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Ajjaji D, Ben M'barek K, Boson B, Omrane M, Gassama-Diagne A, Blaud M, Penin F, Diaz E, Ducos B, Cosset FL, Thiam AR. Hepatitis C virus core protein uses triacylglycerols to fold onto the endoplasmic reticulum membrane. Traffic 2021; 23:63-80. [PMID: 34729868 DOI: 10.1111/tra.12825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 08/22/2021] [Revised: 10/16/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022]
Abstract
Lipid droplets (LDs) are involved in viral infections, but exactly how remains unclear. Here, we study the hepatitis C virus (HCV) whose core capsid protein binds to LDs but is also involved in the assembly of virions at the endoplasmic reticulum (ER) bilayer. We found that the amphipathic helix-containing domain of core, D2, senses triglycerides (TGs) rather than LDs per se. In the absence of LDs, D2 can bind to the ER membrane but only if TG molecules are present in the bilayer. Accordingly, the pharmacological inhibition of the diacylglycerol O-acyltransferase enzymes, mediating TG synthesis in the ER, inhibits D2 association with the bilayer. We found that TG molecules enable D2 to fold into alpha helices. Sequence analysis reveals that D2 resembles the apoE lipid-binding region. Our data support that TG in LDs promotes the folding of core, which subsequently relocalizes to contiguous ER regions. During this motion, core may carry TG molecules to these regions where HCV lipoviroparticles likely assemble. Consistent with this model, the inhibition of Arf1/COPI, which decreases LD surface accessibility to proteins and ER-LD material exchange, severely impedes the assembly of virions. Altogether, our data uncover a critical function of TG in the folding of core and HCV replication and reveals, more broadly, how TG accumulation in the ER may provoke the binding of soluble amphipathic helix-containing proteins to the ER bilayer.
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Affiliation(s)
- Dalila Ajjaji
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Bertrand Boson
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif, France.,Université Paris-Sud, UMR-S 1193, Villejuif, France
| | - Magali Blaud
- Université de Paris, CiTCoM, CNRS, Paris, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - Elise Diaz
- High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - Bertrand Ducos
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France.,High Throughput qPCR Core Facility of the ENS, IBENS, PSL Research University, Paris, France
| | - François-Loïc Cosset
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, Lyon, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 24 rue Lhomond, Paris, 75005, France
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2
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Boukadida C, Fritz M, Blumen B, Fogeron ML, Penin F, Martin A. NS2 proteases from hepatitis C virus and related hepaciviruses share composite active sites and previously unrecognized intrinsic proteolytic activities. PLoS Pathog 2018; 14:e1006863. [PMID: 29415072 PMCID: PMC5819835 DOI: 10.1371/journal.ppat.1006863] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 02/20/2018] [Accepted: 01/08/2018] [Indexed: 12/17/2022] Open
Abstract
Over the recent years, several homologues with varying degrees of genetic relatedness to hepatitis C virus (HCV) have been identified in a wide range of mammalian species. HCV infectious life cycle relies on a first critical proteolytic event of its single polyprotein, which is carried out by nonstructural protein 2 (NS2) and allows replicase assembly and genome replication. In this study, we characterized and evaluated the conservation of the proteolytic mode of action and regulatory mechanisms of NS2 across HCV and animal hepaciviruses. We first demonstrated that NS2 from equine, bat, rodent, New and Old World primate hepaciviruses also are cysteine proteases. Using tagged viral protein precursors and catalytic triad mutants, NS2 of equine NPHV and simian GBV-B, which are the most closely and distantly related viruses to HCV, respectively, were shown to function, like HCV NS2 as dimeric proteases with two composite active sites. Consistent with the reported essential role for NS3 N-terminal domain (NS3N) as HCV NS2 protease cofactor via NS3N key hydrophobic surface patch, we showed by gain/loss of function mutagenesis studies that some heterologous hepacivirus NS3N may act as cofactors for HCV NS2 provided that HCV-like hydrophobic residues are conserved. Unprecedently, however, we also observed efficient intrinsic proteolytic activity of NS2 protease in the absence of NS3 moiety in the context of C-terminal tag fusions via flexible linkers both in transiently transfected cells for all hepaciviruses studied and in the context of HCV dicistronic full-length genomes. These findings suggest that NS3N acts as a regulatory rather than essential cofactor for hepacivirus NS2 protease. Overall, unique features of NS2 including enzymatic function as dimers with two composite active sites and additional NS3-independent proteolytic activity are conserved across hepaciviruses regardless of their genetic distances, highlighting their functional significance in hepacivirus life cycle. Despite remarkable progress in the development of therapeutic options, more than 70 million individuals are chronically infected by hepatitis C virus (HCV) worldwide and major challenges in basic and translational research remain. Phylogenetically-related HCV homologues have recently been identified in the wild in several mammalian species, whose host restriction and potential for zoonosis remain largely unknown. We comparatively characterized the functions and properties of nonstructural proteins 2 (NS2) from several animal hepaciviruses and HCV. We demonstrated that NS2 from animal hepaciviruses, like HCV NS2, are cysteine proteases, which function as dimers with two composite active sites to ensure a key proteolytic event of the single viral polyprotein at the NS2/NS3 junction. In addition to the activation of HCV NS2 protease by NS3 N-terminal domain, our data revealed a novel NS3-independent substrate specificity and efficient intrinsic proteolytic activity of NS2. The conservation of its properties and peculiar mode of action among distantly related hepaciviruses supports an important regulatory role for NS2 protein in the life cycle of these viruses. It also strengthens the value of animal, notably rodent hepaciviruses for the development of surrogate, immunocompetent models of HCV infection to address HCV-associated pathogenesis and vaccine strategies.
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Affiliation(s)
- Célia Boukadida
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Paris, France
- CNRS UMR 3569, Paris, France
- Université Paris Diderot–Sorbonne Paris Cité, Paris, France
| | - Matthieu Fritz
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Paris, France
- CNRS UMR 3569, Paris, France
- Université Paris Diderot–Sorbonne Paris Cité, Paris, France
| | - Brigitte Blumen
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Paris, France
- CNRS UMR 3569, Paris, France
- Université Paris Diderot–Sorbonne Paris Cité, Paris, France
| | - Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - Annette Martin
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Paris, France
- CNRS UMR 3569, Paris, France
- Université Paris Diderot–Sorbonne Paris Cité, Paris, France
- * E-mail:
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3
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Denolly S, Mialon C, Bourlet T, Amirache F, Penin F, Lindenbach B, Boson B, Cosset FL. The amino-terminus of the hepatitis C virus (HCV) p7 viroporin and its cleavage from glycoprotein E2-p7 precursor determine specific infectivity and secretion levels of HCV particle types. PLoS Pathog 2017; 13:e1006774. [PMID: 29253880 PMCID: PMC5749900 DOI: 10.1371/journal.ppat.1006774] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/02/2018] [Accepted: 11/27/2017] [Indexed: 12/18/2022] Open
Abstract
Viroporins are small transmembrane proteins with ion channel activities modulating properties of intracellular membranes that have diverse proviral functions. Hepatitis C virus (HCV) encodes a viroporin, p7, acting during assembly, envelopment and secretion of viral particles (VP). HCV p7 is released from the viral polyprotein through cleavage at E2-p7 and p7-NS2 junctions by signal peptidase, but also exists as an E2p7 precursor, of poorly defined properties. Here, we found that ectopic p7 expression in HCVcc-infected cells reduced secretion of particle-associated E2 glycoproteins. Using biochemical assays, we show that p7 dose-dependently slows down the ER-to-Golgi traffic, leading to intracellular retention of E2, which suggested that timely E2p7 cleavage and p7 liberation are critical events to control E2 levels. By studying HCV mutants with accelerated E2p7 processing, we demonstrate that E2p7 cleavage controls E2 intracellular expression and secretion levels of nucleocapsid-free subviral particles and infectious virions. In addition, our imaging data reveal that, following p7 liberation, the amino-terminus of p7 is exposed towards the cytosol and coordinates the encounter between NS5A and NS2-based assembly sites loaded with E1E2 glycoproteins, which subsequently leads to nucleocapsid envelopment. We identify punctual mutants at p7 membrane interface that, by abrogating NS2/NS5A interaction, are defective for transmission of infectivity owing to decreased secretion of core and RNA and to increased secretion of non/partially-enveloped particles. Altogether, our results indicate that the retarded E2p7 precursor cleavage is essential to regulate the intracellular and secreted levels of E2 through p7-mediated modulation of the cell secretory pathway and to unmask critical novel assembly functions located at p7 amino-terminus.
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Affiliation(s)
- Solène Denolly
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - Chloé Mialon
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - Thomas Bourlet
- GIMAP, EA 3064, Faculté de Médecine, Université de Saint-Etienne, Univ Lyon, Saint Etienne, France
| | - Fouzia Amirache
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - François Penin
- IBCP—Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Univ Lyon, Lyon, France
| | - Brett Lindenbach
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, United States of America
| | - Bertrand Boson
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - François-Loïc Cosset
- CIRI–International Center for Infectiology Research, Team EVIR, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univ Lyon, Lyon, France
- * E-mail:
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4
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Badillo A, Receveur-Brechot V, Sarrazin S, Cantrelle FX, Delolme F, Fogeron ML, Molle J, Montserret R, Bockmann A, Bartenschlager R, Lohmann V, Lippens G, Ricard-Blum S, Hanoulle X, Penin F. Overall Structural Model of NS5A Protein from Hepatitis C Virus and Modulation by Mutations Confering Resistance of Virus Replication to Cyclosporin A. Biochemistry 2017; 56:3029-3048. [PMID: 28535337 DOI: 10.1021/acs.biochem.7b00212] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a RNA-binding phosphoprotein composed of a N-terminal membrane anchor (AH), a structured domain 1 (D1), and two intrinsically disordered domains (D2 and D3). The knowledge of the functional architecture of this multifunctional protein remains limited. We report here that NS5A-D1D2D3 produced in a wheat germ cell-free system is obtained under a highly phosphorylated state. Its NMR analysis revealed that these phosphorylations do not change the disordered nature of D2 and D3 domains but increase the number of conformers due to partial phosphorylations. By combining NMR and small angle X-ray scattering, we performed a comparative structural characterization of unphosphorylated recombinant D2 domains of JFH1 (genotype 2a) and the Con1 (genotype 1b) strains produced in Escherichia coli. These analyses highlighted a higher intrinsic folding of the latter, revealing the variability of intrinsic conformations in HCV genotypes. We also investigated the effect of D2 mutations conferring resistance of HCV replication to cyclophilin A (CypA) inhibitors on the structure of the recombinant D2 Con1 mutants and their binding to CypA. Although resistance mutations D320E and R318W could induce some local and/or global folding perturbation, which could thus affect the kinetics of conformer interconversions, they do not significantly affect the kinetics of CypA/D2 interaction measured by surface plasmon resonance (SPR). The combination of all our data led us to build a model of the overall structure of NS5A, which provides a useful template for further investigations of the structural and functional features of this enigmatic protein.
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Affiliation(s)
- Aurelie Badillo
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | | | - Stéphane Sarrazin
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - François-Xavier Cantrelle
- University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, F 59 000 Lille, France
| | - Frédéric Delolme
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Jennifer Molle
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Roland Montserret
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Anja Bockmann
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg , Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg , Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | - Guy Lippens
- University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, F 59 000 Lille, France
| | - Sylvie Ricard-Blum
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
| | - Xavier Hanoulle
- University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, F 59 000 Lille, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, MMSB, UMR 5086, CNRS, Labex Ecofect, Université de Lyon, 69367 Lyon, France
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5
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Abstract
Due to their hydrophobic nature, membrane proteins are notoriously difficult to express in classical cell-based protein expression systems. Often toxic, they also undergo degradation in cells or aggregate in inclusion bodies, making delicate issues further solubilization and renaturation. These are major bottlenecks in their structural and functional analysis. The wheat germ cell-free (WGE-CF) system offers an effective alternative not only to classical cell-based protein expression systems but also to other cell-free systems for the expression of membrane proteins. The WGE-CF indeed allows the production of milligram amounts of membrane proteins in a detergent-solubilized, homogenous, and active form. Here, we describe the method to produce a viral integral membrane protein, which is the non-structural protein 2 (NS2) of hepatitis C virus, in view of structural studies by solid-state NMR in a native-like lipid environment.
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Affiliation(s)
- Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69007, Lyon, France
| | - Aurélie Badillo
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69007, Lyon, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69007, Lyon, France
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, Molecular Microbiology and Structural Biochemistry, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69007, Lyon, France.
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6
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Stoltz J, Penin F, Voisin P, Gaillard S, Donner M, Streiff F. Blood viscosity and platelet parameters during recent cerebral vascular stroke in elderly patients. Clin Hemorheol Microcirc 2016. [DOI: 10.3233/ch-1985-5613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- J.F. Stoltz
- U.284 INSERM et Centre Régional de Transfusion Sanguine, Brabois, 54511 Vandoeuvre-lès-Nancy Cédex, France
| | - F. Penin
- Service de Gériatrie, C.H.U. Brabois, 54511 Vandoeuvre-Iès-Nancy Cédex, France
| | - Ph. Voisin
- U.284 INSERM et Centre Régional de Transfusion Sanguine, Brabois, 54511 Vandoeuvre-lès-Nancy Cédex, France
| | - S. Gaillard
- U.284 INSERM et Centre Régional de Transfusion Sanguine, Brabois, 54511 Vandoeuvre-lès-Nancy Cédex, France
| | - M. Donner
- U.284 INSERM et Centre Régional de Transfusion Sanguine, Brabois, 54511 Vandoeuvre-lès-Nancy Cédex, France
| | - F. Streiff
- U.284 INSERM et Centre Régional de Transfusion Sanguine, Brabois, 54511 Vandoeuvre-lès-Nancy Cédex, France
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7
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Holzmann N, Chipot C, Penin F, Dehez F. Assessing the physiological relevance of alternate architectures of the p7 protein of hepatitis C virus in different environments. Bioorg Med Chem 2016; 24:4920-4927. [PMID: 27501910 DOI: 10.1016/j.bmc.2016.07.063] [Citation(s) in RCA: 8] [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: 06/13/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 12/12/2022]
Abstract
The viroporin p7 of the hepatitis C virus forms multimeric channels eligible for ion transport across the endoplasmic reticulum membrane. Currently the subject of many studies and discussion, the molecular assembly of the ion channel and the structural characteristics of the p7 monomer are not yet fully understood. Structural investigation of p7 has been carried out only in detergent environments, making the interpretation of the experimental results somewhat questionable. Here, we analyze by means of molecular dynamics simulations the structure of the p7 monomer as a function of its sequence, initial conformation and environment. We investigate the conductance properties of three models of a hexameric p7 ion channel by examining ion translocation in a pure lipid bilayer. It is noteworthy that although none of the models reflects the experimentally observed trend to conduct preferentially cations, we were able to identify the position and orientation of titratable acidic or basic residues playing a crucial role in ion selectivity and in the overall conductance of the channel. In addition, too compact a packing of the monomers leads to channel collapse rather than formation of a reasonable pore, amenable to ion translocation. The present findings are envisioned to help assess the physiological relevance of p7 ion channel models consisting of multimeric structures obtained in non-native environments.
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Affiliation(s)
- Nicole Holzmann
- Unité Mixte de Recherche No. 7565, Université de Lorraine, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France; Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, CNRS, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France
| | - Christophe Chipot
- Unité Mixte de Recherche No. 7565, Université de Lorraine, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France; Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, CNRS, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France; Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801, USA.
| | - François Penin
- Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, UMR 5086, Université de Lyon, 69367 Lyon, France; Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, UMR 5086, CNRS, 69367 Lyon, France
| | - François Dehez
- Unité Mixte de Recherche No. 7565, Université de Lorraine, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France; Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, CNRS, B.P. 70239, 54506 Vandoeuvre-lès-Nancy cedex, France.
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8
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Fogeron ML, Jirasko V, Penzel S, Paul D, Montserret R, Danis C, Lacabanne D, Badillo A, Gouttenoire J, Moradpour D, Bartenschlager R, Penin F, Meier BH, Böckmann A. Cell-free expression, purification, and membrane reconstitution for NMR studies of the nonstructural protein 4B from hepatitis C virus. J Biomol NMR 2016; 65:87-98. [PMID: 27233794 DOI: 10.1007/s10858-016-0040-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/21/2016] [Indexed: 06/05/2023]
Abstract
We describe the expression of the hepatitis C virus nonstructural protein 4B (NS4B), which is an integral membrane protein, in a wheat germ cell-free system, the subsequent purification and characterization of NS4B and its insertion into proteoliposomes in amounts sufficient for multidimensional solid-state NMR spectroscopy. First spectra of the isotopically [(2)H,(13)C,(15)N]-labeled protein are shown to yield narrow (13)C resonance lines and a proper, predominantly α-helical fold. Clean residue-selective leucine, isoleucine and threonine-labeling is demonstrated. These results evidence the suitability of the wheat germ-produced integral membrane protein NS4B for solid-state NMR. Still, the proton linewidth under fast magic angle spinning is broader than expected for a perfect sample and possible causes are discussed.
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Affiliation(s)
- Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
| | - Vlastimil Jirasko
- Physical Chemistry, ETH Zurich, 8093, Zurich, Switzerland
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120, Heidelberg, Germany
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Susanne Penzel
- Physical Chemistry, ETH Zurich, 8093, Zurich, Switzerland
| | - David Paul
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120, Heidelberg, Germany
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Roland Montserret
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
| | - Clément Danis
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
| | - Denis Lacabanne
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
| | - Aurélie Badillo
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
- Recombinant Protein Unit, RD-Biotech, 3 rue Henri Baigue, 25000, Besançon, France
| | - Jérôme Gouttenoire
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, 1011, Lausanne, Switzerland
| | - Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, 1011, Lausanne, Switzerland
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120, Heidelberg, Germany
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France
| | - Beat H Meier
- Physical Chemistry, ETH Zurich, 8093, Zurich, Switzerland.
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367, Lyon, France.
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9
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Poulot A, Penin F. Illustrated overview of vital cycle of Hepatitis C virus. Virologie (Montrouge) 2016; 20:E1-E31. [PMID: 33065857 DOI: 10.1684/vir.2016.0635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Alix Poulot
- Service Innovation Conception et Accompagnement pour la Pédagogie, Université Claude Bernard Lyon 1 43, bd du 11 Novembre 1918, 69622 Villeurbanne cedex
| | - François Penin
- Institut de Biologie et Chimie des protéines, UMR 5086 CNRS, Université Claude Bernard Lyon 1, 7, passage du Vercors, 69367 Lyon cedex 07
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10
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Poulot A, Penin F. Cycle de vie du virus de l'hépatite C, une synthèse graphique. Virologie (Montrouge) 2016; 20:7-37. [PMID: 33065856 DOI: 10.1684/vir.2016.0634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Alix Poulot
- Service Innovation Conception et Accompagnement pour la Pédagogie, Université Claude Bernard Lyon 1 43, bd du 11 Novembre 1918, 69622 Villeurbanne cedex
| | - François Penin
- Institut de Biologie et Chimie des protéines, UMR 5086 CNRS, Université Claude Bernard Lyon 1, 7, passage du Vercors, 69367 Lyon cedex 07
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11
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Fogeron ML, Paul D, Jirasko V, Montserret R, Lacabanne D, Molle J, Badillo A, Boukadida C, Georgeault S, Roingeard P, Martin A, Bartenschlager R, Penin F, Böckmann A. Functional expression, purification, characterization, and membrane reconstitution of non-structural protein 2 from hepatitis C virus. Protein Expr Purif 2015; 116:1-6. [PMID: 26325423 DOI: 10.1016/j.pep.2015.08.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [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: 03/30/2015] [Revised: 08/25/2015] [Accepted: 08/28/2015] [Indexed: 01/14/2023]
Abstract
Non-structural protein 2 (NS2) of the hepatitis C virus (HCV) is an integral membrane protein that contains a cysteine protease and that plays a central organizing role in assembly of infectious progeny virions. While the crystal structure of the protease domain has been solved, the NS2 full-length form remains biochemically and structurally uncharacterized because recombinant NS2 could not be prepared in sufficient quantities from cell-based systems. We show here that functional NS2 in the context of the NS2-NS3pro precursor protein, ensuring NS2-NS3 cleavage, can be efficiently expressed by using a wheat germ cell-free expression system. In this same system, we subsequently successfully produce and purify milligram amounts of a detergent-solubilized form of full-length NS2 exhibiting the expected secondary structure content. Furthermore, immuno-electron microscopy analyses of reconstituted proteoliposomes demonstrate NS2 association with model membranes.
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Affiliation(s)
- Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - David Paul
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany; German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Vlastimil Jirasko
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany; German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Roland Montserret
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - Denis Lacabanne
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - Jennifer Molle
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France
| | - Aurélie Badillo
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France; RD-Biotech, Recombinant Protein Unit, Besançon, France
| | - Célia Boukadida
- Institut Pasteur, Unit of Molecular Genetics of RNA Viruses, CNRS UMR 3569, Université Paris Diderot - Sorbonne Paris Cité, Paris, France
| | - Sonia Georgeault
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
| | - Philippe Roingeard
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France; INSERM U966, Universite François Rabelais and CHRU de Tours, Tours, France
| | - Annette Martin
- Institut Pasteur, Unit of Molecular Genetics of RNA Viruses, CNRS UMR 3569, Université Paris Diderot - Sorbonne Paris Cité, Paris, France
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany; German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France.
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, Lyon, France.
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12
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Hueging K, Weller R, Doepke M, Vieyres G, Todt D, Wölk B, Vondran FWR, Geffers R, Lauber C, Kaderali L, Penin F, Pietschmann T. Several Human Liver Cell Expressed Apolipoproteins Complement HCV Virus Production with Varying Efficacy Conferring Differential Specific Infectivity to Released Viruses. PLoS One 2015; 10:e0134529. [PMID: 26226615 PMCID: PMC4520612 DOI: 10.1371/journal.pone.0134529] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/09/2015] [Indexed: 02/08/2023] Open
Abstract
Apolipoprotein E (ApoE), an exchangeable apolipoprotein, is necessary for production of infectious Hepatitis C virus (HCV) particles. However, ApoE is not the only liver-expressed apolipoprotein and the role of other apolipoproteins for production of infectious HCV progeny is incompletely defined. Therefore, we quantified mRNA expression of human apolipoproteins in primary human hepatocytes. Subsequently, cDNAs encoding apolipoproteins were expressed in 293T/miR-122 cells to explore if they complement HCV virus production in cells that are non-permissive due to limiting endogenous levels of human apolipoproteins. Primary human hepatocytes expressed high mRNA levels of ApoA1, A2, C1, C3, E, and H. ApoA4, A5, B, D, F, J, L1, L2, L3, L4, L6, M, and O were expressed at intermediate levels, and C2, C4, and L5 were not detected. All members of the ApoA and ApoC family of lipoproteins complemented HCV virus production in HCV transfected 293T/miR-122 cells, albeit with significantly lower efficacy compared with ApoE. In contrast, ApoD expression did not support production of infectious HCV. Specific infectivity of released particles complemented with ApoA family members was significantly lower compared with ApoE. Moreover, the ratio of extracellular to intracellular infectious virus was significantly higher for ApoE compared to ApoA2 and ApoC3. Since apolipoproteins complementing HCV virus production share amphipathic alpha helices as common structural features we altered the two alpha helices of ApoC1. Helix breaking mutations in both ApoC1 helices impaired virus assembly highlighting a critical role of alpha helices in apolipoproteins supporting HCV assembly. In summary, various liver expressed apolipoproteins with amphipathic alpha helices complement HCV virus production in human non liver cells. Differences in the efficiency of virus assembly, the specific infectivity of released particles, and the ratio between extracellular and intracellular infectivity point to distinct characteristics of these apolipoproteins that influence HCV assembly and cell entry. This will guide future research to precisely pinpoint how apolipoproteins function during virus assembly and cell entry.
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Affiliation(s)
- Kathrin Hueging
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
| | - Romy Weller
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
| | - Mandy Doepke
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
| | - Gabrielle Vieyres
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
| | - Daniel Todt
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
| | - Benno Wölk
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Florian W. R. Vondran
- Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
- Integrated Research and Treatment Center Transplantation (IFB-Tx), Hannover Medical School, Hannover, Germany
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Hannover, Germany
| | - Robert Geffers
- Research Group Genome Analytics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Chris Lauber
- Institute for Medical Informatics and Biometry, Medical Faculty, Technische Universität Dresden, Dresden, Germany
| | - Lars Kaderali
- Institute for Medical Informatics and Biometry, Medical Faculty, Technische Universität Dresden, Dresden, Germany
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - Thomas Pietschmann
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany
- German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Hannover, Germany
- * E-mail:
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13
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Dujardin M, Madan V, Montserret R, Ahuja P, Huvent I, Launay H, Leroy A, Bartenschlager R, Penin F, Lippens G, Hanoulle X. A Proline-Tryptophan Turn in the Intrinsically Disordered Domain 2 of NS5A Protein Is Essential for Hepatitis C Virus RNA Replication. J Biol Chem 2015; 290:19104-20. [PMID: 26085105 DOI: 10.1074/jbc.m115.644419] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [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: 02/10/2015] [Indexed: 01/11/2023] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) and its interaction with the human chaperone cyclophilin A are both targets for highly potent and promising antiviral drugs that are in the late stages of clinical development. Despite its high interest in regards to the development of drugs to counteract the worldwide HCV burden, NS5A is still an enigmatic multifunctional protein poorly characterized at the molecular level. NS5A is required for HCV RNA replication and is involved in viral particle formation and regulation of host pathways. Thus far, no enzymatic activity or precise molecular function has been ascribed to NS5A that is composed of a highly structured domain 1 (D1), as well as two intrinsically disordered domains 2 (D2) and 3 (D3), representing half of the protein. Here, we identify a short structural motif in the disordered NS5A-D2 and report its NMR structure. We show that this structural motif, a minimal Pro(314)-Trp(316) turn, is essential for HCV RNA replication, and its disruption alters the subcellular distribution of NS5A. We demonstrate that this Pro-Trp turn is required for proper interaction with the host cyclophilin A and influences its peptidyl-prolyl cis/trans isomerase activity on residue Pro(314) of NS5A-D2. This work provides a molecular basis for further understanding of the function of the intrinsically disordered domain 2 of HCV NS5A protein. In addition, our work highlights how very small structural motifs present in intrinsically disordered proteins can exert a specific function.
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Affiliation(s)
- Marie Dujardin
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France
| | - Vanesa Madan
- the Department of Infectious Diseases, Molecular Virology, University of Heidelberg, D-69120, Heidelberg, Germany, and
| | - Roland Montserret
- CNRS, Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, LabEx Ecofect, UMR 5086 and Université Lyon 1, F-69367, Lyon, France
| | - Puneet Ahuja
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France
| | - Isabelle Huvent
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France
| | - Helene Launay
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France
| | - Arnaud Leroy
- the EA4529 and InstruL2, UFR de Pharmacie, Université Paris-Sud, F-92296 Châtenay-Malabry, France
| | - Ralf Bartenschlager
- the Department of Infectious Diseases, Molecular Virology, University of Heidelberg, D-69120, Heidelberg, Germany, and
| | - François Penin
- CNRS, Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, LabEx Ecofect, UMR 5086 and Université Lyon 1, F-69367, Lyon, France
| | - Guy Lippens
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France
| | - Xavier Hanoulle
- From the CNRS, Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576, Université Lille1, F-59655 Villeneuve d'Ascq, France,
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14
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Abstract
ABSTRACT HCV encodes two envelope glycoproteins, E1 and E2, which assemble as a non-covalent heterodimer in infected cells. During HCV morphogenesis, these proteins are incorporated into viral particles and they are the major viral determinants of HCV entry. Functional studies have revealed unique features in these viral envelope glycoproteins. Indeed, E1–E2 interaction, mediated by their transmembrane domain, is essential for HCV assembly and entry. Furthermore, recent data also show that these glycoproteins interact with apolipoproteins. Recent crystallography data provide some structural support to better understand how these proteins interact with the host. In this review, we summarize the biogenesis of HCV envelope glycoproteins and their role in HCV morphogenesis in the context of the hijacking of the very low-density lipoprotein assembly pathway by this virus. We also describe the functions of HCV glycoproteins during virus entry with a special focus on the unexpected structural features of E2 glycoprotein. Finally, we discuss the major neutralizing epitopes in the light of E2 structure.
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Affiliation(s)
- Muriel Lavie
- Center for Infection & Immunity of Lille, Institut Pasteur of Lille, Inserm U1019, CNRS UMR-8204, University of Lille, F-59021 Lille, France
| | - François Penin
- Institut de Biologie & Chimie des Protéines, Bases Moléculaires & Structurales des Systèmes Infectieux, UMR-5086-CNRS, Labex Ecofect, Université de Lyon, Lyon, France
| | - Jean Dubuisson
- Center for Infection & Immunity of Lille, Institut Pasteur of Lille, Inserm U1019, CNRS UMR-8204, University of Lille, F-59021 Lille, France
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15
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Gouttenoire J, Montserret R, Paul D, Castillo R, Meister S, Bartenschlager R, Penin F, Moradpour D. Aminoterminal amphipathic α-helix AH1 of hepatitis C virus nonstructural protein 4B possesses a dual role in RNA replication and virus production. PLoS Pathog 2014; 10:e1004501. [PMID: 25392992 PMCID: PMC4231108 DOI: 10.1371/journal.ppat.1004501] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 10/02/2014] [Indexed: 01/19/2023] Open
Abstract
Nonstructural protein 4B (NS4B) is a key organizer of hepatitis C virus (HCV) replication complex formation. In concert with other nonstructural proteins, it induces a specific membrane rearrangement, designated as membranous web, which serves as a scaffold for the HCV replicase. The N-terminal part of NS4B comprises a predicted and a structurally resolved amphipathic α-helix, designated as AH1 and AH2, respectively. Here, we report a detailed structure-function analysis of NS4B AH1. Circular dichroism and nuclear magnetic resonance structural analyses revealed that AH1 folds into an amphipathic α-helix extending from NS4B amino acid 4 to 32, with positively charged residues flanking the helix. These residues are conserved among hepaciviruses. Mutagenesis and selection of pseudorevertants revealed an important role of these residues in RNA replication by affecting the biogenesis of double-membrane vesicles making up the membranous web. Moreover, alanine substitution of conserved acidic residues on the hydrophilic side of the helix reduced infectivity without significantly affecting RNA replication, indicating that AH1 is also involved in virus production. Selective membrane permeabilization and immunofluorescence microscopy analyses of a functional replicon harboring an epitope tag between NS4B AH1 and AH2 revealed a dual membrane topology of the N-terminal part of NS4B during HCV RNA replication. Luminal translocation was unaffected by the mutations introduced into AH1, but was abrogated by mutations introduced into AH2. In conclusion, our study reports the three-dimensional structure of AH1 from HCV NS4B, and highlights the importance of positively charged amino acid residues flanking this amphipathic α-helix in membranous web formation and RNA replication. In addition, we demonstrate that AH1 possesses a dual role in RNA replication and virus production, potentially governed by different topologies of the N-terminal part of NS4B. With an estimated 180 million chronically infected individuals, hepatitis C virus (HCV) is a leading cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. HCV is a positive-strand RNA virus that builds its replication complex on rearranged intracellular membranes, designated as membranous web. HCV nonstructural protein 4B (NS4B) is a key organizer of HCV membranous web and replication complex formation. Here, we provide a detailed structure-function analysis of an N-terminal amphipathic α-helix of NS4B, named AH1, and demonstrate that it plays key roles in shaping the membranous web as well as in virus production. We also show that the N-terminal part of NS4B adopts a dual membrane topology in a replicative context, possibly reflecting the different roles of this protein in the viral life cycle.
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Affiliation(s)
- Jérôme Gouttenoire
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
| | - Roland Montserret
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - David Paul
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Rosa Castillo
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
| | - Simon Meister
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR 5086, CNRS, Labex Ecofect, University of Lyon, Lyon, France
| | - Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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16
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Fogeron ML, Badillo A, Jirasko V, Gouttenoire J, Paul D, Lancien L, Moradpour D, Bartenschlager R, Meier BH, Penin F, Böckmann A. Wheat germ cell-free expression: Two detergents with a low critical micelle concentration allow for production of soluble HCV membrane proteins. Protein Expr Purif 2014; 105:39-46. [PMID: 25306874 DOI: 10.1016/j.pep.2014.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [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: 06/27/2014] [Revised: 09/26/2014] [Accepted: 10/01/2014] [Indexed: 01/08/2023]
Abstract
Membrane proteins are notoriously difficult to express in a soluble form. Here, we use wheat germ cell-free expression in the presence of various detergents to produce the non-structural membrane proteins 2, 4B and 5A of the hepatitis C virus (HCV). We show that lauryl maltose neopentyl glycol (MNG-3) and dodecyl octaethylene glycol ether (C12E8) detergents can yield essentially soluble membrane proteins at detergent concentrations that do not inhibit the cell-free reaction. This finding can be explained by the low critical micelle concentration (CMC) of these detergents, which keeps the monomer concentrations low while at the same time providing the necessary excess of detergent concentration above CMC required for full target protein solubilization. We estimate that a tenfold excess of detergent micelles with respect to the protein concentration is sufficient for solubilization, a number that we propose as a guideline for detergent screening assays.
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Affiliation(s)
- Marie-Laure Fogeron
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France
| | - Aurélie Badillo
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France; RD-Biotech, Recombinant Protein Unit, 3 rue Henri Baigue, 25000 Besançon, France
| | - Vlastimil Jirasko
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany; German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Jérôme Gouttenoire
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, 1011 Lausanne, Switzerland
| | - David Paul
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | - Loick Lancien
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France
| | - Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, 1011 Lausanne, Switzerland
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany; German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Beat H Meier
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France.
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, Labex Ecofect, UMR 5086 CNRS, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France.
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17
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Kunert B, Gardiennet C, Lacabanne D, Calles-Garcia D, Falson P, Jault JM, Meier BH, Penin F, Böckmann A. Efficient and stable reconstitution of the ABC transporter BmrA for solid-state NMR studies. Front Mol Biosci 2014; 1:5. [PMID: 25988146 PMCID: PMC4428385 DOI: 10.3389/fmolb.2014.00005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 05/26/2014] [Indexed: 01/20/2023] Open
Abstract
We present solid-state NMR sample preparation and first 2D spectra of the Bacillus subtilis ATP-binding cassette (ABC) transporter BmrA, a membrane protein involved in multidrug resistance. The homodimeric 130-kDa protein is a challenge for structural characterization due to its membrane-bound nature, size, inherent flexibility and insolubility. We show that reconstitution of this protein in lipids from Bacillus subtilis at a lipid-protein ratio of 0.5 w/w allows for optimal protein insertion in lipid membranes with respect to two central NMR requirements, high signal-to-noise in the spectra and sample stability over a time period of months. The obtained spectra point to a well-folded protein and a highly homogenous preparation, as witnessed by the narrow resonance lines and the signal dispersion typical for the expected secondary structure distribution of BmrA. This opens the way for studies of the different conformational states of the transporter in the export cycle, as well as on interactions with substrates, via chemical-shift fingerprints and sequential resonance assignments.
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Affiliation(s)
- Britta Kunert
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Carole Gardiennet
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Denis Lacabanne
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Daniel Calles-Garcia
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Pierre Falson
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Jean-Michel Jault
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | | | - François Penin
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
| | - Anja Böckmann
- Labex Ecofect, Bases Moleculaires et Structurales des Systemes Infectieux, UMR 5086 CNRS, IBCP, Université de Lyon 1Lyon, France
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Morikawa K, Gouttenoire J, Hernandez C, Dao Thi VL, Tran HTL, Lange CM, Dill MT, Heim MH, Donzé O, Penin F, Quadroni M, Moradpour D. Quantitative proteomics identifies the membrane-associated peroxidase GPx8 as a cellular substrate of the hepatitis C virus NS3-4A protease. Hepatology 2014; 59:423-33. [PMID: 23929719 DOI: 10.1002/hep.26671] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 07/30/2013] [Indexed: 12/31/2022]
Abstract
UNLABELLED The hepatitis C virus (HCV) NS3-4A protease is not only an essential component of the viral replication complex and a prime target for antiviral intervention but also a key player in the persistence and pathogenesis of HCV. It cleaves and thereby inactivates two crucial adaptor proteins in viral RNA sensing and innate immunity, mitochondrial antiviral signaling protein (MAVS) and TRIF, a phosphatase involved in growth factor signaling, T-cell protein tyrosine phosphatase (TC-PTP), and the E3 ubiquitin ligase component UV-damaged DNA-binding protein 1 (DDB1). Here we explored quantitative proteomics to identify novel cellular substrates of the NS3-4A protease. Cell lines inducibly expressing the NS3-4A protease were analyzed by stable isotopic labeling using amino acids in cell culture (SILAC) coupled with protein separation and mass spectrometry. This approach identified the membrane-associated peroxidase GPx8 as a bona fide cellular substrate of the HCV NS3-4A protease. Cleavage by NS3-4A occurs at Cys 11, removing the cytosolic tip of GPx8, and was observed in different experimental systems as well as in liver biopsies from patients with chronic HCV. Overexpression and RNA silencing studies revealed that GPx8 is involved in viral particle production but not in HCV entry or RNA replication. CONCLUSION We provide proof-of-concept for the use of quantitative proteomics to identify cellular substrates of a viral protease and describe GPx8 as a novel proviral host factor targeted by the HCV NS3-4A protease.
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Affiliation(s)
- Kenichi Morikawa
- From the Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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Abstract
Great progress has been made over the past years in elucidating the structure and function of the hepatitis C virus (HCV) proteins, most of which are now actively being pursued as antiviral targets. The structural proteins, which form the viral particle, include the core protein and the envelope glycoproteins E1 and E2. The nonstructural proteins include the p7 viroporin, the NS2 protease, the NS3-4A complex harboring protease and NTPase/RNA helicase activities, the NS4B and NS5A proteins, and the NS5B RNA-dependent RNA polymerase. NS4B is a master organizer of replication complex formation while NS5A is a zinc-containing phosphoprotein involved in the regulation of HCV RNA replication versus particle production. Core to NS2 make up the assembly module while NS3 to NS5B represent the replication module (replicase). However, HCV proteins exert multiple functions during the viral life cycle, and these may be governed by different structural conformations and/or interactions with viral and/or cellular partners. Remarkably, each viral protein is anchored to intracellular membranes via specific determinants that are essential to protein function in the cell. This review summarizes current knowledge of the structure and function of the HCV proteins and highlights recent advances in the field.
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Affiliation(s)
- Darius Moradpour
- Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland.
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20
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Anjum S, Wahid A, Afzal MS, Albecka A, Alsaleh K, Ahmad T, Baumert TF, Wychowski C, Qadri I, Penin F, Dubuisson J. Additional glycosylation within a specific hypervariable region of subtype 3a of hepatitis C virus protects against virus neutralization. J Infect Dis 2013; 208:1888-97. [PMID: 23908491 DOI: 10.1093/infdis/jit376] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The envelope glycoprotein E2 of hepatitis C virus (HCV) contains several hypervariable regions. Interestingly, 2 regions of intragenotypic hypervariability within E2 have been described as being specific to HCV subtype 3a. Based on their amino acid position in E2, they were named HVR495 and HVR575. Here, we further investigated these regions in order to better understand their role in HCV infection. METHODS Sequences of HCV envelope glycoproteins from Pakistani patients infected with subtype 3a were cloned and compared with other subtype 3a sequences. The entry functions and the sensitivity to antibody neutralization of selected HCV glycoprotein sequences were tested in the HCV pseudotyped particles (HCVpp) system. In addition, the cell-cultured HCV system (HCVcc) was also used to confirm some of the data obtained with the HCVpp system. RESULTS We observed interesting new features within HVR495 and HVR575 for several subtype 3a isolates. Indeed, changes in glycosylation sites were observed with the appearance of a new glycosylation site within HVR495. Importantly, HCVpp and HCVcc that contained this new HVR495 glycosylation site were less sensitive to antibody neutralization. CONCLUSIONS We identified a new glycosylation site within the HVR495 region of HCV subtype 3a that has a protective effect against antibody neutralization.
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Affiliation(s)
- Sadia Anjum
- Institut Pasteur de Lille, Center for Infection and Immunity of Lille
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21
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Wahid A, Helle F, Descamps V, Duverlie G, Penin F, Dubuisson J. Disulfide bonds in hepatitis C virus glycoprotein E1 control the assembly and entry functions of E2 glycoprotein. J Virol 2013; 87:1605-17. [PMID: 23175356 PMCID: PMC3554189 DOI: 10.1128/jvi.02659-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 11/09/2012] [Indexed: 12/24/2022] Open
Abstract
Class II membrane fusion proteins have been described in viruses in which the envelope proteins are derived from a precursor polyprotein containing two transmembrane glycoproteins arranged in tandem. Although the second protein, which carries the membrane fusion function, is in general well characterized, the companion protein, which is a protein chaperone for the folding of the fusion protein, is less well characterized for some viruses, like hepatitis C virus (HCV). To investigate the role of the class II companion glycoprotein E1 of HCV, we chose to target conserved cysteine residues in the protein, and we systematically mutated them in a full-length infectious HCV clone by reverse genetics. All the mutants were infectious, albeit with lower titers than the wild-type virus. The reduced infectivity was in part due to a decrease in viral assembly, as revealed by measurement of intracellular infectivity and by quantification of core protein released from cells transfected with mutant genomes. Analyses of mutated proteins did not show any major defect in folding. However, the mutations reduced virus stability, and they could also affect the density of infectious viral particles. Mutant viruses also showed a defect in cell-to-cell transmission. Finally, our data indicate that HCV glycoprotein E1 can also affect the fusion protein E2 by modulating its recognition by the cellular coreceptor CD81. Therefore, in the context of HCV, our data identify an additional function of a class II companion protein as a molecule that can control the binding capacity of the fusion protein.
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Affiliation(s)
- Ahmed Wahid
- Center for Infection and Immunity of Lille (CIIL), INSERM U1019, CNRS UMR8204, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Department of Biochemistry, Faculty of Pharmacy, Minia, University, Minia, Egypt
| | - François Helle
- Laboratoire de Virologie EA4294, Centre Hospitalier Universitaire d'Amiens, Université de Picardie Jules Verne, Amiens, France
| | - Véronique Descamps
- Laboratoire de Virologie EA4294, Centre Hospitalier Universitaire d'Amiens, Université de Picardie Jules Verne, Amiens, France
| | - Gilles Duverlie
- Laboratoire de Virologie EA4294, Centre Hospitalier Universitaire d'Amiens, Université de Picardie Jules Verne, Amiens, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, Bases Moléculaires et Structurales des Systèmes Infectieux, UMR-5086-CNRS, Université de Lyon, Lyon, France
| | - Jean Dubuisson
- Center for Infection and Immunity of Lille (CIIL), INSERM U1019, CNRS UMR8204, Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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Oehler V, Filipe A, Montserret R, da Costa D, Brown G, Penin F, McLauchlan J. Structural analysis of hepatitis C virus core-E1 signal peptide and requirements for cleavage of the genotype 3a signal sequence by signal peptide peptidase. J Virol 2012; 86:7818-28. [PMID: 22593157 PMCID: PMC3421639 DOI: 10.1128/jvi.00457-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [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: 02/22/2012] [Accepted: 05/07/2012] [Indexed: 12/19/2022] Open
Abstract
The maturation of the hepatitis C virus (HCV) core protein requires proteolytic processing by two host proteases: signal peptidase (SP) and the intramembrane-cleaving protease signal peptide peptidase (SPP). Previous work on HCV genotype 1a (GT1a) and GT2a has identified crucial residues required for efficient signal peptide processing by SPP, which in turn has an effect on the production of infectious virus particles. Here we demonstrate that the JFH1 GT2a core-E1 signal peptide can be adapted to the GT3a sequence without affecting the production of infectious HCV. Through mutagenesis studies, we identified crucial residues required for core-E1 signal peptide processing, including a GT3a sequence-specific histidine (His) at position 187. In addition, the stable knockdown of intracellular SPP levels in HuH-7 cells significantly affects HCV virus titers, further demonstrating the requirement for SPP for the maturation of core and the production of infectious HCV particles. Finally, our nuclear magnetic resonance (NMR) structural analysis of a synthetic HCV JFH1 GT2a core-E1 signal peptide provides an essential structural template for a further understanding of core processing as well as the first model for an SPP substrate within its membrane environment. Our findings give deeper insights into the mechanisms of intramembrane-cleaving proteases and the impact on viral infections.
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Affiliation(s)
- Verena Oehler
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Ana Filipe
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Roland Montserret
- Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, UMR 5086, CNRS, Université de Lyon, Lyon, France
| | - Daniel da Costa
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Gaie Brown
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - François Penin
- Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, UMR 5086, CNRS, Université de Lyon, Lyon, France
| | - John McLauchlan
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
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24
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Dao Thi VL, Granier C, Zeisel MB, Guérin M, Mancip J, Granio O, Penin F, Lavillette D, Bartenschlager R, Baumert TF, Cosset FL, Dreux M. Characterization of hepatitis C virus particle subpopulations reveals multiple usage of the scavenger receptor BI for entry steps. J Biol Chem 2012; 287:31242-57. [PMID: 22767607 DOI: 10.1074/jbc.m112.365924] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hepatitis C virus (HCV) particles assemble along the very low density lipoprotein pathway and are released from hepatocytes as entities varying in their degree of lipid and apolipoprotein (apo) association as well as buoyant densities. Little is known about the cell entry pathway of these different HCV particle subpopulations, which likely occurs by regulated spatiotemporal processes involving several cell surface molecules. One of these molecules is the scavenger receptor BI (SR-BI), a receptor for high density lipoprotein that can bind to the HCV glycoprotein E2. By studying the entry properties of infectious virus subpopulations differing in their buoyant densities, we show that these HCV particles utilize SR-BI in a manifold manner. First, SR-BI mediates primary attachment of HCV particles of intermediate density to cells. These initial interactions involve apolipoproteins, such as apolipoprotein E, present on the surface of HCV particles, but not the E2 glycoprotein, suggesting that lipoprotein components in the virion act as host-derived ligands for important entry factors such as SR-BI. Second, we found that in contrast to this initial attachment, SR-BI mediates entry of HCV particles independent of their buoyant density. This function of SR-BI does not depend on E2/SR-BI interaction but relies on the lipid transfer activity of SR-BI, probably by facilitating entry steps along with other HCV entry co-factors. Finally, our results underscore a third function of SR-BI governed by specific residues in hypervariable region 1 of E2 leading to enhanced cell entry and depending on SR-BI ability to bind to E2.
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Affiliation(s)
- Viet Loan Dao Thi
- INSERM, U758, Human Virology Laboratory, EVIR team, Lyon, F-69007, France
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25
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Lethias C, Exposito JY, Descollonges Y, Penin F, Garrone R. Expression of a new fibrillar collagen class in the sea urchin embryo during spiculogenesis. Biol Cell 2012. [DOI: 10.1016/0248-4900(96)81377-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Abstract
Hepatitis C virus (HCV) nonstructural protein 3-4A (NS3-4A) is a complex composed of NS3 and its cofactor NS4A. It harbours serine protease as well as NTPase/RNA helicase activities and is essential for viral polyprotein processing, RNA replication and virion formation. Specific inhibitors of the NS3-4A protease significantly improve sustained virological response rates in patients with chronic hepatitis C when combined with pegylated interferon-α and ribavirin. The NS3-4A protease can also target selected cellular proteins, thereby blocking innate immune pathways and modulating growth factor signalling. Hence, NS3-4A is not only an essential component of the viral replication complex and prime target for antiviral intervention but also a key player in the persistence and pathogenesis of HCV. This review provides a concise update on the biochemical and structural aspects of NS3-4A, its role in the pathogenesis of chronic hepatitis C and the clinical development of NS3-4A protease inhibitors.
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Affiliation(s)
- K Morikawa
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
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27
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Pascarella S, Clément S, Guilloux K, Conzelmann S, Penin F, Negro F. Effects of hepatitis C virus on suppressor of cytokine signaling mRNA levels: Comparison between different genotypes and core protein sequence analysis. J Med Virol 2011; 83:1005-15. [DOI: 10.1002/jmv.22072] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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28
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Verdegem D, Badillo A, Wieruszeski JM, Landrieu I, Leroy A, Bartenschlager R, Penin F, Lippens G, Hanoulle X. Domain 3 of NS5A protein from the hepatitis C virus has intrinsic alpha-helical propensity and is a substrate of cyclophilin A. J Biol Chem 2011; 286:20441-54. [PMID: 21489988 DOI: 10.1074/jbc.m110.182436] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nonstructural protein 5A (NS5A) is essential for hepatitis C virus (HCV) replication and constitutes an attractive target for antiviral drug development. Although structural data for its in-plane membrane anchor and domain D1 are available, the structure of domains 2 (D2) and 3 (D3) remain poorly defined. We report here a comparative molecular characterization of the NS5A-D3 domains of the HCV JFH-1 (genotype 2a) and Con1 (genotype 1b) strains. Combining gel filtration, CD, and NMR spectroscopy analyses, we show that NS5A-D3 is natively unfolded. However, NS5A-D3 domains from both JFH-1 and Con1 strains exhibit a propensity to partially fold into an α-helix. NMR analysis identifies two putative α-helices, for which a molecular model could be obtained. The amphipathic nature of the first helix and its conservation in all genotypes suggest that it might correspond to a molecular recognition element and, as such, promote the interaction with relevant biological partner(s). Because mutations conferring resistance to cyclophilin inhibitors have been mapped into NS5A-D3, we also investigated the functional interaction between NS5A-D3 and cyclophilin A (CypA). CypA indeed interacts with NS5A-D3, and this interaction is completely abolished by cyclosporin A. NMR heteronuclear exchange experiments demonstrate that CypA has in vitro peptidyl-prolyl cis/trans-isomerase activity toward some, but not all, of the peptidyl-prolyl bonds in NS5A-D3. These studies lead to novel insights into the structural features of NS5A-D3 and its relationships with CypA.
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29
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Popescu CI, Callens N, Trinel D, Roingeard P, Moradpour D, Descamps V, Duverlie G, Penin F, Héliot L, Rouillé Y, Dubuisson J. NS2 protein of hepatitis C virus interacts with structural and non-structural proteins towards virus assembly. PLoS Pathog 2011; 7:e1001278. [PMID: 21347350 PMCID: PMC3037360 DOI: 10.1371/journal.ppat.1001278] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 01/07/2011] [Indexed: 02/07/2023] Open
Abstract
Growing experimental evidence indicates that, in addition to the physical virion components, the non-structural proteins of hepatitis C virus (HCV) are intimately involved in orchestrating morphogenesis. Since it is dispensable for HCV RNA replication, the non-structural viral protein NS2 is suggested to play a central role in HCV particle assembly. However, despite genetic evidences, we have almost no understanding about NS2 protein-protein interactions and their role in the production of infectious particles. Here, we used co-immunoprecipitation and/or fluorescence resonance energy transfer with fluorescence lifetime imaging microscopy analyses to study the interactions between NS2 and the viroporin p7 and the HCV glycoprotein E2. In addition, we used alanine scanning insertion mutagenesis as well as other mutations in the context of an infectious virus to investigate the functional role of NS2 in HCV assembly. Finally, the subcellular localization of NS2 and several mutants was analyzed by confocal microscopy. Our data demonstrate molecular interactions between NS2 and p7 and E2. Furthermore, we show that, in the context of an infectious virus, NS2 accumulates over time in endoplasmic reticulum-derived dotted structures and colocalizes with both the envelope glycoproteins and components of the replication complex in close proximity to the HCV core protein and lipid droplets, a location that has been shown to be essential for virus assembly. We show that NS2 transmembrane region is crucial for both E2 interaction and subcellular localization. Moreover, specific mutations in core, envelope proteins, p7 and NS5A reported to abolish viral assembly changed the subcellular localization of NS2 protein. Together, these observations indicate that NS2 protein attracts the envelope proteins at the assembly site and it crosstalks with non-structural proteins for virus assembly. Hepatitis C virus (HCV) causes major health problems worldwide. Understanding the major steps of the life cycle of this virus is essential to developing new and more efficient antiviral molecules. Virus assembly is the least understood step of the HCV life cycle. Growing experimental evidence indicates that, in addition to the physical virion components, the HCV non-structural proteins are intimately involved in orchestrating morphogenesis. Since it is dispensable for HCV RNA replication, the non-structural viral protein NS2 is suggested to play a central role in HCV particle assembly. Molecular interactions between NS2 and other HCV proteins were demonstrated. Furthermore, NS2 was shown to accumulate over time in endoplasmic reticulum-derived structures and to colocalize with the viral envelope glycoproteins and viral components of the replication complex in close proximity to the HCV core protein and lipid droplets. Importantly, specific mutations within NS2 that affected HCV infectivity could also alter the subcellular localization of NS2 protein and its interactions, suggesting that this subcellular localization and its interactions are essential for HCV particle assembly. Altogether, these observations indicate that NS2 protein plays an important role in connecting different viral components that are essential for virus assembly.
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Affiliation(s)
- Costin-Ioan Popescu
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Nathalie Callens
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Dave Trinel
- Institute of Interdisciplinary Research, University Lille 1, Villeneuve d'Ascq, France
| | - Philippe Roingeard
- INSERM U966, Université François Rabelais and CHRU de Tours, Tours, France
| | - Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Véronique Descamps
- Laboratoire de Virologie, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - Gilles Duverlie
- Laboratoire de Virologie, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, UMR-5086-CNRS, Université de Lyon, Lyon, France
| | - Laurent Héliot
- Institute of Interdisciplinary Research, University Lille 1, Villeneuve d'Ascq, France
| | - Yves Rouillé
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Jean Dubuisson
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- * E-mail:
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30
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Teissier E, Penin F, Pécheur EI. Targeting cell entry of enveloped viruses as an antiviral strategy. Molecules 2010; 16:221-50. [PMID: 21193846 PMCID: PMC6259279 DOI: 10.3390/molecules16010221] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/16/2010] [Accepted: 12/24/2010] [Indexed: 12/16/2022] Open
Abstract
The entry of enveloped viruses into their host cells involves several successive steps, each one being amenable to therapeutic intervention. Entry inhibitors act by targeting viral and/or cellular components, through either the inhibition of protein-protein interactions within the viral envelope proteins or between viral proteins and host cell receptors, or through the inhibition of protein-lipid interactions. Interestingly, inhibitors that concentrate into/onto the membrane in order to target a protein involved in the entry process, such as arbidol or peptide inhibitors of the human immunodeficiency virus (HIV), could allow the use of doses compatible with therapeutic requirements. The efficacy of these drugs validates entry as a point of intervention in viral life cycles. Strategies based upon small molecule antiviral agents, peptides, proteins or nucleic acids, would most likely prove efficient in multidrug combinations, in order to inhibit several steps of virus life cycle and prevent disease progression.
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Affiliation(s)
| | | | - Eve-Isabelle Pécheur
- Institut de Biologie et Chimie des Protéines, UMR 5086, Université de Lyon, IFR 128 BioSciences Gerland-Lyon Sud, 69367 Lyon, France; E-Mails: (E.T.); (F.P.)
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31
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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Bonnafous P, Perrault M, Le Bihan O, Bartosch B, Lavillette D, Penin F, Lambert O, Pécheur EI. Characterization of hepatitis C virus pseudoparticles by cryo-transmission electron microscopy using functionalized magnetic nanobeads. J Gen Virol 2010; 91:1919-1930. [PMID: 20375221 DOI: 10.1099/vir.0.021071-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cell entry and membrane fusion of the hepatitis C virus (HCV) depend on its envelope glycoproteins E1 and E2. HCV pseudotyped particles (HCVpps) are relevant and popular models to study the early steps of the HCV life cycle. However, no structural characterization of HCVpp has been available so far. Using cryo-transmission electron microscopy (cryo-TEM), providing structural information at nanometric resolution, the molecular details of HCVpps and their fusion with liposomes were studied. Cryo-TEM revealed HCVpps as regular 100 nm spherical structures containing the dense retroviral nucleocapsid surrounded by a lipid bilayer. E1-E2 glycoproteins were not readily visible on the membrane surface. Pseudoparticles bearing the E1-E2 glycoproteins of Semliki forest virus looked similar, whereas avian influenza A virus (fowl plague virus) haemagglutinin/neuraminidase-pseudotyped particles exhibited surface spikes. To further characterize HCVpp structurally, a novel method was designed based on magnetic beads covered with anti-HCV antibodies to enrich the samples with particles containing E1-E2. This strategy efficiently sorted HCVpps, which were then directly observed by cryo-TEM in the presence or absence of liposomes at low or neutral pH. After acidification, HCVpps looked the same as at neutral pH and closely contacted the liposomes. These are the first visualizations of early HCV membrane fusion events at the nanometer scale. Furthermore, fluorimetry analysis revealed a relative resistance of HCVpps regarding their fusion capacity when exposed to low pH. This study therefore brings several new molecular details to HCVpp characterization and this efficient strategy of virion immunosorting with magnetic nanobeads is direct, efficient and adaptable to extensive characterization of any virus at a nanometric resolution.
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Affiliation(s)
- Pierre Bonnafous
- CBMN, UMR CNRS 5248, Université Bordeaux 1, ENITAB, IECB, Avenue des Facultés, F-33405 Talence, France
| | - Marie Perrault
- Institut de Biologie et Chimie des Protéines, UMR CNRS 5086, Université Lyon 1, IFR128 Lyon Biosciences Gerland, F-69007 Lyon, France
| | - Olivier Le Bihan
- CBMN, UMR CNRS 5248, Université Bordeaux 1, ENITAB, IECB, Avenue des Facultés, F-33405 Talence, France
| | - Birke Bartosch
- INSERM, U758, F-69007 Lyon, France
- Université de Lyon, UCB-Lyon 1, IFR128, F-69007 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69007 Lyon, France
| | - Dimitri Lavillette
- Ecole Normale Supérieure de Lyon, F-69007 Lyon, France
- INSERM, U758, F-69007 Lyon, France
- Université de Lyon, UCB-Lyon 1, IFR128, F-69007 Lyon, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, UMR CNRS 5086, Université Lyon 1, IFR128 Lyon Biosciences Gerland, F-69007 Lyon, France
| | - Olivier Lambert
- CBMN, UMR CNRS 5248, Université Bordeaux 1, ENITAB, IECB, Avenue des Facultés, F-33405 Talence, France
| | - Eve-Isabelle Pécheur
- Institut de Biologie et Chimie des Protéines, UMR CNRS 5086, Université Lyon 1, IFR128 Lyon Biosciences Gerland, F-69007 Lyon, France
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Gouttenoire J, Penin F, Moradpour D. Hepatitis C virus nonstructural protein 4B: a journey into unexplored territory. Rev Med Virol 2010; 20:117-29. [DOI: 10.1002/rmv.640] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Hanoulle X, Badillo A, Wieruszeski JM, Verdegem D, Landrieu I, Bartenschlager R, Penin F, Lippens G. Hepatitis C virus NS5A protein is a substrate for the peptidyl-prolyl cis/trans isomerase activity of cyclophilins A and B. J Biol Chem 2009; 284:13589-13601. [PMID: 19297321 DOI: 10.1074/jbc.m809244200] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We report here a biochemical and structural characterization of domain 2 of the nonstructural 5A protein (NS5A) from the JFH1 Hepatitis C virus strain and its interactions with cyclophilins A and B (CypA and CypB). Gel filtration chromatography, circular dichroism spectroscopy, and finally NMR spectroscopy all indicate the natively unfolded nature of this NS5A-D2 domain. Because mutations in this domain have been linked to cyclosporin A resistance, we used NMR spectroscopy to investigate potential interactions between NS5A-D2 and cellular CypA and CypB. We observed a direct molecular interaction between NS5A-D2 and both cyclophilins. The interaction surface on the cyclophilins corresponds to their active site, whereas on NS5A-D2, it proved to be distributed over the many proline residues of the domain. NMR heteronuclear exchange spectroscopy yielded direct evidence that many proline residues in NS5A-D2 form a valid substrate for the enzymatic peptidyl-prolyl cis/trans isomerase (PPIase) activity of CypA and CypB.
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Affiliation(s)
- Xavier Hanoulle
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS, IFR 147, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France
| | - Aurélie Badillo
- Institut de Biologie et Chimie des Protéines, UMR 5086, CNRS, Université de Lyon, IFR 128, BioSciences Gerland-Lyon Sud, F-69397 Lyon, France
| | - Jean-Michel Wieruszeski
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS, IFR 147, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France
| | - Dries Verdegem
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS, IFR 147, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France
| | - Isabelle Landrieu
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS, IFR 147, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France
| | - Ralf Bartenschlager
- Department of Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | - François Penin
- Institut de Biologie et Chimie des Protéines, UMR 5086, CNRS, Université de Lyon, IFR 128, BioSciences Gerland-Lyon Sud, F-69397 Lyon, France
| | - Guy Lippens
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS, IFR 147, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France.
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Hanoulle X, Verdegem D, Badillo A, Wieruszeski JM, Penin F, Lippens G. Domain 3 of non-structural protein 5A from hepatitis C virus is natively unfolded. Biochem Biophys Res Commun 2009; 381:634-8. [PMID: 19249289 DOI: 10.1016/j.bbrc.2009.02.108] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 02/20/2009] [Indexed: 11/30/2022]
Abstract
Hepatitis C virus (HCV) non-structural protein 5A (NS5A) is involved both in the viral replication and particle production. Its third domain (NS5A-D3), although not absolutely required for replication, is a key determinant for the production and assembly of novel HCV particles. As a prerequisite to elucidate the precise functions of this domain, we report here the first molecular characterization of purified recombinant HCV NS5A-D3. Sequence analysis indicates that NS5A-D3 is mostly unstructured but that short structural elements may exist at its N-terminus. Gel filtration chromatography, circular dichroism and finally NMR spectroscopy all point out the natively unfolded nature of purified recombinant NS5A-D3. This lack of stable folding is thought to be essential for primary interactions of NS5A-D3 domain with other viral or host proteins, which could stabilize some specific conformations conferring new functional features.
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Affiliation(s)
- Xavier Hanoulle
- UGSF, UMR CNRS, IFR, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France.
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Lindenbach BD, Prágai BM, Montserret R, Beran RKF, Pyle AM, Penin F, Rice CM. The C terminus of hepatitis C virus NS4A encodes an electrostatic switch that regulates NS5A hyperphosphorylation and viral replication. J Virol 2007; 81:8905-18. [PMID: 17581983 PMCID: PMC1951449 DOI: 10.1128/jvi.00937-07] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [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] [Indexed: 12/17/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 4A (NS4A) is only 54 amino acids (aa) in length, yet it is a key regulator of the essential serine protease and RNA helicase activities of the NS3-4A complex, as well as a determinant of NS5A phosphorylation. Here we examine the structure and function of the C-terminal acidic region of NS4A through site-directed mutagenesis of a Con1 subgenomic replicon and through biophysical characterization of a synthetic peptide corresponding to this region. Our genetic studies revealed that in 8 of the 15 C-terminal residues of NS4A, individual Ala substitutions or charge reversal substitutions led to severe replication phenotypes, as well as decreased NS5A hyperphosphorylation. By selecting for replication-competent mutants, several second-site changes in NS3 were identified and shown to suppress these defects in replication and NS5A hyperphosphorylation. Circular-dichroism spectroscopy and nuclear magnetic resonance spectroscopy on a peptide corresponding to the C-terminal 19 aa of NS4A revealed that this region can adopt an alpha-helical conformation, but that this folding requires neutralization of a cluster of acidic residues. Taken together, these data suggest that the C terminus of NS4A acts as a dynamic regulator of NS3-4A interaction, NS5A hyperphosphorylation, and HCV replicase activity.
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Affiliation(s)
- Brett D Lindenbach
- Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10021, USA.
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Lavillette D, Pécheur EI, Donot P, Fresquet J, Molle J, Corbau R, Dreux M, Penin F, Cosset FL. Characterization of fusion determinants points to the involvement of three discrete regions of both E1 and E2 glycoproteins in the membrane fusion process of hepatitis C virus. J Virol 2007; 81:8752-65. [PMID: 17537855 PMCID: PMC1951381 DOI: 10.1128/jvi.02642-06] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Infection of eukaryotic cells by enveloped viruses requires the merging of viral and cellular membranes. Highly specific viral surface glycoproteins, named fusion proteins, catalyze this reaction by overcoming inherent energy barriers. Hepatitis C virus (HCV) is an enveloped virus that belongs to the genus Hepacivirus of the family Flaviviridae. Little is known about the molecular events that mediate cell entry and membrane fusion for HCV, although significant progress has been made due to recent developments in infection assays. Here, using infectious HCV pseudoparticles (HCVpp), we investigated the molecular basis of HCV membrane fusion. By searching for classical features of fusion peptides through the alignment of sequences from various HCV genotypes, we identified six regions of HCV E1 and E2 glycoproteins that present such characteristics. We introduced conserved and nonconserved amino acid substitutions in these regions and analyzed the phenotype of HCVpp generated with mutant E1E2 glycoproteins. This was achieved by (i) quantifying the infectivity of the pseudoparticles, (ii) studying the incorporation of E1E2 and their capacity to mediate receptor binding, and (iii) determining their fusion capacity in cell-cell and liposome/HCVpp fusion assays. We propose that at least three of these regions (i.e., at positions 270 to 284, 416 to 430, and 600 to 620) play a role in the membrane fusion process. These regions may contribute to the merging of viral and cellular membranes either by interacting directly with lipid membranes or by assisting the fusion process through their involvement in the conformational changes of the E1E2 complex at low pH.
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Helle F, Goffard A, Morel V, Duverlie G, McKeating J, Keck ZY, Foung S, Penin F, Dubuisson J, Voisset C. The neutralizing activity of anti-hepatitis C virus antibodies is modulated by specific glycans on the E2 envelope protein. J Virol 2007; 81:8101-11. [PMID: 17522218 PMCID: PMC1951279 DOI: 10.1128/jvi.00127-07] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [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] [Indexed: 12/27/2022] Open
Abstract
Hepatitis C virus (HCV) envelope glycoproteins are highly glycosylated, with up to 5 and 11 N-linked glycans on E1 and E2, respectively. Most of the glycosylation sites on HCV envelope glycoproteins are conserved, and some of the glycans associated with these proteins have been shown to play an essential role in protein folding and HCV entry. Such a high level of glycosylation suggests that these glycans can limit the immunogenicity of HCV envelope proteins and restrict the binding of some antibodies to their epitopes. Here, we investigated whether these glycans can modulate the neutralizing activity of anti-HCV antibodies. HCV pseudoparticles (HCVpp) bearing wild-type glycoproteins or mutants at individual glycosylation sites were evaluated for their sensitivity to neutralization by antibodies from the sera of infected patients and anti-E2 monoclonal antibodies. While we did not find any evidence that N-linked glycans of E1 contribute to the masking of neutralizing epitopes, our data demonstrate that at least three glycans on E2 (denoted E2N1, E2N6, and E2N11) reduce the sensitivity of HCVpp to antibody neutralization. Importantly, these three glycans also reduced the access of CD81 to its E2 binding site, as shown by using a soluble form of the extracellular loop of CD81 in inhibition of entry. These data suggest that glycans E2N1, E2N6, and E2N11 are close to the binding site of CD81 and modulate both CD81 and neutralizing antibody binding to E2. In conclusion, this work indicates that HCV glycans contribute to the evasion of HCV from the humoral immune response.
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Affiliation(s)
- François Helle
- Institut de Biologie de Lille (UMR8161), CNRS, Université Lille I and II and Institut Pasteur de Lille, Lille, France
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Abstract
Exciting progress has recently been made in understanding the replication of hepatitis C virus, a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The development of complete cell-culture systems should now enable the systematic dissection of the entire viral lifecycle, providing insights into the hitherto difficult-to-study early and late steps. These efforts have already translated into the identification of novel antiviral targets and the development of new therapeutic strategies, some of which are currently undergoing clinical evaluation.
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Affiliation(s)
- Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, CH-1011 Lausanne, Switzerland.
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Abstract
Exciting progress has recently been made in understanding the replication of hepatitis C virus, a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The development of complete cell-culture systems should now enable the systematic dissection of the entire viral lifecycle, providing insights into the hitherto difficult-to-study early and late steps. These efforts have already translated into the identification of novel antiviral targets and the development of new therapeutic strategies, some of which are currently undergoing clinical evaluation.
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Affiliation(s)
- Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, CH-1011 Lausanne, Switzerland.
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Etzkorn M, Böckmann A, Penin F, Riedel D, Baldus M. Characterization of folding intermediates of a domain-swapped protein by solid-state NMR spectroscopy. J Am Chem Soc 2007; 129:169-75. [PMID: 17199296 DOI: 10.1021/ja066469x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have employed two-dimensional solid-state NMR to study structure and dynamics of insoluble folding states of the domain-swapped protein Crh. Starting from the protein precipitated at its pI, conformational changes due to a modest temperature increase were investigated at the level of individual residues and in real-time. As compared to the crystalline state, Crh pI-precipitates exhibited a higher degree of molecular mobility for several regions of the protein. A rigidly intact center was observed including a subset of residues of the hydrophobic core. Raising the temperature by 13 K to 282 K created a partially unfolded intermediate state that was converted into beta-sheet-rich aggregates that are mostly of spherical character according to electron microscopy. Residue-by-residue analysis indicated that two out of three alpha-helices in aggregated Crh underwent major structural rearrangements while the third helix was preserved. Residues in the hinge region exhibited major chemical-shift changes, indicating that the domain swap was not conserved in the aggregated form. Our study provides direct evidence that protein aggregates of a domain-swapped protein retain a significant fraction of native secondary structure and demonstrates that solid-state NMR can be used to directly monitor slow molecular folding events.
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Affiliation(s)
- Manuel Etzkorn
- Department of NMR-Based Structural Biology and Electron Microscopy, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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Castelain S, Bonte D, Penin F, François C, Capron D, Dedeurwaerder S, Zawadzki P, Morel V, Wychowski C, Duverlie G. Hepatitis C Virus p7 membrane protein quasispecies variability in chronically infected patients treated with interferon and ribavirin, with or without amantadine. J Med Virol 2007; 79:144-54. [PMID: 17177298 DOI: 10.1002/jmv.20772] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A clinical study was carried out to compare the response rate of two groups of non-responder (NR) hepatitis C virus (HCV) genotype 1 chronically infected patients treated with interferon and ribavirin, with or without amantadine. The viral load decreased more markedly in the group treated by tritherapy including amantadine, but the response rate at the end of treatment was not significantly different between bitherapy and tritherapy. As amantadine could have an antiviral effect on the ion channel activity of the p7 HCV protein, the p7 quasispecies was characterized by cloning and sequencing. Sequence data were analyzed to determine the pattern and significance of p7 genetic heterogeneity and a possible relationship with therapy. Subtype differences were confirmed between p7 HCV genotypes 1a and 1b, and quasispecies analysis showed a reduction of genetic diversity in subtype 1a, but not 1b, during tritherapy. However, the absence of changes at numerous positions, as well as the conservative changes at other positions, indicated the high conservation of the p7 structure. Residue His-17, proposed to interact with amantadine, was fully conserved in both subtypes 1a and 1b, independently of amantadine administration. In conclusion, although the analysis of the p7 sequences revealed a selective pressure during therapy, no specific residues appeared to be linked to the effect of amantadine on viral decline. These results suggest that the potential antiviral effect of amantadine might be non-specific and related to a reduction in endosomal acidification and therefore reduced viral entry of HCV via its pH-dependent pathway.
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Brillet R, Penin F, Hezode C, Chouteau P, Dhumeaux D, Pawlotsky JM. The Nonstructural 5A Protein of Hepatitis C Virus Genotype 1b Does Not Contain an Interferon Sensitivity–Determining Region. J Infect Dis 2007; 195:432-41. [PMID: 17205483 DOI: 10.1086/510316] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 09/11/2006] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The nonstructural (NS) 5A protein of hepatitis C virus (HCV) has been suggested to contain an interferon (IFN) sensitivity-determining region (ISDR). METHODS We studied whether the degree of viral decline on day 1 is associated with differences in NS5A amino acid sequences among patients receiving IFN- alpha. RESULTS Phylogenetic analyses of the full-length protein and of functional domains showed no relationship between the baseline protein sequence and the antiviral response. NS5A quasispecies sequences showed no differences in the number of mutations in the putative ISDR relative to a prototype sequence between responders and nonresponders or according to IFN- alpha antiviral efficacy. No relationship was found between antiviral efficacy at 24 h and the baseline sequence of any NS5A region. Amino acid changes were observed in a few cases at 24 h in both responders and nonresponders, but no consistent pattern of amino acid shifts was observed, ruling out the possibility that IFN- alpha selected IFN-resistant variants. CONCLUSION Our findings show that there is no ISDR in the HCV genotype 1 NS5A protein and that the NS5A sequence does not influence the capacity of IFN- alpha to block viral replication. The findings do not rule out a role for NS5A in subsequent viral clearance.
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Affiliation(s)
- Rozenn Brillet
- French National Reference Center for Viral Hepatitis B, C, and Delta, Department of Virology and Institut National de la Sante et de la Recherche Medicale Unite 635, France
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Brass V, Pal Z, Sapay N, Deléage G, Blum HE, Penin F, Moradpour D. Conserved determinants for membrane association of nonstructural protein 5A from hepatitis C virus and related viruses. J Virol 2006; 81:2745-57. [PMID: 17192310 PMCID: PMC1866014 DOI: 10.1128/jvi.01279-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Nonstructural protein 5A (NS5A) is a membrane-associated essential component of the hepatitis C virus (HCV) replication complex. An N-terminal amphipathic alpha helix mediates in-plane membrane association of HCV NS5A and at the same time is likely involved in specific protein-protein interactions required for the assembly of a functional replication complex. The aim of this study was to identify the determinants for membrane association of NS5A from the related GB viruses and pestiviruses. Although primary amino acid sequences differed considerably, putative membrane anchor domains with amphipathic features were predicted in the N-terminal domains of NS5A proteins from these viruses. Confocal laser scanning microscopy, as well as membrane flotation analyses, demonstrated that NS5As from GB virus B (GBV-B), GBV-C, and bovine viral diarrhea virus, the prototype pestivirus, display membrane association characteristics very similar to those of HCV NS5A. The N-terminal 27 to 33 amino acid residues of these NS5A proteins were sufficient for membrane association. Circular dichroism analyses confirmed the capacity of these segments to fold into alpha helices upon association with lipid-like molecules. Despite structural conservation, only very limited exchanges with sequences from related viruses were tolerated in the context of functional HCV RNA replication, suggesting virus-specific interactions of these segments. In conclusion, membrane association of NS5A by an N-terminal amphipathic alpha helix is a feature shared by HCV and related members of the family Flaviviridae. This observation points to conserved roles of the N-terminal amphipathic alpha helices of NS5A in replication complex formation.
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Affiliation(s)
- Volker Brass
- Department of Medicine II, University of Freiburg, D-79106 Freiburg, Germany
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Ciczora Y, Callens N, Penin F, Pécheur EI, Dubuisson J. Transmembrane domains of hepatitis C virus envelope glycoproteins: residues involved in E1E2 heterodimerization and involvement of these domains in virus entry. J Virol 2006; 81:2372-81. [PMID: 17166909 PMCID: PMC1865936 DOI: 10.1128/jvi.02198-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transmembrane (TM) domains of hepatitis C virus (HCV) envelope glycoproteins E1 and E2 have been shown to play multiple roles during the biogenesis of the E1E2 heterodimer. By using alanine scanning insertion mutagenesis within the TM domains of HCV envelope glycoproteins, we have previously shown that the central regions of these domains as well as the N-terminal part of the TM domain of E1 are involved in heterodimerization. Here, we used a tryptophan replacement scan of these regions to identify individual residues that participate in those interactions. Our mutagenesis study identified at least four residues involved in heterodimerization: Gly 354, Gly 358, Lys 370, and Asp 728. Interestingly, Gly 354 and Gly 358 belong to a GXXXG oligomerization motif. Our tryptophan mutants were also used to generate retrovirus-based, HCV-pseudotyped particles (HCVpp) in order to analyze the effects of these mutations on virus entry. Surprisingly, two mutants consistently displayed higher infectivity compared to that of the wild type. In contrast, HCVpp infectivity was strongly affected for many mutants, despite normal E1E2 heterodimerization and normal levels of incorporation of HCV glycoproteins into HCVpp. The characterization of some of these HCVpp mutants in the recently developed in vitro fusion assay using fluorescent-labeled liposomes indicated that mutations reducing HCVpp infectivity without altering E1E2 heterodimerization affected the fusion properties of HCV envelope glycoproteins. In conclusion, this mutational analysis identified residues involved in E1E2 heterodimerization and revealed that the TM domains of HCV envelope glycoproteins play a major role in the fusion properties of these proteins.
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Affiliation(s)
- Yann Ciczora
- Hepatitis C Laboratory, CNRS-UMR8161, Institut de Biologie de Lille, 1 rue Calmette, BP447, 59021 Lille cedex, France
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Affiliation(s)
- Jerome Gouttenoire
- Division of Gastroenterology and Hepatology Centre Hospitalier Universitaire Vaudois University of Lausanne Lausanne, Switzerland
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Combet C, Garnier N, Charavay C, Grando D, Crisan D, Lopez J, Dehne-Garcia A, Geourjon C, Bettler E, Hulo C, Le Mercier P, Bartenschlager R, Diepolder H, Moradpour D, Pawlotsky JM, Rice CM, Trépo C, Penin F, Deléage G. euHCVdb: the European hepatitis C virus database. Nucleic Acids Res 2006; 35:D363-6. [PMID: 17142229 PMCID: PMC1669729 DOI: 10.1093/nar/gkl970] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The hepatitis C virus (HCV) genome shows remarkable sequence variability, leading to the classification of at least six major genotypes, numerous subtypes and a myriad of quasispecies within a given host. A database allowing researchers to investigate the genetic and structural variability of all available HCV sequences is an essential tool for studies on the molecular virology and pathogenesis of hepatitis C as well as drug design and vaccine development. We describe here the European Hepatitis C Virus Database (euHCVdb, ), a collection of computer-annotated sequences based on reference genomes. The annotations include genome mapping of sequences, use of recommended nomenclature, subtyping as well as three-dimensional (3D) molecular models of proteins. A WWW interface has been developed to facilitate database searches and the export of data for sequence and structure analyses. As part of an international collaborative effort with the US and Japanese databases, the European HCV Database (euHCVdb) is mainly dedicated to HCV protein sequences, 3D structures and functional analyses.
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Affiliation(s)
- Christophe Combet
- Institut de Biologie et Chimie des Protéines (UMR5086), CNRS, University of Lyon 1, IFR 128 BioSciences, Lyon-Gerland, France.
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Lesage A, Emsley L, Penin F, Böckmann A. Investigation of Dipolar-Mediated Water−Protein Interactions in Microcrystalline Crh by Solid-State NMR Spectroscopy. J Am Chem Soc 2006; 128:8246-55. [PMID: 16787089 DOI: 10.1021/ja060866q] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Water-protein interactions play a major role in protein folding, structure, and function, and solid-state NMR has recently been shown to be a powerful tool for the site-resolved observation of these interactions in solid proteins. In this article we report investigations on possible water-protein dipolar transfer mechanisms in the microcrystalline deuterated protein Crh by a set of solid-state NMR techniques. Double-quantum (DQ) filtered and edited heteronuclear correlation experiments are used to follow direct dipolar water-protein magnetization transfers. Experimental data reveal no evidence for "solid-like" water molecules, indicating that residence times of solvent molecules are shorter than required for DQ creation, typically a few hundred microseconds. An alternative magnetization pathway, intermolecular cross-relaxation via heteronuclear nuclear Overhauser effects (NOEs), is probed by saturation transfer experiments. The significant additional enhancements observed when irradiating at the water frequency can possibly be attributed to direct heteronuclear water-protein NOEs; however, a contribution from relayed magnetization transfer via chemical exchange or proton-proton dipolar mechanisms cannot be excluded.
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Affiliation(s)
- Anne Lesage
- Laboratoire de Chimie (UMR 5182 ENS/CNRS), Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon, France
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Ivanyi-Nagy R, Kanevsky I, Gabus C, Lavergne JP, Ficheux D, Penin F, Fossé P, Darlix JL. Analysis of hepatitis C virus RNA dimerization and core-RNA interactions. Nucleic Acids Res 2006; 34:2618-33. [PMID: 16707664 PMCID: PMC1463901 DOI: 10.1093/nar/gkl240] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The core protein of hepatitis C virus (HCV) has been shown previously to act as a potent nucleic acid chaperone in vitro, promoting the dimerization of the 3′-untranslated region (3′-UTR) of the HCV genomic RNA, a process probably mediated by a small, highly conserved palindromic RNA motif, named DLS (dimer linkage sequence) [G. Cristofari, R. Ivanyi-Nagy, C. Gabus, S. Boulant, J. P. Lavergne, F. Penin and J. L. Darlix (2004) Nucleic Acids Res., 32, 2623–2631]. To investigate in depth HCV RNA dimerization, we generated a series of point mutations in the DLS region. We find that both the plus-strand 3′-UTR and the complementary minus-strand RNA can dimerize in the presence of core protein, while mutations in the DLS (among them a single point mutation that abolished RNA replication in a HCV subgenomic replicon system) completely abrogate dimerization. Structural probing of plus- and minus-strand RNAs, in their monomeric and dimeric forms, indicate that the DLS is the major if not the sole determinant of UTR RNA dimerization. Furthermore, the N-terminal basic amino acid clusters of core protein were found to be sufficient to induce dimerization, suggesting that they retain full RNA chaperone activity. These findings may have important consequences for understanding the HCV replicative cycle and the genetic variability of the virus.
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Affiliation(s)
| | - Igor Kanevsky
- CNRS-UMR 8113, LBPA-Alembert, Ecole Normale Supérieure de Cachan94235 Cachan Cedex, France
| | | | - Jean-Pierre Lavergne
- Institut de Biologie et Chimie des Protéines, CNRS-UMR 5086, Université Claude Bernard Lyon IIFR 128 Biosciences Lyon-Gerland, 69367 Lyon Cedex 07, France
| | - Damien Ficheux
- Institut de Biologie et Chimie des Protéines, CNRS-UMR 5086, Université Claude Bernard Lyon IIFR 128 Biosciences Lyon-Gerland, 69367 Lyon Cedex 07, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, CNRS-UMR 5086, Université Claude Bernard Lyon IIFR 128 Biosciences Lyon-Gerland, 69367 Lyon Cedex 07, France
| | - Philippe Fossé
- CNRS-UMR 8113, LBPA-Alembert, Ecole Normale Supérieure de Cachan94235 Cachan Cedex, France
| | - Jean-Luc Darlix
- To whom correspondence should be addressed. Tel: +33 4 72 72 81 69; Fax: +33 4 72 72 87 77;
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Sapay N, Montserret R, Chipot C, Brass V, Moradpour D, Deléage G, Penin F. NMR structure and molecular dynamics of the in-plane membrane anchor of nonstructural protein 5A from bovine viral diarrhea virus. Biochemistry 2006; 45:2221-33. [PMID: 16475810 DOI: 10.1021/bi0517685] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a monotopic membrane protein anchored to the membrane by an N-terminal in-plane amphipathic alpha-helix. This membrane anchor is essential for the assembly of a functional viral replication complex. Although amino acid sequences differ considerably, putative membrane anchors with amphipathic features were predicted in NS5A from related Flaviviridae family members, in particular bovine viral diarrhea virus (BVDV), the prototype representative of the genus Pestivirus. We report here the NMR structure of the membrane anchor 1-28 of NS5A from BVDV in the presence of different membrane mimetic media. This anchor includes a long amphipathic alpha-helix of 21 residues interacting in-plane with the membrane interface and including a putative flexible region. Molecular dynamic simulation at a water-dodecane interface used to mimic the surface separating a lipid bilayer and an aqueous medium demonstrated the stability of the helix orientation and the location at the hydrophobic-hydrophilic interface. The flexible region of the helix appears to be required to allow the most favorable interaction of hydrophobic and hydrophilic side chain residues with their respective environment at the membrane interface. Despite the lack of amino acid sequence similarity, this amphipathic helix shares common structural features with that of the HCV counterpart, including a stable, hydrophobic N-terminal segment separated from the more hydrophilic C-terminal segment by a local, flexible region. These structural conservations point toward conserved roles of the N-terminal in-plane membrane anchors of NS5A in replication complex formation of HCV, BVDV, and other related viruses.
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Affiliation(s)
- Nicolas Sapay
- Institut de Biologie et Chimie des Protéines, CNRS-UMR 5086, IFR128 BioSciences Lyon-Gerland, University of Lyon, France
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