1
|
Computational Study of HCV p7 Channel: Insight into a New Strategy for HCV Inhibitor Design. Interdiscip Sci 2018; 11:292-299. [PMID: 30194627 DOI: 10.1007/s12539-018-0306-3] [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: 05/07/2018] [Revised: 07/23/2018] [Accepted: 09/03/2018] [Indexed: 10/28/2022]
Abstract
HCV p7 protein is a cation-selective ion channel, playing an essential role during the life cycle of HCV viruses. To understand the cation-selective mechanism, we constructed a hexameric model in lipid bilayers of HCV p7 protein for HCB JFH-1 strain, genotype 2a. In this structural model, His9 and Val6 were key factors for the HCV cation-selective ion channel. The histidine residues at position 9 in the hexameric model formed a first gate for HCV p7 channel, acting as a selectivity filter for cations. The valines mentioned above formed a second gate for HCV p7 channel, serving as a hydrophobic filter for the dehydrated cations. The binding pocket for the channel blockers, e.g., amantadine and rimantadine, was composed of residues 20-26 in H2 helix and 52-60 in H3 helix in i + 2 monomer. However, the molecular volumes for both amantadine and rimantadine were too small for the binding pocket of HCV p7 channel. Thus, designing a compound similar with rimantadine and having much larger volume would be an effective strategy for discovering inhibitors against HCV p7 channel. To achieve this point, we used rimantadine as a structural template to search ChEMBL database for the candidates employing favorable binding affinities to HCV p7 channel. As a result, six candidates were identified to have potential to be novel inhibitors against HCV p7 channel.
Collapse
|
2
|
Laasch N, Kalita MM, Griffin S, Fischer WB. Small molecule ligand docking to genotype specific bundle structures of hepatitis C virus (HCV) p7 protein. Comput Biol Chem 2016; 64:56-63. [PMID: 27258799 DOI: 10.1016/j.compbiolchem.2016.04.010] [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: 07/21/2015] [Accepted: 04/28/2016] [Indexed: 01/26/2023]
Abstract
The genome of hepatitis C virus encodes for an essential 63 amino acid polytopic protein p7 of most likely two transmembrane domains (TMDs). The protein is identified to self-assemble thereby rendering lipid membranes permeable to ions. A series of small molecules such as adamantanes, imino sugars and guanidinium compounds are known to interact with p7. A set of 9 of these small molecules is docked against hexameric bundles of genotypes 5a (bundle-5a) and 1b (bundle-1b) using LeadIT. Putative sites for bundle-5a are identified within the pore and at pockets on the outside of the bundle. For bundle-1b preferred sites are found at the site of the loops. Binding energies are in favour of the guanidinium compounds. Rescoring of the identified poses with HYDE reveals a dehydration penalty for the guanidinium compounds, leaving the adamantanes and imino sugar in a better position. Binding energies calculated by HYDE and those by LeadIT indicate that all compounds are moderate binders.
Collapse
Affiliation(s)
- Niklas Laasch
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Monoj Mon Kalita
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Stephen Griffin
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan
| | - Wolfgang B Fischer
- Institute of Biophotonics, School of Biomedical Science and Engineering, and Biophotonics & Molecular Imaging Research Center (BMIRC), National Yang-Ming University, Taipei 112, Taiwan.
| |
Collapse
|
3
|
Abstract
Since the discovery that certain small viral membrane proteins, collectively termed as viroporins, can permeabilize host cellular membranes and also behave as ion channels, attempts have been made to link this feature to specific biological roles. In parallel, most viroporins identified so far are virulence factors, and interest has focused toward the discovery of channel inhibitors that would have a therapeutic effect, or be used as research tools to understand the biological roles of viroporin ion channel activity. However, this paradigm is being shifted by the difficulties inherent to small viral membrane proteins, and by the realization that protein-protein interactions and other diverse roles in the virus life cycle may represent an equal, if not, more important target. Therefore, although targeting the channel activity of viroporins can probably be therapeutically useful in some cases, the focus may shift to their other functions in following years. Small-molecule inhibitors have been mostly developed against the influenza A M2 (IAV M2 or AM2). This is not surprising since AM2 is the best characterized viroporin to date, with a well-established biological role in viral pathogenesis combined the most extensive structural investigations conducted, and has emerged as a validated drug target. For other viroporins, these studies are still mostly in their infancy, and together with those for AM2, are the subject of the present review.
Collapse
|
4
|
Soranzo T, Cortès S, Gilde F, Kreir M, Picart C, Lenormand JL. Functional characterization of p7 viroporin from hepatitis C virus produced in a cell-free expression system. Protein Expr Purif 2015; 118:83-91. [PMID: 26477501 DOI: 10.1016/j.pep.2015.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/21/2015] [Accepted: 10/09/2015] [Indexed: 01/05/2023]
Abstract
Using a cell-free expression system we produced the p7 viroporin embedded into a lipid bilayer in a single-step manner. The protein quality was assessed using different methods. We examined the channel forming activity of p7 and verified its inhibition by 5-(N,N-Hexamethylene) amiloride (HMA). Fourier transformed infrared spectroscopy (FTIR) experiments further showed that when p7 was inserted into synthetic liposomes, the protein displayed a native-like conformation similar to p7 obtained from other sources. Photoactivable amino acid analogs used for p7 protein synthesis enabled oligomerization state analysis in liposomes by cross-linking. Therefore, these findings emphasize the quality of the cell-free produced p7 proteoliposomes which can benefit the field of the hepatitis C virus (HCV) protein production and characterization and also provide tools for the development of new inhibitors to reinforce our therapeutic arsenal against HCV.
Collapse
Affiliation(s)
- Thomas Soranzo
- Synthelis SAS, 5 avenue du Grand Sablon, 38700, La Tronche, France; TheREx Laboratory, TIMC-IMAG, UMR 5525, CNRS /UJF, University Joseph Fourier, UFR de Médecine, 38706, La Tronche, France
| | - Sandra Cortès
- Synthelis SAS, 5 avenue du Grand Sablon, 38700, La Tronche, France
| | - Flora Gilde
- CNRS, UMR 5628 (LMGP), 3 parvis Louis Néel, 38016, Grenoble, France; University of Grenoble Alpes, Grenoble Institute of Technology, 38016, Grenoble, France
| | - Mohamed Kreir
- Nanion Technologies GmbH, Gabrielenstraβe 9, 80636, Munich, Germany
| | - Catherine Picart
- CNRS, UMR 5628 (LMGP), 3 parvis Louis Néel, 38016, Grenoble, France; University of Grenoble Alpes, Grenoble Institute of Technology, 38016, Grenoble, France
| | - Jean-Luc Lenormand
- TheREx Laboratory, TIMC-IMAG, UMR 5525, CNRS /UJF, University Joseph Fourier, UFR de Médecine, 38706, La Tronche, France.
| |
Collapse
|
5
|
Structural and Functional Properties of the Hepatitis C Virus p7 Viroporin. Viruses 2015; 7:4461-81. [PMID: 26258788 PMCID: PMC4576187 DOI: 10.3390/v7082826] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 12/13/2022] Open
Abstract
The high prevalence of hepatitis C virus (HCV) infection in the human population has triggered intensive research efforts that have led to the development of curative antiviral therapy. Moreover, HCV has become a role model to study fundamental principles that govern the replication cycle of a positive strand RNA virus. In fact, for most HCV proteins high-resolution X-ray and NMR (Nuclear Magnetic Resonance)-based structures have been established and profound insights into their biochemical and biological properties have been gained. One example is p7, a small hydrophobic protein that is dispensable for RNA replication, but crucial for the production and release of infectious HCV particles from infected cells. Owing to its ability to insert into membranes and assemble into homo-oligomeric complexes that function as minimalistic ion channels, HCV p7 is a member of the viroporin family. This review compiles the most recent findings related to the structure and dual pore/ion channel activity of p7 of different HCV genotypes. The alternative conformations and topologies proposed for HCV p7 in its monomeric and oligomeric state are described and discussed in detail. We also summarize the different roles p7 might play in the HCV replication cycle and highlight both the ion channel/pore-like function and the additional roles of p7 unrelated to its channel activity. Finally, we discuss possibilities to utilize viroporin inhibitors for antagonizing p7 ion channel/pore-like activity.
Collapse
|
6
|
Atoom AM, Taylor NGA, Russell RS. The elusive function of the hepatitis C virus p7 protein. Virology 2014; 462-463:377-87. [PMID: 25001174 PMCID: PMC7112009 DOI: 10.1016/j.virol.2014.04.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/07/2014] [Accepted: 04/11/2014] [Indexed: 12/12/2022]
Abstract
Hepatitis C virus (HCV) is a major global health burden with 2–3% of the world׳s population being chronically infected. Persistent infection can lead to cirrhosis and hepatocellular carcinoma. Recently available treatment options show enhanced efficacy of virus clearance, but are associated with resistance and significant side effects. This warrants further research into the basic understanding of viral proteins and their pathophysiology. The p7 protein of HCV is an integral membrane protein that forms an ion-channel. The role of p7 in the HCV life cycle is presently uncertain, but most of the research performed to date highlights its role in the virus assembly process. The aim of this review is to provide an overview of the literature investigating p7, its structural and functional details, and to summarize the developments to date regarding potential anti-p7 compounds. A better understanding of this protein may lead to development of a new and effective therapy. This review paper provides an overview of the literature investigating HCV. The content focuses on p7 structural and functional details. We summarize the developments to date regarding potential anti-p7 compounds.
Collapse
Affiliation(s)
- Ali M Atoom
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada
| | - Nathan G A Taylor
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada
| | - Rodney S Russell
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University, Newfoundland, St. John׳s, Canada.
| |
Collapse
|
7
|
Foster TL, Thompson GS, Kalverda AP, Kankanala J, Bentham M, Wetherill LF, Thompson J, Barker AM, Clarke D, Noerenberg M, Pearson AR, Rowlands DJ, Homans SW, Harris M, Foster R, Griffin S. Structure-guided design affirms inhibitors of hepatitis C virus p7 as a viable class of antivirals targeting virion release. Hepatology 2014; 59:408-22. [PMID: 24022996 PMCID: PMC4298801 DOI: 10.1002/hep.26685] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 08/07/2013] [Indexed: 01/02/2023]
Abstract
UNLABELLED Current interferon-based therapy for hepatitis C virus (HCV) infection is inadequate, prompting a shift toward combinations of direct-acting antivirals (DAA) with the first protease-targeted drugs licensed in 2012. Many compounds are in the pipeline yet primarily target only three viral proteins, namely, NS3/4A protease, NS5B polymerase, and NS5A. With concerns growing over resistance, broadening the repertoire for DAA targets is a major priority. Here we describe the complete structure of the HCV p7 protein as a monomeric hairpin, solved using a novel combination of chemical shift and nuclear Overhauser effect (NOE)-based methods. This represents atomic resolution information for a full-length virus-coded ion channel, or "viroporin," whose essential functions represent a clinically proven class of antiviral target exploited previously for influenza A virus therapy. Specific drug-protein interactions validate an allosteric site on the channel periphery and its relevance is demonstrated by the selection of novel, structurally diverse inhibitory small molecules with nanomolar potency in culture. Hit compounds represent a 10,000-fold improvement over prototypes, suppress rimantadine resistance polymorphisms at submicromolar concentrations, and show activity against other HCV genotypes. CONCLUSION This proof-of-principle that structure-guided design can lead to drug-like molecules affirms p7 as a much-needed new target in the burgeoning era of HCV DAA.
Collapse
Affiliation(s)
- Toshana L Foster
- Leeds Institute of Cancer & Pathology & CRUK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of LeedsLeeds, West Yorkshire, UK,School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Gary S Thompson
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Arnout P Kalverda
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Jayakanth Kankanala
- School of Chemistry, Faculty of Mathematics and Physical Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Matthew Bentham
- Leeds Institute of Cancer & Pathology & CRUK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of LeedsLeeds, West Yorkshire, UK
| | - Laura F Wetherill
- Leeds Institute of Cancer & Pathology & CRUK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of LeedsLeeds, West Yorkshire, UK
| | - Joseph Thompson
- School of Chemistry, Faculty of Mathematics and Physical Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Amy M Barker
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Dean Clarke
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Marko Noerenberg
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Arwen R Pearson
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - David J Rowlands
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Steven W Homans
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Mark Harris
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| | - Richard Foster
- School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK,School of Chemistry, Faculty of Mathematics and Physical Sciences, University of LeedsLeeds, West Yorkshire, UK,Address reprint requests to: Stephen Griffin, Leeds Institute of Cancer & Pathology & CRUK Clinical Centre, Faculty of Medicine and Health, St. James’ University Hospital, University of Leeds, Beckett St., Leeds, West Yorkshire, LS9 7TF, UK. E-mail: ; fax: (+44)113 3438501
| | - Stephen Griffin
- Leeds Institute of Cancer & Pathology & CRUK Clinical Centre, Faculty of Medicine and Health, St James’ University Hospital, University of LeedsLeeds, West Yorkshire, UK,School of Molecular & Cellular Biology & Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of LeedsLeeds, West Yorkshire, UK
| |
Collapse
|
8
|
Atoom AM, Jones DM, Russell RS. Evidence suggesting that HCV p7 protects E2 glycoprotein from premature degradation during virus production. Virus Res 2013; 176:199-210. [PMID: 23816605 DOI: 10.1016/j.virusres.2013.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 06/14/2013] [Accepted: 06/20/2013] [Indexed: 10/26/2022]
Abstract
The hepatitis C virus (HCV) genome encodes a 63 amino acid (aa) protein, p7, which is located between the structural and non-structural proteins. p7 localizes to endoplasmic reticulum membranes and is composed of two transmembrane domains (TM1 and TM2) and a cytoplasmic loop. While its exact role is unknown, p7 is crucial for assembly and/or release of infectious virus production in cell culture, as well as infectivity in chimpanzees. The contribution of p7 to the HCV life cycle may result from at least two distinct roles. Firstly, several studies have shown that p7 acts as an ion channel, the functionality of which is critical for infection. Secondly, p7 interacts with NS2 in a manner that may regulate the targeting of other structural proteins during the assembly process. In this study, we observed that mutations in TM1 and the cytoplasmic loop of p7 decreased infectious virus production in a single-cycle virus production assay. Analysis of intra- and extracellular virus titers indicated that p7 functions at a stage prior to generation of infectious particles. These effects were not due to altered RNA replication since no effects on levels of NS3 or NS5A protein were observed, and were not a consequence of altered recruitment of core protein to lipid droplets. Similarly, these mutations seemingly did not prevent nucleocapsid oligomerization. Importantly, we found that an alanine triplet substitution including the two basic residues of the cytoplasmic loop, which is integral to p7 ion channel function, significantly reduced E2 glycoprotein levels. A time course experiment tracking E2 levels indicated that E2 was degraded over time, as opposed to being synthesized in reduced quantities. The results of this study provide strong evidence that one of the functions of p7 is to protect HCV glycoproteins from premature degradation during virion morphogenesis.
Collapse
Affiliation(s)
- Ali M Atoom
- Immunology and Infectious Diseases, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | | | | |
Collapse
|
9
|
Chandler DE, Penin F, Schulten K, Chipot C. The p7 protein of hepatitis C virus forms structurally plastic, minimalist ion channels. PLoS Comput Biol 2012; 8:e1002702. [PMID: 23028296 PMCID: PMC3447957 DOI: 10.1371/journal.pcbi.1002702] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 07/27/2012] [Indexed: 12/20/2022] Open
Abstract
Hepatitis C virus (HCV) p7 is a membrane-associated oligomeric protein harboring ion channel activity. It is essential for effective assembly and release of infectious HCV particles and an attractive target for antiviral intervention. Yet, the self-assembly and molecular mechanism of p7 ion channelling are currently only partially understood. Using molecular dynamics simulations (aggregate time 1.2 µs), we show that p7 can form stable oligomers of four to seven subunits, with a bias towards six or seven subunits, and suggest that p7 self-assembles in a sequential manner, with tetrameric and pentameric complexes forming as intermediate states leading to the final hexameric or heptameric assembly. We describe a model of a hexameric p7 complex, which forms a transiently-open channel capable of conducting ions in simulation. We investigate the ability of the hexameric model to flexibly rearrange to adapt to the local lipid environment, and demonstrate how this model can be reconciled with low-resolution electron microscopy data. In the light of these results, a view of p7 oligomerization is proposed, wherein hexameric and heptameric complexes may coexist, forming minimalist, yet robust functional ion channels. In the absence of a high-resolution p7 structure, the models presented in this paper can prove valuable as a substitute structure in future studies of p7 function, or in the search for p7-inhibiting drugs.
Collapse
Affiliation(s)
- Danielle E. Chandler
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - François Penin
- Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, Université Lyon 1, Univ Lyon, France; CNRS, UMR 5086, Lyon, France
| | - Klaus Schulten
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Christophe Chipot
- Beckman Institute, University of Illinois at Urbana-Champaign Urbana, Illinois, United States of America
- Équipe de Dynamique des Assemblages Membranaires UMR 7565, Université de Lorraine, Vanduvre-lès-Nancy, France
| |
Collapse
|
10
|
Foster TL, Verow M, Wozniak AL, Bentham MJ, Thompson J, Atkins E, Weinman SA, Fishwick C, Foster R, Harris M, Griffin S. Resistance mutations define specific antiviral effects for inhibitors of the hepatitis C virus p7 ion channel. Hepatology 2011; 54:79-90. [PMID: 21520195 DOI: 10.1002/hep.24371] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
UNLABELLED The hepatitis C virus (HCV) p7 ion channel plays a critical role during infectious virus production and represents an important new therapeutic target. Its activity is blocked by structurally distinct classes of small molecules, with sensitivity varying between isolate p7 sequences. Although this is indicative of specific protein-drug interactions, a lack of high-resolution structural information has precluded the identification of inhibitor binding sites, and their modes of action remain undefined. Furthermore, a lack of clinical efficacy for existing p7 inhibitors has cast doubt over their specific antiviral effects. We identified specific resistance mutations that define the mode of action for two classes of p7 inhibitor: adamantanes and alkylated imino sugars (IS). Adamantane resistance was mediated by an L20F mutation, which has been documented in clinical trials. Molecular modeling revealed that L20 resided within a membrane-exposed binding pocket, where drug binding prevented low pH-mediated channel opening. The peripheral binding pocket was further validated by a panel of adamantane derivatives as well as a bespoke molecule designed to bind the region with high affinity. By contrast, an F25A polymorphism found in genotype 3a HCV conferred IS resistance and confirmed that these compounds intercalate between p7 protomers, preventing channel oligomerization. Neither resistance mutation significantly reduced viral fitness in culture, consistent with a low genetic barrier to resistance occurring in vivo. Furthermore, no cross-resistance was observed for the mutant phenotypes, and the two inhibitor classes showed additive effects against wild-type HCV. CONCLUSION These observations support the notion that p7 inhibitor combinations could be a useful addition to future HCV-specific therapies.
Collapse
Affiliation(s)
- Toshana L Foster
- Section of Oncology and Clinical Research, Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds, United Kingdom
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Montserret R, Saint N, Vanbelle C, Salvay AG, Simorre JP, Ebel C, Sapay N, Renisio JG, Böckmann A, Steinmann E, Pietschmann T, Dubuisson J, Chipot C, Penin F. NMR structure and ion channel activity of the p7 protein from hepatitis C virus. J Biol Chem 2010; 285:31446-61. [PMID: 20667830 DOI: 10.1074/jbc.m110.122895] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The small membrane protein p7 of hepatitis C virus forms oligomers and exhibits ion channel activity essential for virus infectivity. These viroporin features render p7 an attractive target for antiviral drug development. In this study, p7 from strain HCV-J (genotype 1b) was chemically synthesized and purified for ion channel activity measurements and structure analyses. p7 forms cation-selective ion channels in planar lipid bilayers and at the single-channel level by the patch clamp technique. Ion channel activity was shown to be inhibited by hexamethylene amiloride but not by amantadine. Circular dichroism analyses revealed that the structure of p7 is mainly α-helical, irrespective of the membrane mimetic medium (e.g. lysolipids, detergents, or organic solvent/water mixtures). The secondary structure elements of the monomeric form of p7 were determined by (1)H and (13)C NMR in trifluoroethanol/water mixtures. Molecular dynamics simulations in a model membrane were combined synergistically with structural data obtained from NMR experiments. This approach allowed us to determine the secondary structure elements of p7, which significantly differ from predictions, and to propose a three-dimensional model of the monomeric form of p7 associated with the phospholipid bilayer. These studies revealed the presence of a turn connecting an unexpected N-terminal α-helix to the first transmembrane helix, TM1, and a long cytosolic loop bearing the dibasic motif and connecting TM1 to TM2. These results provide the first detailed experimental structural framework for a better understanding of p7 processing, oligomerization, and ion channel gating mechanism.
Collapse
Affiliation(s)
- Roland Montserret
- Institut de Biologie et Chimie des Protéines, UMR 5086, CNRS, Université de Lyon, IFR128 BioSciences Gerland-Lyon Sud, 69367 Lyon, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Channel-forming proteins are found in a number of viral genomes. In some cases, their role in the viral life cycle is well understood, in some cases it needs still to be elucidated. A common theme is that their mode of action involves a change of electrochemical or proton gradient across the lipid membrane which modulates the viral or cellular activity. Blocking these proteins can be a suitable therapeutic strategy as for some viruses this may be "lethal." Besides the many biological relevant questions still to be answered, there are also many open questions concerning the biophysical side as well as structural information and the mechanism of function on a molecular level. The immanent biophysical issues are addressed and the work in the field is summarized.
Collapse
|
13
|
von Wagner M, Hofmann WP, Teuber G, Berg T, Goeser T, Spengler U, Hinrichsen H, Weidenbach H, Gerken G, Manns M, Buggisch P, Herrmann E, Zeuzem S. Placebo-controlled trial of 400 mg amantadine combined with peginterferon alfa-2a and ribavirin for 48 weeks in chronic hepatitis C virus-1 infection. Hepatology 2008; 48:1404-11. [PMID: 18846541 DOI: 10.1002/hep.22483] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
UNLABELLED The impact of amantadine on virologic response rates of interferon-based treatment of chronic hepatitis C is controversial. The aim of this study was to compare virological response rates in patients with chronic hepatitis C virus (HCV)-1 infection treated with 400 mg amantadine or placebo in combination with peginterferon alfa-2a (40 kD) and ribavirin for 48 weeks. Seven hundred four previously untreated chronically HCV-1-infected patients (mean age, 46 +/- 12 years) were randomized to (A) amantadine-sulphate (400 mg/day) (n = 352) or (B) placebo (n = 352), both in combination with 180 microg peginterferon alfa-2a once weekly and ribavirin (1000-1200 mg/day) for 48 weeks. End of treatment and sustained virological response after a 24-week follow-up period were assessed by qualitative reverse transcription polymerase chain reaction (RT-PCR) (sensitivity, 50 IU/mL). Demographic and baseline virological parameters were similar in both treatment groups. In groups A and B, 231 of 352 patients (66%) and 256 of 352 patients (72%) achieved an end of treatment response, and 171 of 352 patients (49 %) and 186 of 352 patients (53 %) a sustained virological response, respectively. On-treatment dropout rate in the amantadine group was significantly higher than in the placebo group (32% versus 23%; P = 0.01). However, adverse events and laboratory abnormalities were similar between both groups. Per-protocol analysis revealed similar sustained virological response rates in both treatment groups (53% versus 55%). CONCLUSION In this large placebo-controlled multicenter study, amantadine even at a dose of 400 mg/day did not improve virological response rates of peginterferon alfa-2a and ribavirin in patients with chronic genotype HCV-1 infection.
Collapse
|
14
|
Torres-Puente M, Cuevas JM, Jiménez-Hernández N, Bracho MA, García-Robles I, Carnicer F, Del Olmo J, Ortega E, Moya A, González-Candelas F. Contribution of insertions and deletions to the variability of hepatitis C virus populations. J Gen Virol 2007; 88:2198-2203. [PMID: 17622623 DOI: 10.1099/vir.0.82855-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Little is known about the potential effects of insertions and deletions (indels) on the evolutionary dynamics of hepatitis C virus (HCV). In fact, the consequences of indels on antiviral treatment response are a field of investigation completely unexplored. Here, an extensive sequencing project was undertaken by cloning and sequencing serum samples from 25 patients infected with HCV subtype 1a and 48 patients with subtype 1b. For 23 patients, samples obtained after treatment with alpha interferon plus ribavirin were also available. Two genome fragments containing the hypervariable regions in the envelope 2 glycoprotein and the PKR-BD domain in NS5A were sequenced, yielding almost 16 000 sequences. Our results show that insertions are quite rare, but they are often present in biologically relevant domains of the HCV genome. Moreover, their frequency distributions between different time samples reflect the quasispecies dynamics of HCV populations. Deletions seem to be subject to negative selection.
Collapse
Affiliation(s)
- Manuela Torres-Puente
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | - José M Cuevas
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | - Nuria Jiménez-Hernández
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | - María A Bracho
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | - Inmaculada García-Robles
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | | | - Juan Del Olmo
- Servicio de Hepatologia, Hospital Clínico de Valencia, Spain
| | - Enrique Ortega
- Unidad de Enfermedades Infecciosas, Hospital General de Valencia, Spain
| | - Andrés Moya
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| | - Fernando González-Candelas
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Genética, Universidad de Valencia, Spain
| |
Collapse
|
15
|
Murray CL, Jones CT, Tassello J, Rice CM. Alanine scanning of the hepatitis C virus core protein reveals numerous residues essential for production of infectious virus. J Virol 2007; 81:10220-31. [PMID: 17634240 PMCID: PMC2045476 DOI: 10.1128/jvi.00793-07] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hepatitis C virus (HCV) is an important human pathogen affecting an estimated 3% of the world's population. Recent advances have enabled in vitro propagation of the virus and allow assembly and egress to be investigated for the first time. As a component of the virion, the HCV core protein likely functions primarily in infectious virus production, although little is known about the determinants of this activity. To investigate the roles of core in the viral life cycle, we performed a comprehensive deletion and alanine scanning mutagenesis study of this protein in the context of a genotype 2a reporter virus. We have confirmed that core protein is essential for infectious virion production and have identified numerous residues required for this role. The infectivity of several assembly-defective core mutants could be rescued by compensatory mutations identified in p7 and NS2, suggesting genetic interactions with core and highlighting the importance of these nonstructural proteins in infectious virion morphogenesis.
Collapse
Affiliation(s)
- Catherine L Murray
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, 1230 York Ave., New York, NY 10021, USA
| | | | | | | |
Collapse
|