1
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Shoup D, Priola SA. Cell biology of prion strains in vivo and in vitro. Cell Tissue Res 2023; 392:269-283. [PMID: 35107622 PMCID: PMC11249200 DOI: 10.1007/s00441-021-03572-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/22/2021] [Indexed: 02/01/2023]
Abstract
The properties of infectious prions and the pathology of the diseases they cause are dependent upon the unique conformation of each prion strain. How the pathology of prion disease correlates with different strains and genetic backgrounds has been investigated via in vivo assays, but how interactions between specific prion strains and cell types contribute to the pathology of prion disease has been dissected more effectively using in vitro cell lines. Observations made through in vivo and in vitro assays have informed each other with regard to not only how genetic variation influences prion properties, but also how infectious prions are taken up by cells, modified by cellular processes and propagated, and the cellular components they rely on for persistent infection. These studies suggest that persistent cellular infection results from a balance between prion propagation and degradation. This balance may be shifted depending upon how different cell lines process infectious prions, potentially altering prion stability, and how fast they can be transported to the lysosome. Thus, in vitro studies have given us a deeper understanding of the interactions between different prions and cell types and how they may influence prion disease phenotypes in vivo.
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Affiliation(s)
- Daniel Shoup
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Hamilton, MT, 59840, USA
| | - Suzette A Priola
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Hamilton, MT, 59840, USA.
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2
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Prosswimmer T, Daggett V. The role of α-sheet structure in amyloidogenesis: characterization and implications. Open Biol 2022; 12:220261. [PMID: 36416010 PMCID: PMC9682440 DOI: 10.1098/rsob.220261] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Amyloid diseases are linked to protein misfolding whereby the amyloidogenic protein undergoes a conformational change, aggregates and eventually forms amyloid fibrils. While the amyloid fibrils and plaques are hallmarks of these diseases, they typically form late in the disease process and do not correlate with disease. Instead, there is growing evidence that smaller, soluble toxic oligomers form prior and appear to be early triggers of the molecular pathology underlying these diseases. Nearly 20 years ago, we proposed the α-sheet hypothesis after discovering that the early conformational changes observed during atomistic molecular dynamics simulations involve the formation of a non-standard protein structure, α-sheet. Furthermore, we proposed that toxic oligomers contain α-sheet structure and that preferentially targeting this structure could neutralize the toxicity, prevent further aggregation and serve as the basis for early detection of disease. Here, we present the origin of the α-sheet hypothesis and describe α-sheet structure and the corresponding mechanisms of conversion. We discuss experimental studies demonstrating that both mammalian and bacterial amyloid systems form α-sheet oligomers before converting to conventional β-sheet fibrils. Furthermore, we show that the process can be inhibited with de novo designed α-sheet peptides complementary to the structure in the toxic oligomers.
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Affiliation(s)
- Tatum Prosswimmer
- Molecular Engineering Program, University of Washington, Seattle, WA 98195-5013, USA
| | - Valerie Daggett
- Molecular Engineering Program, University of Washington, Seattle, WA 98195-5013, USA,Department of Bioengineering, University of Washington, Seattle, WA 98195-5013, USA
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3
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Xia K, Shen H, Wang P, Tan R, Xun D. Investigation of the conformation of human prion protein in ethanol solution using molecular dynamics simulations. J Biomol Struct Dyn 2022:1-10. [PMID: 35838152 DOI: 10.1080/07391102.2022.2099466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
When the conformation of protein is changed from its natural state to a misfolded state, some diseases will happen like prion disease. Prion diseases are a set of deadly neurodegenerative diseases caused by prion protein misfolding and aggregation. Monohydric alcohols have a strong influence on the structure of protein. However, whether monohydric alcohols inhibit amyloid fibrosis remains uncertain. Here, to elucidate the effect of ethanol on the structural stability of human prion protein, molecular dynamics simulations were employed to analyze the conformational changes and dynamics characteristics of human prion proteins at different temperatures. The results show that the extension of β-sheet occurs more easily and the α-helix is more easily disrupted at high temperatures. We found that ethanol can destroy the hydrophobic interactions and make the hydrogen bonds stable, which protects the secondary structure of the protein, especially at 500 K.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Kui Xia
- Department of Physics, Jiangxi Science and Technology Normal University, Nanchang, China
| | - Haolei Shen
- Department of Physics, Jiangxi Science and Technology Normal University, Nanchang, China
| | - Peng Wang
- Department of Physics, Jiangxi Science and Technology Normal University, Nanchang, China
| | - Rongri Tan
- Department of Physics, Jiangxi Science and Technology Normal University, Nanchang, China
| | - Damao Xun
- Department of Physics, Jiangxi Science and Technology Normal University, Nanchang, China
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4
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Hao J, Lei Y, Gan Z, Zhao W, Shi J, Jia C, Sun A. Synergetic Inactivation Mechanism of Protocatechuic Acid and High Hydrostatic Pressure against Escherichia coli O157:H7. Foods 2021; 10:foods10123053. [PMID: 34945604 PMCID: PMC8701084 DOI: 10.3390/foods10123053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/12/2021] [Accepted: 12/03/2021] [Indexed: 11/16/2022] Open
Abstract
With the wide application of high hydrostatic pressure (HHP) technology in the food industry, safety issues regarding food products, resulting in potential food safety hazards, have arisen. To address such problems, this study explored the synergetic bactericidal effects and mechanisms of protocatechuic acid (PCA) and HHP against Escherichia coli O157:H7. At greater than 200 MPa, PCA (1.25 mg/mL for 60 min) plus HHP treatments had significant synergetic bactericidal effects that positively correlated with pressure. After a combined treatment at 500 MPa for 5 min, an approximate 9.0 log CFU/mL colony decline occurred, whereas the individual HHP and PCA treatments caused 4.48 and 1.06 log CFU/mL colony decreases, respectively. Mechanistically, membrane integrity and morphology were damaged, and the permeability increased when E. coli O157: H7 was exposed to the synergetic stress of PCA plus HHP. Inside cells, the synergetic treatment additionally targeted the activities of enzymes such as superoxide dismutase, catalase and ATPase, which were inhibited significantly (p ≤ 0.05) when exposed to high pressure. Moreover, an analysis of circular dichroism spectra indicated that the synergetic treatment caused a change in DNA structure, which was expressed as the redshift of the characteristic absorption peak. Thus, the synergetic treatment of PCA plus HHP may be used as a decontamination method owing to the good bactericidal effects on multiple targets.
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Affiliation(s)
- Jingyi Hao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Yuqing Lei
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Zhilin Gan
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Wanbin Zhao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Junyan Shi
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Chengli Jia
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
| | - Aidong Sun
- College of Biological Sciences and Biotechnology, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China; (J.H.); (Y.L.); (Z.G.); (W.Z.); (J.S.); (C.J.)
- Beijing Key Laboratory of Food Processing and Safety in Forestry, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China
- Correspondence: ; Tel.: +86-010-62336700
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5
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Adhikari UK, Tayebi M. Epitope-specific anti-PrP antibody toxicity: a comparative in-silico study of human and mouse prion proteins. Prion 2021; 15:155-176. [PMID: 34632945 PMCID: PMC8900626 DOI: 10.1080/19336896.2021.1964326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Despite having therapeutic potential, anti-PrP antibodies caused a major controversy due to their neurotoxic effects. For instance, treating mice with ICSM antibodies delayed prion disease onset, but both were found to be either toxic or innocuous to neurons by researchers following cross-linking PrPC. In order to elucidate and understand the reasons that led to these contradictory outcomes, we conducted a comprehensive in silico study to assess the antibody-specific toxicity. Since most therapeutic anti-PrP antibodies were generated against human truncated recombinant PrP91-231 or full-length mouse PrP23-231, we reasoned that host specificity (human vs murine) of PrPC might influence the nature of the specific epitopes recognized by these antibodies at the structural level possibly explaining the 'toxicity' discrepancies reported previously. Initially, molecular dynamics simulation and pro-motif analysis of full-length human (hu)PrP and mouse (mo)PrP 3D structure displayed conspicuous structural differences between huPrP and moPrP. We identified 10 huPrP and 6 moPrP linear B-cell epitopes from the prion protein 3D structure where 5 out of 10 huPrP and 3 out of 6 moPrP B-cell epitopes were predicted to be potentially toxic in immunoinformatics approaches. Herein, we demonstrate that some of the predicted potentially 'toxic' epitopes identified by the in silico analysis were similar to the epitopes recognized by the toxic antibodies such as ICSM18 (146-159), POM1 (138-147), D18 (133-157), ICSM35 (91-110), D13 (95-103) and POM3 (95-100). This in silico study reveals the role of host specificity of PrPC in epitope-specific anti-PrP antibody toxicity.
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Affiliation(s)
| | - Mourad Tayebi
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
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6
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Bhate SH, Udgaonkar JB, Das R. Destabilization of polar interactions in the prion protein triggers misfolding and oligomerization. Protein Sci 2021; 30:2258-2271. [PMID: 34558139 DOI: 10.1002/pro.4188] [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: 07/24/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 12/25/2022]
Abstract
The prion protein (PrP) misfolds and oligomerizes at pH 4 in the presence of physiological salt concentrations. Low pH and salt cause structural perturbations in the monomeric prion protein that lead to misfolding and oligomerization. However, the changes in stability within different regions of the PrP prior to oligomerization are poorly understood. In this study, we have characterized the local stability in PrP at high resolution using amide temperature coefficients (TC ) measured by nuclear magnetic resonance (NMR) spectroscopy. The local stability of PrP was investigated under native as well as oligomerizing conditions. We have also studied the rapidly oligomerizing PrP variant (Q216R) and the protective PrP variant (A6). We report that at low pH, salt destabilizes PrP at several polar residues, and the hydrogen bonds in helices α2 and α3 are weakened. In addition, salt changes the curvature of the α3 helix, which likely disrupts α2-α3 contacts and leads to oligomerization. These results are corroborated by the TC values of rapidly oligomerizing Q216R-PrP. The poly-alanine substitution in A6-PrP stabilizes α2, which prevents oligomerization. Altogether, these results highlight the importance of native polar interactions in determining the stability of PrP and reveal the structural disruptions in PrP that lead to misfolding and oligomerization.
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Affiliation(s)
- Suhas H Bhate
- National Centre for Biological Sciences, TIFR, Bangalore, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, TIFR, Bangalore, India.,Indian Institute for Science Education and Research, Pune, India
| | - Ranabir Das
- National Centre for Biological Sciences, TIFR, Bangalore, India
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7
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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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8
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Shoup D, Priola SA. The Size and Stability of Infectious Prion Aggregates Fluctuate Dynamically during Cellular Uptake and Disaggregation. Biochemistry 2021; 60:398-411. [PMID: 33497187 DOI: 10.1021/acs.biochem.0c00923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prion diseases arise when PrPSc, an aggregated, infectious, and insoluble conformer of the normally soluble mammalian prion protein, PrPC, catalyzes the conversion of PrPC into more PrPSc, which then accumulates in the brain leading to disease. PrPSc is the primary, if not sole, component of the infectious prion. Despite the stability and protease insensitivity of PrPSc aggregates, they can be degraded after cellular uptake. However, how cells disassemble and degrade PrPSc is poorly understood. In this work, we analyzed how the protease sensitivity and size distribution of PrPSc aggregates from two different mouse-adapted prion strains, 22L, that can persistently infect cells and 87V, that cannot, changed during cellular uptake. We show that within the first 4 h following uptake large PrPSc aggregates from both prion strains become less resistant to digestion by proteinase K (PK) through a mechanism that is dependent upon the acidic environment of endocytic vesicles. We further show that during disassembly, PrPSc aggregates from both strains become more resistant to PK digestion through the apparent removal of protease-sensitive PrPSc, with PrPSc from the 87V strain disassembled more readily than PrPSc from the 22L strain. Taken together, our data demonstrate that the sizes and stabilities of PrPSc from different prion strains change during cellular uptake and degradation, thereby potentially impacting the ability of prions to infect cells.
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Affiliation(s)
- Daniel Shoup
- Rocky Mountain Laboratories, Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, United States
| | - Suzette A Priola
- Rocky Mountain Laboratories, Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, United States
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9
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Pedrioli G, Paganetti P. Hijacking Endocytosis and Autophagy in Extracellular Vesicle Communication: Where the Inside Meets the Outside. Front Cell Dev Biol 2021; 8:595515. [PMID: 33490063 PMCID: PMC7817780 DOI: 10.3389/fcell.2020.595515] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 11/18/2020] [Indexed: 12/25/2022] Open
Abstract
Extracellular vesicles, phospholipid bilayer-membrane vesicles of cellular origin, are emerging as nanocarriers of biological information between cells. Extracellular vesicles transport virtually all biologically active macromolecules (e.g., nucleotides, lipids, and proteins), thus eliciting phenotypic changes in recipient cells. However, we only partially understand the cellular mechanisms driving the encounter of a soluble ligand transported in the lumen of extracellular vesicles with its cytosolic receptor: a step required to evoke a biologically relevant response. In this context, we review herein current evidence supporting the role of two well-described cellular transport pathways: the endocytic pathway as the main entry route for extracellular vesicles and the autophagic pathway driving lysosomal degradation of cytosolic proteins. The interplay between these pathways may result in the target engagement between an extracellular vesicle cargo protein and its cytosolic target within the acidic compartments of the cell. This mechanism of cell-to-cell communication may well own possible implications in the pathogenesis of neurodegenerative disorders.
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Affiliation(s)
- Giona Pedrioli
- Neurodegeneration Research Group, Laboratory for Biomedical Neurosciences, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Torricella-Taverne, Switzerland
- Member of the International Ph.D. Program of the Biozentrum, University of Basel, Basel, Switzerland
| | - Paolo Paganetti
- Neurodegeneration Research Group, Laboratory for Biomedical Neurosciences, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Torricella-Taverne, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
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10
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Soto P, Claflin IA, Bursott AL, Schwab-McCoy AD, Bartz JC. Cellular prion protein gene polymorphisms linked to differential scrapie susceptibility correlate with distinct residue connectivity between secondary structure elements. J Biomol Struct Dyn 2021; 39:129-139. [PMID: 31900058 PMCID: PMC7340567 DOI: 10.1080/07391102.2019.1708794] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The conformational conversion of the cellular prion protein (PrPC) to the misfolded and aggregated isoform, termed scrapie prion protein (PrPSc), is key to the development of a group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). Although the conversion mechanism is not fully understood, the role of gene polymorphisms in varying susceptibilities to prion diseases is well established. In ovine, specific gene polymorphisms in PrPC alter prion disease susceptibility: the Valine136-Glutamine171 variant (Susceptible structure) displays high susceptibility to classical scrapie while the Alanine136-Arginine171 variant (Resistant structure) displays reduced susceptibility. The opposite trend has been reported in atypical scrapie. Despite the differentiation between classical and atypical scrapie, a complete understanding of the effect of polymorphisms on the structural dynamics of PrPC is lacking. From our structural bioinformatics study, we propose that polymorphisms locally modulate the network of residue interactions in the globular C-terminus of the ovine recombinant prion protein while maintaining the overall fold. Although the two variants we examined exhibit a densely connected group of residues that includes both β-sheets, the β2-α2 loop and the N-terminus of α-helix 2, only in the Resistant structure do most residues of α-helix 2 belong to this group. We identify the structural role of Valine136Alanine and Glutamine171Arginine: modulation of residue interaction networks that affect the connectivity between α-helix 2 and α-helix 3. We propose blocking interactions of residue 171 as a potential target for the design of therapeutics to prevent efficient PrPC misfolding. We discuss our results in the context of initial PrPC conversion and extrapolate to recently proposed PrPSc structures.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Patricia Soto
- Department of Physics, Creighton University, Omaha, Nebraska, 68178,Corresponding author: Patricia Soto, Creighton University – Department of Physics, 2500 California Plaza, Omaha, NE 68178, Phone number: 402.280.3361, Fax: 402.280.2140,
| | - India A. Claflin
- Department of Biology, Creighton University, Omaha, Nebraska, 68178
| | | | | | - Jason C. Bartz
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, 68178
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11
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Chandrasekaran P, Santosh Kumar C, Rangachari K, Sekar K. Disassociation of β1-α1-β2 from the α2-α3 domain of prion protein (PrP) is a prerequisite for the conformational conversion of PrPC into PrPSc: Driven by the free energy landscape. Int J Biol Macromol 2019; 136:368-376. [DOI: 10.1016/j.ijbiomac.2019.06.099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/29/2019] [Accepted: 06/13/2019] [Indexed: 12/16/2022]
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12
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Zhou S, Shi D, Liu X, Yao X, Da LT, Liu H. pH-Induced Misfolding Mechanism of Prion Protein: Insights from Microsecond-Accelerated Molecular Dynamics Simulations. ACS Chem Neurosci 2019; 10:2718-2729. [PMID: 31070897 DOI: 10.1021/acschemneuro.8b00582] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The conformational transition of prion protein (PrP) from a native form PrPC to a pathological isoform PrPSc is the main cause of a number of prion diseases in human and animals. Thus, understanding the molecular basis of conformational transition of PrP will be valuable for unveiling the etiology of PrP-related diseases. Here, to explore the potential misfolding mechanism of PrP under the acidic condition, which is known to promote PrP misfolding and trigger its aggregation, the conventional and accelerated molecular dynamics (MD) simulations combined with the Markov state model (MSM) analysis were performed. The conventional MD simulations reveal that, at an acidic pH, the globular domain of PrP is partially unfolded, particularly for the α2 C-terminus. Structural analysis of the key macrostates obtained by MSM indicates that the α2 C-terminus and the β2-α2 loop may serve as important sites for the pH-induced PrP misfolding. Meanwhile, the α1 may also participate in the pH-induced structural conversion by moving away from the α2-α3 subdomain. Notably, dynamical network analysis of the key metastable states indicates that the protonated H187 weakens the interactions between the α2 C-terminus, α1-β2 loop, and α2-α3 loop, leading these domains, especially the α2 C-terminus, to become unstable and to begin to misfold. Therefore, the α2 C-terminus plays a key role in the PrP misfolding process and serves as a potential site for drug targeting. Overall, our findings can deepen the understanding of the pathogenesis related to PrP and provide useful guidance for the future drug discovery.
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Affiliation(s)
- Shuangyan Zhou
- School of Pharmacy, Lanzhou University, Lanzhou 730000, China
- Chongqing Key Laboratory on Big Data for Bio Intelligence, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
| | - Danfeng Shi
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Xuewei Liu
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau, China
| | - Lin-Tai Da
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai JiaoTong University, Shanghai 200240, China
| | - Huanxiang Liu
- School of Pharmacy, Lanzhou University, Lanzhou 730000, China
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13
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Jani V, Sonavane U, Joshi R. Detecting early stage structural changes in wild type, pathogenic and non-pathogenic prion variants using Markov state model. RSC Adv 2019; 9:14567-14579. [PMID: 35519320 PMCID: PMC9064127 DOI: 10.1039/c9ra01507h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/28/2019] [Indexed: 12/19/2022] Open
Abstract
The conversion of prion protein from normal to scrapie followed by the aggregation and deposition of this scrapie form leads to various neurodegenerative diseases. A few studies carried out by researchers suggest that E219K prion mutant (glutamate to lysine mutation at residue position 219) is more stable than wild type protein. However a similar point mutation E200K (glutamate to lysine mutation at residue position 200) is pathogenic. In this study we have carried out detailed atomistic simulation of the wild type, pathogenic mutant E200K and E219K mutant which provides more stability. The aim of the study was to detect the early structural changes present in all the three variants which might be responsible for the stability or for their conversion from PrPC to PrPSc. MSM based analyses have been carried out to find out the differences between WT, E200K and E219K systems. Markov state model (MSM) analysis was able to predict the intermediate states which helped to understand the effect of same mutation at two different locations. The MSM analysis was able to show that the extra stability of E219K mutant may be a result of the increase in number of native contacts, strong salt bridges and less random motions. While pathogenicity of E200K mutant can be attributed to loss of some crucial salt-bridge interactions, increased random motions between helix 2 and helix 3. Markov state model to find out the differences between WT, E200K and E219K systems.![]()
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Affiliation(s)
- Vinod Jani
- High Performance Computing-Medical & Bioinformatics Applications Group
- Centre for Development of Advanced Computing (C-DAC)
- Savitribai Phule Pune University Campus
- Pune 411007
- India
| | - Uddhavesh Sonavane
- High Performance Computing-Medical & Bioinformatics Applications Group
- Centre for Development of Advanced Computing (C-DAC)
- Savitribai Phule Pune University Campus
- Pune 411007
- India
| | - Rajendra Joshi
- High Performance Computing-Medical & Bioinformatics Applications Group
- Centre for Development of Advanced Computing (C-DAC)
- Savitribai Phule Pune University Campus
- Pune 411007
- India
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14
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Lima AN, de Oliveira RJ, Braz ASK, de Souza Costa MG, Perahia D, Scott LPB. Effects of pH and aggregation in the human prion conversion into scrapie form: a study using molecular dynamics with excited normal modes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 47:583-590. [PMID: 29546436 DOI: 10.1007/s00249-018-1292-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 02/19/2018] [Accepted: 03/12/2018] [Indexed: 12/20/2022]
Abstract
There are two different prion conformations: (1) the cellular natural (PrPC) and (2) the scrapie (PrPSc), an infectious form that tends to aggregate under specific conditions. PrPC and PrPSc are widely different regarding secondary and tertiary structures. PrPSc contains more and longer β-strands compared to PrPC. The lack of solved PrPSc structures precludes a proper understanding of the mechanisms related to the transition between cellular and scrapie forms, as well as the aggregation process. In order to investigate the conformational transition between PrPC and PrPSc, we applied MDeNM (molecular dynamics with excited normal modes), an enhanced sampling simulation technique that has been recently developed to probe large structural changes. These simulations yielded new structural rearrangements of the cellular prion that would have been difficult to obtain with standard MD simulations. We observed an increase in β-sheet formation under low pH (≤ 4) and upon oligomerization, whose relevance was discussed on the basis of the energy landscape theory for protein folding. The characterization of intermediate structures corresponding to transition states allowed us to propose a conversion model from the cellular to the scrapie prion, which possibly ignites the fibril formation. This model can assist the design of new drugs to prevent neurological disorders related to the prion aggregation mechanism.
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Affiliation(s)
- Angelica Nakagawa Lima
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Antônio Sérgio Kimus Braz
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil
| | | | - David Perahia
- Laboratorie de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure Paris-Saclay, Cachan, France
| | - Luis Paulo Barbour Scott
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil.
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15
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Kovač V, Čurin Šerbec V. Prion Proteins Without the Glycophosphatidylinositol Anchor: Potential Biomarkers in Neurodegenerative Diseases. Biomark Insights 2018; 13:1177271918756648. [PMID: 29449775 PMCID: PMC5808966 DOI: 10.1177/1177271918756648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/23/2017] [Indexed: 01/17/2023] Open
Abstract
Prion protein (PrP) is a biomolecule that is involved in neuronal signaling, myelinization, and the development of neurodegenerative diseases. In the cell, PrP is shed by the ADAM10 protease. This process generates PrP molecules that lack glycophosphatidylinositol anchor, and these molecules incorporate into toxic aggregates and neutralize toxic oligomers. Due to this dual role, these molecules are important biomarkers for neurodegenerative diseases. In this review, we present shed PrP as a potential biomarker, with a focus on PrP226*, which may be the main biomarker for predicting neurodegenerative diseases in humans.
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Affiliation(s)
- Valerija Kovač
- Department for the Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Vladka Čurin Šerbec
- Department for the Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
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16
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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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17
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Chamachi NG, Chakrabarty S. Temperature-Induced Misfolding in Prion Protein: Evidence of Multiple Partially Disordered States Stabilized by Non-Native Hydrogen Bonds. Biochemistry 2017; 56:833-844. [DOI: 10.1021/acs.biochem.6b01042] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Neharika G. Chamachi
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Suman Chakrabarty
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
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18
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Understanding the Effect of Disease-Related Mutations on Human Prion Protein Structure: Insights From NMR Spectroscopy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:83-103. [DOI: 10.1016/bs.pmbts.2017.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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19
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Structural Modeling of Human Prion Protein's Point Mutations. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:105-122. [DOI: 10.1016/bs.pmbts.2017.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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20
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Wu EL, Qi Y, Park S, Mallajosyula SS, MacKerell AD, Klauda JB, Im W. Insight into Early-Stage Unfolding of GPI-Anchored Human Prion Protein. Biophys J 2016; 109:2090-100. [PMID: 26588568 DOI: 10.1016/j.bpj.2015.10.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/04/2015] [Accepted: 10/08/2015] [Indexed: 11/29/2022] Open
Abstract
Prion diseases are fatal neurodegenerative disorders, which are characterized by the accumulation of misfolded prion protein (PrPSc) converted from a normal host cellular prion protein (PrPC). Experimental studies suggest that PrPC is enriched with α-helical structure, whereas PrPSc contains a high proportion of β-sheet. In this study, we report the impact of N-glycosylation and the membrane on the secondary structure stability utilizing extensive microsecond molecular dynamics simulations. Our results reveal that the HB (residues 173 to 194) C-terminal fragment undergoes conformational changes and helix unfolding in the absence of membrane environments because of the competition between protein backbone intramolecular and protein-water intermolecular hydrogen bonds as well as its intrinsic instability originated from the amino acid sequence. This initiation of the unfolding process of PrPC leads to a subsequent increase in the length of the HB-HC loop (residues 195 to 199) that may trigger larger rigid body motions or further unfolding around this region. Continuous interactions between prion protein and the membrane not only constrain the protein conformation but also decrease the solvent accessibility of the backbone atoms, thereby stabilizing the secondary structure, which is enhanced by N-glycosylation via additional interactions between the N-glycans and the membrane surface.
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Affiliation(s)
- Emilia L Wu
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Yifei Qi
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Soohyung Park
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Sairam S Mallajosyula
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland; Department of Chemistry, Indian Institute of Technology Gandhinagar, Chandkheda, Ahmedabad, Gujarat, India
| | - Alexander D MacKerell
- Department of Chemistry, Indian Institute of Technology Gandhinagar, Chandkheda, Ahmedabad, Gujarat, India
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering and the Biophysics Program, The University of Maryland, College Park, Maryland
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas.
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21
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Singh J, Udgaonkar JB. Unraveling the Molecular Mechanism of pH-Induced Misfolding and Oligomerization of the Prion Protein. J Mol Biol 2016; 428:1345-1355. [PMID: 26854758 DOI: 10.1016/j.jmb.2016.01.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 12/31/2022]
Abstract
The misfolding of the prion protein (PrP) to aggregated forms is linked to several neurodegenerative diseases. Misfolded oligomeric forms of PrP are associated with neurotoxicity and/or infectivity, but the molecular mechanism by which they form is still poorly understood. A reduction in pH is known to be a key factor that triggers misfolded oligomer formation by PrP, but the residues whose protonation is linked with misfolding remain unidentified. The structural consequences of the protonation of these residues also remain to be determined. In the current study, amino acid residues whose protonation is critical for PrP misfolding and oligomerization have been identified using site-directed mutagenesis and misfolding/oligomerization assays. It is shown that the protonation of either H186 or D201, which mimics the effects of pathogenic mutations (H186R and D201N) at both residue sites, is critically linked to the stability, misfolding and oligomerization of PrP. Hydrogen-deuterium exchange studies coupled with mass spectrometry show that the protonation of either H186 or D201 leads to the same common structural change: increased structural dynamics in helix 1 and that in the loop between helix 1 and β-strand 2. It is shown that the protonation of either of these residues is sufficient for accelerating misfolded oligomer formation, most likely because the protonation of either residue causes the same structural perturbation. Hence, the increased structural dynamics in helix 1 and that in the loop between helix 1 and β-strand 2 appear to play an early critical role in acid-induced misfolding of PrP.
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Affiliation(s)
- Jogender Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India.
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22
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Menon S, Sengupta N. Perturbations in inter-domain associations may trigger the onset of pathogenic transformations in PrP(C): insights from atomistic simulations. MOLECULAR BIOSYSTEMS 2016; 11:1443-53. [PMID: 25855580 DOI: 10.1039/c4mb00689e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Conversion of the predominantly α-helical cellular prion protein (PrP(C)) to the misfolded β-sheet enriched Scrapie form (PrP(Sc)) is a critical event in prion pathogenesis. However, the conformational triggers that lead to the isoform conversion (PrP(C) to PrP(Sc)) remain obscure, and conjectures about the role of unusually hydrophilic, short helix H1 of the C-terminal globular domain in the transition are varied. Helix H1 is anchored to helix H3 via a few stabilizing polar interactions. We have employed fully atomistic molecular dynamics simulations to study the effects triggered by a minor perturbation in the network of these non-bonded interactions in PrP(C). The elimination of just one of the key H1-H3 hydrogen bonds led to a cascade of conformational changes that are consistent with those observed in partially unfolded intermediates of PrP(C), with pathogenic mutations and in low pH environments. Our analyses reveal that the perturbation results in the enhanced conformational flexibility of the protein. The resultant enhancement in the dynamics leads to overall increased solvent exposure of the hydrophobic core residues and concomitant disruption of the H1-H3 inter-domain salt bridge network. This study lends credence to the hypothesis that perturbing the cooperativity of the stabilizing interactions in the PrP(C) globular domain can critically affect its dynamics and may lead to structural transitions of pathological relevance.
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Affiliation(s)
- Sneha Menon
- Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
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23
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Tao W, Yoon G, Cao P, Eom K, Park HS. β-sheet-like formation during the mechanical unfolding of prion protein. J Chem Phys 2015; 143:125101. [DOI: 10.1063/1.4931819] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Weiwei Tao
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Gwonchan Yoon
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
- Department of Mechanical Engineering, Korea University, Seoul 136-701, South Korea
| | - Penghui Cao
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Kilho Eom
- Biomechanics Laboratory, College of Sport Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Harold S. Park
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
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24
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Singh J, Udgaonkar JB. Molecular Mechanism of the Misfolding and Oligomerization of the Prion Protein: Current Understanding and Its Implications. Biochemistry 2015; 54:4431-42. [PMID: 26171558 DOI: 10.1021/acs.biochem.5b00605] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Prion diseases, also known as transmissible spongiform encephalopathies, make up a group of fatal neurodegenerative disorders linked with the misfolding and aggregation of the prion protein (PrP). Although it is not yet understood how the misfolding of PrP induces neurodegeneration, it is widely accepted that the formation of misfolded prion protein (termed PrP(Sc)) is both the triggering event in the disease and the main component of the infectious agent responsible for disease transmission. Despite the clear involvement of PrP(Sc) in prion diseases, the exact composition of PrP(Sc) is not yet well-known. Recent studies show that misfolded oligomers of PrP could, however, be responsible for neurotoxicity and/or infectivity in the prion diseases. Hence, understanding the molecular mechanism of formation of the misfolded oligomers of PrP is critical for developing an understanding about the prion diseases and for developing anti-prion therapeutics. This review discusses recent advances in understanding the molecular mechanism of misfolded oligomer formation by PrP and its implications for the development of anti-prion therapeutics.
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Affiliation(s)
- Jogender Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India
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25
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Ban JJ, Lee M, Im W, Kim M. Low pH increases the yield of exosome isolation. Biochem Biophys Res Commun 2015; 461:76-9. [PMID: 25849885 DOI: 10.1016/j.bbrc.2015.03.172] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 03/29/2015] [Indexed: 12/11/2022]
Abstract
Exosomes are the extracellular vesicles secreted by various cells. Exosomes mediate intercellular communication by delivering a variety of molecules between cells. Cancer cell derived exosomes seem to be related with tumor progression and metastasis. Tumor microenvironment is thought to be acidic and this low pH controls exosome physiology, leading to tumor progression. Despite the importance of microenvironmental pH on exosome, most of exosome studies have been performed without regard to pH. Therefore, the difference of exosome stability and yield of isolation by different pH need to be studied. In this research, we investigated the yield of total exosomal protein and RNA after incubation in acidic, neutral and alkaline conditioned medium. Representative exosome markers were investigated by western blot after incubation of exosomes in different pH. As a result, the concentrations of exosomal protein and nucleic acid were significantly increased after incubation in the acidic medium compared with neutral medium. The higher levels of exosome markers including CD9, CD63 and HSP70 were observed after incubation in an acidic environment. On the other hand, no exosomal protein, exosomal RNA and exosome markers have been detected after incubation in an alkaline condition. In summary, our results indicate that the acidic condition is the favorable environment for existence and isolation of exosomes.
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Affiliation(s)
- Jae-Jun Ban
- Department of Bioscience and Biotechnology, College of Life Science, Institute of Biotechnology, Sejong University, Seoul, South Korea
| | - Mijung Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Wooseok Im
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.
| | - Manho Kim
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea; Protein Metabolism Medical Research Center, College of Medicine, Seoul National University, Seoul, South Korea.
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26
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Cheng CJ, Daggett V. Different misfolding mechanisms converge on common conformational changes: human prion protein pathogenic mutants Y218N and E196K. Prion 2015; 8:125-35. [PMID: 24509603 DOI: 10.4161/pri.27807] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Prion diseases are caused by misfolding and aggregation of the prion protein (PrP). Pathogenic mutations such as Y218N and E196K are known to cause Gerstmann-Sträussler-Scheinker syndrome and Creutzfeldt-Jakob disease, respectively. Here we describe molecular dynamics simulations of these mutant proteins to better characterize the detailed conformational effects of these sequence substitutions. Our results indicate that the mutations disrupt the wild-type native PrP(C) structure and cause misfolding. Y218N reduced hydrophobic packing around the X-loop (residues 165-171), and E196K abolished an important wild-type salt bridge. While differences in the mutation site led PrP mutants to misfold along different pathways, we observed multiple traits of misfolding that were common to both mutants. Common traits of misfolding included: 1) detachment of the short helix (HA) from the PrP core; 2) exposure of side chain F198; and 3) formation of a nonnative strand at the N-terminus. The effect of the E196K mutation directly abolished the wild-type salt bridge E196-R156, which further destabilized the F198 hydrophobic pocket and HA. The Y218N mutation propagated its effect by increasing the HB-HC interhelical angle, which in turn disrupted the packing around F198. Furthermore, a nonnative contact formed between E221 and S132 on the S1-HA loop, which offered a direct mechanism for disrupting the hydrophobic packing between the S1-HA loop and HC. While there were common misfolding features shared between Y218N and E196K, the differences in the orientation of HB and HC and the X-loop conformation might provide a structural basis for identifying different prion strains.
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27
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Structural and dynamic properties of the human prion protein. Biophys J 2014; 106:1152-63. [PMID: 24606939 DOI: 10.1016/j.bpj.2013.12.053] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/11/2013] [Accepted: 12/26/2013] [Indexed: 11/23/2022] Open
Abstract
Prion diseases involve the conformational conversion of the cellular prion protein (PrP(C)) to its misfolded pathogenic form (PrP(Sc)). To better understand the structural mechanism of this conversion, we performed extensive all-atom, explicit-solvent molecular-dynamics simulations for three structures of the wild-type human PrP (huPrP) at different pH values and temperatures. Residue 129 is polymorphic, being either Met or Val. Two of the three structures have Met in position 129 and the other has Val. Lowering the pH or raising the temperature induced large conformational changes of the C-terminal globular domain and increased exposure of its hydrophobic core. In some simulations, HA and its preceding S1-HA loop underwent large displacements. The C-terminus of HB was unstable and sometimes partially unfolded. Two hydrophobic residues, Phe-198 and Met-134, frequently became exposed to solvent. These conformational changes became more dramatic at lower pH or higher temperature. Furthermore, Tyr-169 and the S2-HB loop, or the X-loop, were different in the starting structures but converged to common conformations in the simulations for the Met-129, but not the Val-129, protein. α-Strands and β-strands formed in the initially unstructured N-terminus. α-Strand propensity in the N-terminus was different between the Met-129 and Val129 proteins, but β-strand propensity was similar. This study reveals detailed structural and dynamic properties of huPrP, providing insight into the mechanism of the conversion of PrP(C) to PrP(Sc).
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28
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Yamamoto N. Hot Spot of Structural Ambivalence in Prion Protein Revealed by Secondary Structure Principal Component Analysis. J Phys Chem B 2014; 118:9826-33. [DOI: 10.1021/jp5034245] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Norifumi Yamamoto
- Department of Life and Environmental
Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan
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29
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The challenges of understanding glycolipid functions: An open outlook based on molecular simulations. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:1130-45. [DOI: 10.1016/j.bbalip.2013.12.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 11/20/2022]
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30
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The role of Cys179–Cys214 disulfide bond in the stability and folding of prion protein: insights from molecular dynamics simulations. J Mol Model 2014; 20:2106. [DOI: 10.1007/s00894-014-2106-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 12/07/2013] [Indexed: 01/23/2023]
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31
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Cheng CJ, Daggett V. Molecular dynamics simulations capture the misfolding of the bovine prion protein at acidic pH. Biomolecules 2014; 4:181-201. [PMID: 24970211 PMCID: PMC4030982 DOI: 10.3390/biom4010181] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 02/07/2014] [Accepted: 02/09/2014] [Indexed: 12/24/2022] Open
Abstract
Bovine spongiform encephalopathy (BSE), or mad cow disease, is a fatal neurodegenerative disease that is transmissible to humans and that is currently incurable. BSE is caused by the prion protein (PrP), which adopts two conformers; PrPC is the native innocuous form, which is α-helix rich; and PrPSc is the β-sheet rich misfolded form, which is infectious and forms neurotoxic species. Acidic pH induces the conversion of PrPC to PrPSc. We have performed molecular dynamics simulations of bovine PrP at various pH regimes. An acidic pH environment induced conformational changes that were not observed in neutral pH simulations. Putative misfolded structures, with nonnative β-strands formed in the flexible N-terminal domain, were found in acidic pH simulations. Two distinct pathways were observed for the formation of nonnative β-strands: at low pH, hydrophobic contacts with M129 nucleated the nonnative β-strand; at mid-pH, polar contacts involving Q168 and D178 facilitated the formation of a hairpin at the flexible N-terminus. These mid- and low pH simulations capture the process of nonnative β-strand formation, thereby improving our understanding of how PrPC misfolds into the β-sheet rich PrPSc and how pH factors into the process.
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Affiliation(s)
- Chin Jung Cheng
- Department of Bioengineering, University of Washington, Seattle WA 98195-5013, USA.
| | - Valerie Daggett
- Department of Bioengineering, University of Washington, Seattle WA 98195-5013, USA.
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32
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Yamaguchi KI, Kamatari YO, Fukuoka M, Miyaji R, Kuwata K. Nearly Reversible Conformational Change of Amyloid Fibrils as Revealed by pH-Jump Experiments. Biochemistry 2013; 52:6797-806. [DOI: 10.1021/bi400698u] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Kei-ichi Yamaguchi
- United Graduate School of Drug Discovery and Medical
Information
Sciences, ‡Center for Emerging Infectious Diseases, §Life Science Research Center, and ¶Supporting and Development
Center for Technology Education, Faculty of Engineering, Gifu University, Yanagido
1-1, Gifu 501-1193, Japan
| | - Yuji O. Kamatari
- United Graduate School of Drug Discovery and Medical
Information
Sciences, ‡Center for Emerging Infectious Diseases, §Life Science Research Center, and ¶Supporting and Development
Center for Technology Education, Faculty of Engineering, Gifu University, Yanagido
1-1, Gifu 501-1193, Japan
| | - Mayuko Fukuoka
- United Graduate School of Drug Discovery and Medical
Information
Sciences, ‡Center for Emerging Infectious Diseases, §Life Science Research Center, and ¶Supporting and Development
Center for Technology Education, Faculty of Engineering, Gifu University, Yanagido
1-1, Gifu 501-1193, Japan
| | - Reiji Miyaji
- United Graduate School of Drug Discovery and Medical
Information
Sciences, ‡Center for Emerging Infectious Diseases, §Life Science Research Center, and ¶Supporting and Development
Center for Technology Education, Faculty of Engineering, Gifu University, Yanagido
1-1, Gifu 501-1193, Japan
| | - Kazuo Kuwata
- United Graduate School of Drug Discovery and Medical
Information
Sciences, ‡Center for Emerging Infectious Diseases, §Life Science Research Center, and ¶Supporting and Development
Center for Technology Education, Faculty of Engineering, Gifu University, Yanagido
1-1, Gifu 501-1193, Japan
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33
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Chen X, Zhu S, Wang S, Yang D, Zhang J. Molecular dynamics study on the stability of wild-type and the R220K mutant of human prion protein. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.824572] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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34
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Molecular dynamics simulation of temperature induced unfolding of animal prion protein. J Mol Model 2013; 19:4433-41. [DOI: 10.1007/s00894-013-1955-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 07/22/2013] [Indexed: 01/22/2023]
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35
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Giachin G, Biljan I, Ilc G, Plavec J, Legname G. Probing early misfolding events in prion protein mutants by NMR spectroscopy. Molecules 2013; 18:9451-76. [PMID: 23966072 PMCID: PMC6270549 DOI: 10.3390/molecules18089451] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/01/2013] [Accepted: 08/05/2013] [Indexed: 01/17/2023] Open
Abstract
The post-translational conversion of the ubiquitously expressed cellular form of the prion protein, PrPC, into its misfolded and pathogenic isoform, known as prion or PrPSc, plays a key role in prion diseases. These maladies are denoted transmissible spongiform encephalopathies (TSEs) and affect both humans and animals. A prerequisite for understanding TSEs is unraveling the molecular mechanism leading to the conversion process whereby most α-helical motifs are replaced by β-sheet secondary structures. Importantly, most point mutations linked to inherited prion diseases are clustered in the C-terminal domain region of PrPC and cause spontaneous conversion to PrPSc. Structural studies with PrP variants promise new clues regarding the proposed conversion mechanism and may help identify "hot spots" in PrPC involved in the pathogenic conversion. These investigations may also shed light on the early structural rearrangements occurring in some PrPC epitopes thought to be involved in modulating prion susceptibility. Here we present a detailed overview of our solution-state NMR studies on human prion protein carrying different pathological point mutations and the implications that such findings may have for the future of prion research.
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Affiliation(s)
- Gabriele Giachin
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265,Trieste I-34136, Italy; E-Mail:
| | - Ivana Biljan
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102A, Zagreb HR-10000, Croatia; E-Mail:
| | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, Ljubljana SI-1000, Slovenia; E-Mails: (G.I.); (J.P.)
- EN-FIST Center of Excellence, Ljubljana SI-1000, Slovenia
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, Ljubljana SI-1000, Slovenia; E-Mails: (G.I.); (J.P.)
- EN-FIST Center of Excellence, Ljubljana SI-1000, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana SI-1000, Slovenia
| | - Giuseppe Legname
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265,Trieste I-34136, Italy; E-Mail:
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Bin Y, Li X, He Y, Chen S, Xiang J. Amyloid-β peptide (1-42) aggregation induced by copper ions under acidic conditions. Acta Biochim Biophys Sin (Shanghai) 2013; 45:570-7. [PMID: 23747389 DOI: 10.1093/abbs/gmt044] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It is well known that the aggregation of amyloid-β peptide (Aβ) induced by Cu²⁺ is related to incubation time, solution pH, and temperature. In this work, the aggregation of Aβ₁₋₄₂ in the presence of Cu²⁺ under acidic conditions was studied at different incubation time and temperature (e.g. 25 and 37°C). Incubation temperature, pH, and the presence of Cu²⁺ in Aβ solution were confirmed to alter the morphology of aggregation (fibrils or amorphous aggregates), and the morphology is pivotal for Aβ neurotoxicity and Alzheimer disease (AD) development. The results of atomic force microscopy (AFM) indicated that the formation of Aβ fibrous morphology is preferred at lower pH, but Cu²⁺ induced the formation of amorphous aggregates. The aggregation rate of Aβ was increased with the elevation of temperature. These results were further confirmed by fluorescence spectroscopy and circular dichroism spectroscopy and it was found that the formation of β-sheet structure was inhibited by Cu²⁺ binding to Aβ. The result was consistent with AFM observation and the fibrillation process was restrained. We believe that the local charge state in hydrophilic domain of Aβ may play a dominant role in the aggregate morphology due to the strong steric hindrance. This research will be valuable for understanding of Aβ toxicity in AD.
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Affiliation(s)
- Yannan Bin
- Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
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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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38
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Exploring charged biased regions in the human proteome. Gene 2012; 515:277-80. [PMID: 23266628 DOI: 10.1016/j.gene.2012.11.077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 11/12/2012] [Accepted: 11/28/2012] [Indexed: 11/23/2022]
Abstract
There has been an increasing interest in biased regions in proteins especially ever since it was shown that such regions are frequently associated with a structural role in the cell, or with protein disorder. In this study, we focus on charged biased protein sequences in human genome. We have identified 446 charged biased proteins within human proteome, 70% of them constitute proteins harboring negative run that correspond to transcription factor zinc finger proteins, importins and some protein kinases involving acidic activating domains. Basic charge clusters are often associated with DNA-binding, zinc-finger, basic-leucine zipper and homeobox domains. The data show that significant positive clusters correspond to ribosomal proteins. Most of proteins with zinc-binding fingers have a mixed positive and negative charged biased regions. Altogether, the Gene Ontology analysis revealed that the charged proteins are involved mainly in regulatory functions.
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Baillod P, Garrec J, Colombo MC, Tavernelli I, Rothlisberger U. Enhanced Sampling Molecular Dynamics Identifies PrPSc Structures Harboring a C-Terminal β-Core. Biochemistry 2012; 51:9891-9. [DOI: 10.1021/bi301091x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Pascal Baillod
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Julian Garrec
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Maria-Carola Colombo
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ivano Tavernelli
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ursula Rothlisberger
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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40
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Gallion SL. Modeling amyloid-beta as homogeneous dodecamers and in complex with cellular prion protein. PLoS One 2012; 7:e49375. [PMID: 23145167 PMCID: PMC3493521 DOI: 10.1371/journal.pone.0049375] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 10/11/2012] [Indexed: 12/16/2022] Open
Abstract
Soluble amyloid beta (Aβ) peptide has been linked to the pathology of Alzheimer's disease. A variety of soluble oligomers have been observed to be toxic, ranging from dimers to protofibrils. No tertiary structure has been identified as a single biologically relevant form, though many models are comprised of highly ordered β-sheets. Evidence exists for much less ordered toxic oligomers. The mechanism of toxicity remains highly debated and probably involves multiple pathways. Interaction of Aβ oligomers with the N-terminus of the cellular form of the prion protein (PrP(c)) has recently been proposed. The intrinsically disordered nature of this protein and the highly polymorphic nature of Aβ oligomers make structural resolution of the complex exceptionally challenging. In this study, molecular dynamics simulations are performed for dodecameric assemblies of Aβ comprised of monomers having a single, short antiparallel β-hairpin at the C-terminus. The resulting models, devoid of any intermolecular hydrogen bonds, are shown to correlate well with experimental data and are found to be quite stable within the hydrophobic core, whereas the α-helical N-termini transform to a random coil state. This indicates that highly ordered assemblies are not required for stability and less ordered oligomers are a viable component in the population of soluble oligomers. In addition, a tentative model is proposed for the association of Aβ dimers with a double deletion mutant of the intrinsically disordered N-terminus of PrP(c). This may be useful as a conceptual working model for the binding of higher order oligomers and in the design of further experiments.
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41
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Arena G, La Mendola D, Pappalardo G, Sóvágó I, Rizzarelli E. Interactions of Cu2+ with prion family peptide fragments: Considerations on affinity, speciation and coordination. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.03.038] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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42
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Singh J, Sabareesan A, Mathew M, Udgaonkar JB. Development of the Structural Core and of Conformational Heterogeneity during the Conversion of Oligomers of the Mouse Prion Protein to Worm-like Amyloid Fibrils. J Mol Biol 2012; 423:217-31. [DOI: 10.1016/j.jmb.2012.06.040] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Revised: 06/15/2012] [Accepted: 06/28/2012] [Indexed: 10/28/2022]
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Biljan I, Ilc G, Giachin G, Plavec J, Legname G. Structural Rearrangements at Physiological pH: Nuclear Magnetic Resonance Insights from the V210I Human Prion Protein Mutant. Biochemistry 2012; 51:7465-74. [DOI: 10.1021/bi3009856] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ivana Biljan
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000
Ljubljana, Slovenia
| | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000
Ljubljana, Slovenia
- EN→FIST Centre of Excellence, Dunajska 156, SI-1001 Ljubljana,
Slovenia
| | - Gabriele Giachin
- Laboratory of Prion
Biology, Department
of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, Trieste, Italy
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000
Ljubljana, Slovenia
- EN→FIST Centre of Excellence, Dunajska 156, SI-1001 Ljubljana,
Slovenia
- Faculty of Chemistry and Chemical
Technology, University of Ljubljana, Aškerčeva
cesta 5, SI-1000 Ljubljana, Slovenia
| | - Giuseppe Legname
- Laboratory of Prion
Biology, Department
of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, Trieste, Italy
- ELETTRA Laboratory, Sincrotrone Trieste S.C.p.A., I-34149 Basovizza, Trieste,
Italy
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Vila-Viçosa D, Campos SRR, Baptista AM, Machuqueiro M. Reversibility of prion misfolding: insights from constant-pH molecular dynamics simulations. J Phys Chem B 2012; 116:8812-21. [PMID: 22803931 DOI: 10.1021/jp3034837] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The prion protein (PrP) is the cause of a group of diseases known as transmissible spongiform encephalopathies (TSEs). Creutzfeldt-Jakob disease and bovine spongiform encephalopathy are examples of TSEs. Although the normal form of PrP (PrP(C)) is monomeric and soluble, it can misfold into a pathogenic form (PrP(Sc)) that has a high content of β-structure and can aggregate forming amyloid fibrils. The mechanism of conversion of PrP(C) into PrP(Sc) is not known but different triggers have been proposed. It can be catalyzed by a PrP(Sc) sample, or it can be induced by an external factor, such as low pH. The pH effect on the structure of PrP was recently studied by computational methods [Campos et al. J. Phys. Chem. B 2010, 114, 12692-12700], and an evident trend of loss of helical structure was observed with pH decrease, together with a gain of β-structures. In particular, one simulation at pH 2 showed an evident misfolding transition. The main goal of the present work was to study the effects of a change in pH to 7 in several transient conformations of this simulation, in order to draw some conclusions about the reversibility of PrP misfolding. Although the most significant effect caused by the change of pH to 7 was a global stabilization of the protein structure, we could also observe that some conformational transitions induced by pH 2 were reversible in many of our simulations, namely those started from the early moments of the misfolding transition. This observation is in good agreement with experiments showing that, even at pH as low as 1.7, it is possible to revert the misfolding process [Bjorndahl et al. Biochemistry 2011, 50, 1162-1173].
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Affiliation(s)
- Diogo Vila-Viçosa
- Centro de Química e Bioquímica e Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
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Santo KP, Berjanskii M, Wishart DS, Stepanova M. Comparative analysis of essential collective dynamics and NMR-derived flexibility profiles in evolutionarily diverse prion proteins. Prion 2011; 5:188-200. [PMID: 21869604 DOI: 10.4161/pri.5.3.16097] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Collective motions on ns-μs time scales are known to have a major impact on protein folding, stability, binding and enzymatic efficiency. It is also believed that these motions may have an important role in the early stages of prion protein misfolding and prion disease. In an effort to accurately characterize these motions and their potential influence on the misfolding and prion disease transmissibility we have conducted a combined analysis of molecular dynamic simulations and NMR-derived flexibility measurements over a diverse range of prion proteins. Using a recently developed numerical formalism, we have analyzed the essential collective dynamics (ECD) for prion proteins from 8 different species including human, cow, elk, cat, hamster, chicken, turtle and frog. We also compared the numerical results with flexibility profiles generated by the random coil index (RCI) from NMR chemical shifts. Prion protein backbone flexibility derived from experimental NMR data and from theoretical computations show strong agreement with each other, demonstrating that it is possible to predict the observed RCI profiles employing the numerical ECD formalism. Interestingly, flexibility differences in the loop between second beta strand (S2) and the second alpha helix (HB) appear to distinguish prion proteins from species that are susceptible to prion disease and those that are resistant. Our results show that the different levels of flexibility in the S2-HB loop in various species are predictable via the ECD method, indicating that ECD may be used to identify disease resistant variants of prion proteins, as well as the influence of prion proteins mutations on disease susceptibility or misfolding propensity.
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Hafner-Bratkovic I, Bester R, Pristovsek P, Gaedtke L, Veranic P, Gaspersic J, Mancek-Keber M, Avbelj M, Polymenidou M, Julius C, Aguzzi A, Vorberg I, Jerala R. Globular domain of the prion protein needs to be unlocked by domain swapping to support prion protein conversion. J Biol Chem 2011; 286:12149-56. [PMID: 21324909 DOI: 10.1074/jbc.m110.213926] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Prion diseases are fatal transmissible neurodegenerative diseases affecting many mammalian species. The normal prion protein (PrP) converts into a pathological aggregated form, PrPSc, which is enriched in the β-sheet structure. Although the high resolution structure of the normal PrP was determined, the structure of the converted form of PrP remains inaccessible to high resolution techniques. To map the PrP conversion process we introduced disulfide bridges into different positions within the globular domain of PrP, tethering selected secondary structure elements. The majority of tethered PrP mutants exhibited increased thermodynamic stability, nevertheless, they converted efficiently. Only the disulfides that tether subdomain B1-H1-B2 to subdomain H2-H3 prevented PrP conversion in vitro and in prion-infected cell cultures. Reduction of disulfides recovered the ability of these mutants to convert, demonstrating that the separation of subdomains is an essential step in conversion. Formation of disulfide-linked proteinase K-resistant dimers in fibrils composed of a pair of single cysteine mutants supports the model based on domain-swapped dimers as the building blocks of prion fibrils. In contrast to previously proposed structural models of PrPSc suggesting conversion of large secondary structural segments, we provide evidence for the conservation of secondary structural elements of the globular domain upon PrP conversion. Previous studies already showed that dimerization is the rate-limiting step in PrP conversion. We show that separation and swapping of subdomains of the globular domain is necessary for conversion. Therefore, we propose that the domain-swapped dimer of PrP precedes amyloid formation and represents a potential target for therapeutic intervention.
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Affiliation(s)
- Iva Hafner-Bratkovic
- Department of Biotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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47
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van der Kamp MW, Daggett V. Influence of pH on the human prion protein: insights into the early steps of misfolding. Biophys J 2011; 99:2289-98. [PMID: 20923664 DOI: 10.1016/j.bpj.2010.07.063] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/22/2010] [Accepted: 07/27/2010] [Indexed: 01/02/2023] Open
Abstract
Transmissible spongiform encephalopathies, or prion diseases, are caused by misfolding and aggregation of the prion protein PrP. Conversion from the normal cellular form (PrP(C)) or recombinant PrP (recPrP) to a misfolded form is pH-sensitive, in that misfolding and aggregation occur more readily at lower pH. To gain more insight into the influence of pH on the dynamics of PrP and its potential to misfold, we performed extensive molecular-dynamics simulations of the recombinant PrP protein (residues 90-230) in water at three different pH regimes: neutral (or cytoplasmic) pH (∼7.4), middle (or endosomal) pH (∼5), and low pH (<4). We present five different simulations of 50 ns each for each pH regime, amounting to a total of 750 ns of simulation time. A detailed analysis and comparison with experiment validate the simulations and lead to new insights into the mechanism of pH-induced misfolding. The mobility of the globular domain increases with decreasing pH, through displacement of the first helix and instability of the hydrophobic core. At middle pH, conversion to a misfolded (PrP(Sc)-like) conformation is observed. The observed changes in conformation and stability are consistent with experimental data and thus provide a molecular basis for the initial steps in the misfolding process.
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48
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Babin V, Roland C, Sagui C. The α-sheet: A missing-in-action secondary structure? Proteins 2011; 79:937-46. [DOI: 10.1002/prot.22935] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/26/2010] [Accepted: 10/28/2010] [Indexed: 11/06/2022]
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Guest WC, Plotkin SS, Cashman NR. Toward a mechanism of prion misfolding and structural models of PrP(Sc): current knowledge and future directions. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:154-160. [PMID: 21218344 DOI: 10.1080/15287394.2011.529065] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Despite extensive investigation, many features of prion protein misfolding remain enigmatic. Physicochemical variables known to influence misfolding are reviewed to help elucidate the mechanism of prionogenesis and identify salient features of PrP(Sc), the misfolded conformer of the prion protein. Prospective work on refinement of candidate PrP(Sc) models based on thermodynamic considerations will help to complete atomic-scale structural details missing from experimental studies and may explain the basis for the templating activity of PrP(Sc) in disease.
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Affiliation(s)
- Will C Guest
- Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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50
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van der Kamp MW, Daggett V. Molecular dynamics as an approach to study prion protein misfolding and the effect of pathogenic mutations. Top Curr Chem (Cham) 2011; 305:169-97. [PMID: 21526434 DOI: 10.1007/128_2011_158] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Computer simulation of protein dynamics offers unique high-resolution information that complements experiment. Using experimentally derived structures of the natively folded prion protein (PrP), physically realistic dynamics and conformational changes can be simulated, including the initial steps of misfolding. By introducing mutations in silico, the effect of pathogenic mutations on PrP conformation and dynamics can be assessed. Here, we briefly introduce molecular dynamics methods and review the application of molecular dynamics simulations to obtain insight into various aspects of the PrP, including the mechanism of misfolding, the response to changes in the environment, and the influence of disease-related mutations.
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Affiliation(s)
- Marc W van der Kamp
- Department of Bioengineering, University of Washington, Seattle, WA 98195-5013, USA
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