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Monti M, Milanetti E, Frans MT, Miotto M, Di Rienzo L, Baranov MV, Gosti G, Somavarapu AK, Nagaraj M, Golbek TW, Rossing E, Moons SJ, Boltje TJ, van den Bogaart G, Weidner T, Otzen DE, Tartaglia GG, Ruocco G, Roeters SJ. Two Receptor Binding Strategy of SARS-CoV-2 Is Mediated by Both the N-Terminal and Receptor-Binding Spike Domain. J Phys Chem B 2024; 128:451-464. [PMID: 38190651 PMCID: PMC10801686 DOI: 10.1021/acs.jpcb.3c06258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/06/2023] [Accepted: 12/21/2023] [Indexed: 01/10/2024]
Abstract
It is not well understood why severe acute respiratory syndrome (SARS)-CoV-2 spreads much faster than other β-coronaviruses such as SARS-CoV and Middle East respiratory syndrome (MERS)-CoV. In a previous publication, we predicted the binding of the N-terminal domain (NTD) of SARS-CoV-2 spike to sialic acids (SAs). Here, we experimentally validate this interaction and present simulations that reveal a second possible interaction between SAs and the spike protein via a binding site located in the receptor-binding domain (RBD). The predictions from molecular-dynamics simulations and the previously-published 2D-Zernike binding-site recognition approach were validated through flow-induced dispersion analysis (FIDA)─which reveals the capability of the SARS-CoV-2 spike to bind to SA-containing (glyco)lipid vesicles, and flow-cytometry measurements─which show that spike binding is strongly decreased upon inhibition of SA expression on the membranes of angiotensin converting enzyme-2 (ACE2)-expressing HEK cells. Our analyses reveal that the SA binding of the NTD and RBD strongly enhances the infection-inducing ACE2 binding. Altogether, our work provides in silico, in vitro, and cellular evidence that the SARS-CoV-2 virus utilizes a two-receptor (SA and ACE2) strategy. This allows the SARS-CoV-2 spike to use SA moieties on the cell membrane as a binding anchor, which increases the residence time of the virus on the cell surface and aids in the binding of the main receptor, ACE2, via 2D diffusion.
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Affiliation(s)
- Michele Monti
- RNA
Systems Biology, Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), Via Enrico Melen, 83, 16152 Genova, Italy
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
| | - Edoardo Milanetti
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
- Department
of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Myrthe T. Frans
- Molecular
Immunology—Groningen Biomolecular Sciences and Biotechnology, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Mattia Miotto
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
| | - Lorenzo Di Rienzo
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
| | - Maksim V. Baranov
- Molecular
Immunology—Groningen Biomolecular Sciences and Biotechnology, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Giorgio Gosti
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
- DHILab,
Istituto di Scienze del Patrimonio Culturale, Sede di Roma, Consiglio Nazionale delle Ricerche, Via Salaria km, 29300, 00010 Rome, Italy
| | - Arun Kumar Somavarapu
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Madhu Nagaraj
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Thaddeus W. Golbek
- Department
of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Emiel Rossing
- Synthetic
Organic Chemistry, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Sam J. Moons
- Synthetic
Organic Chemistry, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Thomas J. Boltje
- Synthetic
Organic Chemistry, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Molecular
Immunology—Groningen Biomolecular Sciences and Biotechnology, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Tobias Weidner
- Department
of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Daniel E. Otzen
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Gian Gaetano Tartaglia
- RNA
Systems Biology, Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), Via Enrico Melen, 83, 16152 Genova, Italy
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
| | - Giancarlo Ruocco
- Center
for Life Nanoscience, Istituto Italiano
di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
- Department
of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Steven J. Roeters
- Department
of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
- Amsterdam
UMC, Vrije Universiteit, Department of Anatomy
and Neurosciences, De
Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
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2
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Somavarapu AK, Kleijwegt G, Nagaraj M, Alam P, Nielsen J, Otzen DE. Drug repurposing screens identify compounds that inhibit α-synuclein oligomers' membrane disruption and block antibody interactions. Chem Sci 2023; 14:3030-3047. [PMID: 36937574 PMCID: PMC10016340 DOI: 10.1039/d2sc05534a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/21/2023] [Indexed: 02/25/2023] Open
Abstract
Small soluble oligomers of the protein α-synuclein (αSO) have been linked to disruptions in neuronal homeostasis, contributing to the development of Parkinson's Disease (PD). While this makes αSO an obvious drug target, the development of effective therapeutics against αSO is challenged by its low abundance and structural and morphological complexity. Here, we employ two different approaches to neutralize toxic interactions made by αSOs with different cellular components. First, we use available data to identify four neuronal proteins as likely candidates for αSO interactions, namely Cfl1, Uchl1, Sirt2 and SerRS. However, despite promising results when immobilized, all 4 proteins only bind weakly to αSO in solution in microfluidic assays, making them inappropriate for screening. In contrast, the formation of stable contacts formed between αSO and vesicles consisting of anionic lipids not only mimics a likely biological role of αSO but also provided a platform to screen two small molecule libraries for disruptors of these contacts. Of the 7 best leads obtained in this way, 2 significantly impaired αSO contacts with other proteins in a sandwich ELISA assay using αSO-binding monoclonal antibodies and nanobodies. In addition, 5 of these leads suppressed α-synuclein amyloid formation. Thus, a repurposing screening that directly targets a key culprit in PD pathogenesis shows therapeutic potential.
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Affiliation(s)
- Arun Kumar Somavarapu
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
| | - Giulia Kleijwegt
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
| | - Madhu Nagaraj
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
| | - Parvez Alam
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
| | - Janni Nielsen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University Gustav Wieds Vej 14, 8000 Aarhus C Denmark
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Farzadfard A, Pedersen JN, Meisl G, Somavarapu AK, Alam P, Goksøyr L, Nielsen MA, Sander AF, Knowles TPJ, Pedersen JS, Otzen DE. The C-terminal tail of α-synuclein protects against aggregate replication but is critical for oligomerization. Commun Biol 2022; 5:123. [PMID: 35145226 PMCID: PMC8831632 DOI: 10.1038/s42003-022-03059-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 01/18/2022] [Indexed: 12/16/2022] Open
Abstract
Aggregation of the 140-residue protein α-synuclein (αSN) is a key factor in the etiology of Parkinson’s disease. Although the intensely anionic C-terminal domain (CTD) of αSN does not form part of the amyloid core region or affect membrane binding ability, truncation or reduction of charges in the CTD promotes fibrillation through as yet unknown mechanisms. Here, we study stepwise truncated CTDs and identify a threshold region around residue 121; constructs shorter than this dramatically increase their fibrillation tendency. Remarkably, these effects persist even when as little as 10% of the truncated variant is mixed with the full-length protein. Increased fibrillation can be explained by a substantial increase in self-replication, most likely via fragmentation. Paradoxically, truncation also suppresses toxic oligomer formation, and oligomers that can be formed by chemical modification show reduced membrane affinity and cytotoxicity. These remarkable changes correlate to the loss of negative electrostatic potential in the CTD and highlight a double-edged electrostatic safety guard. Farzadfard et al. present a comprehensive analysis of a range of C-terminal truncations of aSN, linking the importance of high C-terminus charge for decreased fibrillation rates. The ability to formation oligomers, to disrupt synthetic vesicles and cell toxicity was reduced with truncated aSN, aiding in understanding of the intramolecular interactions of aSN which promote/inhibit aggregation.
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Affiliation(s)
- Azad Farzadfard
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark.,School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Jannik Nedergaard Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Georg Meisl
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Arun Kumar Somavarapu
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Parvez Alam
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark.,Department of Biomedicine, Aarhus University, 8000, Aarhus C, Denmark
| | - Louise Goksøyr
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Morten Agertoug Nielsen
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Adam Frederik Sander
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Tuomas P J Knowles
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.,Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark.,Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Daniel Erik Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark. .,Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000, Aarhus C, Denmark.
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4
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Otzen DE, Pedersen JN, Somavarapu AK, Clement A, Ji M, Petersen EH, Pedersen JS, Urban S, Schafer NP. Cys-labeling kinetics of membrane protein GlpG: a role for specific SDS binding and micelle changes? Biophys J 2021; 120:4115-4128. [PMID: 34370995 DOI: 10.1016/j.bpj.2021.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/20/2021] [Accepted: 08/03/2021] [Indexed: 01/01/2023] Open
Abstract
Empirically, α-helical membrane protein folding stability in surfactant micelles can be tuned by varying the mole fraction MFSDS of anionic (sodium dodecyl sulfate (SDS)) relative to nonionic (e.g., dodecyl maltoside (DDM)) surfactant, but we lack a satisfying physical explanation of this phenomenon. Cysteine labeling (CL) has thus far only been used to study the topology of membrane proteins, not their stability or folding behavior. Here, we use CL to investigate membrane protein folding in mixed DDM-SDS micelles. Labeling kinetics of the intramembrane protease GlpG are consistent with simple two-state unfolding-and-exchange rates for seven single-Cys GlpG variants over most of the explored MFSDS range, along with exchange from the native state at low MFSDS (which inconveniently precludes measurement of unfolding kinetics under native conditions). However, for two mutants, labeling rates decline with MFSDS at 0-0.2 MFSDS (i.e., native conditions). Thus, an increase in MFSDS seems to be a protective factor for these two positions, but not for the five others. We propose different scenarios to explain this and find the most plausible ones to involve preferential binding of SDS monomers to the site of CL (based on computational simulations) along with changes in size and shape of the mixed micelle with changing MFSDS (based on SAXS studies). These nonlinear impacts on protein stability highlights a multifaceted role for SDS in membrane protein denaturation, involving both direct interactions of monomeric SDS and changes in micelle size and shape along with the general effects on protein stability of changes in micelle composition.
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Affiliation(s)
- Daniel E Otzen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark.
| | - Jannik Nedergaard Pedersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Arun Kumar Somavarapu
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Anders Clement
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Ming Ji
- Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Emil Hartvig Petersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark; Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Sinisa Urban
- Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nicholas P Schafer
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
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5
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van Diggelen F, Frank SA, Somavarapu AK, Scavenius C, Apetri MM, Nielsen J, Tepper AWJW, Enghild JJ, Otzen DE. The interactome of stabilized α-synuclein oligomers and neuronal proteins. FEBS J 2019; 287:2037-2054. [PMID: 31686426 DOI: 10.1111/febs.15124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 08/21/2019] [Accepted: 11/04/2019] [Indexed: 12/11/2022]
Abstract
While it is generally accepted that α-synuclein oligomers (αSOs) play an important role in neurodegeneration in Parkinson's disease, the basis for their cytotoxicity remains unclear. We have previously shown that docosahexaenoic acid (DHA) stabilizes αSOs against dissociation without compromising their ability to colocalize with glutamatergic synapses of primary hippocampal neurons, suggesting that they bind to synaptic proteins. Here, we develop a proteomic screen for putative αSO binding partners in rat primary neurons using DHA-stabilized human αSOs as a bait protein. The protocol involved co-immunoprecipitation in combination with a photoactivatable heterobifunctional sulfo-LC-SDA crosslinker which did not compromise neuronal binding and preserved the interaction between the αSOs-binding partners. We identify in total 29 proteins associated with DHA-αSO of which eleven are membrane proteins, including synaptobrevin-2B (VAMP-2B), the sodium-potassium pump (Na+ /K+ ATPase), the V-type ATPase, the voltage-dependent anion channel and calcium-/calmodulin-dependent protein kinase type II subunit gamma; only these five hits were also found in previous studies which used unmodified αSOs as bait. We also identified Rab-3A as a target with likely disease relevance. Three out of four selected hits were subsequently validated with dot-blot binding assays. In addition, likely binding sites on these ligands were identified by computational analysis, highlighting a diversity of possible interactions between αSOs and target proteins. These results constitute an important step in the search for disease-modifying treatments targeting toxic αSOs.
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Affiliation(s)
- Femke van Diggelen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Denmark.,Crossbeta Biosciences AB, Utrecht, the Netherlands
| | - Signe Andrea Frank
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Denmark
| | | | - Carsten Scavenius
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | | | | | | | - Jan J Enghild
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Denmark
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Abstract
γ-Secretase produces β-amyloid (Aβ) within its presenilin (PS1) subunit, mutations in which cause Alzheimer's disease, and current therapies thus seek to modulate its activity. While the general structure is known from recent electron microscopy studies, direct loop and membrane interactions and explicit dynamics relevant to substrate processing remain unknown. We report a modeled structure utilizing the optimal multitemplate information available, including loops and missing side chains, account of maturation cleavage, and explicit all-atom molecular dynamics in the membrane. We observe three distinct conformations of γ-secretase (open, semiopen, and closed) that remarkably differ by tilting of helices 2 and 3 of PS1, directly controlling active site availability. The large hydrophilic loop of PS1 where maturation occurs reveals a new helix segment that parallels the likely helix character of other substrates. The semiopen conformation consistently shows the best fit of Aβ peptides, that is, longer residence before release and by inference more trimming. In contrast, the closed, hydrophobic conformation is largely inactive and the open conformation is active but provides fewer optimal interactions and induces shorter residence time and by inference releases Aβ peptides of longer lengths. Our simulations thus provide a molecular basis for substrate processing and changes in the Aβ42/Aβ40 ratio. Accordingly, selective binding to protect the semiopen "innocent" conformation provides a molecular recipe for effective γ-secretase modulators; we provide the full atomic structures for these states that may play a key role in developing selective γ-secretase modulators for treatment of Alzheimer's disease.
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Affiliation(s)
| | - Kasper P. Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark
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7
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Somavarapu AK, Kepp KP. Loss of stability and hydrophobicity of presenilin 1 mutations causing Alzheimer's disease. J Neurochem 2016; 137:101-11. [PMID: 26756738 DOI: 10.1111/jnc.13535] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/23/2015] [Accepted: 12/29/2015] [Indexed: 12/15/2022]
Abstract
Nearly 200 mutations in the gene coding for presenilin 1 (PSEN1) cause early-onset Alzheimer's disease, yet the molecular mechanism remains obscure. As a meta-analysis, we compiled available clinical and biochemical data for PSEN1 variants and correlated these to chemical properties of the mutants. We found statistically significant relationships between relative Aβ42 levels and clinical age of onset. We then computed chemical properties of the mutants from a variety of computational chemistry tools. Relative Aβ42 levels correlated significantly (95% confidence or more from p-values of linear regression) with loss of hydrophobicity for four different regression analyses (squared correlation coefficient of linear regression R(2) of 0.41-0.53) and with increased polarity (R(2) = 0.47, 0.59) and loss of protein stability (R(2) = 0.39, 0.63) for two independent data sets. Age of onset of patients carrying PSEN1 variants correlated with increased polarity (R(2) = 0.49, 0.40) and loss of stability (R(2) = 0.75, 0.44) of the protein for both data sets. These relations suggest that mutants impair the membrane-associated structural integrity of presenilin by reducing hydrophobic membrane association and overall protein stability. This explains why the many mutations that spread out across the protein and far from the catalytic aspartates can cause disease. The identified molecular determinants of clinical age of symptom onset may be relevant to future presenilin-modulating therapies specifically directed towards increasing the structural integrity and packing of the protein. Close to 200 mutations in presenilin 1 (PSEN1) cause Alzheimer's disease, but the biochemical relating these to disease remains debated. The chemical properties of PSEN1 variants were computed and correlated against clinical age of symptom onset. Loss of stability and hydrophobicity and gain of polarity relate to disease onset, suggesting that mutants impair the membrane structure of PSEN1 and that therapies should increase PSEN1 structural integrity.
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Affiliation(s)
| | - Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, Kongens Lyngby, Denmark
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8
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Somavarapu AK, Kepp KP. The dynamic mechanism of presenilin-1 function: Sensitive gate dynamics and loop unplugging control protein access. Neurobiol Dis 2016; 89:147-56. [PMID: 26852951 DOI: 10.1016/j.nbd.2016.02.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/02/2016] [Accepted: 02/03/2016] [Indexed: 12/20/2022] Open
Abstract
There is no molecular explanation for the many presenilin 1 (PSEN1) mutations causing Alzheimer's disease, but both gain of function relating to amyloid production and loss of isolated PSEN1 function have been implied. We report here the first detailed dynamic all-atom model of mature PSEN1 from molecular dynamics in an explicit membrane with particular account of the as yet unexplored loop dynamics. We find that mature PSEN1 contains multiple distinct conformational states whereas non-mature PSEN1 is a typical one-state protein. We confirm a previously suggested gating mechanism, and find that the 106-131 loop acts as a "hinge" for the TM2 and TM6 "doors". More importantly, we identify an unplugging mechanism of the Exon 9 loop associated only with mature PSEN1. Proper opening of both the "gate" and "plug" in the membrane produces channel-like morphologies and access to the catalytic aspartates. Dynamically, these features seem linked. The long-range sensitivity of this gate-plug system to subtle conformational changes can explain why so many PSEN1 mutants cause disease. Reduced access and imprecise substrate cleavage associated with impaired gate-plug dynamics is directly illustrated by the effect of maturation in our work and could explain the overall reduction in Aβ levels upon PSEN1 mutation and the increase in the Aβ 42/40 ratio. Yet, our PSEN1-only dynamics are particularly insightful in revealing PSEN1-only dynamics relating to e.g. its role as membrane channel. Thus, our identified gate-plug mechanism is relevant for designing PSEN1 modulating therapies for treatment of Alzheimer's disease within both the amyloid/γ-secretase hypothesis and within the PSEN1 loss of function paradigm.
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Affiliation(s)
| | - Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark.
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Abstract
We report a systematic analysis of conformational ensembles generated from multiseed molecular dynamics simulations of all 15 known genetic variants of Aβ42. We show that experimentally determined variant toxicities are largely explained by random coil content of the amyloid ensembles (correlation with smaller EC50 values; R(2) = 0.54, p = 0.01), and to some extent the helix character (more helix-character is less toxic, R(2) = 0.32, p = 0.07) and hydrophobic surface (R(2) = 0.37, p = 0.04). Our findings suggest that qualitative structural features of the amyloids, rather than the quantitative levels, are fundamentally related to neurodegeneration. The data provide molecular explanations for the high toxicity of E22 variants and for the protective features of the recently characterized A2T variant. The identified conformational features, for example, the local helix-coil-strand transitions of the C-terminals of the peptides, are of likely interest in the direct targeting of amyloids by rational drug design.
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Affiliation(s)
- Arun Kumar Somavarapu
- DTU Chemistry, Technical University of Denmark, Kemiorvet 206, DK-2800 Kongens Lyngby, Denmark
| | - Kasper P. Kepp
- DTU Chemistry, Technical University of Denmark, Kemiorvet 206, DK-2800 Kongens Lyngby, Denmark
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Nanduri R, Bhutani I, Somavarapu AK, Mahajan S, Parkesh R, Gupta P. ONRLDB--manually curated database of experimentally validated ligands for orphan nuclear receptors: insights into new drug discovery. Database (Oxford) 2015; 2015:bav112. [PMID: 26637529 PMCID: PMC4669993 DOI: 10.1093/database/bav112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 10/30/2015] [Indexed: 12/26/2022]
Abstract
Orphan nuclear receptors are potential therapeutic targets. The Orphan Nuclear Receptor Ligand Binding Database (ONRLDB) is an interactive, comprehensive and manually curated database of small molecule ligands targeting orphan nuclear receptors. Currently, ONRLDB consists of ∼11 000 ligands, of which ∼6500 are unique. All entries include information for the ligand, such as EC50 and IC50, number of aromatic rings and rotatable bonds, XlogP, hydrogen donor and acceptor count, molecular weight (MW) and structure. ONRLDB is a cross-platform database, where either the cognate small molecule modulators of a receptor or the cognate receptors to a ligand can be searched. The database can be searched using three methods: text search, advanced search or similarity search. Substructure search, cataloguing tools, and clustering tools can be used to perform advanced analysis of the ligand based on chemical similarity fingerprints, hierarchical clustering, binning partition and multidimensional scaling. These tools, together with the Tree function provided, deliver an interactive platform and a comprehensive resource for identification of common and unique scaffolds. As demonstrated, ONRLDB is designed to allow selection of ligands based on various properties and for designing novel ligands or to improve the existing ones. Database URL:http://www.onrldb.org/
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Affiliation(s)
| | | | | | | | | | - Pawan Gupta
- Corresponding author: Tel: +91 1726665221; Fax: +91 1722690585;
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Abstract
We studied the dynamics of Aβ40 , involved in Alzheimer's disease, by using 21 methods combined from Amber03, Amber99sb-ILDN, Charmm27, Charmm22*, OPLS-2001, OPLS-2006, OPLS-2008, Gromos96-43a1, Gromos96-53a6, Gromos96-54a7, and the water models SPC, TIP3P, TIP4P. Major differences in the structural ensembles were systematized: Amber03, Charmm27, and Gromos96-54a7 stabilize the helices; Gromos96-43a1 and Gromos53a6 favor the β-strands (with Charmm22* and Amber99sb-ILDN in between), and OPLS produces unstructured ensembles. The accuracy of the NMR chemical shifts was in the order: Charmm22*>Amber99sb-ILDN>OPLS-2008≈Gromos96-43a1>Gromos96-54a7≈OPLS-2001>OPLS-2006>Gromos96-53a6>Charmm27>Amber03. The computed (3) JHNHα -coupling constants were sensitive to experiment type and Karplus parameterization. Overall, the ensembles of Charmm22* and Amber99sb-ILDN provided the best agreement with experimental NMR and circular dichroism data, providing a model for the real Aβ monomer ensemble. Also, the polar water model TIP3P significantly favored helix and compact conformations.
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Affiliation(s)
| | - Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800, Kongens Lyngby, Denmark.
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12
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Dkhar HK, Nanduri R, Mahajan S, Dave S, Saini A, Somavarapu AK, Arora A, Parkesh R, Thakur KG, Mayilraj S, Gupta P. Mycobacterium tuberculosis keto-mycolic acid and macrophage nuclear receptor TR4 modulate foamy biogenesis in granulomas: a case of a heterologous and noncanonical ligand-receptor pair. J Immunol 2014; 193:295-305. [PMID: 24907344 DOI: 10.4049/jimmunol.1400092] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The cell wall of Mycobacterium tuberculosis is configured of bioactive lipid classes that are essential for virulence and potentially involved in the formation of foamy macrophages (FMs) and granulomas. Our recent work established crosstalk between M. tuberculosis cell wall lipids and the host lipid-sensing nuclear receptor TR4. In this study, we have characterized, identified, and adopted a heterologous ligand keto-mycolic acid from among M. tuberculosis lipid repertoire for the host orphan NR TR4. Crosstalk between cell wall lipids and TR4 was analyzed by transactivation and promoter reporter assays. Mycolic acid (MA) was found to transactivate TR4 significantly compared with other cell wall lipids. Among the MA, the oxygenated form, keto-MA, was responsible for transactivation, and the identity was validated by TR4 binding assays followed by TLC and nuclear magnetic resonance. Isothermal titration calorimetry revealed that keto-MA binding to TR4 is energetically favorable. This keto-MA-TR4 axis seems to be essential to this oxygenated MA induction of FMs and granuloma formation as evaluated by in vitro and in vivo model of granuloma formation. TR4 binding with keto-MA features a unique association of host nuclear receptor with a bacterial lipid and adds to the presently known ligand repertoire beyond dietary lipids. Pharmacologic modulation of this heterologous axis may hold promise as an adjunct therapy to frontline tuberculosis drugs.
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Affiliation(s)
- Hedwin Kitdorlang Dkhar
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Ravikanth Nanduri
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Sahil Mahajan
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Sandeep Dave
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Ankita Saini
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Arun Kumar Somavarapu
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Ashish Arora
- Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow 226031, India
| | - Raman Parkesh
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Krishan Gopal Thakur
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Shanmugam Mayilraj
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
| | - Pawan Gupta
- Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh 160036, India; and
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13
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Somavarapu AK, Balakrishnan S, Gautam AKS, Palmer DS, Venkatraman P. Structural interrogation of phosphoproteome identified by mass spectrometry reveals allowed and disallowed regions of phosphoconformation. BMC Struct Biol 2014; 14:9. [PMID: 24618394 PMCID: PMC4007652 DOI: 10.1186/1472-6807-14-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 03/04/2014] [Indexed: 12/22/2022]
Abstract
Background High-throughput mass spectrometric (HT-MS) study is the method of choice for monitoring global changes in proteome. Data derived from these studies are meant for further validation and experimentation to discover novel biological insights. Here we evaluate use of relative solvent accessible surface area (rSASA) and DEPTH as indices to assess experimentally determined phosphorylation events deposited in PhosphoSitePlus. Results Based on accessibility, we map these identifications on allowed (accessible) or disallowed (inaccessible) regions of phosphoconformation. Surprisingly a striking number of HT-MS/MS derived events (1461/5947 sites or 24.6%) are present in the disallowed region of conformation. By considering protein dynamics, autophosphorylation events and/or the sequence specificity of kinases, 13.8% of these phosphosites can be moved to the allowed region of conformation. We also demonstrate that rSASA values can be used to increase the confidence of identification of phosphorylation sites within an ambiguous MS dataset. Conclusion While MS is a stand-alone technique for the identification of vast majority of phosphorylation events, identifications within disallowed region of conformation will benefit from techniques that independently probe for phosphorylation and protein dynamics. Our studies also imply that trapping alternate protein conformations may be a viable alternative to the design of inhibitors against mutation prone drug resistance kinases.
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Affiliation(s)
| | | | | | | | - Prasanna Venkatraman
- Protein Interactome Lab for Structural and Functional Biology, Advanced Center for Treatment Research and Education in Cancer, Tata Memorial Centre, Kharghar, Navi Mumbai, Maharashtra 410210, India.
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14
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Ramteke MP, Shelke P, Ramamoorthy V, Somavarapu AK, Gautam AKS, Nanaware PP, Karanam S, Mukhopadhyay S, Venkatraman P. Identification of a novel ATPase activity in 14-3-3 proteins--evidence from enzyme kinetics, structure guided modeling and mutagenesis studies. FEBS Lett 2013; 588:71-8. [PMID: 24269678 DOI: 10.1016/j.febslet.2013.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/16/2013] [Accepted: 11/05/2013] [Indexed: 12/21/2022]
Abstract
14-3-3 Proteins bind phosphorylated sequences in proteins and regulate multiple cellular functions. For the first time, we show that pure recombinant human 14-3-3 ζ, γ, ε and τ isofoms hydrolyze ATP with similar Km and kcat values. In sharp contrast the sigma isoform has no detectable activity. Docking studies identify two putative binding pockets in 14-3-3 zeta. Mutation of D124A in the amphipathic pocket enhances binding affinity and catalysis. Mutation of a critical Arg (R55A) at the dimer interface in zeta reduces binding and decreases catalysis. These experimental results coincide with a binding pose at the dimer interface. This newly identified function could be a moon lighting function in some of these isoforms.
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Affiliation(s)
- Manoj P Ramteke
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Pradnya Shelke
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Vidhya Ramamoorthy
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Arun Kumar Somavarapu
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Amit Kumar Singh Gautam
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Padma P Nanaware
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India
| | - Sudheer Karanam
- Vlife Sciences Technologies Pvt. Ltd., 2nd Floor, Plot No-05, Ram Indu Park, Baner Road, Pune 411045, India
| | - Sami Mukhopadhyay
- Vlife Sciences Technologies Pvt. Ltd., 2nd Floor, Plot No-05, Ram Indu Park, Baner Road, Pune 411045, India
| | - Prasanna Venkatraman
- Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Kharghar, Navi Mumbai 410210, India.
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