concentration of guanidine hydrochloride can lead to different kinetic traces in a typical thioflavin T(ThT) assay. Morphological and structural analysis of these aggregates by atomic force microscopy indicates a variation in the structure of the PrP molecular assemblies. In particular, ThT positive PrP aggregates produced from rec mouse PrP residues 89 to 230 lead to mostly oligomeric structures at low concentrations of guanidine hydrochloride, while more amyloidal structures were observed at higher concentrations of the denaturant. These findings highlight the presence of numerous and complex pathways in deciphering prion constraints for infectivity and toxicity.
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A model of amyloid's role in disease based on fibril fracture. Biophys Chem 2009; 145:17-28. [PMID: 19735971 DOI: 10.1016/j.bpc.2009.08.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/09/2009] [Accepted: 08/09/2009] [Indexed: 02/04/2023]
Abstract
Although the correlative evidence relating the presence of amyloid fibrils and certain disease states (e.g. Alzheimer's disease and Type 2 Diabetes) is overwhelming, a direct causative role for amyloid has proved harder to establish. Current thinking links a narrow region of the aggregate protein size distribution, the so called 'early aggregate' domain to cellular toxicity. A troubling feature of this theory however is that the nucleated reaction mechanism by which amyloid formation is believed to occur results in a very low number concentration of early aggregates which are rapidly extended to form amyloid fibrils. This situation means that the concentration of early aggregates is very low at the time when they are supposedly at their most toxic. Here we adopt a novel explicit simulation strategy to examine a kinetic regime involving nucleated growth combined with fibril fragmentation under which this situation can be reversed so as to produce a high number concentration of small on-pathway toxic aggregates. Dependent upon the rate of fragmentation, the time scale for generation of toxic early aggregates may be coupled, uncoupled or disassociated from the time scale for the appearance of amyloid fibrils. Furthermore the model presents itself as a biochemical 'switch' transitioning between modes of amyloid induced cell death dependent upon either specific amyloid toxicity or non-specific solid mass induced tissue damage.
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Hall D, Hirota N. Multi-scale modelling of amyloid formation from unfolded proteins using a set of theory derived rate constants. Biophys Chem 2009; 140:122-8. [DOI: 10.1016/j.bpc.2008.11.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 11/17/2008] [Accepted: 11/17/2008] [Indexed: 01/05/2023]
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