1
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Pal S, Udgaonkar JB. Mutations of evolutionarily conserved aromatic residues suggest that misfolding of the mouse prion protein may commence in multiple ways. J Neurochem 2023; 167:696-710. [PMID: 37941487 DOI: 10.1111/jnc.16007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 11/10/2023]
Abstract
The misfolding of the mammalian prion protein from its α-helix rich cellular isoform to its β-sheet rich infectious isoform is associated with several neurodegenerative diseases. The determination of the structural mechanism by which misfolding commences, still remains an unsolved problem. In the current study, native-state hydrogen exchange coupled with mass spectrometry has revealed that the N state of the mouse prion protein (moPrP) at pH 4 is in dynamic equilibrium with multiple partially unfolded forms (PUFs) capable of initiating misfolding. Mutation of three evolutionarily conserved aromatic residues, Tyr168, Phe174, and Tyr217 present at the interface of the β2-α2 loop and the C-terminal end of α3 in the structured C-terminal domain of moPrP significantly destabilize the native state (N) of the protein. They also reduce the free energy differences between the N state and two PUFs identified as PUF1 and PUF2**. It is shown that PUF2** in which the β2-α2 loop and the C-terminal end of α3 are disordered, has the same stability as the previously identified PUF2*, but to have a very different structure. Misfolding can commence from both PUF1 and PUF2**, as it can from PUF2*. Hence, misfolding can commence and proceed in multiple ways from structurally distinct precursor conformations. The increased extents to which PUF1 and PUF2** are populated at equilibrium in the case of the mutant variants, greatly accelerate their misfolding. The results suggest that the three aromatic residues may have been evolutionarily selected to impede the misfolding of moPrP.
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Affiliation(s)
- Suman Pal
- Indian Institute of Science Education and Research Pune, Pune, India
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2
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Cembran A, Fernandez-Funez P. Intrinsic determinants of prion protein neurotoxicity in Drosophila: from sequence to (dys)function. Front Mol Neurosci 2023; 16:1231079. [PMID: 37645703 PMCID: PMC10461008 DOI: 10.3389/fnmol.2023.1231079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 08/02/2023] [Indexed: 08/31/2023] Open
Abstract
Prion diseases are fatal brain disorders characterized by deposition of insoluble isoforms of the prion protein (PrP). The normal and pathogenic structures of PrP are relatively well known after decades of studies. Yet our current understanding of the intrinsic determinants regulating PrP misfolding are largely missing. A 3D subdomain of PrP comprising the β2-α2 loop and helix 3 contains high sequence and structural variability among animals and has been proposed as a key domain regulating PrP misfolding. We combined in vivo work in Drosophila with molecular dynamics (MD) simulations, which provide additional insight to assess the impact of candidate substitutions in PrP from conformational dynamics. MD simulations revealed that in human PrP WT the β2-α2 loop explores multiple β-turn conformations, whereas the Y225A (rabbit PrP-like) substitution strongly favors a 310-turn conformation, a short right-handed helix. This shift in conformational diversity correlates with lower neurotoxicity in flies. We have identified additional conformational features and candidate amino acids regulating the high toxicity of human PrP and propose a new strategy for testing candidate modifiers first in MD simulations followed by functional experiments in flies. In this review we expand on these new results to provide additional insight into the structural and functional biology of PrP through the prism of the conformational dynamics of a 3D domain in the C-terminus. We propose that the conformational dynamics of this domain is a sensitive measure of the propensity of PrP to misfold and cause toxicity. This provides renewed opportunities to identify the intrinsic determinants of PrP misfolding through the contribution of key amino acids to different conformational states by MD simulations followed by experimental validation in transgenic flies.
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Affiliation(s)
- Alessandro Cembran
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN, United States
| | - Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, United States
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3
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Myers RR, John A, Zhang W, Zou WQ, Cembran A, Fernandez-Funez P. Y225A induces long-range conformational changes in human prion protein that are protective in Drosophila. J Biol Chem 2023; 299:104881. [PMID: 37269948 PMCID: PMC10339063 DOI: 10.1016/j.jbc.2023.104881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 05/20/2023] [Accepted: 05/22/2023] [Indexed: 06/05/2023] Open
Abstract
Prion protein (PrP) misfolding is the key trigger in the devastating prion diseases. Yet the sequence and structural determinants of PrP conformation and toxicity are not known in detail. Here, we describe the impact of replacing Y225 in human PrP with A225 from rabbit PrP, an animal highly resistant to prion diseases. We first examined human PrP-Y225A by molecular dynamics simulations. We next introduced human PrP in Drosophila and compared the toxicity of human PrP-WT and Y225A in the eye and in brain neurons. Y225A stabilizes the β2-α2 loop into a 310-helix from six different conformations identified in WT and lowers hydrophobic exposure. Transgenic flies expressing PrP-Y225A exhibit less toxicity in the eye and in brain neurons and less accumulation of insoluble PrP. Overall, we determined that Y225A lowers toxicity in Drosophila assays by promoting a structured loop conformation that increases the stability of the globular domain. These findings are significant because they shed light on the key role of distal α-helix 3 on the dynamics of the loop and the entire globular domain.
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Affiliation(s)
- Ryan R Myers
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, Minnesota, USA
| | - Aliciarose John
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, Minnesota, USA
| | - Weiguanliu Zhang
- Department of Pathology and Neurology, National Prion Disease Pathology Surveillance Center, National Center for Regenerative Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Wen-Quan Zou
- Department of Pathology and Neurology, National Prion Disease Pathology Surveillance Center, National Center for Regenerative Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Alessandro Cembran
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, Minnesota, USA.
| | - Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, Minnesota, USA.
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4
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Šulskis D, Šneiderienė G, Žiaunys M, Smirnovas V. The seeding barrier between human and Syrian hamster prion protein amyloid fibrils is determined by β2-α2 loop sequence elements. Int J Biol Macromol 2023; 238:124038. [PMID: 36921824 DOI: 10.1016/j.ijbiomac.2023.124038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/28/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023]
Abstract
Transmissive spongiform encephalopathies (TSE) are a group of neurodegenerative diseases caused by infectious protein particles, known as prions. Prions are formed from cellular prion proteins (PrP) and can be transmitted between different mammalian species. Subsequently, the host's PrPs are then converted to prions, followed by the onset of TSE. Interspecies prion infectivity is governed by the amino acid sequence differences of PrPs and prions' inability to replicate in a host is termed a species barrier. Here, we investigated the amino acid sequence determinants of species barrier between recombinant human (rHuPrP) and hamster (rShaPrP) prion protein amyloid fibrils. We discovered that a unidirectional species barrier between rShaPrP and rHuPrP amyloid fibrils exists. This barrier stems from the difference of amino acid sequences in the conserved β2-α2 loop region. Our results revealed that individual amino acids in the β2-α2 loop region are critical for overcoming the barrier between human and hamster prion protein amyloid fibrils in vitro. Furthermore, the barrier was only possible to observe through aggregation kinetics, as the secondary structure rHuPrP fibrils was not affected by the cross-seeding. Overall, we demonstrated the mechanistic pathway behind this interspecies barrier phenomenon, which increases our understanding of prion-related disease development.
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Affiliation(s)
- Darius Šulskis
- Amyloid Research Sector, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania.
| | - Greta Šneiderienė
- Amyloid Research Sector, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Mantas Žiaunys
- Amyloid Research Sector, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Amyloid Research Sector, Institute of Biotechnology, Vilnius University, Vilnius, Lithuania
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5
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Ilie IM, Caflisch A. Antibody binding increases the flexibility of the prion protein. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140827. [PMID: 35931365 DOI: 10.1016/j.bbapap.2022.140827] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/29/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
Prion diseases are associated with the conversion of the cellular prion protein (PrP) into a pathogenic conformer (PrPSc). A proposed therapeutic approach to avoid the pathogenic transformation is to develop antibodies that bind to PrP and stabilize its structure. POM1 and POM6 are two monoclonal antibodies that bind the globular domain of PrP and have different biological responses, i.e., trigger neurotoxicity mimicking prion infections (POM1) or prevent neurotoxicity (POM6). The crystal structures of PrP in complex with the two antibodies show similar epitopes which seems inconsistent with the opposite phenotypes. Here, we investigate the influence of the POM1 and POM6 antibodies on the flexibility of the mouse PrP by molecular dynamics simulations. The simulations reveal that the POM6/PrP interface is less stable than the POM1/PrP interface, ascribable to localized polar mismatches at the interface, despite the former complex having a larger epitope than the latter. In the presence of any of the two antibodies, the flexibility of the globular domain increases everywhere except for the β1-α1 loop in the POM1/PrP complex which suggests the involvement of this loop in the pathological conversion. The secondary structure of PrP is preserved whereas the polar interactions involving residues Glu146, Arg156 and Arg208 are modified upon antibody binding.
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Affiliation(s)
- Ioana M Ilie
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
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6
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Ilie IM, Bacci M, Vitalis A, Caflisch A. Antibody binding modulates the dynamics of the membrane-bound prion protein. Biophys J 2022; 121:2813-2825. [PMID: 35672948 DOI: 10.1016/j.bpj.2022.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/20/2022] [Accepted: 06/01/2022] [Indexed: 11/18/2022] Open
Abstract
Misfolding of the cellular prion protein (PrPC) is associated with lethal neurodegeneration. PrPC consists of a flexible tail (residues 23-123) and a globular domain (residues 124-231) whose C-terminal end is anchored to the cell membrane. The neurotoxic antibody POM1 and the innocuous antibody POM6 recognize the globular domain. Experimental evidence indicates that POM1 binding to PrPC emulates the influence on PrPC of the misfolded prion protein (PrPSc) while the binding of POM6 has the opposite biological response. Little is known about the potential interactions between flexible tail, globular domain, and the membrane. Here, we used atomistic simulations to investigate how these interactions are modulated by the binding of the Fab fragments of POM1 and POM6 to PrPC and by interstitial sequence truncations to the flexible tail. The simulations show that the binding of the antibodies restricts the range of orientations of the globular domain with respect to the membrane and decreases the distance between tail and membrane. Five of the six sequence truncations influence only marginally this distance and the contact patterns between tail and globular domain. The only exception is a truncation coupled to a charge inversion mutation of four N-terminal residues, which increases the distance of the flexible tail from the membrane. The interactions of the flexible tail and globular domain are modulated differently by the two antibodies.
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Affiliation(s)
- Ioana M Ilie
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Marco Bacci
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Andreas Vitalis
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zürich, Zürich, Switzerland.
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7
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Choi B, Kim NH, Jin GY, Kim YS, Kim YH, Eom K. Sequence-dependent aggregation-prone conformations of islet amyloid polypeptide. Phys Chem Chem Phys 2021; 23:22532-22542. [PMID: 34590645 DOI: 10.1039/d1cp01061a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Amyloid proteins, which aggregate to form highly ordered structures, play a crucial role in various disease pathologies. Despite many previous studies on amyloid fibrils, which are an end product of protein aggregation, the structural characteristics of amyloid proteins in the early stage of aggregation and their related aggregation mechanism still remain elusive. The role of the amino acid sequence in the aggregation-prone structures of amyloid proteins at such a stage is not understood. Here, we have studied the sequence-dependent structural characteristics of islet amyloid polypeptide based on atomistic simulations and spectroscopic experiments. We show that the amino acid sequence determines non-bonded interactions that play a leading role in the formation of aggregation-prone conformations. Specifically, a single point mutation critically changes the population of aggregation-prone conformations, resulting in a change of the aggregation mechanism. Our simulation results were supported by experimental results suggesting that mutation affects the kinetics of aggregation and the structural characteristics of amyloid aggregates. Our study provides an insight into the role of sequence-dependent aggregation-prone conformations in the underlying mechanisms of amyloid aggregation.
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Affiliation(s)
- Bumjoon Choi
- Biomechanics Laboratory, College of Sport Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
| | - Nam Hyeong Kim
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
| | - Geun Young Jin
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Yung Sam Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Yong Ho Kim
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea. .,Department of Nano Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.,Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
| | - Kilho Eom
- Biomechanics Laboratory, College of Sport Science, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
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8
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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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9
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Zajkowski T, Lee MD, Mondal SS, Carbajal A, Dec R, Brennock PD, Piast RW, Snyder JE, Bense NB, Dzwolak W, Jarosz DF, Rothschild LJ. The Hunt for Ancient Prions: Archaeal Prion-Like Domains Form Amyloid-Based Epigenetic Elements. Mol Biol Evol 2021; 38:2088-2103. [PMID: 33480998 DOI: 10.1093/molbev/msab010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Prions, proteins that can convert between structurally and functionally distinct states and serve as non-Mendelian mechanisms of inheritance, were initially discovered and only known in eukaryotes, and consequently considered to likely be a relatively late evolutionary acquisition. However, the recent discovery of prions in bacteria and viruses has intimated a potentially more ancient evolutionary origin. Here, we provide evidence that prion-forming domains exist in the domain archaea, the last domain of life left unexplored with regard to prions. We searched for archaeal candidate prion-forming protein sequences computationally, described their taxonomic distribution and phylogeny, and analyzed their associated functional annotations. Using biophysical in vitro assays, cell-based and microscopic approaches, and dye-binding analyses, we tested select candidate prion-forming domains for prionogenic characteristics. Out of the 16 tested, eight formed amyloids, and six acted as protein-based elements of information transfer driving non-Mendelian patterns of inheritance. We also identified short peptides from our archaeal prion candidates that can form amyloid fibrils independently. Lastly, candidates that tested positively in our assays had significantly higher tyrosine and phenylalanine content than candidates that tested negatively, an observation that may help future archaeal prion predictions. Taken together, our discovery of functional prion-forming domains in archaea provides evidence that multiple archaeal proteins are capable of acting as prions-thus expanding our knowledge of this epigenetic phenomenon to the third and final domain of life and bolstering the possibility that they were present at the time of the last universal common ancestor.
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Affiliation(s)
- Tomasz Zajkowski
- Centre of New Technologies, University of Warsaw, Warsaw, Poland.,University Space Research Association, Mountain View, CA, USA.,Blue Marble Space Institute of Science, Seattle, WA, USA
| | - Michael D Lee
- Blue Marble Space Institute of Science, Seattle, WA, USA
| | - Shamba S Mondal
- Laboratory of Bioinformatics, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Amanda Carbajal
- University Space Research Association, Mountain View, CA, USA.,University of California Santa Cruz, Santa Cruz, CA, USA
| | - Robert Dec
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | | | - Radoslaw W Piast
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | | | | | - Wojciech Dzwolak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Daniel F Jarosz
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Lynn J Rothschild
- Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, CA, USA
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10
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Agamennone M, Storchi L, Marrone A, Paciotti R. Hampering the early aggregation of PrP-E200K protein by charge-based inhibitors: a computational study. J Comput Aided Mol Des 2021; 35:751-770. [PMID: 34110550 PMCID: PMC8213589 DOI: 10.1007/s10822-021-00393-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 06/04/2021] [Indexed: 11/25/2022]
Abstract
A multilayered computational workflow was designed to identify a druggable binding site on the surface of the E200K pathogenic mutant of the human prion protein, and to investigate the effect of the binding of small molecules in the inhibition of the early aggregation of this protein. At this purpose, we developed an efficient computational tool to scan the molecular interaction properties of a whole MD trajectory, thus leading to the characterization of plausible binding regions on the surface of PrP-E200K. These structural data were then employed to drive structure-based virtual screening and fragment-based approaches to the seeking of small molecular binders of the PrP-E200K. Six promising compounds were identified, and their binding stabilities were assessed by MD simulations. Therefore, analyses of the molecular electrostatic potential similarity between the bound complexes and unbound protein evidenced their potential activity as charged-based inhibitors of the PrP-E200K early aggregation.
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Affiliation(s)
| | - Loriano Storchi
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy
- Molecular Discovery Limited, Middlesex, London, UK
| | - Alessandro Marrone
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy
| | - Roberto Paciotti
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy.
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11
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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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12
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Myers R, Cembran A, Fernandez-Funez P. Insight From Animals Resistant to Prion Diseases: Deciphering the Genotype - Morphotype - Phenotype Code for the Prion Protein. Front Cell Neurosci 2020; 14:254. [PMID: 33013324 PMCID: PMC7461849 DOI: 10.3389/fncel.2020.00254] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/24/2020] [Indexed: 12/30/2022] Open
Abstract
Prion diseases are a group of neurodegenerative diseases endemic in humans and several ruminants caused by the misfolding of native prion protein (PrP) into pathological conformations. Experimental work and the mad-cow epidemic of the 1980s exposed a wide spectrum of animal susceptibility to prion diseases, including a few highly resistant animals: horses, rabbits, pigs, and dogs/canids. The variable susceptibility to disease offers a unique opportunity to uncover the mechanisms governing PrP misfolding, neurotoxicity, and transmission. Previous work indicates that PrP-intrinsic differences (sequence) are the main contributors to disease susceptibility. Several residues have been cited as critical for encoding PrP conformational stability in prion-resistant animals, including D/E159 in dog, S167 in horse, and S174 in rabbit and pig PrP (all according to human numbering). These amino acids alter PrP properties in a variety of assays, but we still do not clearly understand the structural correlates of PrP toxicity. Additional insight can be extracted from comparative structural studies, followed by molecular dynamics simulations of selected mutations, and testing in manipulable animal models. Our working hypothesis is that protective amino acids generate more compact and stable structures in a C-terminal subdomain of the PrP globular domain. We will explore this idea in this review and identify subdomains within the globular domain that may hold the key to unravel how conformational stability and disease susceptibility are encoded in PrP.
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Affiliation(s)
- Ryan Myers
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, United States
| | - Alessandro Cembran
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN, United States
| | - Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, United States
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13
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Baral PK, Yin J, Aguzzi A, James MNG. Transition of the prion protein from a structured cellular form (PrP C ) to the infectious scrapie agent (PrP Sc ). Protein Sci 2019; 28:2055-2063. [PMID: 31583788 DOI: 10.1002/pro.3735] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 11/07/2022]
Abstract
Prion diseases in mammals are caused by a conformational transition of the cellular prion protein from its native conformation (PrPC ) to a pathological isoform called "prion protein scrapie" (PrPSc ). A molecular level of understanding of this conformational transition will be helpful in unveiling the disease etiology. Experimental structural biological techniques (NMR and X-ray crystallography) have been used to unravel the atomic level structural information for the prion and its binding partners. More than one hundred three-dimensional structures of the mammalian prions have been deposited in the protein databank. Structural studies on the prion protein and its structural transitions will deepen our understanding of the molecular basis of prion pathogenesis and will provide valuable guidance for future structure-based drug discovery endeavors.
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Affiliation(s)
- Pravas K Baral
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jiang Yin
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Michael N G James
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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14
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Ilie IM, Caflisch A. Simulation Studies of Amyloidogenic Polypeptides and Their Aggregates. Chem Rev 2019; 119:6956-6993. [DOI: 10.1021/acs.chemrev.8b00731] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Ioana M. Ilie
- Department of Biochemistry, University of Zürich, Zürich CH-8057, Switzerland
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zürich, Zürich CH-8057, Switzerland
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15
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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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16
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Gao Y, Zhu T, Zhang C, Zhang JZ, Mei Y. Comparison of the unfolding and oligomerization of human prion protein under acidic and neutral environments by molecular dynamics simulations. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Hnasko R, Lin A, McGarvey J, Stanker L. Enhanced detection of infectious prions by direct ELISA from the brains of asymptomatic animals using DRM2-118 monoclonal antibody and Gdn-HCl. J Immunol Methods 2018; 456:38-43. [PMID: 29462604 DOI: 10.1016/j.jim.2018.02.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/15/2017] [Accepted: 02/15/2018] [Indexed: 11/16/2022]
Abstract
In this report we describe the use of a novel anti-prion monoclonal antibody (DRM2-118) for the direct detection of infectious prions by ELISA. Epitope mapping using overlapping hamster (SHa) prion peptides indicates DRM2-118 binding occurs between residues 93-100 and at the 310-helix (residues 163-170) between alpha helix-A and -B. This antibody shows broad species binding to endogenous prions from brain homogenates and corresponding recombinant prion proteins. To evaluate the performance of this MAb for the detection of prion proteins we performed an animal time course and evaluated prion detection from both crude brain homogenates and lipid raft fractions (DRM) by direct ELISA. Prion detection was significantly enhanced by the addition of the chaotropic guanidine-HCl (Gdn-HCl) during protein immobilization with detection of PK-resistant prion from asymptomatic animal brains at (45-DPI) and from lipid rafts at (24-DPI). Our data demonstrates enhanced prion detection from brain lipid rafts of asymptomatic animals by a simple direct ELISA using the DRM2-118 MAb combined with Gdn-HCl.
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Affiliation(s)
- Robert Hnasko
- United States Department of Agriculture (USDA), Agriculture Research Service (ARS), Pacific West Area (PWA), Western Regional Research Center (WRRC), Produce Safety and Microbiology Research Unit (PSM), 800 Buchanan Street, Albany, CA 94710, United States.
| | - Alice Lin
- United States Department of Agriculture (USDA), Agriculture Research Service (ARS), Pacific West Area (PWA), Western Regional Research Center (WRRC), Produce Safety and Microbiology Research Unit (PSM), 800 Buchanan Street, Albany, CA 94710, United States
| | - Jeffery McGarvey
- United States Department of Agriculture (USDA), Agriculture Research Service (ARS), Pacific West Area (PWA), Western Regional Research Center (WRRC), Foodborne Toxin Detection and Prevention (FTDP), 800 Buchanan Street, Albany, CA 94710, United States
| | - Larry Stanker
- United States Department of Agriculture (USDA), Agriculture Research Service (ARS), Pacific West Area (PWA), Western Regional Research Center (WRRC), Foodborne Toxin Detection and Prevention (FTDP), 800 Buchanan Street, Albany, CA 94710, United States
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18
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Abstract
In transmissible spongiform encephalopathies (TSEs), which are lethal neurodegenerative diseases that affect humans and a wide range of other mammalian species, the normal "cellular" prion protein ([Formula: see text]) is transformed into amyloid aggregates representing the "scrapie form" of the protein ([Formula: see text]). Continued research on this system is of keen interest, since new information on the physiological function of [Formula: see text] in healthy organisms is emerging, as well as new data on the mechanism of the transformation of [Formula: see text] to [Formula: see text] In this paper we used two different approaches: a combination of the well-tempered ensemble (WTE) and parallel tempering (PT) schemes and metadynamics (MetaD) to characterize the conformational free-energy surface of [Formula: see text] The focus of the data analysis was on an 11-residue polypeptide segment in mouse [Formula: see text](121-231) that includes the [Formula: see text]2-[Formula: see text]2 loop of residues 167-170, for which a correlation between structure and susceptibility to prion disease has previously been described. This study includes wild-type mouse [Formula: see text] and a variant with the single-residue replacement Y169A. The resulting detailed conformational landscapes complement in an integrative manner the available experimental data on [Formula: see text], providing quantitative insights into the nature of the structural transition-related function of the [Formula: see text]2-[Formula: see text]2 loop.
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19
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Choi J, Govindaraj RG, Hyeon JW, Lee K, Ma S, Kim SY, Lee J, No KT. Structural insight into the antiprion compound inhibition mechanism of native prion folding over misfolding. Chem Biol Drug Des 2017; 89:907-917. [PMID: 27933736 DOI: 10.1111/cbdd.12916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 12/24/2022]
Abstract
Transition of a physiological folded prion (PrPC ) into a pathogenic misfolded prion (PrPSc ) causes lethal neurodegenerative disorders and prion diseases. Antiprion compounds have been developed to prevent this conversion; however, their mechanism of action remains unclear. Recently, we reported two antiprion compounds, BMD29 and BMD35, identified by in silico and in vitro screening. In this study, we used extensive explicit-solvent molecular dynamics simulations to investigate ligand-binding inhibition by antiprion compounds in prion folding over misfolding behavior at acidic pH. The two antiprion compounds and the previously reported GN8 compound resulted in a remarkably stabilized intermediate by binding to the hotspot region of PrPC , whereas free PrPC and the inactive compound BMD01 destabilized the structure of PrPC leading to the misfolded form. The results uncovered a secondary structural transition of free PrPC and transition suppression by the antiprion compounds. One of the major misfolding processes in PrPC , alternation of hydrophobic core residues, disruption of intramolecular interactions, and the increase in residue solvent exposure were significantly inhibited by both antiprion compounds. These findings provide insights into prion misfolding and inhibition by antiprion compounds.
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Affiliation(s)
- Jiwon Choi
- Bioinformatics and Molecular Design Research Center, Yonsei University, Seoul, Korea
| | - Rajiv Gandhi Govindaraj
- Bioinformatics and Molecular Design Research Center, Yonsei University, Seoul, Korea.,Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Jae Wook Hyeon
- Division of Zoonoses, Center for Immunology & Pathology, National Institute of Health, Korea Centers for Disease Control & Prevention, Seoul, Chungcheongbuk-do, Korea
| | - Kyungro Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - SongLing Ma
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Su Yeon Kim
- Division of Zoonoses, Center for Immunology & Pathology, National Institute of Health, Korea Centers for Disease Control & Prevention, Seoul, Chungcheongbuk-do, Korea
| | - Jeongmin Lee
- Division of Zoonoses, Center for Immunology & Pathology, National Institute of Health, Korea Centers for Disease Control & Prevention, Seoul, Chungcheongbuk-do, Korea
| | - Kyoung Tai No
- Bioinformatics and Molecular Design Research Center, Yonsei University, Seoul, Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
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20
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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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21
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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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22
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Pandini A, Fornili A. Using Local States To Drive the Sampling of Global Conformations in Proteins. J Chem Theory Comput 2016; 12:1368-79. [PMID: 26808351 PMCID: PMC5356493 DOI: 10.1021/acs.jctc.5b00992] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Conformational
changes associated with protein function often occur
beyond the time scale currently accessible to unbiased molecular dynamics
(MD) simulations, so that different approaches have been developed
to accelerate their sampling. Here we investigate how the knowledge
of backbone conformations preferentially adopted by protein fragments,
as contained in precalculated libraries known as structural alphabets
(SA), can be used to explore the landscape of protein conformations
in MD simulations. We find that (a) enhancing the sampling of native
local states in both metadynamics and steered MD simulations allows
the recovery of global folded states in small proteins; (b) folded
states can still be recovered when the amount of information on the
native local states is reduced by using a low-resolution version of
the SA, where states are clustered into macrostates; and (c) sequences
of SA states derived from collections of structural motifs can be
used to sample alternative conformations of preselected protein regions.
The present findings have potential impact on several applications,
ranging from protein model refinement to protein folding and design.
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Affiliation(s)
- Alessandro Pandini
- Department of Computer Science, College of Engineering, Design and Physical Sciences and Synthetic Biology Theme, Institute of Environment, Health and Societies, Brunel University London , Uxbridge UB8 3PH, United Kingdom
| | - Arianna Fornili
- School of Biological and Chemical Sciences, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
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23
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Blöchliger N, Caflisch A, Vitalis A. Weighted Distance Functions Improve Analysis of High-Dimensional Data: Application to Molecular Dynamics Simulations. J Chem Theory Comput 2015; 11:5481-92. [DOI: 10.1021/acs.jctc.5b00618] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicolas Blöchliger
- Department of Biochemistry, University of Zurich, Winterthurerstrasse
190, CH-8057 Zurich, Zurich, Switzerland
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse
190, CH-8057 Zurich, Zurich, Switzerland
| | - Andreas Vitalis
- Department of Biochemistry, University of Zurich, Winterthurerstrasse
190, CH-8057 Zurich, Zurich, Switzerland
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24
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Abstract
It was reported that buffalo is a low susceptibility species resisting to transmissible spongiform encephalopathies (TSEs) (same as rabbits, horses, and dogs). TSEs, also called prion diseases, are invariably fatal and highly infectious neurodegenerative diseases that affect a wide variety of species (except for rabbits, dogs, horses, and buffalo), manifesting as scrapie in sheep and goats; bovine spongiform encephalopathy (BSE or "mad-cow" disease) in cattle; chronic wasting disease in deer and elk; and Creutzfeldt-Jakob diseases, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, and Kulu in humans etc. In molecular structures, these neurodegenerative diseases are caused by the conversion from a soluble normal cellular prion protein (PrP(C)), predominantly with α-helices, into insoluble abnormally folded infectious prions (PrP(Sc)), rich in β-sheets. In this article, we studied the molecular structure and structural dynamics of buffalo PrP(C) (BufPrP(C)), in order to understand the reason why buffalo is resistant to prion diseases. We first did molecular modeling of a homology structure constructed by one mutation at residue 143 from the NMR structure of bovine and cattle PrP(124-227); immediately we found that for BufPrP(C)(124-227), there are five hydrogen bonds (HBs) at Asn143, but at this position, bovine/cattle do not have such HBs. Same as that of rabbits, dogs, or horses, our molecular dynamics studies also revealed there is a strong salt bridge (SB) ASP178-ARG164 (O-N) keeping the β2-α2 loop linked in buffalo. We also found there is a very strong HB SER170-TYR218 linking this loop with the C-terminal end of α-helix H3. Other information, such as (i) there is a very strong SB HIS187-ARG156 (N-O) linking α-helices H2 and H1 (if mutation H187R is made at position 187, then the hydrophobic core of PrP(C) will be exposed (L.H. Zhong (2010). Exposure of hydrophobic core in human prion protein pathogenic mutant H187R. Journal of Biomolecular Structure and Dynamics 28(3), 355-361)), (ii) at D178, there is a HB Y169-D178 and a polar contact R164-D178 for BufPrP(C) instead of a polar contact Q168-D178 for bovine PrP(C) (C.J. Cheng, & V. Daggett. (2014). Molecular dynamics simulations capture the misfolding of the bovine prion protein at acidic pH. Biomolecules 4(1), 181-201), (iii) BufPrP(C) owns three 310 helices at 125-127, 152-156, and in the β2-α2 loop, respectively, and (iv) in the β2-α2 loop, there is a strong π-π stacking and a strong π-cation F175-Y169-R164.(N)NH2, has been discovered.
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Affiliation(s)
- Jiapu Zhang
- a Molecular Model Discovery Laboratory, Faculty of Science, Engineering & Technology, Department of Chemistry & Biotechnology , Swinburne University of Technology , Hawthorn Campus, Hawthorn , Victoria 3122 , Australia.,b Faculty of Science, Graduate School of Sciences, Information Technology and Engineering & Centre of Informatics and Applied Optimisation , The Federation University Australia , Mount Helen Campus, Mount Helen, Ballarat , Victoria 3353 , Australia
| | - Feng Wang
- a Molecular Model Discovery Laboratory, Faculty of Science, Engineering & Technology, Department of Chemistry & Biotechnology , Swinburne University of Technology , Hawthorn Campus, Hawthorn , Victoria 3122 , Australia
| | - Subhojyoti Chatterjee
- a Molecular Model Discovery Laboratory, Faculty of Science, Engineering & Technology, Department of Chemistry & Biotechnology , Swinburne University of Technology , Hawthorn Campus, Hawthorn , Victoria 3122 , Australia
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25
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Blöchliger N, Xu M, Caflisch A. Peptide Binding to a PDZ Domain by Electrostatic Steering via Nonnative Salt Bridges. Biophys J 2015; 108:2362-70. [PMID: 25954893 PMCID: PMC4423040 DOI: 10.1016/j.bpj.2015.03.038] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 03/11/2015] [Accepted: 03/17/2015] [Indexed: 12/15/2022] Open
Abstract
We have captured the binding of a peptide to a PDZ domain by unbiased molecular dynamics simulations. Analysis of the trajectories reveals on-pathway encounter complex formation, which is driven by electrostatic interactions between negatively charged carboxylate groups in the peptide and positively charged side chains surrounding the binding site. In contrast, the final stereospecific complex, which matches the crystal structure, features completely different interactions, namely the burial of the hydrophobic side chain of the peptide C-terminal residue and backbone hydrogen bonds. The simulations show that nonnative salt bridges stabilize kinetically the encounter complex during binding. Unbinding follows the inverse sequence of events with the same nonnative salt bridges in the encounter complex. Thus, in contrast to protein folding, which is driven by native interactions, the binding of charged peptides can be steered by nonnative interactions, which might be a general mechanism, e.g., in the recognition of histone tails by bromodomains.
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Affiliation(s)
| | - Min Xu
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
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26
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Abstract
Prions cause neurodegenerative diseases for which no cure exists. Despite decades of research activities the function of the prion protein (PrP) in mammalians is not known. Moreover, little is known on the molecular mechanisms of the self-assembly of the PrP from its monomeric state (cellular PrP, PrP(C)) to the multimeric state. The latter state includes the toxic species (scrapie PrP, PrP(Sc)) knowledge of which would facilitate the development of drugs against prion diseases. Here we analyze the role of a tyrosine residue (Y169) which is strictly conserved in mammalian PrPs. Nuclear magnetic resonance (NMR) spectroscopy studies of many mammalian PrP(C) proteins have provided evidence of a conformational equilibrium between a 3(10)-helical turn and a type I β turn conformation in the β2-α2 loop (residues 165-175). In vitro cell-free experiments of the seeded conversion of PrP(C) indicate that non-aromatic residues at position 169 reduce the formation of proteinase K-resistant PrP. Recent molecular dynamics (MD) simulations of monomeric PrP and several single-point mutants show that Y169 stabilizes the 3(10)-helical turn conformation more than single-point mutants at position 169 or residues in contact with it. In the 3(10)-helical turn conformation the hydrophobic and aggregation-prone segment 169-YSNQNNF-175 is buried and thus not-available for self-assembly. From the combined analysis of simulation and experimental results it emerges that Y169 is an aggregation gatekeeper with a twofold role. Mutations related to 3 human prion diseases are interpreted on the basis of the gatekeeper role in the monomeric state. Another potential role of the Y169 side chain is the stabilization of the ordered aggregates, i.e., reduction of frangibility of filamentous protofibrils and fibrils, which is likely to reduce the generation of toxic species.
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Affiliation(s)
- Danzhi Huang
- Department of Biochemistry; University of Zurich; Zurich, Switzerland
- Correspondance to: Danzhi Huang; , Amedeo Caflisch;
| | - Amedeo Caflisch
- Department of Biochemistry; University of Zurich; Zurich, Switzerland
- Correspondance to: Danzhi Huang; , Amedeo Caflisch;
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