1
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Mitra A, Mitra A, Sarkar N. Differential effects of DTT on HEWL amyloid fibrillation and fibril morphology at different pH. Biophys Chem 2023; 294:106962. [PMID: 36716681 DOI: 10.1016/j.bpc.2023.106962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 01/26/2023]
Abstract
Proteins can transform from their native state to a state having fibrillar aggregates characterized by cross β sheet structure. The fibrillar aggregates are known as amyloid and have been linked to several disorders. Disulfide bonds in proteins are one of the important factors that determine the propensity of aggregation. Hen Egg White Lysozyme (HEWL) was used by us as a model protein to decipher the role disulfide bonds play in the amyloid fibril formation and fibril morphology by using Dithiothreitol (DTT) as reducing agent at pH 2.7 and pH 7.4. We found that DTT can have different effects on HEWL amyloid depending on pH and the buffer used for preparing the amyloid fibrils. Our studies highlight the critical role of non-native disulfide bonds in amyloidogenesis and how disruption of these bonds can greatly affect the fibrillation process. Overall, these studies throw light on the fibrillation mechanism and can be explored further in designing effective inhibitors against amyloidosis.
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Affiliation(s)
- Aranyak Mitra
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India
| | - Amit Mitra
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India
| | - Nandini Sarkar
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela 769008, Odisha, India.
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2
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The role of intra and inter-molecular disulfide bonds in modulating amyloidogenesis: A review. Arch Biochem Biophys 2021; 716:109113. [PMID: 34958750 DOI: 10.1016/j.abb.2021.109113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 11/20/2022]
Abstract
All proteins have the inherent ability to undergo transformation from their native structure to a β sheet rich fibrillar structure, called amyloid when subjected to specific conditions. Proteins with a high propensity to form amyloid fibrils have been implicated in a variety of disorders like Alzheimer's disease, Parkinson's disease, Type II diabetes, Amyotrophic Lateral Sclerosis (ALS) and prion diseases. Among the various critical factors that modulate the process of amyloid formation, disulfide bonds have been identified as one of the key determinants of amyloid propensity in proteins. Studies have shown that intra-molecular disulfide bonds impart stability to the native structure of a protein and decrease the tendency for amyloid aggregation, whereas intermolecular disulfide bonds aid in the process of aggregation. In this review, we will analyze the varying effects of both intra as well as inter-molecular disulfide bonds on the amyloid aggregation propensities of a few proteins associated with amyloid disorders.
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3
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Bergasa-Caceres F, Rabitz HA. Identification of Two Early Folding Stage Prion Non-Local Contacts Suggested to Serve as Key Steps in Directing the Final Fold to Be Either Native or Pathogenic. Int J Mol Sci 2021; 22:ijms22168619. [PMID: 34445324 PMCID: PMC8395309 DOI: 10.3390/ijms22168619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/30/2021] [Accepted: 08/04/2021] [Indexed: 12/16/2022] Open
Abstract
The initial steps of the folding pathway of the C-terminal domain of the murine prion protein mPrP(90–231) are predicted based on the sequential collapse model (SCM). A non-local dominant contact is found to form between the connecting region between helix 1 and β-sheet 1 and the C-terminal region of helix 3. This non-local contact nucleates the most populated molten globule-like intermediate along the folding pathway. A less stable early non-local contact between segments 120–124 and 179–183, located in the middle of helix 2, promotes the formation of a less populated molten globule-like intermediate. The formation of the dominant non-local contact constitutes an example of the postulated Nature’s Shortcut to the prion protein collapse into the native structure. The possible role of the less populated molten globule-like intermediate is explored as the potential initiation point for the folding for three pathogenic mutants (T182A, I214V, and Q211P in mouse prion numbering) of the prion protein.
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4
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Palaniappan C, Narayanan RC, Sekar K. Mutation-Dependent Refolding of Prion Protein Unveils Amyloidogenic-Related Structural Ramifications: Insights from Molecular Dynamics Simulations. ACS Chem Neurosci 2021; 12:2810-2819. [PMID: 34296847 DOI: 10.1021/acschemneuro.1c00142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The main focus of prion structural biology studies is to understand the molecular basis of prion diseases caused by misfolding, and aggregation of the cellular prion protein PrPC remains elusive. Several genetic mutations are linked with human prion diseases and driven by the conformational conversion of PrPC to the toxic PrPSc. The main goal of this study is to gain a better insight into the molecular effect of disease-associated V210I mutation on this process by molecular dynamics simulations. This inherited mutation elicited copious structural changes in the β1-α1-β2 subdomain, including an unfolding of a helix α1 and the elongation of the β-sheet. These unusual structural changes likely appeared to detach the β1-α1-β2 subdomain from the α2-α3 core, an early misfolding event necessary for the conformational conversion of PrPC to PrPSc. Ultimately, the unfolded α1 and its prior β1-α1 loop further engaged with unrestrained conformational dynamics and were widely considered as amyloidogenic-inducing traits. Furthermore, the resulting folding intermediate possesses a highly unstable β1-α1-β2 subdomain, thereby enhancing the aggregation of misfolded PrPC through intermolecular interactions between frequently refolding regions. Briefly, these remarkable changes as seen in the mutant β1-α1-β2 subdomain are consistent with previous experimental results and thus provide a molecular basis of PrPC misfolding associated with the conformational conversion of PrPC to PrPSc.
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Affiliation(s)
| | - Rahul C. Narayanan
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore 560 012, India
| | - Kanagaraj Sekar
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore 560 012, India
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5
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Bettinger J, Ghaemmaghami S. Methionine oxidation within the prion protein. Prion 2020; 14:193-205. [PMID: 32744136 PMCID: PMC7518762 DOI: 10.1080/19336896.2020.1796898] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/09/2020] [Accepted: 07/11/2020] [Indexed: 11/01/2022] Open
Abstract
Prion diseases are characterized by the self-templated misfolding of the cellular prion protein (PrPC) into infectious aggregates (PrPSc). The detailed molecular basis of the misfolding and aggregation of PrPC remains incompletely understood. It is believed that the transient misfolding of PrPC into partially structured intermediates precedes the formation of insoluble protein aggregates and is a critical component of the prion misfolding pathway. A number of environmental factors have been shown to induce the destabilization of PrPC and promote its initial misfolding. Recently, oxidative stress and reactive oxygen species (ROS) have emerged as one possible mechanism by which the destabilization of PrPC can be induced under physiological conditions. Methionine residues are uniquely vulnerable to oxidation by ROS and the formation of methionine sulfoxides leads to the misfolding and subsequent aggregation of PrPC. Here, we provide a review of the evidence for the oxidation of methionine residues in PrPC and its potential role in the formation of pathogenic prion aggregates.
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Affiliation(s)
- John Bettinger
- Department of Biology, University of Rochester, Rochester, NY, USA
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6
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Muronetz VI, Barinova K, Kudryavtseva S, Medvedeva M, Melnikova A, Sevostyanova I, Semenyuk P, Stroylova Y, Sova M. Natural and Synthetic Derivatives of Hydroxycinnamic Acid Modulating the Pathological Transformation of Amyloidogenic Proteins. Molecules 2020; 25:E4647. [PMID: 33053854 PMCID: PMC7594092 DOI: 10.3390/molecules25204647] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/08/2020] [Accepted: 10/09/2020] [Indexed: 02/06/2023] Open
Abstract
This review presents the main properties of hydroxycinnamic acid (HCA) derivatives and their potential application as agents for the prevention and treatment of neurodegenerative diseases. It is partially focused on the successful use of these compounds as inhibitors of amyloidogenic transformation of proteins. Firstly, the prerequisites for the emergence of interest in HCA derivatives, including natural compounds, are described. A separate section is devoted to synthesis and properties of HCA derivatives. Then, the results of molecular modeling of HCA derivatives with prion protein as well as with α-synuclein fibrils are summarized, followed by detailed analysis of the experiments on the effect of natural and synthetic HCA derivatives, as well as structurally similar phenylacetic and benzoic acid derivatives, on the pathological transformation of prion protein and α-synuclein. The ability of HCA derivatives to prevent amyloid transformation of some amyloidogenic proteins, and their presence not only in food products but also as natural metabolites in human blood and tissues, makes them promising for the prevention and treatment of neurodegenerative diseases of amyloid nature.
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Affiliation(s)
- Vladimir I. Muronetz
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia; (S.K.); (M.M.)
| | - Kseniya Barinova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
| | - Sofia Kudryavtseva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia; (S.K.); (M.M.)
| | - Maria Medvedeva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia; (S.K.); (M.M.)
| | - Aleksandra Melnikova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia; (S.K.); (M.M.)
| | - Irina Sevostyanova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
| | - Pavel Semenyuk
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
| | - Yulia Stroylova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; (K.B.); (A.M.); (I.S.); (P.S.); (Y.S.)
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University Trubetskaya St. 8, Bldg. 2, 119991 Moscow, Russia
| | - Matej Sova
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia;
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Das N, Sen P. Shape-Dependent Macromolecular Crowding on the Thermodynamics and Microsecond Conformational Dynamics of Protein Unfolding Revealed at the Single-Molecule Level. J Phys Chem B 2020; 124:5858-5871. [DOI: 10.1021/acs.jpcb.0c03897] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP India
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8
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PrPSc Oligomerization Appears Dynamic, Quickly Engendering Inherent M1000 Acute Synaptotoxicity. Biophys J 2020; 119:128-141. [PMID: 32562618 DOI: 10.1016/j.bpj.2020.04.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/07/2020] [Accepted: 04/24/2020] [Indexed: 11/23/2022] Open
Abstract
Prion diseases are neurodegenerative disorders pathogenically linked to cellular prion protein (PrPC) misfolding into abnormal conformers (PrPSc), with PrPSc underpinning both transmission and synaptotoxicity. Although the biophysical features of PrPSc required to induce acute synaptic dysfunction remain incompletely defined, we recently reported that acutely synaptotoxic PrPSc appeared to be oligomeric. We herein provide further insights into the kinetic and requisite biophysical characteristics of acutely synaptotoxic ex vivo PrPSc derived from the brains of mice dying from M1000 prion disease. Pooled fractions of M1000 PrPSc located within the molecular weight range approximating monomeric PrP (mM1000) generated through size exclusion chromatography were found to harbor acute synaptotoxicity equivalent to preformed oligomeric fractions (oM1000). Subsequent investigation showed mM1000 corresponded to PrPSc rapidly concatenating in physiological buffer to exist as predominantly, closely associated, small oligomers. The oligomerization of PrP in mM1000 could be substantially mitigated by treatment with the antiaggregation compound epigallocatechin gallate, thereby maintaining the PrPSc as primarily nonoligomeric with completely abrogated acute synaptotoxicity; moreover, despite epigallocatechin gallate treatment, pooled oM1000 remained oligomeric and acutely synaptotoxic. A similar tendency to rapid formation of oligomers was observed for PrPC when monomeric fractions derived from size exclusion chromatography of normal brain homogenates (mNBH) were pooled, but neither mNBH nor preformed higher-order NBH complexes (oNBH) were acutely synaptotoxic. Oligomers formed from mNBH could be reduced to mainly monomers (<100 kDa) after enzymatic digestion of nucleic acids, whereas higher-order PrP assemblies derived from pooled mM1000, oM1000, and oNBH resisted such treatment. Collectively, these findings support that oligomerization of PrPSc into small multimeric assemblies appears to be a critical biophysical feature for engendering inherent acute synaptotoxicity, with preformed oligomers found in oM1000 appearing to be stable, tightly self-associated ensembles that coexist in dynamic equilibrium with mM1000, with the latter appearing capable of rapid aggregation, albeit initially forming smaller, weakly self-associated, acutely synaptotoxic oligomers.
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9
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Li L, Li X, Tang Y, Lao Z, Lei J, Wei G. Common cancer mutations R175H and R273H drive the p53 DNA-binding domain towards aggregation-prone conformations. Phys Chem Chem Phys 2020; 22:9225-9232. [DOI: 10.1039/c9cp06671c] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cancer mutations R175H and R273H induce p53C towards aggregation-prone conformations by increasing their SASA, water exposure of H-bonds and flexibility of loop2.
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Affiliation(s)
- Le Li
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
| | - Xuhua Li
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
| | - Yiming Tang
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
| | - Zenghui Lao
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
| | - Jiangtao Lei
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
| | - Guanghong Wei
- Department of Physics
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Multiscale Research Institute of Complex Systems
- Fudan University
- Shanghai 200438
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10
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Foliaki ST, Lewis V, Islam AMT, Ellett LJ, Senesi M, Finkelstein DI, Roberts B, Lawson VA, Adlard PA, Collins SJ. Early existence and biochemical evolution characterise acutely synaptotoxic PrPSc. PLoS Pathog 2019; 15:e1007712. [PMID: 30970042 PMCID: PMC6490942 DOI: 10.1371/journal.ppat.1007712] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 04/30/2019] [Accepted: 03/18/2019] [Indexed: 11/19/2022] Open
Abstract
Although considerable evidence supports that misfolded prion protein (PrPSc) is the principal component of “prions”, underpinning both transmissibility and neurotoxicity, clear consensus around a number of fundamental aspects of pathogenesis has not been achieved, including the time of appearance of neurotoxic species during disease evolution. Utilizing a recently reported electrophysiology paradigm, we assessed the acute synaptotoxicity of ex vivo PrPSc prepared as crude homogenates from brains of M1000 infected wild-type mice (cM1000) harvested at time-points representing 30%, 50%, 70% and 100% of the terminal stage of disease (TSD). Acute synaptotoxicity was assessed by measuring the capacity of cM1000 to impair hippocampal CA1 region long-term potentiation (LTP) and post-tetanic potentiation (PTP) in explant slices. Of particular note, cM1000 from 30% of the TSD was able to cause significant impairment of LTP and PTP, with the induced failure of LTP increasing over subsequent time-points while the capacity of cM1000 to induce PTP failure appeared maximal even at this early stage of disease progression. Evidence that the synaptotoxicity directly related to PrP species was demonstrated by the significant rescue of LTP dysfunction at each time-point through immuno-depletion of >50% of total PrP species from cM1000 preparations. Moreover, similar to our previous observations at the terminal stage of M1000 prion disease, size fractionation chromatography revealed that capacity for acute synpatotoxicity correlated with predominance of oligomeric PrP species in infected brains across all time points, with the profile appearing maximised by 50% of the TSD. Using enhanced sensitivity western blotting, modestly proteinase K (PK)-resistant PrPSc was detectable at very low levels in cM1000 at 30% of the TSD, becoming robustly detectable by 70% of the TSD at which time substantial levels of highly PK-resistant PrPSc was also evident. Further illustrating the biochemical evolution of acutely synaptotoxic species the synaptotoxicity of cM1000 from 30%, 50% and 70% of the TSD, but not at 100% TSD, was abolished by digestion of immuno-captured PrP species with mild PK treatment (5μg/ml for an hour at 37°C), demonstrating that the predominant synaptotoxic PrPSc species up to and including 70% of the TSD were proteinase-sensitive. Overall, these findings in combination with our previous assessments of transmitting prions support that synaptotoxic and infectious M1000 PrPSc species co-exist from at least 30% of the TSD, simultaneously increasing thereafter, albeit with eventual plateauing of transmitting conformers. Although evidence clearly supports that misfolded prion protein (PrPSc) is the principal component of “prions”, underpinning both transmissibility and neurotoxicity, consensus is lacking around the time of appearance and biochemical profile of neurotoxic species during disease evolution. Employing an electrophysiology model, measuring the capacity of brain homogenates derived from across the disease time-course to impair CA1 region long-term potentiation (LTP) and post-tetanic potentiation (PTP) in hippocampal slices, we observed that synaptotoxic species were present from 30% of the terminal stage of disease (TSD). Evidence that synaptotoxicity directly related to PrP species was demonstrated by significant rescue of LTP dysfunction at each time-point through immuno-depleting >~50% of total PrP species from cM1000 preparations. Moreover, size fractionation chromatography revealed that acute synpatotoxicity correlated with predominance of oligomeric PrP species in infected brains across all time points, while additional characterisation of cM1000 demonstrated that the predominant synaptotoxic PrPSc species up to and including 70% of the TSD were quite proteinase-sensitive. These findings in combination with our previous assessments of transmitting prions support that synaptotoxic and infectious M1000 PrPSc species co-exist from at least 30% of the TSD, simultaneously increasing thereafter, with biochemical transformation of synaptotoxic conformers continuing until late in disease.
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Affiliation(s)
- Simote Totauhelotu Foliaki
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Victoria Lewis
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | | | - Laura Jane Ellett
- Department of Pathology The University of Melbourne, Parkville, Victoria, Australia
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Matteo Senesi
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | | | - Blaine Roberts
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Victoria A. Lawson
- Department of Pathology The University of Melbourne, Parkville, Victoria, Australia
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Paul Anthony Adlard
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Steven John Collins
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- * E-mail:
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11
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Sengupta I, Udgaonkar JB. Structural mechanisms of oligomer and amyloid fibril formation by the prion protein. Chem Commun (Camb) 2018; 54:6230-6242. [PMID: 29789820 DOI: 10.1039/c8cc03053g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Misfolding and aggregation of the prion protein is responsible for multiple neurodegenerative diseases. Works from several laboratories on folding of both the WT and multiple pathogenic mutant variants of the prion protein have identified several structurally dissimilar intermediates, which might be potential precursors to misfolding and aggregation. The misfolded aggregates themselves are morphologically distinct, critically dependent on the solution conditions under which they are prepared, but always β-sheet rich. Despite the lack of an atomic resolution structure of the infectious pathogenic agent in prion diseases, several low resolution models have identified the β-sheet rich core of the aggregates formed in vitro, to lie in the α2-α3 subdomain of the prion protein, albeit with local stabilities that vary with the type of aggregate. This feature article describes recent advances in the investigation of in vitro prion protein aggregation using multiple spectroscopic probes, with particular focus on (1) identifying aggregation-prone conformations of the monomeric protein, (2) conditions which trigger misfolding and oligomerization, (3) the mechanism of misfolding and aggregation, and (4) the structure of the misfolded intermediates and final aggregates.
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Affiliation(s)
- Ishita Sengupta
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
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12
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Pedrote MM, de Oliveira GAP, Felix AL, Mota MF, Marques MDA, Soares IN, Iqbal A, Norberto DR, Gomes AMO, Gratton E, Cino EA, Silva JL. Aggregation-primed molten globule conformers of the p53 core domain provide potential tools for studying p53C aggregation in cancer. J Biol Chem 2018; 293:11374-11387. [PMID: 29853637 PMCID: PMC6065177 DOI: 10.1074/jbc.ra118.003285] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/10/2018] [Indexed: 12/16/2022] Open
Abstract
The functionality of the tumor suppressor p53 is altered in more than 50% of human cancers, and many individuals with cancer exhibit amyloid-like buildups of aggregated p53. An understanding of what triggers the pathogenic amyloid conversion of p53 is required for the further development of cancer therapies. Here, perturbation of the p53 core domain (p53C) with subdenaturing concentrations of guanidine hydrochloride and high hydrostatic pressure revealed native-like molten globule (MG) states, a subset of which were highly prone to amyloidogenic aggregation. We found that MG conformers of p53C, probably representing population-weighted averages of multiple states, have different volumetric properties, as determined by pressure perturbation and size-exclusion chromatography. We also found that they bind the fluorescent dye 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and have a native-like tertiary structure that occludes the single Trp residue in p53. Fluorescence experiments revealed conformational changes of the single Trp and Tyr residues before p53 unfolding and the presence of MG conformers, some of which were highly prone to aggregation. p53C exhibited marginal unfolding cooperativity, which could be modulated from unfolding to aggregation pathways with chemical or physical forces. We conclude that trapping amyloid precursor states in solution is a promising approach for understanding p53 aggregation in cancer. Our findings support the use of single-Trp fluorescence as a probe for evaluating p53 stability, effects of mutations, and the efficacy of therapeutics designed to stabilize p53.
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Affiliation(s)
- Murilo M Pedrote
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908.
| | - Adriani L Felix
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Michelle F Mota
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Mayra de A Marques
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Iaci N Soares
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Anwar Iqbal
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Douglas R Norberto
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Andre M O Gomes
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California, Irvine, California 92697-2717
| | - Elio A Cino
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - Jerson L Silva
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-901, Brazil.
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13
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Cieplak AS. Protein folding, misfolding and aggregation: The importance of two-electron stabilizing interactions. PLoS One 2017; 12:e0180905. [PMID: 28922400 PMCID: PMC5603215 DOI: 10.1371/journal.pone.0180905] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 06/22/2017] [Indexed: 12/17/2022] Open
Abstract
Proteins associated with neurodegenerative diseases are highly pleiomorphic and may adopt an all-α-helical fold in one environment, assemble into all-β-sheet or collapse into a coil in another, and rapidly polymerize in yet another one via divergent aggregation pathways that yield broad diversity of aggregates’ morphology. A thorough understanding of this behaviour may be necessary to develop a treatment for Alzheimer’s and related disorders. Unfortunately, our present comprehension of folding and misfolding is limited for want of a physicochemical theory of protein secondary and tertiary structure. Here we demonstrate that electronic configuration and hyperconjugation of the peptide amide bonds ought to be taken into account to advance such a theory. To capture the effect of polarization of peptide linkages on conformational and H-bonding propensity of the polypeptide backbone, we introduce a function of shielding tensors of the Cα atoms. Carrying no information about side chain-side chain interactions, this function nonetheless identifies basic features of the secondary and tertiary structure, establishes sequence correlates of the metamorphic and pH-driven equilibria, relates binding affinities and folding rate constants to secondary structure preferences, and manifests common patterns of backbone density distribution in amyloidogenic regions of Alzheimer’s amyloid β and tau, Parkinson’s α-synuclein and prions. Based on those findings, a split-intein like mechanism of molecular recognition is proposed to underlie dimerization of Aβ, tau, αS and PrPC, and divergent pathways for subsequent association of dimers are outlined; a related mechanism is proposed to underlie formation of PrPSc fibrils. The model does account for: (i) structural features of paranuclei, off-pathway oligomers, non-fibrillar aggregates and fibrils; (ii) effects of incubation conditions, point mutations, isoform lengths, small-molecule assembly modulators and chirality of solid-liquid interface on the rate and morphology of aggregation; (iii) fibril-surface catalysis of secondary nucleation; and (iv) self-propagation of infectious strains of mammalian prions.
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Affiliation(s)
- Andrzej Stanisław Cieplak
- Department of Chemistry, Bilkent University, Ankara, Turkey
- Department of Chemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Chemistry, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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14
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Sabareesan AT, Singh J, Roy S, Udgaonkar JB, Mathew MK. The Pathogenic A116V Mutation Enhances Ion-Selective Channel Formation by Prion Protein in Membranes. Biophys J 2017; 110:1766-1776. [PMID: 27119637 DOI: 10.1016/j.bpj.2016.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/23/2016] [Accepted: 03/07/2016] [Indexed: 11/19/2022] Open
Abstract
Prion diseases are a group of fatal neurodegenerative disorders that afflict mammals. Misfolded and aggregated forms of the prion protein (PrP(Sc)) have been associated with many prion diseases. A transmembrane form of PrP favored by the pathogenic mutation A116V is associated with Gerstmann-Sträussler-Scheinker syndrome, but no accumulation of PrP(Sc) is detected. However, the role of the transmembrane form of PrP in pathological processes leading to neuronal death remains unclear. This study reports that the full-length mouse PrP (moPrP) significantly increases the permeability of living cells to K(+), and forms K(+)- and Ca(2+)-selective channels in lipid membranes. Importantly, the pathogenic mutation A116V greatly increases the channel-forming capability of moPrP. The channels thus formed are impermeable to sodium and chloride ions, and are blocked by blockers of voltage-gated ion channels. Hydrogen-deuterium exchange studies coupled with mass spectrometry (HDX-MS) show that upon interaction with lipid, the central hydrophobic region (109-132) of the protein is protected against exchange, making it a good candidate for inserting into the membrane and lining the channel. HDX-MS also shows a dramatic increase in the protein-lipid stoichiometry for A116V moPrP, providing a rationale for its increased channel-forming capability. The results suggest that ion channel formation may be a possible mechanism of PrP-mediated neurodegeneration by the transmembrane forms of PrP.
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Affiliation(s)
- Ambadi Thody Sabareesan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Jogender Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Samrat Roy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India; Biocon Bristol Myers Squibb Research Center, Bengaluru, India; School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
| | - M K Mathew
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
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15
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Moulick R, Udgaonkar JB. Identification and Structural Characterization of the Precursor Conformation of the Prion Protein which Directly Initiates Misfolding and Oligomerization. J Mol Biol 2017; 429:886-899. [DOI: 10.1016/j.jmb.2017.01.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/19/2017] [Accepted: 01/19/2017] [Indexed: 12/11/2022]
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16
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Bemporad F, Ramazzotti M. From the Evolution of Protein Sequences Able to Resist Self-Assembly to the Prediction of Aggregation Propensity. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 329:1-47. [PMID: 28109326 DOI: 10.1016/bs.ircmb.2016.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Folding of polypeptide chains into biologically active entities is an astonishingly complex process, determined by the nature and the sequence of residues emerging from ribosomes. While it has been long believed that evolution has pressed genomes so that specific sequences could adopt unique, functional three-dimensional folds, it is now clear that complex protein machineries act as quality control system and supervise folding. Notwithstanding that, events such as erroneous folding, partial folding, or misfolding are frequent during the life of a cell or a whole organism, and they can escape controls. One of the possible outcomes of this misbehavior is cross-β aggregation, a super secondary structure which represents the hallmark of self-assembled, well organized, and extremely ordered structures termed amyloid fibrils. What if evolution would have not taken into account such possibilities? Twenty years of research point toward the idea that, in fact, evolution has constantly supervised the risk of errors and minimized their impact. In this review we tried to survey the major findings in the amyloid field, trying to describe what the real pitfalls of protein folding are-from an evolutionary perspective-and how sequence and structural features have evolved to balance the need for perfect, dynamic, functionally efficient structures, and the detrimental effects implicit in the dangerous process of folding. We will discuss how the knowledge obtained from these studies has been employed to produce computational methods able to assess, predict, and discriminate the aggregation properties of protein sequences.
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Affiliation(s)
- F Bemporad
- Università degli Studi di Firenze, Firenze, Italy.
| | - M Ramazzotti
- Università degli Studi di Firenze, Firenze, Italy.
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17
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Žganec M, Žerovnik E, Urbanc B. Assembly of Stefin B into Polymorphic Oligomers Probed by Discrete Molecular Dynamics. J Chem Theory Comput 2016; 11:2355-66. [PMID: 26574430 DOI: 10.1021/acs.jctc.5b00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Assembly of an amyloidogenic protein stefin B into molten globule oligomers is studied by efficient discrete molecular dynamics. Consistent with in vitro findings, tetramers form primarily through dimer association, resulting in a decreased trimer abundance. Oligomers up to heptamers display elongated rod-like morphologies akin to protofibrils, whereas larger oligomers, decamers through dodecamers, form elongated, branched, as well as annular structures, providing structural insights into pore forming ability and toxicity of amyloidogenic proteins.
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Affiliation(s)
- Matjaž Žganec
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Brigita Urbanc
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Physics, Drexel University , Philadelphia, Pennsylvania 19104, United States
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18
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Yu Z, Huang P, Yu Y, Zheng Z, Huang Z, Guo C, Lin D. Unique Properties of the Rabbit Prion Protein Oligomer. PLoS One 2016; 11:e0160874. [PMID: 27529173 PMCID: PMC4987043 DOI: 10.1371/journal.pone.0160874] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 07/26/2016] [Indexed: 11/26/2022] Open
Abstract
Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of fatal neurodegenerative disorders infecting both humans and animals. Recent works have demonstrated that the soluble prion protein oligomer (PrPO), the intermediate of the conformational transformation from the host-derived cellular form (PrPC) to the disease-associated Scrapie form (PrPSc), exerts the major neurotoxicity in vitro and in vivo. Rabbits show strong resistance to TSEs, the underlying mechanism is unclear to date. It is expected that the relative TSEs-resistance of rabbits is closely associated with the unique properties of rabbit prion protein oligomer which remain to be addressed in detail. In the present work, we prepared rabbit prion protein oligomer (recRaPrPO) and human prion protein oligomer (recHuPrPO) under varied conditions, analyzed the effects of pH, NaCl concentration and incubation temperature on the oligomerization, and compared the properties of recRaPrPO and recHuPrPO. We found that several factors facilitated the formation of prion protein oligomers, including low pH, high NaCl concentration, high incubation temperature and low conformational stability of monomeric prion protein. RecRaPrPO was formed more slowly than recHuPrPO at physiological-like conditions (< 57°C, < 150 mM NaCl). Furthermore, recRaPrPO possessed higher susceptibility to proteinase K and lower cytotoxicity in vitro than recHuPrPO. These unique properties of recRaPrPO might substantially contribute to the TSEs-resistance of rabbits. Our work sheds light on the oligomerization of prion proteins and is of benefit to mechanistic understanding of TSEs-resistance of rabbits.
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Affiliation(s)
- Ziyao Yu
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Pei Huang
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yuanhui Yu
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Zhen Zheng
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Zicheng Huang
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Chenyun Guo
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Donghai Lin
- The Key Laboratory for Chemical Biology of Fujian Province, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
- * E-mail:
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19
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Moulick R, Das R, Udgaonkar JB. Partially Unfolded Forms of the Prion Protein Populated under Misfolding-promoting Conditions: CHARACTERIZATION BY HYDROGEN EXCHANGE MASS SPECTROMETRY AND NMR. J Biol Chem 2015; 290:25227-40. [PMID: 26306043 DOI: 10.1074/jbc.m115.677575] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Indexed: 12/16/2022] Open
Abstract
The susceptibility of the cellular prion protein (PrP(C)) to convert to an alternative misfolded conformation (PrP(Sc)), which is the key event in the pathogenesis of prion diseases, is indicative of a conformationally flexible native (N) state. In the present study, hydrogen-deuterium exchange (HDX) in conjunction with mass spectrometry and nuclear magnetic resonance spectroscopy were used for the structural and energetic characterization of the N state of the full-length mouse prion protein, moPrP(23-231), under conditions that favor misfolding. The kinetics of HDX of 34 backbone amide hydrogens in the N state were determined at pH 4. In contrast to the results of previous HDX studies on the human and Syrian hamster prion proteins at a higher pH, various segments of moPrP were found to undergo different extents of subglobal unfolding events at pH 4, a pH at which the protein is known to be primed to misfold to a β-rich conformation. No residual structure around the disulfide bond was observed for the unfolded state at pH 4. The N state of the prion protein was observed to be at equilibrium with at least two partially unfolded forms (PUFs). These PUFs, which are accessed by stochastic fluctuations of the N state, have altered surface area exposure relative to the N state. One of these PUFs resembles a conformation previously implicated to be an initial intermediate in the conversion of monomeric protein into misfolded oligomer at pH 4.
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Affiliation(s)
- Roumita Moulick
- From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Ranabir Das
- From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Jayant B Udgaonkar
- From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
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20
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Valipour M, Maghami P, Habibi-Rezaei M, Sadeghpour M, Khademian MA, Mosavi K, Sheibani N, Moosavi-Movahedi AA. Interaction of insulin with methyl tert-butyl ether promotes molten globule-like state and production of reactive oxygen species. Int J Biol Macromol 2015; 80:610-4. [PMID: 26193678 DOI: 10.1016/j.ijbiomac.2015.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 07/14/2015] [Accepted: 07/15/2015] [Indexed: 11/25/2022]
Abstract
Interaction of methyl tert-butyl ether (MTBE) with proteins is a new look at its potential adverse biological effects. When MTBE is released to the environment it enters the blood stream through inhalation, and could affect the properties of various proteins. Here we investigated the interaction of MTBE with insulin and its effect on insulin structural changes. Our results showed that insulin formed a molten globule (MG)-like structure in the presence of 8 μM MTBE under physiological pH. The insulin structural changes were studied using spectroscopy methods, viscosity calculation, dynamic light scattering and differential scanning calorimetry. To delineate the mechanisms involved in MTBE-protein interactions, the formation of reactive oxygen specious (ROS) and formation of protein aggregates were measured. The chemiluminscence experiments revealed an increase in ROS production in the presence of MTBE especially in the MG-like state. These results were further confirmed by the aggregation tests, which indicated more aggregation of insulin at 40 μM MTBE compared with 8 μM. Thus, the formation of initial aggregates and exposure of the hydrophobic patches upon formation of the MG-like state in the presence of MTBE drives protein oxidation and ROS generation.
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Affiliation(s)
- Masoumeh Valipour
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran
| | - Parvaneh Maghami
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | | | - Mostafa Sadeghpour
- Office of Health, Safety and Environment (HSE) Oil Ministry, Tehran, Iran
| | | | - Khadijeh Mosavi
- Office of Health, Safety and Environment (HSE) Oil Ministry, Bandar Mahshahr, Iran
| | - Nader Sheibani
- Departments of Ophthalmology and Visual Sciences and Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Ali Akbar Moosavi-Movahedi
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran.
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21
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Hoop CL, Lin HK, Kar K, Hou Z, Poirier MA, Wetzel R, van der Wel PCA. Polyglutamine amyloid core boundaries and flanking domain dynamics in huntingtin fragment fibrils determined by solid-state nuclear magnetic resonance. Biochemistry 2014; 53:6653-66. [PMID: 25280367 PMCID: PMC4211650 DOI: 10.1021/bi501010q] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
In Huntington’s disease, expansion
of a polyglutamine (polyQ)
domain in the huntingtin (htt) protein leads to misfolding and aggregation.
There is much interest in the molecular features that distinguish
monomeric, oligomeric, and fibrillar species that populate the aggregation
pathway and likely differ in cytotoxicity. The mechanism and rate
of aggregation are greatly affected by the domains flanking the polyQ
segment within exon 1 of htt. A “protective” C-terminal
proline-rich flanking domain inhibits aggregation by inducing polyproline
II structure (PPII) within an extended portion of polyQ. The N-terminal
flanking segment (httNT) adopts an α-helical structure
as it drives aggregation, helps stabilize oligomers and fibrils, and
is seemingly integral to their supramolecular assembly. Via solid-state
nuclear magnetic resonance (ssNMR), we probe how, in the mature fibrils,
the htt flanking domains impact the polyQ domain and in particular
the localization of the β-structured amyloid core. Using residue-specific
and uniformly labeled samples, we find that the amyloid core occupies
most of the polyQ domain but ends just prior to the prolines. We probe
the structural and dynamical features of the remarkably abrupt β-sheet
to PPII transition and discuss the potential connections to certain
htt-binding proteins. We also examine the httNT α-helix
outside the polyQ amyloid core. Despite its presumed structural and
demonstrated stabilizing roles in the fibrils, quantitative ssNMR
measurements of residue-specific dynamics show that it undergoes distinct
solvent-coupled motion. This dynamical feature seems reminiscent of
molten-globule-like α-helix-rich features attributed to the
nonfibrillar oligomeric species of various amyloidogenic proteins.
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Affiliation(s)
- Cody L Hoop
- Department of Structural Biology, University of Pittsburgh School of Medicine , Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15260, United States
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22
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Crowded milieu prevents fibrillation of hen egg white lysozyme with retention of enzymatic activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:8-16. [DOI: 10.1016/j.jphotobiol.2014.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 11/18/2022]
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23
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Trevitt CR, Hosszu LLP, Batchelor M, Panico S, Terry C, Nicoll AJ, Risse E, Taylor WA, Sandberg MK, Al-Doujaily H, Linehan JM, Saibil HR, Scott DJ, Collinge J, Waltho JP, Clarke AR. N-terminal domain of prion protein directs its oligomeric association. J Biol Chem 2014; 289:25497-508. [PMID: 25074940 PMCID: PMC4162156 DOI: 10.1074/jbc.m114.566588] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The self-association of prion protein (PrP) is a critical step in the pathology of prion diseases. It is increasingly recognized that small non-fibrillar β-sheet-rich oligomers of PrP may be of crucial importance in the prion disease process. Here, we characterize the structure of a well defined β-sheet-rich oligomer, containing ∼12 PrP molecules, and often enclosing a central cavity, formed using full-length recombinant PrP. The N-terminal region of prion protein (residues 23-90) is required for the formation of this distinct oligomer; a truncated form comprising residues 91-231 forms a broad distribution of aggregated species. No infectivity or toxicity was found using cell and animal model systems. This study demonstrates that examination of the full repertoire of conformers and assembly states that can be accessed by PrP under specific experimental conditions should ideally be done using the full-length protein.
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Affiliation(s)
- Clare R Trevitt
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Laszlo L P Hosszu
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Mark Batchelor
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Silvia Panico
- the Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX
| | - Cassandra Terry
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Andrew J Nicoll
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Emmanuel Risse
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - William A Taylor
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Malin K Sandberg
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Huda Al-Doujaily
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Jacqueline M Linehan
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Helen R Saibil
- the Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX
| | - David J Scott
- the National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD, the ISIS Spallation Neutron and Muon Source and Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, OX11 0FA, and
| | - John Collinge
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG
| | - Jonathan P Waltho
- the Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Anthony R Clarke
- From the Department of Neurodegenerative Disease, MRC Prion Unit, UCL Institute of Neurology, Queen Square, London WC1N 3BG,
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24
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Ghosh S, Pandey NK, Banerjee P, Chaudhury K, Nagy NV, Dasgupta S. Copper(II) directs formation of toxic amorphous aggregates resulting in inhibition of hen egg white lysozyme fibrillation under alkaline salt-mediated conditions. J Biomol Struct Dyn 2014; 33:991-1007. [PMID: 24806136 DOI: 10.1080/07391102.2014.921864] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hen egg white lysozyme (HEWL) adopts a molten globule-like state at high pH (~12.75) and is found to form amyloid fibrils at alkaline pH. Here, we report that Cu(II) inhibits self-association of HEWL at pH 12.75 both at 37 and 65 °C. A significant reduction in Thioflavin T fluorescence intensity, attenuation in β-sheet content and reduction in hydrophobic exposure were observed with increasing Cu(II) stoichiometry. Electron paramagnetic resonance spectroscopy suggests a 4N type of coordination pattern around Cu(II) during fibrillation. Cu(II) is also capable of altering the cytotoxicity of the proteinaceous aggregates. Fibrillar species of diverse morphology were found in the absence of Cu(II) with the generation of amorphous aggregates in the presence of Cu(II), which are more toxic compared to the fibrils alone.
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Affiliation(s)
- Sudeshna Ghosh
- a Department of Chemistry , Indian Institute of Technology , Kharagpur 721302 , India
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25
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WU XUE, FU TING, XIU ZHILONG, YIN LIU, WANG JINGUANG, LI GUOHUI. COMPARING FOLDING MECHANISMS OF DIFFERENT PRION PROTEINS BY Gō MODEL. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2013. [DOI: 10.1142/s0219633613410046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prions are associated with neurodegenerative diseases induced by transmissible spongiform encephalopathies. The infectious scrapie form is referred to as PrP Sc , which has conformational change from normal prion with predominant α-helical conformation to the abnormal PrP Sc that is rich in β-sheet content. Neurodegenerative diseases have been found from both human and bovine sources, but there are no reports about infected by transmissible spongiform encephalopathies from rabbit, canine and horse sources. Here we used coarse-grained Gō model to compare the difference among human, bovine, rabbit, canine, and horse normal (cellular) prion proteins. The denatured state of normal prion has relation with the conversion from normal to abnormal prion protein, so we used all-atom Gō model to investigate the folding pathway and energy landscape for human prion protein. Through using coarse-grained Gō model, the cooperativity of the five prion proteins was characterized in terms of calorimetric criterion, sigmoidal transition, and free-energy profile. The rabbit and horse prion proteins have higher folding free-energy barrier and cooperativity, and canine prion protein has slightly higher folding free-energy barrier comparing with human and bovine prion proteins. The results from all-atom Gō model confirmed the validity of C α-Gō model. The correlations of our results with previous experimental and theoretical researches were discussed.
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Affiliation(s)
- XUE WU
- School of Life Science and Biotechnology, Dalian University of Technology, Linggong Road 2, Dalian 116024, P. R. China
- Laboratory of Molecular Modeling and Design, State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science 457, Zhongshan Road, Dalian, Liaoning, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - TING FU
- School of Life Science and Biotechnology, Dalian University of Technology, Linggong Road 2, Dalian 116024, P. R. China
- Laboratory of Molecular Modeling and Design, State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science 457, Zhongshan Road, Dalian, Liaoning, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - ZHI-LONG XIU
- School of Life Science and Biotechnology, Dalian University of Technology, Linggong Road 2, Dalian 116024, P. R. China
| | - LIU YIN
- Oncology Department in the 1st Affiliated Hospital of Dalian, Medical University, 222 Zhongshan Road, Liaoning Province, Dalian 116011, P. R. China
| | - JIN-GUANG WANG
- Thoracic Surgery Department in the 1st Affiliated Hospital of Dalian, Medical University, 222 Zhongshan Road, Liaoning Province, Dalian 116011, P. R. China
| | - GUO-HUI LI
- Laboratory of Molecular Modeling and Design, State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science 457, Zhongshan Road, Dalian, Liaoning, P. R. China
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Schlepckow K, Schwalbe H. Molecular mechanism of prion protein oligomerization at atomic resolution. Angew Chem Int Ed Engl 2013; 52:10002-5. [PMID: 23934741 DOI: 10.1002/anie.201305184] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Indexed: 11/08/2022]
Abstract
Prion protein oligomerization: Despite the crucial role of oligomers during prion protein (PrP) pathogenesis the molecular mechanism of their formation has remained largely elusive. A 2D time-resolved NMR study which made it possible to characterize the oligomerization kinetics with unprecedented site-specificity is reported.
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Affiliation(s)
- Kai Schlepckow
- Institut für Organische Chemie und Chemische Biologie, Zentrum für Biomolekulare Magnetische Resonanz (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main (Germany) http://schwalbe.org.chemie.uni-frankfurt.de
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Schlepckow K, Schwalbe H. Molecular Mechanism of Prion Protein Oligomerization at Atomic Resolution. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Sarkar N, Dubey VK. Exploring critical determinants of protein amyloidogenesis: a review. J Pept Sci 2013; 19:529-36. [DOI: 10.1002/psc.2539] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/03/2013] [Accepted: 06/17/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Nandini Sarkar
- Department of Biotechnology and Medical Engineering; National Institute of Technology Rourkela; Rourkela Odisha 769008 India
| | - Vikash Kumar Dubey
- Department of Biotechnology; Indian Institute of Technology Guwahati; Guwahati Assam 781039 India
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Larda ST, Simonetti K, Al-Abdul-Wahid MS, Sharpe S, Prosser RS. Dynamic Equilibria between Monomeric and Oligomeric Misfolded States of the Mammalian Prion Protein Measured by 19F NMR. J Am Chem Soc 2013; 135:10533-41. [DOI: 10.1021/ja404584s] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Sacha Thierry Larda
- Department of Chemistry, University of Toronto, Toronto, Ontario,
Canada M5S 3H6
| | - Karen Simonetti
- Molecular
Structure and Function
Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | | | - Simon Sharpe
- Molecular
Structure and Function
Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
- Department of Biochemistry, University of Toronto, Toronto, Ontario,
Canada M5S 1A8
| | - R. Scott Prosser
- Department of Chemistry, University of Toronto, Toronto, Ontario,
Canada M5S 3H6
- Department of Biochemistry, University of Toronto, Toronto, Ontario,
Canada M5S 1A8
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Huang P, Lian F, Wen Y, Guo C, Lin D. Prion protein oligomer and its neurotoxicity. Acta Biochim Biophys Sin (Shanghai) 2013; 45:442-51. [PMID: 23557632 DOI: 10.1093/abbs/gmt037] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The prion diseases, also known as transmissible spongiform encephalopathies, are fatal neurodegenerative disorders. According to the 'protein only' hypothesis, the key molecular event in the pathogenesis of prion disease is the conformational conversion of the host-derived cellular prion protein (PrP(C)) into a misfolded form (scrapie PrP, PrP(Sc)). Increasing evidence has shown that the most infectious factor is the smaller subfibrillar oligomers formed by prion proteins. Both the prion oligomer and PrP(Sc) are rich in β-sheet structure and resistant to the proteolysis of proteinase K. The prion oligomer is soluble in physiologic environments whereas PrP(Sc) is insoluble. Various prion oligomers are formed in different conditions. Prion oligomers exhibited more neurotoxicity both in vitro and in vivo than the fibrillar forms of PrP(Sc), implying that prion oligomers could be potential drug targets for attacking prion diseases. In this article, we describe recent experimental evidence regarding prion oligomers, with a special focus on prion oligomer formation and its neurotoxicity.
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Affiliation(s)
- Pei Huang
- School of Life Science and Technology, China Pharmaceutical University, Nanjing 21009, China
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Jiang D, Rauda I, Han S, Chen S, Zhou F. Aggregation pathways of the amyloid β(1-42) peptide depend on its colloidal stability and ordered β-sheet stacking. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:12711-12721. [PMID: 22870885 PMCID: PMC3464049 DOI: 10.1021/la3021436] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Amyloid β (Aβ) fibrils are present as a major component in senile plaques, the hallmark of Alzheimer's disease (AD). Diffuse plaques (nonfibrous, loosely packed Aβ aggregates) containing amorphous Aβ aggregates are also formed in brain. This work examines the influence of Cu(2+) complexation by Aβ on the aggregation process in the context of charge and structural variations. Changes in the surface charges of Aβ molecules due to Cu(2+) binding, measured with a ζ-potential measurement device, were correlated with the aggregate morphologies examined by atomic force microscopy. As a result of the charge variation, the "colloid-like" stability of the aggregation intermediates, which is essential to the fibrillation process, is affected. Consequently, Cu(2+) enhances the amorphous aggregate formation. By monitoring variations in the secondary structures with circular dichroism spectroscopy, a direct transformation from the unstructured conformation to the β-sheet structure was observed for all types of aggregates observed (oligomers, fibrils, and/or amorphous aggregates). Compared to the Aβ aggregation pathway in the absence of Cu(2+) and taking other factors affecting Aβ aggregation (i.e., pH and temperature) into account, our investigation indicates that formations of amorphous and fibrous aggregates diverge from the same β-sheet-containing partially folded intermediate. This study suggests that the hydrophilic domain of Aβ also plays a role in the Aβ aggregation process. A kinetic model was proposed to account for the effects of the Cu(2+) binding on these two aggregation pathways in terms of charge and structural variations.
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Affiliation(s)
| | | | - Shubo Han
- Department of Natural Sciences, Fayetteville State University, Fayetteville, NC
| | | | - Feimeng Zhou
- Corresponding author. Phone: 323-343-2390. Fax: 323-343-6490.
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Abstract
Prion diseases comprise a family of fatal neurodegenerative disorders caused by the conformational re-arrangement of a normal host-encoded protein, PrP (C) , to an abnormal infectious isoform termed PrP (Sc) . Currently, the precise cellular mechanism(s) underlying prion disease pathogenesis remain unclear. Evidence suggests a role for the ubiquitin proteasome system (UPS), a protein degradation pathway that is critical for maintaining cellular proteostasis. Dysfunction of the UPS has been implicated in various neurodegenerative diseases. However, the mechanisms of this impairment remain unknown in many cases, and evidence that disease-associated misfolded proteins are able to directly inhibit the function of the proteasome has been lacking. Recently, we have shown data describing a mechanism of proteasome impairment by the direct interaction of β-sheet-rich PrP to reduce gate opening and inhibit substrate entry. This novel mechanism may provide a model for how other misfolded, disease-associated proteins might interact with the proteasome to disrupt its function. Targeting the UPS to restore proteostasis in neurodegenerative disorders in which misfolded proteins accumulate offers a possible target for therapeutic intervention.
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Affiliation(s)
- Ralph Andre
- Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London, UK
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Younan ND, Nadal RC, Davies P, Brown DR, Viles JH. Methionine oxidation perturbs the structural core of the prion protein and suggests a generic misfolding pathway. J Biol Chem 2012; 287:28263-75. [PMID: 22654104 PMCID: PMC3436581 DOI: 10.1074/jbc.m112.354779] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Oxidative stress and misfolding of the prion protein (PrPC) are fundamental to prion diseases. We have therefore probed the effect of oxidation on the structure and stability of PrPC. Urea unfolding studies indicate that H2O2 oxidation reduces the thermodynamic stability of PrPC by as much as 9 kJ/mol. 1H-15N NMR studies indicate methionine oxidation perturbs key hydrophobic residues on one face of helix-C as follows: Met-205, Val-209, and Met-212 together with residues Val-160 and Tyr-156. These hydrophobic residues pack together and form the structured core of the protein, stabilizing its ternary structure. Copper-catalyzed oxidation of PrPC causes a more significant alteration of the structure, generating a monomeric molten globule species that retains its native helical content. Further copper-catalyzed oxidation promotes extended β-strand structures that lack a cooperative fold. This transition from the helical molten globule to β-conformation has striking similarities to a misfolding intermediate generated at low pH. PrP may therefore share a generic misfolding pathway to amyloid fibers, irrespective of the conditions promoting misfolding. Our observations support the hypothesis that oxidation of PrP destabilizes the native fold of PrPC, facilitating the transition to PrPSc. This study gives a structural and thermodynamic explanation for the high levels of oxidized methionine in scrapie isolates.
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Affiliation(s)
- Nadine D Younan
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
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Direct observation of multiple misfolding pathways in a single prion protein molecule. Proc Natl Acad Sci U S A 2012; 109:5283-8. [PMID: 22421432 DOI: 10.1073/pnas.1107736109] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Protein misfolding is a ubiquitous phenomenon associated with a wide range of diseases. Single-molecule approaches offer a powerful tool for deciphering the mechanisms of misfolding by measuring the conformational fluctuations of a protein with high sensitivity. We applied single-molecule force spectroscopy to observe directly the misfolding of the prion protein PrP, a protein notable for having an infectious misfolded state that is able to propagate by recruiting natively folded PrP. By measuring folding trajectories of single PrP molecules held under tension in a high-resolution optical trap, we found that the native folding pathway involves only two states, without evidence for partially folded intermediates that have been proposed to mediate misfolding. Instead, frequent but fleeting transitions were observed into off-pathway intermediates. Three different misfolding pathways were detected, all starting from the unfolded state. Remarkably, the misfolding rate was even higher than the rate for native folding. A mutant PrP with higher aggregation propensity showed increased occupancy of some of the misfolded states, suggesting these states may act as intermediates during aggregation. These measurements of individual misfolding trajectories demonstrate the power of single-molecule approaches for characterizing misfolding directly by mapping out nonnative folding pathways.
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Kubota T, Hamazoe Y, Hashiguchi S, Ishibashi D, Akasaka K, Nishida N, Katamine S, Sakaguchi S, Kuroki R, Nakashima T, Sugimura K. Direct evidence of generation and accumulation of β-sheet-rich prion protein in scrapie-infected neuroblastoma cells with human IgG1 antibody specific for β-form prion protein. J Biol Chem 2012; 287:14023-39. [PMID: 22356913 DOI: 10.1074/jbc.m111.318352] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We prepared β-sheet-rich recombinant full-length prion protein (β-form PrP) (Jackson, G. S., Hosszu, L. L., Power, A., Hill, A. F., Kenney, J., Saibil, H., Craven, C. J., Waltho, J. P., Clarke, A. R., and Collinge, J. (1999) Science 283, 1935-1937). Using this β-form PrP and a human single chain Fv-displaying phage library, we have established a human IgG1 antibody specific to β-form but not α-form PrP, PRB7 IgG. When prion-infected ScN2a cells were cultured with PRB7 IgG, they generated and accumulated PRB7-binding granules in the cytoplasm with time, consequently becoming apoptotic cells bearing very large PRB7-bound aggregates. The SAF32 antibody recognizing the N-terminal octarepeat region of full-length PrP stained distinct granules in these cells as determined by confocal laser microscopy observation. When the accumulation of proteinase K-resistant PrP was examined in prion-infected ScN2a cells cultured in the presence of PRB7 IgG or SAF32, it was strongly inhibited by SAF32 but not at all by PRB7 IgG. Thus, we demonstrated direct evidence of the generation and accumulation of β-sheet-rich PrP in ScN2a cells de novo. These results suggest first that PRB7-bound PrP is not responsible for the accumulation of β-form PrP aggregates, which are rather an end product resulting in the triggering of apoptotic cell death, and second that SAF32-bound PrP lacking the PRB7-recognizing β-form may represent so-called PrP(Sc) with prion propagation activity. PRB7 is the first human antibody specific to β-form PrP and has become a powerful tool for the characterization of the biochemical nature of prion and its pathology.
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Affiliation(s)
- Toshiya Kubota
- Department of Chemistry, Biotechnology, and Chemical Engineering, Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan
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Saiki M, Hidaka Y, Nara M, Morii H. Stem-forming regions that are essential for the amyloidogenesis of prion proteins. Biochemistry 2012; 51:1566-76. [PMID: 22324778 DOI: 10.1021/bi201688r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Prion diseases represent fatal neurodegenerative disorders caused by the aggregation of prion proteins. With regard to the formation of the amyloidogenic cross-β-structure, the initial mechanism in the conversion to a β-structure is critically important. To explore the core regions forming a stem of the amyloid, we designed and prepared a series of peptides comprised of two native sequences linked by a turn-inducing dipeptide moiety and examined their ability to produce amyloids. A sequence alignment of the peptides bearing the ability to form amyloid structures revealed that paired strands consisting of VNITI (residues 180-184) and VTTTT (residues 189-193) are the core regions responsible for initiating the formation of cross-β-structures and for further ordered aggregation. In addition, most of the causative mutations responsible for inherited prion diseases were found to be located in these stem-forming regions on helix H2 and their counterpart on helix H3. Moreover, the volume effect of the nonstem domain, which contains ~200 residues, was deduced to be a determinant of the nature of the association such as oligomerization, because the stem-forming domain is only a small part of a prion protein. Taken together, we conclude that the mechanism underlying the initial stage of amyloidogenesis is the exposure of a newly formed intramolecular β-sheet to a solvent through the partial transition of a native structure from an α-helix to a β-structure. Our results also demonstrate that prion diseases caused by major prion proteins except the prions of some fungi such as yeast are inherent only in mammals, as evidenced by a comparison of the corresponding sequences to the stem-forming regions among different animals.
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Affiliation(s)
- Masatoshi Saiki
- School of Science and Engineering, Kinki University, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan
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Kyratsous CA, Panagiotidis CA. Heat-shock protein fusion vectors for improved expression of soluble recombinant proteins in Escherichia coli. Methods Mol Biol 2012; 824:109-129. [PMID: 22160895 DOI: 10.1007/978-1-61779-433-9_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Molecular chaperones or heat-shock proteins (HSPs) are protein machines that interact with unfolded or partially folded polypeptides and assist them in attaining their proper conformation. The folding reaction relies on a complex array of scaffolding effects and ATP-driven conformational changes that mediate the temporary unfolding and subsequent refolding of protein substrates. DnaK and GroEL are the two major Escherichia coli chaperones. They belong to the HSP70 and HSP60 families of proteins, respectively, and play a major role in protein folding. Here, we describe a set of bacterial expression vectors that permits the fusion of a protein of interest to DnaK or GroEL and its subsequent quantitative expression in a soluble, easily purifiable form. We also provide a set of compatible co-chaperone expression constructs that permit the simultaneous co-expression of the DnaK and GroEL physiological partners to further increase protein solubility. The system was successfully tested using the murine prion protein (PrP). Although PrP is normally insoluble when expressed in E. coli, we show that utilizing our vectors it can be produced in a soluble form as a DnaK or GroEL fusion. This system is useful for the production of a large array of proteins that fail to fold properly when expressed in E. coli.
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Einert TR, Sing CE, Alexander-Katz A, Netz RR. Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:1-16. [PMID: 22167584 DOI: 10.1140/epje/i2011-11130-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 11/03/2011] [Indexed: 05/31/2023]
Abstract
We study the conformational dynamics within homopolymer globules by solvent-implicit Brownian dynamics simulations. A strong dependence of the internal chain dynamics on the Lennard-Jones cohesion strength ε and the globule size N (G) is observed. We find two distinct dynamical regimes: a liquid-like regime (for ε < ε(s) with fast internal dynamics and a solid-like regime (for ε > ε(s) with slow internal dynamics. The cohesion strength ε(s) of this freezing transition depends on N (G) . Equilibrium simulations, where we investigate the diffusional chain dynamics within the globule, are compared with non-equilibrium simulations, where we unfold the globule by pulling the chain ends with prescribed velocity (encompassing low enough velocities so that the linear-response, viscous regime is reached). From both simulation protocols we derive the internal viscosity within the globule. In the liquid-like regime the internal friction increases continuously with ε and scales extensive in N (G) . This suggests an internal friction scenario where the entire chain (or an extensive fraction thereof) takes part in conformational reorganization of the globular structure.
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Affiliation(s)
- T R Einert
- Physik Department, Technische Universität München, James-Franck-Straße, Garching, Germany.
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Misfolded PrP impairs the UPS by interaction with the 20S proteasome and inhibition of substrate entry. EMBO J 2011; 30:3065-77. [PMID: 21743439 DOI: 10.1038/emboj.2011.224] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 06/16/2011] [Indexed: 01/07/2023] Open
Abstract
Prion diseases are associated with the conversion of cellular prion protein (PrP(C)) to toxic β-sheet isoforms (PrP(Sc)), which are reported to inhibit the ubiquitin-proteasome system (UPS). Accordingly, UPS substrates accumulate in prion-infected mouse brains, suggesting impairment of the 26S proteasome. A direct interaction between its 20S core particle and PrP isoforms was demonstrated by immunoprecipitation. β-PrP aggregates associated with the 20S particle, but did not impede binding of the PA26 complex, suggesting that the aggregates do not bind to its ends. Aggregated β-PrP reduced the 20S proteasome's basal peptidase activity, and the enhanced activity induced by C-terminal peptides from the 19S ATPases or by the 19S regulator itself, including when stimulated by polyubiquitin conjugates. However, the 20S proteasome was not inhibited when the gate in the α-ring was open due to a truncation mutation or by association with PA26/PA28. These PrP aggregates inhibit by stabilising the closed conformation of the substrate entry channel. A similar inhibition of substrate entry into the proteasome may occur in other neurodegenerative diseases where misfolded β-sheet-rich proteins accumulate.
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Fox JH, Connor T, Stiles M, Kama J, Lu Z, Dorsey K, Lieberman G, Liebermann G, Sapp E, Cherny RA, Banks M, Volitakis I, DiFiglia M, Berezovska O, Bush AI, Hersch SM. Cysteine oxidation within N-terminal mutant huntingtin promotes oligomerization and delays clearance of soluble protein. J Biol Chem 2011; 286:18320-30. [PMID: 21454633 PMCID: PMC3093904 DOI: 10.1074/jbc.m110.199448] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 03/13/2011] [Indexed: 02/01/2023] Open
Abstract
Huntington disease (HD) is a progressive neurodegenerative disorder caused by expression of polyglutamine-expanded mutant huntingtin protein (mhtt). Most evidence indicates that soluble mhtt species, rather than insoluble aggregates, are the important mediators of HD pathogenesis. However, the differential roles of soluble monomeric and oligomeric mhtt species in HD and the mechanisms of oligomer formation are not yet understood. We have shown previously that copper interacts with and oxidizes the polyglutamine-containing N171 fragment of huntingtin. In this study we report that oxidation-dependent oligomers of huntingtin form spontaneously in cell and mouse HD models. Levels of these species are modulated by copper, hydrogen peroxide, and glutathione. Mutagenesis of all cysteine residues within N171 blocks the formation of these oligomers. In cells, levels of oligomerization-blocked mutant N171 were decreased compared with native N171. We further show that a subset of the oligomerization-blocked form of glutamine-expanded N171 huntingtin is rapidly depleted from the soluble pool compared with "native " mutant N171. Taken together, our data indicate that huntingtin is subject to specific oxidations that are involved in the formation of stable oligomers and that also delay removal from the soluble pool. These findings show that inhibiting formation of oxidation-dependent huntingtin oligomers, or promoting their dissolution, may have protective effects in HD by decreasing the burden of soluble mutant huntingtin.
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Affiliation(s)
- Jonathan H Fox
- Department of Veterinary Science and Neuroscience Graduate Program, University of Wyoming, Laramie, Wyoming 82070, USA.
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Bjorndahl TC, Zhou GP, Liu X, Perez-Pineiro R, Semenchenko V, Saleem F, Acharya S, Bujold A, Sobsey CA, Wishart DS. Detailed biophysical characterization of the acid-induced PrP(c) to PrP(β) conversion process. Biochemistry 2011; 50:1162-73. [PMID: 21189021 DOI: 10.1021/bi101435c] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Prions are believed to spontaneously convert from a native, monomeric highly helical form (called PrP(c)) to a largely β-sheet-rich, multimeric and insoluble aggregate (called PrP(sc)). Because of its large size and insolubility, biophysical characterization of PrP(sc) has been difficult, and there are several contradictory or incomplete models of the PrP(sc) structure. A β-sheet-rich, soluble intermediate, called PrP(β), exhibits many of the same features as PrP(sc) and can be generated using a combination of low pH and/or mild denaturing conditions. Studies of the PrP(c) to PrP(β) conversion process and of PrP(β) folding intermediates may provide insights into the structure of PrP(sc). Using a truncated, recombinant version of Syrian hamster PrP(β) (shPrP(90-232)), we used NMR spectroscopy, in combination with other biophysical techniques (circular dichroism, dynamic light scattering, electron microscopy, fluorescence spectroscopy, mass spectrometry, and proteinase K digestion), to characterize the pH-driven PrP(c) to PrP(β) conversion process in detail. Our results show that below pH 2.8 the protein oligomerizes and conversion to the β-rich structure is initiated. At pH 1.7 and above, the oligomeric protein can recover its native monomeric state through dialysis to pH 5.2. However, when conversion is completed at pH 1.0, the large oligomer "locks down" irreversibly into a stable, β-rich form. At pH values above 3.0, the protein is amenable to NMR investigation. Chemical shift perturbations, NOE, amide line width, and T(2) measurements implicate the putative "amylome motif" region, "NNQNNF" as the region most involved in the initial helix-to-β conversion phase. We also found that acid-induced PrP(β) oligomers could be converted to fibrils without the use of chaotropic denaturants. The latter finding represents one of the first examples wherein physiologically accessible conditions (i.e., only low pH) were used to achieve PrP conversion and fibril formation.
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Affiliation(s)
- Trent C Bjorndahl
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E8
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Kayed R, Canto I, Breydo L, Rasool S, Lukacsovich T, Wu J, Albay R, Pensalfini A, Yeung S, Head E, Marsh JL, Glabe C. Conformation dependent monoclonal antibodies distinguish different replicating strains or conformers of prefibrillar Aβ oligomers. Mol Neurodegener 2010; 5:57. [PMID: 21144050 PMCID: PMC3019145 DOI: 10.1186/1750-1326-5-57] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 12/13/2010] [Indexed: 01/01/2023] Open
Abstract
Background Age-related neurodegenerative diseases share a number of important pathological features, such as accumulation of misfolded proteins as amyloid oligomers and fibrils. Recent evidence suggests that soluble amyloid oligomers and not the insoluble amyloid fibrils may represent the primary pathological species of protein aggregates. Results We have produced several monoclonal antibodies that specifically recognize prefibrillar oligomers and do not recognize amyloid fibrils, monomer or natively folded proteins. Like the polyclonal antisera, the individual monoclonals recognize generic epitopes that do not depend on a specific linear amino acid sequence, but they display distinct preferences for different subsets of prefibrillar oligomers. Immunological analysis of a number of different prefibrillar Aβ oligomer preparations show that structural polymorphisms exist in Aβ prefibrillar oligomers that can be distinguished on the basis of their reactivity with monoclonal antibodies. Western blot analysis demonstrates that the conformers defined by the monoclonal antibodies have distinct size distributions, indicating that oligomer structure varies with size. The different conformational types of Aβ prefibrillar oligomers can serve as they serve as templates for monomer addition, indicating that they seed the conversion of Aβ monomer into more prefibrillar oligomers of the same type. Conclusions These results indicate that distinct structural variants or conformers of prefibrillar Aβ oligomers exist that are capable of seeding their own replication. These conformers may be analogous to different strains of prions.
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Affiliation(s)
- Rakez Kayed
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, USA.
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Prion protein self-interactions: A gateway to novel therapeutic strategies? Vaccine 2010; 28:7810-23. [DOI: 10.1016/j.vaccine.2010.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 08/31/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022]
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Sweeting B, Khan MQ, Chakrabartty A, Pai EF. Structural factors underlying the species barrier and susceptibility to infection in prion disease. Biochem Cell Biol 2010; 88:195-202. [PMID: 20453922 DOI: 10.1139/o09-172] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The term prion disease describes a group of fatal neurodegenerative diseases that are believed to be caused by the pathogenic misfolding of a host cell protein, PrP. Susceptibility to prion disease differs between species and incubation periods before symptom onset can change dramatically when infectious prion strains are transmitted between species. This effect is referred to as the species or transmission barrier. Prion strains represent different structures of PrPSc and the conformational selection model proposes that the source of theses barriers is the preferential incorporation of PrP from a given species into only a subset of PrPSc structures of another species. The basis of this preferential incorporation is predicted to reside in subtle structural differences in PrP from varying species. The overall fold of PrP is highly conserved among species, but small differences in the amino acid sequence give rise to structural variability. In particular, the loop between the second beta-strand and the second alpha-helix has shown structural variability between species, with loop mobility correlating with resistance to prion disease. Single amino acid polymorphisms in PrP within a species can also affect prion susceptibility, but do not appear to drastically alter the biophysical properties of the native form. These polymorphisms affect the propensity of self-association, in recombinant PrP, to form beta-sheet enriched, oligomeric, and amyloid-like forms. These results indicate that the major factor in determining susceptibility to prion disease is the ability of PrP to adopt these misfolded forms by promoting conformational change and self association.
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Affiliation(s)
- B Sweeting
- Department of Medical Biophysics, University of Toronto, MaRS Centre TMDT 4-307, Toronto, ON M5G 1L7, Canada.
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Changing the solvent accessibility of the prion protein disulfide bond markedly influences its trafficking and effect on cell function. Biochem J 2010; 428:169-82. [PMID: 20337594 DOI: 10.1042/bj20091635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Prion diseases are fatal transmissible neurodegenerative diseases that result from structural conversion of the prion protein into a disease-associated isoform. The prion protein contains a single disulfide bond. Our analysis of all NMR structures of the prion protein (total of 440 structures over nine species) containing an explicit disulfide bond reveals that the bond exists predominantly in a stable low-energy state, but can also adopt a high-energy configuration. The side chains of two tyrosine residues and one phenylalanine residue control access of solvent to the disulfide bond. Notably, the side chains rotate away from the disulfide bond in the high-energy state, exposing the disulfide bond to solvent. The importance of these aromatic residues for protein function was analysed by mutating them to alanine residues and analysing the properties of the mutant proteins using biophysical and cell biological approaches. Whereas the mutant protein behaved similarly to wild-type prion protein in recombinant systems, the mutants were retained in the endoplasmic reticulum of mammalian cells and degraded by the proteasomal system. The cellular behaviour of the aromatic residue mutants was similar to the cellular behaviour of a disulfide bond mutant prion protein in which the cysteine residues were replaced with alanine, a result which is consistent with an unstable disulfide bond in the aromatic residue mutants. These observations suggest that the conformation of the prion protein disulfide bond may have implications for correct maturation and function of this protein.
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Hinz U. From protein sequences to 3D-structures and beyond: the example of the UniProt knowledgebase. Cell Mol Life Sci 2010; 67:1049-64. [PMID: 20043185 PMCID: PMC2835715 DOI: 10.1007/s00018-009-0229-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 12/01/2009] [Accepted: 12/07/2009] [Indexed: 11/12/2022]
Abstract
With the dramatic increase in the volume of experimental results in every domain of life sciences, assembling pertinent data and combining information from different fields has become a challenge. Information is dispersed over numerous specialized databases and is presented in many different formats. Rapid access to experiment-based information about well-characterized proteins helps predict the function of uncharacterized proteins identified by large-scale sequencing. In this context, universal knowledgebases play essential roles in providing access to data from complementary types of experiments and serving as hubs with cross-references to many specialized databases. This review outlines how the value of experimental data is optimized by combining high-quality protein sequences with complementary experimental results, including information derived from protein 3D-structures, using as an example the UniProt knowledgebase (UniProtKB) and the tools and links provided on its website ( http://www.uniprot.org/ ). It also evokes precautions that are necessary for successful predictions and extrapolations.
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Affiliation(s)
- Ursula Hinz
- Swiss-Prot Group, Swiss Institute of Bioinformatics, 1 rue Michel Servet, 1211, Geneva, Switzerland.
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Gaspersic J, Hafner-Bratkovic I, Stephan M, Veranic P, Bencina M, Vorberg I, Jerala R. Tetracysteine-tagged prion protein allows discrimination between the native and converted forms. FEBS J 2010; 277:2038-50. [PMID: 20345906 DOI: 10.1111/j.1742-4658.2010.07619.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The conformational conversion of prion protein (PrP) from a native conformation to the amyloid form is a hallmark of transmissible spongiform encephalopathies. Conversion is usually monitored by fluorescent dyes, which bind generic amyloids and are less suited for living cell imaging. We report a new method for the synthesis of membrane-permeable and membrane-impermeable biarsenical reagents, which are then used to monitor murine PrP (mPrP) misfolding. We introduced tetracysteine (TC) tags into three different positions of mPrP, which folded into a native-like structure. Whereas mPrPs with a TC tag inserted at the N-terminus or C-terminus supported fibril formation, insertion into the helix 2-helix 3 loop inhibited conversion. We devised a quantitative protease-free method to determine the fraction of converted PrP, based on the ability of the fluorescein arsenical helix binder reagent to differentiate between the monomeric and fibrilized form of TC-tagged PrP, and showed that TC-tagged mPrP could be detected on transfected cells, thereby expanding the potential use of this method for the detection and study of conformational diseases.
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Affiliation(s)
- Jernej Gaspersic
- Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia
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Varshney A, Ahmad B, Rabbani G, Kumar V, Yadav S, Khan RH. Acid-induced unfolding of didecameric keyhole limpet hemocyanin: detection and characterizations of decameric and tetrameric intermediate states. Amino Acids 2010; 39:899-910. [DOI: 10.1007/s00726-010-0524-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
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Rigter A, Priem J, Timmers-Parohi D, Langeveld JPM, van Zijderveld FG, Bossers A. Prion protein self-peptides modulate prion interactions and conversion. BMC BIOCHEMISTRY 2009; 10:29. [PMID: 19943977 PMCID: PMC2789745 DOI: 10.1186/1471-2091-10-29] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 11/30/2009] [Indexed: 12/30/2022]
Abstract
Background Molecular mechanisms underlying prion agent replication, converting host-encoded cellular prion protein (PrPC) into the scrapie associated isoform (PrPSc), are poorly understood. Selective self-interaction between PrP molecules forms a basis underlying the observed differences of the PrPC into PrPSc conversion process (agent replication). The importance of previously peptide-scanning mapped ovine PrP self-interaction domains on this conversion was investigated by studying the ability of six of these ovine PrP based peptides to modulate two processes; PrP self-interaction and conversion. Results Three peptides (octarepeat, binding domain 2 -and C-terminal) were capable of inhibiting self-interaction of PrP in a solid-phase PrP peptide array. Three peptides (N-terminal, binding domain 2, and amyloidogenic motif) modulated prion conversion when added before or after initiation of the prion protein misfolding cyclic amplification (PMCA) reaction using brain homogenates. The C-terminal peptides (core region and C-terminal) only affected conversion (increased PrPres formation) when added before mixing PrPC and PrPSc, whereas the octarepeat peptide only affected conversion when added after this mixing. Conclusion This study identified the putative PrP core binding domain that facilitates the PrPC-PrPSc interaction (not conversion), corroborating evidence that the region of PrP containing this domain is important in the species-barrier and/or scrapie susceptibility. The octarepeats can be involved in PrPC-PrPSc stabilization, whereas the N-terminal glycosaminoglycan binding motif and the amyloidogenic motif indirectly affected conversion. Binding domain 2 and the C-terminal domain are directly implicated in PrPC self-interaction during the conversion process and may prove to be prime targets in new therapeutic strategy development, potentially retaining PrPC function. These results emphasize the importance of probable PrPC-PrPC and required PrPC-PrPSc interactions during PrP conversion. All interactions are probably part of the complex process in which polymorphisms and species barriers affect TSE transmission and susceptibility.
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Affiliation(s)
- Alan Rigter
- Department of Bacteriology and TSEs, Central Veterinary Institute (CVI) of Wageningen UR, Lelystad, 8200 AB, the Netherlands.
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Bom APDA, Freitas MS, Moreira FS, Ferraz D, Sanches D, Gomes AMO, Valente AP, Cordeiro Y, Silva JL. The p53 core domain is a molten globule at low pH: functional implications of a partially unfolded structure. J Biol Chem 2009; 285:2857-66. [PMID: 19933157 PMCID: PMC2807339 DOI: 10.1074/jbc.m109.075861] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p53 is a transcription factor that maintains genome integrity, and its function is lost in 50% of human cancers. The majority of p53 mutations are clustered within the core domain. Here, we investigate the effects of low pH on the structure of the wild-type (wt) p53 core domain (p53C) and the R248Q mutant. At low pH, the tryptophan residue is partially exposed to the solvent, suggesting a fluctuating tertiary structure. On the other hand, the secondary structure increases, as determined by circular dichroism. Binding of the probe bis-ANS (bis-8-anilinonaphthalene-1-sulfonate) indicates that there is an increase in the exposure of hydrophobic pockets for both wt and mutant p53C at low pH. This behavior is accompanied by a lack of cooperativity under urea denaturation and decreased stability under pressure when p53C is in acidic pH. Together, these results indicate that p53C acquires a partially unfolded conformation (molten-globule state) at low pH (5.0). The hydrodynamic properties of this conformation are intermediate between the native and denatured conformation. 1H-15N HSQC NMR spectroscopy confirms that the protein has a typical molten-globule structure at acidic pH when compared with pH 7.2. Human breast cells in culture (MCF-7) transfected with p53-GFP revealed localization of p53 in acidic vesicles, suggesting that the low pH conformation is present in the cell. Low pH stress also tends to favor high levels of p53 in the cells. Taken together, all of these data suggest that p53 may play physiological or pathological roles in acidic microenvironments.
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Affiliation(s)
- Ana Paula D Ano Bom
- Centro Nacional de Ressonância Magnética Nuclear de Macromoléculas, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil
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