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Sequential Phosphorylation of Hepatitis C Virus NS5A Protein Requires the ATP-Binding Domain of NS3 Helicase. J Virol 2022; 96:e0010722. [PMID: 35293767 DOI: 10.1128/jvi.00107-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The propagation of the hepatitis C virus (HCV) is regulated in part by the phosphorylation of its nonstructural protein NS5A that undergoes sequential phosphorylation on several highly conserved serine residues and switches from a hypo- to a hyperphosphorylated state. Previous studies have shown that NS5A sequential phosphorylation requires NS3 encoded on the same NS3-NS4A-NS4B-NS5A polyprotein. Subtle mutations in NS3 without affecting its protease activity could affect NS5A phosphorylation. Given the ATPase domain in the NS3 COOH terminus, we tested whether NS3 participates in NS5A phosphorylation similarly to the nucleoside diphosphate kinase-like activity of the rotavirus NSP2 nucleoside triphosphatase (NTPase). Mutations in the NS3 ATP-binding motifs blunted NS5A hyperphosphorylation and phosphorylation at serines 225, 232, and 235, whereas a mutation in the RNA-binding domain did not. The phosphorylation events were not rescued with wild-type NS3 provided in trans. When provided with an NS3 ATPase-compatible ATP analog, N6-benzyl-ATP-γ-S, thiophosphorylated NS5A was detected in the cells expressing the wild-type NS3-NS5B polyprotein. The thiophosphorylation level was lower in the cells expressing NS3-NS5B with a mutation in the NS3 ATP-binding domain. In vitro assays with a synthetic peptide and purified wild-type NS3 followed by dot blotting and mass spectrometry found weak NS5A phosphorylation at serines 222 and 225 that was sensitive to an inhibitor of casein kinase Iα but not helicase. When casein kinase Iα was included in the assay, much stronger phosphorylation was observed at serines 225, 232, and 235. We concluded that NS5A sequential phosphorylation requires the ATP-binding domain of the NS3 helicase and that casein kinase Iα is a potent NS5A kinase. IMPORTANCE For more than 20 years, NS3 was known to participate in NS5A sequential phosphorylation. In the present study, we show for the first time that the ATP-binding domain of NS3 is involved in NS5A phosphorylation. In vitro assays showed that casein kinase Iα is a very potent kinase responsible for NS5A phosphorylation at serines 225, 232, and 235. Our data suggest that ATP binding by NS3 probably results in conformational changes that recruit casein kinase Iα to phosphorylate NS5A, initially at S225 and subsequently at S232 and S235. Our discovery reveals intricate requirements of the structural integrity of NS3 for NS5A hyperphosphorylation and HCV replication.
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Mousa MHA, Ahmed NS, Schwedtmann K, Frakolaki E, Vassilaki N, Zoidis G, Weigand JJ, Abadi AH. Design and Synthesis of Novel Symmetric Fluorene-2,7-Diamine Derivatives as Potent Hepatitis C Virus Inhibitors. Pharmaceuticals (Basel) 2021; 14:ph14040292. [PMID: 33806139 PMCID: PMC8064491 DOI: 10.3390/ph14040292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/14/2021] [Accepted: 03/16/2021] [Indexed: 12/24/2022] Open
Abstract
Hepatitis C virus (HCV) is an international challenge. Since the discovery of NS5A direct-acting antivirals, researchers turned their attention to pursue novel NS5A inhibitors with optimized design and structure. Herein we explore highly potent hepatitis C virus (HCV) NS5A inhibitors; the novel analogs share a common symmetrical prolinamide 2,7-diaminofluorene scaffold. Modification of the 2,7-diaminofluorene backbone included the use of (S)-prolinamide or its isostere (S,R)-piperidine-3-caboxamide, both bearing different amino acid residues with terminal carbamate groups. Compound 26 exhibited potent inhibitory activity against HCV genotype (GT) 1b (effective concentration (EC50) = 36 pM and a selectivity index of >2.78 × 106). Compound 26 showed high selectivity on GT 1b versus GT 4a. Interestingly, it showed a significant antiviral effect against GT 3a (EC50 = 1.2 nM). The structure-activity relationship (SAR) analysis revealed that picomolar inhibitory activity was attained with the use of S-prolinamide capped with R- isoleucine or R-phenylglycine residues bearing a terminal alkyl carbamate group.
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Affiliation(s)
- Mai H. A. Mousa
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt;
| | - Nermin S. Ahmed
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt;
- Correspondence: (N.S.A.); (A.H.A.); Tel.: +202-27590700 (ext. 3429) (N.S.A.); +202-27590700 (ext. 3400) (A.H.A.); Fax: +202-27581041 (N.S.A. & A.H.A.)
| | - Kai Schwedtmann
- Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany; (K.S.); (J.J.W.)
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 11521 Athens, Greece; (E.F.); (N.V.)
| | - Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 11521 Athens, Greece; (E.F.); (N.V.)
| | - Grigoris Zoidis
- Department of Pharmacy, Division of Pharmaceutical Chemistry, School of Health Sciences, National and Kapodistrian University of Athens, 15771 Athens, Greece;
| | - Jan J. Weigand
- Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany; (K.S.); (J.J.W.)
| | - Ashraf H. Abadi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt;
- Correspondence: (N.S.A.); (A.H.A.); Tel.: +202-27590700 (ext. 3429) (N.S.A.); +202-27590700 (ext. 3400) (A.H.A.); Fax: +202-27581041 (N.S.A. & A.H.A.)
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Gao T, Gao Y, Liu X, Nie Z, Sun H, Lin K, Peng H, Wang S. Identification and functional analysis of the SARS-COV-2 nucleocapsid protein. BMC Microbiol 2021; 21:58. [PMID: 33618668 PMCID: PMC7898026 DOI: 10.1186/s12866-021-02107-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/27/2021] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND A severe form of pneumonia, named coronavirus disease 2019 (COVID-19) by the World Health Organization is widespread on the whole world. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was proved to be the main agent of COVID-19. In the present study, we conducted an in depth analysis of the SARS-COV-2 nucleocapsid to identify potential targets that may allow identification of therapeutic targets. METHODS The SARS-COV-2 N protein subcellular localization and physicochemical property was analyzed by PSORT II Prediction and ProtParam tool. Then SOPMA tool and swiss-model was applied to analyze the structure of N protein. Next, the biological function was explored by mass spectrometry analysis and flow cytometry. At last, its potential phosphorylation sites were analyzed by NetPhos3.1 Server and PROVEAN PROTEIN. RESULTS SARS-COV-2 N protein composed of 419 aa, is a 45.6 kDa positively charged unstable hydrophobic protein. It has 91 and 49% similarity to SARS-CoV and MERS-CoV and is predicted to be predominantly a nuclear protein. It mainly contains random coil (55.13%) of which the tertiary structure was further determined with high reliability (95.76%). Cells transfected with SARS-COV-2 N protein usually show a G1/S phase block company with an increased expression of TUBA1C, TUBB6. At last, our analysis of SARS-COV-2 N protein predicted a total number of 12 phosphorylated sites and 9 potential protein kinases which would significantly affect SARS-COV-2 N protein function. CONCLUSION In this study, we report the physicochemical properties, subcellular localization, and biological function of SARS-COV-2 N protein. The 12 phosphorylated sites and 9 potential protein kinase sites in SARS-COV-2 N protein may serve as promising targets for drug discovery and development for of a recombinant virus vaccine.
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Affiliation(s)
- Tianyi Gao
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Yingdong Gao
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Xiangxiang Liu
- Central Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Zhenlin Nie
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Huilin Sun
- Central Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Kang Lin
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Hongxin Peng
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China
| | - Shukui Wang
- Department of clinical Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China. .,Central Laboratory, Nanjing First Hospital, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China. .,Jiangsu Collaborative Innovation Center on Cancer Personalized Medicine, Nanjing Medical University, 68 Changle Road, Nanjing, 210006, Jiangsu, China.
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Ward JC, Bowyer S, Chen S, Fernandes Campos GR, Ramirez S, Bukh J, Harris M. Insights into the unique characteristics of hepatitis C virus genotype 3 revealed by development of a robust sub-genomic DBN3a replicon. J Gen Virol 2020; 101:1182-1190. [PMID: 32897181 PMCID: PMC7879556 DOI: 10.1099/jgv.0.001486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/03/2020] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) is an important human pathogen causing 400 000 chronic liver disease-related deaths annually. Until recently, the majority of laboratory-based investigations into the biology of HCV have focused on the genotype 2 isolate, JFH-1, involving replicons and infectious cell culture systems. However, genotype 2 is one of eight major genotypes of HCV and there is great sequence variation among these genotypes (>30 % nucleotide divergence). In this regard, genotype 3 is the second most common genotype and accounts for 30 % of global HCV cases. Further, genotype 3 is associated with both high levels of inherent resistance to direct-acting antiviral (DAA) therapy, and a more rapid progression to chronic liver diseases. Neither of these two attributes are fully understood, thus robust genotype 3 culture systems to unravel viral replication are required. Here we describe the generation of robust genotype 3 sub-genomic replicons (SGRs) based on the adapted HCV NS3-NS5B replicase from the DBN3a cell culture infectious clone. Such infectious cell culture-adaptive mutations could potentially promote the development of robust SGRs for other HCV strains and genotypes. The novel genotype 3 SGRs have been used both transiently and to establish stable SGR-harbouring cell lines. We show that these resources can be used to investigate aspects of genotype 3 biology, including NS5A function and DAA resistance. They will be useful tools for these studies, circumventing the need to work under the biosafety level 3 (BSL3) containment required in many countries.
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Affiliation(s)
- Joseph C. Ward
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Sebastian Bowyer
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Shucheng Chen
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Guilherme Rodrigues Fernandes Campos
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
- Present address: São Paulo State University, Institute of Biosciences, Languages and Exact Sciences, Cristóvão Colombo Street, 2265, Post Code 15054-000, São José do Rio Preto, São Paulo State, Brazil
| | - Santseharay Ramirez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital, Kettegård Allé 30, DK-2650 Hvidovre, Denmark
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital, Kettegård Allé 30, DK-2650 Hvidovre, Denmark
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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Sequential Phosphorylation of the Hepatitis C Virus NS5A Protein Depends on NS3-Mediated Autocleavage between NS3 and NS4A. J Virol 2020; 94:JVI.00420-20. [PMID: 32699091 DOI: 10.1128/jvi.00420-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 07/15/2020] [Indexed: 02/07/2023] Open
Abstract
Replication of the genotype 2 hepatitis C virus (HCV) requires hyperphosphorylation of the nonstructural protein NS5A. It has been known that NS5A hyperphosphorylation results from the phosphorylation of a cluster of highly conserved serine residues (S2201, S2208, S2211, and S2214) in a sequential manner. It has also been known that NS5A hyperphosphorylation requires an NS3 protease encoded on one single NS3-5A polyprotein. It was unknown whether NS3 protease participates in this sequential phosphorylation process. Using an inventory of antibodies specific to S2201, S2208, S2211, and S2214 phosphorylation, we found that protease-dead S1169A mutation abrogated NS5A hyperphosphorylation and phosphorylation at all serine residues measured, consistent with the role of NS3 in NS5A sequential phosphorylation. These effects were not rescued by a wild-type NS3 protease provided in trans by another molecule. Mutations (T1661R, T1661Y, or T1661D) that prohibited proper cleavage at the NS3-4A junction also abolished NS5A hyperphosphorylation and phosphorylation at all serine residues, whereas mutations at the other cleavage sites, NS4A-4B (C1715S) or NS4B-5A (C1976F), did not. In fact, any combinatory mutations that prohibited NS3-4A cleavage (T1661Y/C1715S or T1661Y/C1976F) abrogated NS5A hyperphosphorylation and phosphorylation at all serine residues. In the C1715S/C1976F double mutant, which resulted in an NS4A-NS4B-NS5A fusion polyprotein, a hyperphosphorylated band was observed and was phosphorylated at all serine residues. We conclude that NS3-mediated autocleavage at the NS3-4A junction is critical to NS5A hyperphosphorylation at S2201, S2208, S2211, and S2214 and that NS5A hyperphosphorylation could occur in an NS4A-NS4B-NS5A polyprotein.IMPORTANCE For ca. 20 years, the HCV protease NS3 has been implicated in NS5A hyperphosphorylation. We now show that it is the NS3-mediated cis cleavage at the NS3-4A junction that permits NS5A phosphorylation at serines 2201, 2208, 2211, and 2214, leading to hyperphosphorylation, which is a necessary condition for genotype 2 HCV replication. We further show that NS5A may already be phosphorylated at these serine residues right after NS3-4A cleavage and before NS5A is released from the NS4A-5A polyprotein. Our data suggest that the dual-functional NS3, a protease and an ATP-binding RNA helicase, could have a direct or indirect role in NS5A hyperphosphorylation.
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HCV-2a NS5A downregulates viral translation predominantly through domain I. Biochem Biophys Res Commun 2020; 529:77-84. [PMID: 32560823 DOI: 10.1016/j.bbrc.2020.05.177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 05/25/2020] [Indexed: 11/21/2022]
Abstract
Hepatitis C virus (HCV) non-structural protein NS5A is a multifunctional protein with critical roles in viral replication and assembly. We previously showed that HCV-1b NS5A downregulates viral translation only in the presence of the poly(U/UC) tract in 3'UTR. As NS5A of different HCV genotypes may have different functions or carry out the same functions through genotype-specific mechanisms, we investigated the effect of HCV-2a NS5A on viral translation. We found that HCV-2a NS5A downregulates RNA translation of both HCV-2a and -1b, whereas the effect of HCV-1b NS5A is limited to HCV-1b only. In addition, individual regions of 3'UTR are not required for HCV-2a NS5A to downregulate viral RNA translation. We also found that HCV-2a NS5A inhibits capped mRNA translation. Mapping experiments showed that the translation downregulation by HCV-2a NS5A is predominantly mediated by domain I. Furthermore, we found that the integrity of serine-146 residue plays an important role in translation downregulation by NS5A. Our results increased our understanding on genotype-specific functions of HCV NS5A.
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7
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Tabata K, Neufeldt CJ, Bartenschlager R. Hepatitis C Virus Replication. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a037093. [PMID: 31570388 DOI: 10.1101/cshperspect.a037093] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Replication and amplification of the viral genome is a key process for all viruses. For hepatitis C virus (HCV), a positive-strand RNA virus, amplification of the viral genome requires the synthesis of a negative-sense RNA template, which is in turn used for the production of new genomic RNA. This process is governed by numerous proteins, both host and viral, as well as distinct lipids and specific RNA elements within the positive- and negative-strand RNAs. Moreover, this process requires specific changes to host cell ultrastructure to create microenvironments conducive to viral replication. This review will focus on describing the processes and factors involved in facilitating or regulating HCV genome replication.
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Affiliation(s)
- Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,Division of Virus-Associated Carcinogenesis, German Cancer Research Center, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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8
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Goonawardane N, Yin C, Harris M. Phenotypic analysis of mutations at residue 146 provides insights into the relationship between NS5A hyperphosphorylation and hepatitis C virus genome replication. J Gen Virol 2020; 101:252-264. [PMID: 31821131 PMCID: PMC7416608 DOI: 10.1099/jgv.0.001366] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/19/2019] [Indexed: 12/23/2022] Open
Abstract
The hepatitis C virus genotype 2a isolate, JFH-1, exhibits much more efficient genome replication than other isolates. Although basic replication mechanisms must be conserved, this raises the question of whether the regulation of replication might exhibit isolate- and/or genotype-specific characteristics. Exemplifying this, the phenotype of NS5A hyperphosphorylation is genotype-dependent; in genotype 1b a loss of hyperphosphorylation correlates with an enhancement of replication. In contrast, the replication of JFH-1 is not regulated by hyperphosphorylation. We previously identified a novel phosphorylation site in JFH-1 NS5A: S146. A phosphomimetic substitution (S146D) had no effect on replication but correlated with a loss of hyperphosphorylation. In genotype 1b, residue 146 is alanine and we therefore investigated whether the substitution of A146 with a phosphorylatable (S), or phosphomimetic, residue would recapitulate the JFH-1 phenotype, decoupling hyperphosphorylation from replication. This was not the case, as A146D exhibited both a loss of hyperphosphorylation and a reduction in replication, accompanied by a perinuclear restriction of replication complexes, reductions in lipid droplet and PI4P lipid accumulation, and a disruption of NS5A dimerization. In contrast, the S232I culture-adaptive mutation in the low-complexity sequence I (LCSI) also exhibited a loss of hyperphosphorylation, but was associated with an increase in replication. Taken together, these data imply that hyperphosphorylation does not directly regulate replication. In contrast, the loss of hyperphosphorylation is a consequence of perturbing genome replication and NS5A function. Furthermore, we show that mutations in either domain I or LCSI of NS5A can disrupt hyperphosphorylation, demonstrating that multiple parameters influence the phosphorylation status of NS5A.
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Affiliation(s)
- Niluka Goonawardane
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
- Present address: Experimental Medicine, Nuffield Department of Medicine, The Peter Medawar Building for Pathogen Research, South Parks Road, University of Oxford, Oxford, OX1 3SY, UK
| | - Chunhong Yin
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
- Present address: Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, PR China
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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Serine 229 Balances the Hepatitis C Virus Nonstructural Protein NS5A between Hypo- and Hyperphosphorylated States. J Virol 2019; 93:JVI.01028-19. [PMID: 31511391 DOI: 10.1128/jvi.01028-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/08/2019] [Indexed: 12/19/2022] Open
Abstract
The nonstructural protein NS5A of hepatitis C virus (HCV) is a phosphorylated protein that is indispensable for viral replication and assembly. We previously showed that NS5A undergoes sequential serine S232/S235/S238 phosphorylation resulting in NS5A transition from a hypo- to a hyperphosphorylated state. Here, we studied functions of S229 with a newly generated antibody specific to S229 phosphorylation. In contrast to S232, S235, or S238 phosphorylation detected only in the hyperphosphorylated NS5A, S229 phosphorylation was found in both hypo- and hyperphosphorylated NS5A, suggesting that S229 phosphorylation initiates NS5A sequential phosphorylation. Immunoblotting showed an inverse relationship between S229 phosphorylation and S235 phosphorylation. When S235 was phosphorylated as in the wild-type NS5A, the S229 phosphorylation level was low; when S235 could not be phosphorylated as in the S235A mutant NS5A, the S229 phosphorylation level was high. These results suggest an intrinsic feedback regulation between S229 phosphorylation and S235 phosphorylation. It has been known that NS5A distributes in large static and small dynamic intracellular structures and that both structures are required for the HCV life cycle. We found that S229A or S229D mutation was lethal to the virus and that both increased NS5A in large intracellular structures. Similarly, the lethal S235A mutation also increased NS5A in large structures. Likewise, the replication-compromised S235D mutation also increased NS5A in large structures, albeit to a lesser extent. Our data suggest that S229 probably cycles through phosphorylation and dephosphorylation to maintain a delicate balance of NS5A between hypo- and hyperphosphorylated states and the intracellular distribution necessary for the HCV life cycle.IMPORTANCE This study joins our previous efforts to elucidate how NS5A transits between hypo- and hyperphosphorylated states via phosphorylation on a series of highly conserved serine residues. Of the serine residues, serine 229 is the most interesting since phosphorylation-mimicking and phosphorylation-ablating mutations at this serine residue are both lethal. With a new high-quality antibody specific to serine 229 phosphorylation, we concluded that serine 229 must remain wild type so that it can dynamically cycle through phosphorylation and dephosphorylation that govern NS5A between hypo- and hyperphosphorylated states. Both are required for the HCV life cycle. When phosphorylated, serine 229 signals phosphorylation on serine 232 and 235 in a sequential manner, leading NS5A to the hyperphosphorylated state. As serine 235 phosphorylation is reached, serine 229 is dephosphorylated, stopping signal for hyperphosphorylation. This balances NS5A between two phosphorylation states and in intracellular structures that warrant a productive HCV life cycle.
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Pan TC, Lo CW, Chong WM, Tsai CN, Lee KY, Chen PY, Liao JC, Yu MJ. Differential Proteomics Reveals Discrete Functions of Proteins Interacting with Hypo- versus Hyper-phosphorylated NS5A of the Hepatitis C Virus. J Proteome Res 2019; 18:2813-2825. [PMID: 31199160 DOI: 10.1021/acs.jproteome.9b00130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein phosphorylation is a reversible post-translational modification that regulates many biological processes in almost all living forms. In the case of the hepatitis C virus (HCV), the nonstructural protein 5A (NS5A) is believed to transit between hypo- and hyper-phosphorylated forms that interact with host proteins to execute different functions; however, little was known about the proteins that bind either form of NS5A. Here, we generated two high-quality antibodies specific to serine 235 nonphosphorylated hypo- vs serine 235 phosphorylated (pS235) hyper-phosphorylated form of NS5A and for the first time segregated these two forms of NS5A plus their interacting proteins for dimethyl-labeling based proteomics. We identified 629 proteins, of which 238 were quantified in three replicates. Bioinformatics showed 46 proteins that preferentially bind hypo-phosphorylated NS5A are involved in antiviral response and another 46 proteins that bind pS235 hyper-phosphorylated NS5A are involved in liver cancer progression. We further identified a DNA-dependent kinase (DNA-PK) that binds hypo-phosphorylated NS5A. Inhibition of DNA-PK with an inhibitor or via gene-specific knockdown significantly reduced S232 phosphorylation and NS5A hyper-phosphorylation. Because S232 phosphorylation initiates sequential S232/S235/S238 phosphorylation leading to NS5A hyper-phosphorylation, we identified a new protein kinase that regulates a delicate balance of NS5A between hypo- and hyper-phosphorylation states, respectively, involved in host antiviral responses and liver cancer progression.
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Affiliation(s)
- Ting-Chun Pan
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
| | - Chieh-Wen Lo
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
| | - Weng Man Chong
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Chia-Ni Tsai
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
| | - Kuan-Ying Lee
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
| | - Pin-Yin Chen
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
| | - Jung-Chi Liao
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Ming-Jiun Yu
- Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan
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Klinker S, Stindt S, Gremer L, Bode JG, Gertzen CGW, Gohlke H, Weiergräber OH, Hoffmann S, Willbold D. Phosphorylated tyrosine 93 of hepatitis C virus nonstructural protein 5A is essential for interaction with host c-Src and efficient viral replication. J Biol Chem 2019; 294:7388-7402. [PMID: 30862675 DOI: 10.1074/jbc.ra119.007656] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/11/2019] [Indexed: 12/23/2022] Open
Abstract
The hepatitis C virus (HCV) nonstructural protein 5A (NS5A) plays a key role in viral replication and virion assembly, and the regulation of the assembly process critically depends on phosphorylation of both serine and threonine residues in NS5A. We previously identified SRC proto-oncogene, nonreceptor tyrosine kinase (c-Src), as an essential host component of the HCV replication complex consisting of NS5A, the RNA-dependent RNA polymerase NS5B, and c-Src. Pulldown assays revealed an interaction between NS5A and the Src homology 2 (SH2) domain of c-Src; however, the precise binding mode remains undefined. In this study, using a variety of biochemical and biophysical techniques, along with molecular dynamics simulations, we demonstrate that the interaction between NS5A and the c-Src SH2 domain strictly depends on an intact phosphotyrosine-binding competent SH2 domain and on tyrosine phosphorylation within NS5A. Detailed analysis of c-Src SH2 domain binding to a panel of phosphorylation-deficient NS5A variants revealed that phosphorylation of Tyr-93 located within domain 1 of NS5A, but not of any other tyrosine residue, is crucial for complex formation. In line with these findings, effective replication of subgenomic HCV replicons as well as production of infectious virus particles in mammalian cell culture models were clearly dependent on the presence of tyrosine at position 93 of NS5A. These findings indicate that phosphorylated Tyr-93 in NS5A plays an important role during viral replication by facilitating NS5A's interaction with the SH2 domain of c-Src.
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Affiliation(s)
- Stefan Klinker
- From the Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf
| | - Sabine Stindt
- the Department of Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf
| | - Lothar Gremer
- From the Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf.,the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich
| | - Johannes G Bode
- the Department of Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf
| | - Christoph G W Gertzen
- the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich.,the John von Neumann Institute for Computing (NIC) and Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich, 52425 Jülich, and.,the Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Holger Gohlke
- the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich.,the John von Neumann Institute for Computing (NIC) and Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich, 52425 Jülich, and.,the Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Oliver H Weiergräber
- the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich
| | - Silke Hoffmann
- the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich
| | - Dieter Willbold
- From the Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf, .,the Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich
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12
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Gao Y, Goonawardane N, Ward J, Tuplin A, Harris M. Multiple roles of the non-structural protein 3 (nsP3) alphavirus unique domain (AUD) during Chikungunya virus genome replication and transcription. PLoS Pathog 2019; 15:e1007239. [PMID: 30668592 PMCID: PMC6358111 DOI: 10.1371/journal.ppat.1007239] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 02/01/2019] [Accepted: 12/10/2018] [Indexed: 11/18/2022] Open
Abstract
Chikungunya virus (CHIKV) is a re-emerging Alphavirus causing fever, joint pain, skin rash, arthralgia, and occasionally death. Antiviral therapies and/or effective vaccines are urgently required. CHIKV biology is poorly understood, in particular the functions of the non-structural protein 3 (nsP3). Here we present the results of a mutagenic analysis of the alphavirus unique domain (AUD) of nsP3. Informed by the structure of the Sindbis virus AUD and an alignment of amino acid sequences of multiple alphaviruses, a series of mutations in the AUD were generated in a CHIKV sub-genomic replicon. This analysis revealed an essential role for the AUD in CHIKV RNA replication, with mutants exhibiting species- and cell-type specific phenotypes. To test if the AUD played a role in other stages of the virus lifecycle, the mutants were analysed in the context of infectious CHIKV. This analysis indicated that the AUD was also required for virus assembly. In particular, one mutant (P247A/V248A) exhibited a dramatic reduction in production of infectious virus. This phenotype was shown to be due to a block in transcription of the subgenomic RNA leading to reduced synthesis of the structural proteins and a concomitant reduction in virus production. This phenotype could be further explained by both a reduction in the binding of the P247A/V248A mutant nsP3 to viral genomic RNA in vivo, and the reduced affinity of the mutant AUD for the subgenomic promoter RNA in vitro. We propose that the AUD is a pleiotropic protein domain, with multiple functions during CHIKV RNA synthesis.
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Affiliation(s)
- Yanni Gao
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Niluka Goonawardane
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Joseph Ward
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Andrew Tuplin
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
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13
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Schenk C, Meyrath M, Warnken U, Schnölzer M, Mier W, Harak C, Lohmann V. Characterization of a Threonine-Rich Cluster in Hepatitis C Virus Nonstructural Protein 5A and Its Contribution to Hyperphosphorylation. J Virol 2018; 92:JVI.00737-18. [PMID: 30258001 PMCID: PMC6258934 DOI: 10.1128/jvi.00737-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 09/20/2018] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a phosphoprotein with key functions in regulating viral RNA replication and assembly. Two phosphoisoforms are discriminated by their different apparent molecular weights: a basally phosphorylated (p56) and a hyperphosphorylated (p58) variant. The precise mechanisms governing p58 synthesis and specific functions of the isoforms are poorly understood. Our study aimed at a deeper understanding of determinants involved in p58 synthesis. We analyzed two variants of p56 and p58 of isolate JFH-1 separately by mass spectrometry using an expression model and thereby identified a threonine-rich phosphopeptide exclusively found in the hyperphosphorylated variant. Individual exchange of possible phosphoacceptor sites to phosphoablatant or -mimetic residues had little impact on HCV replication or assembly in cell culture. A phosphospecific antibody recognizing pT242 revealed that this position was indeed phosphorylated only in p58 and depended on casein kinase Iα. Importantly, phosphoablative mutations at positions T244 and S247 abrogated pT242 detection without substantial effects on global p58 levels, whereas mutations in the preceding serine-rich cluster dramatically reduced total p58 levels but had minor impact on pT242 levels, suggesting the existence of distinct subspecies of hyperphosphorylated NS5A. Mass spectrometry analyses of different genotypes showed variable phosphorylation patterns across NS5A and suggested that the threonine-rich region is also phosphorylated at T242 in gt4a and at S249 in gt1a, gt1b, and gt4a. Our data therefore indicate that p58 is not a single homogenously phosphorylated protein species but rather a population of various phosphoisoforms, with high variability between genotypes.IMPORTANCE Hepatitis C virus infections affect 71 million people worldwide and cause severe chronic liver disease. Recently, efficient antiviral therapies have been established, with inhibitors of nonstructural protein NS5A as a cornerstone. NS5A is a central regulator of HCV replication and assembly but is still enigmatic in its molecular functions. It exists in two phosphoisoforms, p56 and p58. We identified a phosphopeptide exclusively found in p58 and analyzed the determinants involved in phosphorylation of this region. We found evidence for very different phosphorylation patterns resulting in p58. These results challenge the concept of p58 being a homogenous species of NS5A molecules phosphorylated at the same positions and argues for at least two independently phosphorylated variants showing the same electrophoretic mobility, likely serving different functions.
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Affiliation(s)
- Christian Schenk
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Max Meyrath
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Uwe Warnken
- Functional Proteome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martina Schnölzer
- Functional Proteome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Walter Mier
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Christian Harak
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
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14
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Sequential S232/S235/S238 Phosphorylation of the Hepatitis C Virus Nonstructural Protein 5A. J Virol 2018; 92:JVI.01295-18. [PMID: 30089697 DOI: 10.1128/jvi.01295-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 07/30/2018] [Indexed: 02/06/2023] Open
Abstract
The hepatitis C virus (HCV) protein NS5A is a phosphorylated protein with crucial roles in viral replication and assembly. NS5A was thought to undergo sequential phosphorylation on a series of conserved serine residues; however, the phosphorylation cascade remained obscure. Using three phosphorylation-specific antibodies, we found that phosphorylation at S232, S235, and S238 occurred in parallel in HCV-infected Huh7.5.1 cells, suggestive of intramolecular sequential NS5A phosphorylation from S232 through S235 to S238 by casein kinase Iα (CKIα). In line with this, alanine mutation at S225, S229, or S232 reduced, whereas aspartate mutation at the same sites rescued, NS5A phosphorylation at S232, S235, and S238. In contrast, alanine or aspartate mutation at S235 or S238 had little or no effect on S232 or S235 phosphorylation. Consistent with an intramolecular sequential phosphorylation cascade, S232, S235, and S238 phosphorylation coexisted on one single NS5A molecule. Phosphorylation of NH2-terminal serine residues in one NS5A molecule did not rescue phosphorylation of COOH-terminal serine residues in another NS5A molecule. CKIα inhibition reduced NS5A phosphorylation at S232, S235, and S238. In summary, our results are indicative of a CKIα-mediated intramolecular, sequential phosphorylation cascade from S232 through S235 to S238 of the HCV NS5A protein. S225 and S229 also contribute substantially to the above sequential phosphorylation cascade of NS5A.IMPORTANCE The nonstructural protein 5A (NS5A) of the hepatitis C virus was thought to undergo sequential intramolecular phosphorylation on a series of serine residues; however, direct evidence was missing. We offer the first direct evidence of a CKIα-mediated intramolecular sequential NS5A phosphorylation cascade from serine 232 through 235 to 238. This sequential phosphorylation cascade occurs in the disordered low-complexity sequence I region, which together with the domain I region forms an RNA-binding groove in an NS5A dimer. Sequential phosphorylation in the disordered region adds charge-charge repulsion to the RNA-binding groove and probably thereby regulates NS5A's RNA-binding ability and functions in viral RNA replication and assembly.
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15
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Shanmugam S, Nichols AK, Saravanabalaji D, Welsch C, Yi M. HCV NS5A dimer interface residues regulate HCV replication by controlling its self-interaction, hyperphosphorylation, subcellular localization and interaction with cyclophilin A. PLoS Pathog 2018; 14:e1007177. [PMID: 30036383 PMCID: PMC6072203 DOI: 10.1371/journal.ppat.1007177] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/02/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022] Open
Abstract
The HCV NS5A protein plays multiple roles during viral replication, including viral genome replication and virus particle assembly. The crystal structures of the NS5A N-terminal domain indicated the potential existence of the NS5A dimers formed via at least two or more distinct dimeric interfaces. However, it is unknown whether these different forms of NS5A dimers are involved in its numerous functions. To address this question, we mutated the residues lining the two different NS5A dimer interfaces and determined their effects on NS5A self-interaction, NS5A-cyclophilin A (CypA) interaction, HCV RNA replication and infectious virus production. We found that the mutations targeting either of two dimeric interfaces disrupted the NS5A self-interaction in cells. The NS5A dimer-interrupting mutations also inhibited both viral RNA replication and infectious virus production with some genotypic differences. We also determined that reduced NS5A self-interaction was associated with altered NS5A-CypA interaction, NS5A hyperphosphorylation and NS5A subcellular localization, providing the mechanistic bases for the role of NS5A self-interaction in multiple steps of HCV replication. The NS5A oligomers formed via different interfaces are likely its functional form, since the residues at two different dimeric interfaces played similar roles in different aspects of NS5A functions and, consequently, HCV replication. In conclusion, this study provides novel insight into the functional significance of NS5A self-interaction in different steps of the HCV replication, potentially, in the form of oligomers formed via multiple dimeric interfaces. HCV NS5A is a multifunctional protein involved in both viral RNA replication and infectious virus production, and is a target of one of the most potent antivirals available to date. However, the mode of action of NS5A inhibitors is still unclear due to the lack of mechanistic detail regarding NS5A functions during HCV life cycles. In this study, we have provided evidence that surface-exposed NS5A residues involved in two different dimeric interactions in crystal structures are indeed involved in NS5A self-interactions in cells. We also showed that these NS5A residues play critical role in HCV RNA replication and infectious virus production by regulating NS5A hyperphosphorylation, its subcellular localization and its interaction with host protein CypA. Overall, our data support the functional significance of “NS5A oligomers” formed via multiple interfaces in HCV replication. We speculate that the NS5A inhibitors exploited the NS5A oligomer-dependent functions during HCV replication, rather than targeting individual NS5A, which consequently resulted in their high potency.
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Affiliation(s)
- Saravanabalaji Shanmugam
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Alyssa K. Nichols
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Dhanaranjani Saravanabalaji
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Christoph Welsch
- Department of Internal Medicine I, Goethe University, Frankfurt/Main, Germany
| | - MinKyung Yi
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- * E-mail:
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Bessa LM, Schneider R, Hanoulle X. NMR and circular dichroism data for domain 2 of the HCV NS5A protein phosphorylated by the Casein Kinase II. Data Brief 2018; 17:325-333. [PMID: 29876401 PMCID: PMC5988295 DOI: 10.1016/j.dib.2018.01.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/04/2017] [Accepted: 01/16/2018] [Indexed: 11/22/2022] Open
Abstract
The Hepatitis C Virus (HCV)1 nonstructural 5A protein (NS5A) is a phosphoprotein (Evans et al., 2004; Ross-Thriepland and Harris, 2014) [1], [2] composed of an N-terminal well-structured domain and two C-terminal intrinsically disordered domains (Moradpour et al., 2007; Bartenschlager et al., 2013; Badillo et al., 2017) [3], [4], [5]. So far, no precise molecular function has been identified for this viral protein (Ross-Thriepland and Harris, 2015) [6] which is required for viral replication (Tellinghuisen et al., 2008) [7]. In this article, we present datasets of NMR and circular dichroism analyses of the domain 2 of the HCV NS5A protein (NS5A-D2) phosphorylated in vitro by the Casein Kinase II (CKII) (Dal Pero et al., 2007; Clemens et al., 2015; Masak et al., 2014; Kim et al., 2014) [8], [9], [10], [11]. We describe the in vitro phosphorylation of the serine 288 (pS288) of NS5A-D2 by CKII and report the circular dichroism spectrum of the phosphorylated domain (NS5-D2_CKII). This data article also contains the 1H, 15N and 13C NMR chemical shift assignments (HN, N, Cα, Cβ and C’) for the phosphorylated NS5A-D2 domain, and an assigned 1H,15N-HSQC spectrum is shown. The NMR data have been acquired on an 800 MHz spectrometer. These NMR data have been used to calculate both the 1H,15N combined chemical shift perturbations (CSP) induced by the phosphorylation of pS288 and the secondary structural propensity (SSP) scores that describe the structural tendencies in this intrinsically disordered domain. The circular dichroism spectrum and the SSP scores of NS5A-D2_CKII have been compared with those of unphosphorylated NS5A-D2 [12,13].
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17
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A role for domain I of the hepatitis C virus NS5A protein in virus assembly. PLoS Pathog 2018; 14:e1006834. [PMID: 29352312 PMCID: PMC5792032 DOI: 10.1371/journal.ppat.1006834] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 01/31/2018] [Accepted: 12/19/2017] [Indexed: 12/12/2022] Open
Abstract
The NS5A protein of hepatitis C virus (HCV) plays roles in both virus genome replication and assembly. NS5A comprises three domains, of these domain I is believed to be involved exclusively in genome replication. In contrast, domains II and III are required for the production of infectious virus particles and are largely dispensable for genome replication. Domain I is highly conserved between HCV and related hepaciviruses, and is highly structured, exhibiting different dimeric conformations. To investigate the functions of domain I in more detail, we conducted a mutagenic study of 12 absolutely conserved and surface-exposed residues within the context of a JFH-1-derived sub-genomic replicon and infectious virus. Whilst most of these abrogated genome replication, three mutants (P35A, V67A and P145A) retained the ability to replicate but showed defects in virus assembly. P35A exhibited a modest reduction in infectivity, however V67A and P145A produced no infectious virus. Using a combination of density gradient fractionation, biochemical analysis and high resolution confocal microscopy we demonstrate that V67A and P145A disrupted the localisation of NS5A to lipid droplets. In addition, the localisation and size of lipid droplets in cells infected with these two mutants were perturbed compared to wildtype HCV. Biophysical analysis revealed that V67A and P145A abrogated the ability of purified domain I to dimerize and resulted in an increased affinity of binding to HCV 3’UTR RNA. Taken together, we propose that domain I of NS5A plays multiple roles in assembly, binding nascent genomic RNA and transporting it to lipid droplets where it is transferred to Core. Domain I also contributes to a change in lipid droplet morphology, increasing their size. This study reveals novel functions of NS5A domain I in assembly of infectious HCV and provides new perspectives on the virus lifecycle. Hepatitis C virus infects 170 million people worldwide, causing long term liver disease. Recently new therapies comprising direct-acting antivirals (DAAs), small molecule inhibitors of virus proteins, have revolutionised treatment for infected patients. Despite this, we have a limited understanding of how the virus replicates in infected liver cells. Here we identify a previously uncharacterised function of the NS5A protein–a target for one class of DAAs. NS5A is comprised of three domains–we show that the first of these (domain I) plays a role in the production of new, infectious virus particles. Previously it was thought that domain I was only involved in replicating the virus genome. Mutations in domain I perturb dimer formation, enhanced binding to the 3’ end of the virus RNA genome and prevented NS5A from interacting with lipid droplets, cellular lipid storage organelles that are required for assembly of new viruses. We propose that domain I of NS5A plays multiple roles in virus assembly. As domain I is the putative target for one class of DAAs, our observations may have implications for the as yet undefined mode of action of these compounds.
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18
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Beldar S, Manimekalai MSS, Cho NJ, Baek K, Grüber G, Yoon HS. Self-association and conformational variation of NS5A domain 1 of hepatitis C virus. J Gen Virol 2018; 99:194-208. [PMID: 29300159 DOI: 10.1099/jgv.0.001000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Direct-acting antivirals (DAAs) targeting the non-structural 5A (NS5A) protein of the hepatitis C virus (HCV) are crucial drugs that have shown exceptional clinical success in patients. However, their mode of action (MoA) remains unclear, and drug-resistant HCV strains are rapidly emerging. It is critical to characterize the behaviour of the NS5A protein in solution, which can facilitate the development of new classes of inhibitors or improve the efficacy of the currently available DAAs. Using biophysical methods, including dynamic light scattering, size exclusion chromatography and chemical cross-linking experiments, we showed that the NS5A domain 1 from genotypes 1b and 1a of the HCV intrinsically self-associated and existed as a heterogeneous mixture in solution. Interestingly, the NS5A domain 1 from genotypes 1b and 1a exhibited different dynamic equilibria of monomers to higher-order structures. Using small-angle X-ray scattering, we studied the structural dynamics of the various states of the NS5A domain 1 in solution. We also tested the effect of daclatasvir (DCV), the most prominent DAA, on self-association of the wild and DCV-resistant mutant (Y93H) NS5A domain 1 proteins, and demonstrated that DCV induced the formation of large and irreversible protein aggregates that eventually precipitated out. This study highlights the conformational variability of the NS5A domain 1 of HCV, which may be an intrinsic structural behaviour of the HCV NS5A domain 1 in solution.
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Affiliation(s)
- Serap Beldar
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | | | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Kwanghee Baek
- Department of Genetic Engineering, College of Life Sciences, Kyung Hee University, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea
| | - Gerhard Grüber
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Ho Sup Yoon
- Department of Genetic Engineering, College of Life Sciences, Kyung Hee University, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea.,School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
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Goonawardane N, Ross-Thriepland D, Harris M. Regulation of hepatitis C virus replication via threonine phosphorylation of the NS5A protein. J Gen Virol 2017; 99:62-72. [PMID: 29139348 PMCID: PMC5882090 DOI: 10.1099/jgv.0.000975] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The hepatitis C virus non-structural 5A (NS5A) protein is highly phosphorylated and plays roles in both virus genome replication and assembly of infectious virus particles. NS5A comprises three domains separated by low complexity sequences (LCS). Mass spectrometry analysis of NS5A revealed the existence of a singly phosphorylated tryptic peptide corresponding to the end of LCS I and the beginning of domain II that contained a number of potential phosphorylatable residues (serines and threonines). Here we use a mutagenic approach to investigate the potential role of three of these threonine residues. Phosphomimetic mutations of two of these (T242E and T244E) resulted in significant reductions in virus genome replication and the production of infectious virus, suggesting that the phosphorylation of these residues negatively regulated virus RNA synthesis. Mutation of T245 had no effect, however when T245E was combined with the other two phosphomimetic mutations (TripleE) the inhibitory effect on replication was less pronounced. Effects of the mutations on the ratio of basally/hyperphosphorylated NS5A, together with the apparent molecular weight of the basally phosphorylated species were also observed. Lastly, two of the mutations (T245A and TripleE) resulted in a perinuclear restricted localization of NS5A. These data add further complexity to NS5A phosphorylation and suggest that this analysis be extended outwith the serine-rich cluster within LCS I.
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Affiliation(s)
- Niluka Goonawardane
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Douglas Ross-Thriepland
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.,Present address: AstraZeneca, Cambridge Biomedical Campus, Cambridge, CB20AA, UK
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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20
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Evaluation of a range of mammalian and mosquito cell lines for use in Chikungunya virus research. Sci Rep 2017; 7:14641. [PMID: 29116243 PMCID: PMC5677012 DOI: 10.1038/s41598-017-15269-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/24/2017] [Indexed: 01/29/2023] Open
Abstract
Chikungunya virus (CHIKV) is becoming an increasing global health issue which has spread across the globe and as far north as southern Europe. There is currently no vaccine or anti-viral treatment available. Although there has been a recent increase in CHIKV research, many of these in vitro studies have used a wide range of cell lines which are not physiologically relevant to CHIKV infection in vivo. In this study, we aimed to evaluate a panel of cell lines to identify a subset that would be both representative of the infectious cycle of CHIKV in vivo, and amenable to in vitro applications such as transfection, luciferase assays, immunofluorescence, western blotting and virus infection. Based on these parameters we selected four mammalian and two mosquito cell lines, and further characterised these as potential tools in CHIKV research.
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21
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Phosphorylation of Serine 225 in Hepatitis C Virus NS5A Regulates Protein-Protein Interactions. J Virol 2017; 91:JVI.00805-17. [PMID: 28615203 PMCID: PMC5553161 DOI: 10.1128/jvi.00805-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/03/2017] [Indexed: 12/31/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a phosphoprotein that plays key, yet poorly defined, roles in both virus genome replication and virion assembly/release. It has been proposed that differential phosphorylation could act as a switch to regulate the various functions of NS5A; however, the mechanistic details of the role of this posttranslational modification in the virus life cycle remain obscure. We previously reported (D. Ross-Thriepland, J. Mankouri, and M. Harris, J Virol 89:3123–3135, 2015, doi:10.1128/JVI.02995-14) a role for phosphorylation at serine 225 (S225) of NS5A in the regulation of JFH-1 (genotype 2a) genome replication. A phosphoablatant (S225A) mutation resulted in a 10-fold reduction in replication and a perinuclear restricted distribution of NS5A, whereas the corresponding phosphomimetic mutation (S225D) had no phenotype. To determine the molecular mechanisms underpinning this phenotype we conducted a label-free proteomics approach to identify cellular NS5A interaction partners. This analysis revealed that the S225A mutation disrupted the interactions of NS5A with a number of cellular proteins, in particular the nucleosome assembly protein 1-like protein 1 (NAP1L1), bridging integrator 1 (Bin1, also known as amphiphysin II), and vesicle-associated membrane protein-associated protein A (VAP-A). These interactions were validated by immunoprecipitation/Western blotting, immunofluorescence, and proximity ligation assay. Importantly, small interfering RNA (siRNA)-mediated knockdown of NAP1L1, Bin1 or VAP-A impaired viral genome replication and recapitulated the perinuclear redistribution of NS5A seen in the S225A mutant. These results demonstrate that S225 phosphorylation regulates the interactions of NS5A with a defined subset of cellular proteins. Furthermore, these interactions regulate both HCV genome replication and the subcellular localization of replication complexes. IMPORTANCE Hepatitis C virus is an important human pathogen. The viral nonstructural 5A protein (NS5A) is the target for new antiviral drugs. NS5A has multiple functions during the virus life cycle, but the biochemical details of these roles remain obscure. NS5A is known to be phosphorylated by cellular protein kinases, and in this study, we set out to determine whether this modification is required for the binding of NS5A to other cellular proteins. We identified 3 such proteins and show that they interacted only with NS5A that was phosphorylated on a specific residue. Furthermore, these proteins were required for efficient virus replication and the ability of NS5A to spread throughout the cytoplasm of the cell. Our results help to define the function of NS5A and may contribute to an understanding of the mode of action of the highly potent antiviral drugs that are targeted to NS5A.
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Hsu SC, Lo CW, Pan TC, Lee KY, Yu MJ. Serine 235 Is the Primary NS5A Hyperphosphorylation Site Responsible for Hepatitis C Virus Replication. J Virol 2017; 91:e00194-17. [PMID: 28446668 PMCID: PMC5487554 DOI: 10.1128/jvi.00194-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/17/2017] [Indexed: 12/30/2022] Open
Abstract
The nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) is a phosphoprotein with two phosphorylation states: hypo- and hyperphosphorylation. Genetic mutation studies have demonstrated a cluster of serine residues responsible for NS5A hyperphosphorylation and functions in viral replication and assembly; however, the phosphorylation levels and potential interactions among the serine residues are unclear. We used three specific antibodies to measure NS5A phosphorylation at S222, S235, and S238 that were identified in our previous proteomics study. In the HCV (J6/JFH-1)-infected Huh7.5.1 cells, S222 phosphorylation was barely detected, whereas S235 phosphorylation and S238 phosphorylation were always detected in parallel in time and intracellular spaces. S235A mutation eliminated S238 phosphorylation whereas S238A mutation did not affect S235 phosphorylation, indicating that S235 phosphorylation occurs independently of S238 phosphorylation while S238 phosphorylation depends on S235 phosphorylation. In line with this, immunoprecipitation coupled with immunoblotting showed that S235 phosphorylation existed alone without S238 phosphorylation, whereas S238 phosphorylation existed only when S235 was phosphorylated on the same NS5A molecule. S235-phosphorylated NS5A constituted the primary hyperphosphorylated NS5A species. S235A mutation blunted viral replication, whereas S238A mutation did not affect replication. We concluded that S235 is the primary NS5A hyperphosphorylation site required for HCV replication. S238 is likely phosphorylated by casein kinase Iα, which requires a priming phosphorylation at S235.IMPORTANCE It has been known for years that the hepatitis C virus nonstructural protein 5A (NS5A) undergoes transition between two phosphorylation states: hypo- and hyperphosphorylation. It is also known that a cluster of serine residues is responsible for NS5A hyperphosphorylation and functions; however, the primary serine residue responsible for NS5A hyperphosphorylation is not clear. Here, we show for the first time that serine 235-phosphorylated NS5A constitutes the primary hyperphosphorylated NS5A species required for viral replication. We also show that NS5A phosphorylation among the serine residues is interdependent and occurs in a directional manner, i.e., phosphorylation at serine 235 leads to phosphorylation at serine 238. Our data provide the first proof-of-principle evidence that NS5A undergoes a sequential phosphorylation cascade.
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Affiliation(s)
- Shih-Chin Hsu
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Chieh-Wen Lo
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ting-Chun Pan
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Kuan-Ying Lee
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ming-Jiun Yu
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
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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] [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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Lougiakis N, Frakolaki E, Karmou P, Pouli N, Marakos P, Madan V, Bartenschlager R, Vassilaki N. Novel nucleoside analogues targeting HCV replication through an NS5A-dependent inhibition mechanism. Chem Biol Drug Des 2017; 90:352-367. [PMID: 28245093 DOI: 10.1111/cbdd.12966] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/20/2017] [Accepted: 02/10/2017] [Indexed: 12/25/2022]
Abstract
A series of new tricyclic nucleosides were synthesized and evaluated as hepatitis C virus (HCV) replication inhibitors. Initial screening in a HCV replicon system, derived from a genotype 1b isolate, identified 9-benzylamino-3-(β-D-ribofuranosyl)-3H-imidazo[4',5':5,6]pyrido[2,3-b]pyrazine (15d) as the most potent analogue. Comparative assessment of 15d activity against HCV full-length viruses or subgenomic replicons derived from genotypes 1 to 4 revealed a specificity of the compound for genotypes 1 and 3. Surprisingly, resistance mutations selected against 15d were mapped to domains II and III of the non-structural protein 5A (NS5A), but not to the RNA-dependent RNA polymerase residing in NS5B. These results argue that compound 15d might represent a lead for the development of a novel class of NS5A inhibitors.
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Affiliation(s)
- Nikolaos Lougiakis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | - Panagiota Karmou
- Division of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece
| | - Nicole Pouli
- Division of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece
| | - Panagiotis Marakos
- Division of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece
| | - Vanesa Madan
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany.,German Center for Infection Research, Heidelberg University, Heidelberg, Germany.,Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
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Ivanenkov YA, Aladinskiy VA, Bushkov NA, Ayginin AA, Majouga AG, Ivachtchenko AV. Small-molecule inhibitors of hepatitis C virus (HCV) non-structural protein 5A (NS5A): a patent review (2010-2015). Expert Opin Ther Pat 2017; 27:401-414. [PMID: 27967269 DOI: 10.1080/13543776.2017.1272573] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Non-structural 5A (NS5A) protein has achieved a considerable attention as an attractive target for the treatment of hepatitis C (HCV). A number of novel NS5A inhibitors have been reported to date. Several drugs having favorable ADME properties and mild side effects were launched into the pharmaceutical market. For instance, daclatasvir was launched in 2014, elbasvir is currently undergoing registration, ledipasvir was launched in 2014 as a fixed-dose combination with sofosbuvir (NS5B inhibitor). Areas covered: Thomson integrity database and SciFinder database were used as a valuable source to collect the patents on small-molecule NS5A inhibitors. All the structures were ranked by the date of priority. Patent holder and antiviral activity for each scaffold claimed were summarized and presented in a convenient manner. A particular focus was placed on the best-in-class bis-pyrrolidine-containing NS5A inhibitors. Expert opinion: Several first generation NS5A inhibitors have recently progressed into advanced clinical trials and showed superior efficacy in reducing viral load in infected subjects. Therapy schemes of using these agents in combination with other established antiviral drugs with complementary mechanisms of action can address the emergence of resistance and poor therapeutic outcome frequently attributed to antiviral drugs.
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Affiliation(s)
- Yan A Ivanenkov
- a Department of Biological and Medical Physics , Moscow Institute of Physics and Technology (State University) , Dolgoprudny City , Moscow Region , Russia.,b Department of Computational and Medicinal Chemistry , ChemDiv , San Diego , CA , USA.,c Chemistry Department , Moscow State University , Moscow , Russia
| | - Vladimir A Aladinskiy
- a Department of Biological and Medical Physics , Moscow Institute of Physics and Technology (State University) , Dolgoprudny City , Moscow Region , Russia
| | - Nikolay A Bushkov
- a Department of Biological and Medical Physics , Moscow Institute of Physics and Technology (State University) , Dolgoprudny City , Moscow Region , Russia
| | - Andrey A Ayginin
- a Department of Biological and Medical Physics , Moscow Institute of Physics and Technology (State University) , Dolgoprudny City , Moscow Region , Russia
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26
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Lee KY, Chen YH, Hsu SC, Yu MJ. Phosphorylation of Serine 235 of the Hepatitis C Virus Non-Structural Protein NS5A by Multiple Kinases. PLoS One 2016; 11:e0166763. [PMID: 27875595 PMCID: PMC5119781 DOI: 10.1371/journal.pone.0166763] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/03/2016] [Indexed: 12/14/2022] Open
Abstract
Phosphorylation at serine 235 (S235) of the hepatitis C virus (HCV) non-structural protein 5A (NS5A) plays a critical role in the viral life cycle. For medical and virological interests, we exploited the HEK293T kidney cells to test 3 candidate protein kinases on NS5A S235 phosphorylation. Inhibitors that inhibit casein kinase I α (CKIα), polo-like kinase I (PlKI) or calmodulin-dependent kinase II (CaMKII) all reduced NS5A S235 phosphorylation. CKIα was studied previously and PlKI had severe cytotoxicity, thus CaMKII was selected for validation in the Huh7.5.1 liver cells. In the HCV (J6/JFH1)-infected Huh7.5.1 cells, CaMKII inhibitor reduced NS5A S235 phosphorylation and HCV RNA levels without apparent cytotoxicity. RT-PCR analysis showed expression of CaMKII γ and δ isoforms in the Huh7.5.1 cells. Both CaMKII γ and δ directly phosphorylated NS5A S235 in vitro. CaMKII γ or δ single knockdown did not affect NS5A S235 phosphorylation but elevated the HCV RNA levels in the infected cells. CKIα plus CaMKII (γ or δ) double knockdown reduced NS5A S235 phosphorylation and reduced HCV RNA levels; however, the HCV RNA levels were higher than those in the infected cells with CKIα single knockdown. We conclude that CKIα-mediated NS5A S235 phosphorylation is critical for HCV replication. CaMKII γ and δ may have negative roles in the HCV life cycle.
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Affiliation(s)
- Kuan-Ying Lee
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan
| | - Yi-Hung Chen
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan
| | - Shih-Chin Hsu
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan
| | - Ming-Jiun Yu
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, 10051, Taiwan
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Miyamura T, Lemon SM, Walker CM, Wakita T. The HCV Replicase Complex and Viral RNA Synthesis. HEPATITIS C VIRUS I 2016. [PMCID: PMC7122888 DOI: 10.1007/978-4-431-56098-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Replication of hepatitis C virus (HCV) is tightly linked to membrane alterations designated the membranous web, harboring the viral replicase complex. In this chapter we describe the morphology and 3D architecture of the HCV-induced replication organelles, mainly consisting of double membrane vesicles, which are generated by a concerted action of the nonstructural proteins NS3 to NS5B. Recent studies have furthermore identified a number of host cell proteins and lipids contributing to the biogenesis of the membranous web, which are discussed in this chapter. Viral RNA synthesis is tightly associated with these membrane alterations and mainly driven by the viral RNA dependent RNA polymerase NS5B. We summarize our current knowledge of the structure and function of NS5B, the role of cis-acting replication elements at the termini of the genome in regulating RNA synthesis and the contribution of additional viral and host factors to viral RNA synthesis, which is still ill defined.
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Affiliation(s)
- Tatsuo Miyamura
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
| | - Stanley M. Lemon
- Departments of Medicine and Microbiology & Immunology , The University of North Carolina, Chapel Hill, North Carolina USA
| | - Christopher M. Walker
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio USA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
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28
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Sólyom Z, Ma P, Schwarten M, Bosco M, Polidori A, Durand G, Willbold D, Brutscher B. The Disordered Region of the HCV Protein NS5A: Conformational Dynamics, SH3 Binding, and Phosphorylation. Biophys J 2016; 109:1483-96. [PMID: 26445449 DOI: 10.1016/j.bpj.2015.06.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/01/2015] [Accepted: 06/16/2015] [Indexed: 12/16/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) perform their physiological role without possessing a well-defined three-dimensional structure. Still, residual structure and conformational dynamics of IDPs are crucial for the mechanisms underlying their functions. For example, regions of transient secondary structure are often involved in molecular recognition, with the structure being stabilized (or not) upon binding. Long-range interactions, on the other hand, determine the hydrodynamic radius of the IDP, and thus the distance over which the protein can catch binding partners via so-called fly-casting mechanisms. The modulation of long-range interactions also presents a convenient way of fine-tuning the protein's interaction network, by making binding sites more or less accessible. Here we studied, mainly by nuclear magnetic resonance spectroscopy, residual secondary structure and long-range interactions in nonstructural protein 5A (NS5A) from hepatitis C virus (HCV), a typical viral IDP with multiple functions during the viral life cycle. NS5A comprises an N-terminal folded domain, followed by a large (∼250-residue) disordered C-terminal part. Comparing nuclear magnetic resonance spectra of full-length NS5A with those of a protein construct composed of only the C-terminal residues 191-447 (NS5A-D2D3) allowed us to conclude that there is no significant interaction between the globular and disordered parts of NS5A. NS5A-D2D3, despite its overall high flexibility, shows a large extent of local residual (α-helical and β-turn) structure, as well as a network of electrostatic long-range interactions. Furthermore, we could demonstrate that these long-range interactions become modulated upon binding to the host protein Bin1, as well as after NS5A phosphorylation by CK2. As the charged peptide regions involved in these interactions are well conserved among the different HCV genotypes, these transient long-range interactions may be important for some of the functions of NS5A over the course of the HCV life cycle.
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Affiliation(s)
- Zsófia Sólyom
- Institut de Biologie Structurale, Université Grenoble 1, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France; Centre National de Recherche Scientifique, Grenoble, France
| | - Peixiang Ma
- Institut de Biologie Structurale, Université Grenoble 1, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France; Centre National de Recherche Scientifique, Grenoble, France; Institute of Complex Systems-6 Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
| | - Melanie Schwarten
- Institute of Complex Systems-6 Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany
| | - Michaël Bosco
- Institut des Biomolécules Max Mousseron, UMR 5247, Centre National de Recherche Scientifique, École Nationale Supérieure de Chimie de Montpellier, Université Montpellier, Montpellier, France; Equipe Chimie Bioorganique et Systèmes Amphiphiles, Avignon Université, Avignon, France
| | - Ange Polidori
- Institut des Biomolécules Max Mousseron, UMR 5247, Centre National de Recherche Scientifique, École Nationale Supérieure de Chimie de Montpellier, Université Montpellier, Montpellier, France; Equipe Chimie Bioorganique et Systèmes Amphiphiles, Avignon Université, Avignon, France
| | - Grégory Durand
- Institut des Biomolécules Max Mousseron, UMR 5247, Centre National de Recherche Scientifique, École Nationale Supérieure de Chimie de Montpellier, Université Montpellier, Montpellier, France; Equipe Chimie Bioorganique et Systèmes Amphiphiles, Avignon Université, Avignon, France
| | - Dieter Willbold
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France; Institute of Complex Systems-6 Structural Biochemistry, Forschungszentrum Jülich, Jülich, Germany; Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Bernhard Brutscher
- Institut de Biologie Structurale, Université Grenoble 1, Grenoble, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, Grenoble, France; Centre National de Recherche Scientifique, Grenoble, France.
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Release of Infectious Hepatitis C Virus from Huh7 Cells Occurs via a trans-Golgi Network-to-Endosome Pathway Independent of Very-Low-Density Lipoprotein Secretion. J Virol 2016; 90:7159-70. [PMID: 27226379 PMCID: PMC4984645 DOI: 10.1128/jvi.00826-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/23/2016] [Indexed: 12/12/2022] Open
Abstract
The release of infectious hepatitis C virus (HCV) particles from infected cells remains poorly characterized. We previously demonstrated that virus release is dependent on the endosomal sorting complex required for transport (ESCRT). Here, we show a critical role of trans-Golgi network (TGN)-endosome trafficking during the assembly, but principally the secretion, of infectious virus. This was demonstrated by both small interfering RNA (siRNA)-mediated silencing of TGN-associated adaptor proteins and a panel of dominant negative (DN) Rab GTPases involved in TGN-endosome trafficking steps. Importantly, interfering with factors critical for HCV release did not have a concomitant effect on secretion of triglycerides, ApoB, or ApoE, indicating that particles are likely released from Huh7 cells via pathways distinct from that of very-low-density lipoprotein (VLDL). Finally, we show that HCV NS2 perturbs TGN architecture, redistributing TGN membranes to closely associate with HCV core protein residing on lipid droplets. These findings support the notion that HCV hijacks TGN-endosome trafficking to facilitate particle assembly and release. Moreover, although essential for assembly and infectivity, the trafficking of mature virions is seemingly independent of host lipoproteins. IMPORTANCE The mechanisms by which infectious hepatitis C virus particles are assembled and released from the cell are poorly understood. We show that the virus subverts host cell trafficking pathways to effect the release of virus particles and disrupts the structure of the Golgi apparatus, a key cellular organelle involved in secretion. In addition, we demonstrate that the mechanisms used by the virus to exit the cell are distinct from those used by the cell to release lipoproteins, suggesting that the virus effects a unique modification to cellular trafficking pathways.
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30
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Chung A, Jin B, Han KH, Ahn SH, Kim S. Cell culture-adaptive mutations of NS5A affect replication of hepatitis C virus differentially depending on the viral genotypes. J Med Virol 2016; 89:146-152. [PMID: 27253731 DOI: 10.1002/jmv.24591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2016] [Indexed: 01/19/2023]
Abstract
Most of HCV RNAs require cell culture-adaptive mutations for efficient replication in cell culture and a number of such mutations have been described including a well-known S2204I substitution mutation in NS5A protein. In contrast, the replication of genotype 2a JFH1 RNA in cell culture does not require any cell culture-adaptive mutation. Rather, the presence of S2204I mutation impaired the JFH1 RNA replication. In this study, we examined the effect of reversions and substitutions of NS5A cell culture-adaptive mutations on virus replication in different genotypic backgrounds after either placing genotype 1a NS5A in the genotype 2a JFH1 or vice versa. The results from this investigation suggest that the S2204I mutation affects HCV RNA replication differentially depending on the viral genotypes but that the effect was not simply explained by the genotypic background. Perhaps, the effect of the S2204I mutation on HCV replication reflects both intra- and intergenic interactions of NS5A protein. J. Med. Virol. 89:146-152, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Aeri Chung
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Bora Jin
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Kwang-Hyub Han
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.,Department of Internal Medicine, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.,Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Sang Hoon Ahn
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea. .,Department of Internal Medicine, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
| | - Seungtaek Kim
- Department of Internal Medicine, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea. .,Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
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Eyre NS, Hampton-Smith RJ, Aloia AL, Eddes JS, Simpson KJ, Hoffmann P, Beard MR. Phosphorylation of NS5A Serine-235 is essential to hepatitis C virus RNA replication and normal replication compartment formation. Virology 2016; 491:27-44. [PMID: 26874015 DOI: 10.1016/j.virol.2016.01.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/21/2016] [Accepted: 01/23/2016] [Indexed: 01/09/2023]
Abstract
Hepatitis C virus (HCV) NS5A protein is essential for HCV RNA replication and virus assembly. Here we report the identification of NS5A phosphorylation sites Ser-222, Ser-235 and Thr-348 during an infectious HCV replication cycle and demonstrate that Ser-235 phosphorylation is essential for HCV RNA replication. Confocal microscopy revealed that both phosphoablatant (S235A) and phosphomimetic (S235D) mutants redistribute NS5A to large juxta-nuclear foci that display altered colocalization with known replication complex components. Using electron microscopy (EM) we found that S235D alters virus-induced membrane rearrangements while EM using 'APEX2'-tagged viruses demonstrated S235D-mediated enrichment of NS5A in irregular membranous foci. Finally, using a customized siRNA screen of candidate NS5A kinases and subsequent analysis using a phospho-specific antibody, we show that phosphatidylinositol-4 kinase III alpha (PI4KIIIα) is important for Ser-235 phosphorylation. We conclude that Ser-235 phosphorylation of NS5A is essential for HCV RNA replication and normal replication complex formation and is regulated by PI4KIIIα.
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Affiliation(s)
- Nicholas S Eyre
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia.
| | - Rachel J Hampton-Smith
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
| | - Amanda L Aloia
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
| | - James S Eddes
- Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Kaylene J Simpson
- Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, East Melbourne, Australia; The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia
| | - Peter Hoffmann
- Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide, Australia; Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, Australia
| | - Michael R Beard
- School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, SA Pathology, Adelaide, Australia
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Secci E, Luchinat E, Banci L. The Casein Kinase 2-Dependent Phosphorylation of NS5A Domain 3 from Hepatitis C Virus Followed by Time-Resolved NMR Spectroscopy. Chembiochem 2016; 17:328-33. [PMID: 26684216 DOI: 10.1002/cbic.201500551] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) chronically affects millions of individuals worldwide. The HCV nonstructural protein 5A (NS5A) plays a critical role in the viral assembly pathway. Domain 3 (D3) of NS5A is an unstructured polypeptide responsible for the interaction with the core particle assembly structure. Casein kinase 2 (CK2) phosphorylates NS5A-D3 at multiple sites that have mostly been predicted and only observed indirectly. In order to identify the CK2-dependent phosphorylation sites, we monitored the reaction between NS5A-D3 and CK2 in vitro by time-resolved NMR. We unambiguously identified four serine residues as substrates of CK2. The apparent rate constant for each site was determined from the reaction curves. Ser408 was quickly phosphorylated, whereas the three other serine residues reacted more slowly. These results provide a starting point from which to elucidate the role of phosphorylation in the mechanisms of viral assembly-and in the modulation of the viral activity-at the molecular level.
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Affiliation(s)
- Erica Secci
- Magnetic Resonance Center-CERM, University of Florence, via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
| | - Enrico Luchinat
- Magnetic Resonance Center-CERM, University of Florence, via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy.,Department of Biomedical, Experimental and Clinical Sciences, University of Florence, viale Morgagni 50, 50134, Florence, Italy
| | - Lucia Banci
- Magnetic Resonance Center-CERM, University of Florence, via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy. .,Department of Chemistry, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
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Chong WM, Hsu SC, Kao WT, Lo CW, Lee KY, Shao JS, Chen YH, Chang J, Chen SSL, Yu MJ. Phosphoproteomics Identified an NS5A Phosphorylation Site Involved in Hepatitis C Virus Replication. J Biol Chem 2015; 291:3918-31. [PMID: 26702051 DOI: 10.1074/jbc.m115.675413] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 01/28/2023] Open
Abstract
The non-structural protein 5A (NS5A) is a hepatitis C virus (HCV) protein indispensable for the viral life cycle. Many prior papers have pinpointed several serine residues in the low complexity sequence I region of NS5A responsible for NS5A phosphorylation; however, the functions of specific phosphorylation sites remained obscure. Using phosphoproteomics, we identified three phosphorylation sites (serines 222, 235, and 238) in the NS5A low complexity sequence I region. Reporter virus and replicon assays using phosphorylation-ablated alanine mutants of these sites showed that Ser-235 dominated over Ser-222 and Ser-238 in HCV replication. Immunoblotting using an Ser-235 phosphorylation-specific antibody showed a time-dependent increase in Ser-235 phosphorylation that correlated with the viral replication activity. Ser-235 phosphorylated NS5A co-localized with double-stranded RNA, consistent with its role in HCV replication. Mechanistically, Ser-235 phosphorylation probably promotes the replication complex formation via increasing NS5A interaction with the human homologue of the 33-kDa vesicle-associated membrane protein-associated protein. Casein kinase Iα (CKIα) directly phosphorylated Ser-235 in vitro. Inhibition of CKIα reduced Ser-235 phosphorylation and the HCV RNA levels in the infected cells. We concluded that NS5A Ser-235 phosphorylated by CKIα probably promotes HCV replication via increasing NS5A interaction with the 33-kDa vesicle-associated membrane protein-associated protein.
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Affiliation(s)
- Weng Man Chong
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Shih-Chin Hsu
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Wei-Ting Kao
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Chieh-Wen Lo
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Kuan-Ying Lee
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Jheng-Syuan Shao
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Yi-Hung Chen
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Justin Chang
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
| | - Steve S-L Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Jiun Yu
- From the Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Rm. 816, No. 1 Sec. 1 Jen-Ai Road, Taipei 10051, Taiwan and
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Arginine 112 is involved in HCV translation modulation by NS5A domain I. Biochem Biophys Res Commun 2015; 465:95-100. [DOI: 10.1016/j.bbrc.2015.07.136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 07/28/2015] [Indexed: 01/08/2023]
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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 PMCID: PMC4521034 DOI: 10.1074/jbc.m115.644419] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 06/16/2015] [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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Yamauchi S, Takeuchi K, Chihara K, Sun X, Honjoh C, Yoshiki H, Hotta H, Sada K. Hepatitis C Virus Particle Assembly Involves Phosphorylation of NS5A by the c-Abl Tyrosine Kinase. J Biol Chem 2015. [PMID: 26203192 DOI: 10.1074/jbc.m115.666859] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is thought to regulate the replication of viral RNA and the assembly of virus particles in a serine/threonine phosphorylation-dependent manner. However, the host kinases that phosphorylate NS5A have not been fully identified. Here, we show that HCV particle assembly involves the phosphorylation of NS5A by the c-Abl tyrosine kinase. Pharmacological inhibition or knockdown of c-Abl reduces the production of infectious HCV (J6/JFH1) particles in Huh-7.5 cells without markedly affecting viral RNA translation and replication. NS5A is tyrosine-phosphorylated in HCV-infected cells, and this phosphorylation is also reduced by the knockdown of c-Abl. Mutational analysis reveals that NS5A tyrosine phosphorylation is dependent, at least in part, on Tyr(330) (Tyr(2306) in polyprotein numbering). Mutation of this residue to phenylalanine reduces the production of infectious HCV particles but does not affect the replication of the JFH1 subgenomic replicon. These findings suggest that c-Abl promotes HCV particle assembly by phosphorylating NS5A at Tyr(330).
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Affiliation(s)
- Shota Yamauchi
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Kenji Takeuchi
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Kazuyasu Chihara
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
| | - Xuedong Sun
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences
| | - Chisato Honjoh
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Third Department of Internal Medicine, Faculty of Medical Sciences, and
| | - Hatsumi Yoshiki
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences
| | - Hak Hotta
- the Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Kiyonao Sada
- From the Division of Genome Science and Microbiology, Department of Pathological Sciences, Faculty of Medical Sciences, the Organization for Life Science Advancement Programs, University of Fukui, Fukui 910-1193, Japan and
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Masaki T, Suzuki T. NS5A phosphorylation: its functional role in the life cycle of hepatitis C virus. Future Virol 2015. [DOI: 10.2217/fvl.15.33] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
ABSTRACT Hepatitis C virus (HCV) is a major cause of liver disease. HCV RNA replicates in a membrane-associated replication complex. Nonstructural protein 5A (NS5A) is phosphorylated on multiple serine and threonine residues and exists in basally phosphorylated and hyperphosphorylated forms. To date, studies have identified several serine/threonine kinases responsible for NS5A phosphorylation. Although NS5A has no known enzymatic activity, it is a multifunctional protein required for HCV RNA replication and virion assembly. The phosphorylation status of NS5A is considered to have a significant impact on its function and the viral life cycle. Furthermore, NS5A inhibitors represent a new class of direct acting antivirals and have become a key component for effective combination therapies against HCV infection.
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Affiliation(s)
- Takahiro Masaki
- Department of Virology II, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Tetsuro Suzuki
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka 431-3192, Japan
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Vinexin β Interacts with Hepatitis C Virus NS5A, Modulating Its Hyperphosphorylation To Regulate Viral Propagation. J Virol 2015; 89:7385-400. [PMID: 25972535 DOI: 10.1128/jvi.00567-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/05/2015] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is essential for HCV genome replication and virion production and is involved in the regulation of multiple host signaling pathways. As a proline-rich protein, NS5A is capable of interacting with various host proteins containing Src homology 3 (SH3) domains. Previous studies have suggested that vinexin, a member of the sorbin homology (SoHo) adaptor family, might be a potential binding partner of NS5A by yeast two-hybrid screening. However, firm evidence for this interaction is lacking, and the significance of vinexin in the HCV life cycle remains unclear. In this study, we demonstrated that endogenously and exogenously expressed vinexin β coimmunoprecipitated with NS5A derived from different HCV genotypes. Two residues, tryptophan (W307) and tyrosine (Y325), in the third SH3 domain of vinexin β and conserved Pro-X-X-Pro-X-Arg motifs at the C terminus of NS5A were indispensable for the vinexin-NS5A interaction. Furthermore, downregulation of endogenous vinexin β significantly suppressed NS5A hyperphosphorylation and decreased HCV replication, which could be rescued by expressing a vinexin β short hairpin RNA-resistant mutant. We also found that vinexin β modulated the hyperphosphorylation of NS5A in a casein kinase 1α-dependent on manner. Taken together, our findings suggest that vinexin β modulates NS5A phosphorylation via its interaction with NS5A, thereby regulating HCV replication, implicating vinexin β in the viral life cycle. IMPORTANCE Hepatitis C virus (HCV) nonstructural protein NS5A is a phosphoprotein, and its phosphorylation states are usually modulated by host kinases and other viral nonstructural elements. Additionally, cellular factors containing Src homology 3 (SH3) domains have been reported to interact with proline-rich regions of NS5A. However, it is unclear whether there are any relationships between NS5A phosphorylation and the NS5A-SH3 interaction, and little is known about the significance of this interaction in the HCV life cycle. In this work, we demonstrate that vinexin β modulates NS5A hyperphosphorylation through the NS5A-vinexin β interaction. Hyperphosphorylated NS5A induced by vinexin β is casein kinase 1α dependent and is also crucial for HCV propagation. Overall, our findings not only elucidate the relationships between NS5A phosphorylation and the NS5A-SH3 interaction but also shed new mechanistic insight on Flaviviridae NS5A (NS5) phosphorylation. We believe that our results may afford the potential to offer an antiviral therapeutic strategy.
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Host cell kinases and the hepatitis C virus life cycle. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1657-62. [PMID: 25896387 DOI: 10.1016/j.bbapap.2015.04.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Revised: 04/08/2015] [Accepted: 04/09/2015] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) infection relies on virus-host interactions with human hepatocytes, a context in which host cell kinases play critical roles in every step of the HCV life cycle. During viral entry, cellular kinases, including EGFR, EphA2 and PKA, regulate the localization of host HCV entry factors and induce receptor complex assembly. Following virion internalization, viral genomes replicate on endoplasmic reticulum-derived membranous webs. The formation of membranous webs depends on interactions between the HCV NS5a protein and PI4KIIIα. The phosphorylation status of NS5a, regulated by PI4KIIIα, CKI and other kinases, also acts as a molecular switch to virion assembly, which takes place on lipid droplets. The formation of lipid droplets is enhanced by HCV activation of IKKα. In view of the multiple crucial steps in the viral life cycle that are mediated by host cell kinases, these enzymes also represent complementary targets for antiviral therapy. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases.
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Igloi Z, Kazlauskas A, Saksela K, Macdonald A, Mankouri J, Harris M. Hepatitis C virus NS5A protein blocks epidermal growth factor receptor degradation via a proline motif- dependent interaction. J Gen Virol 2015; 96:2133-2144. [PMID: 25872741 PMCID: PMC4681064 DOI: 10.1099/vir.0.000145] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) establishes a persistent infection that in many cases leads to cirrhosis and hepatocellular carcinoma. The non-structural 5A protein (NS5A) has been implicated in this process as it contains a C-terminal polyproline motif (termed P2) that binds to Src homology 3 (SH3) domains to regulate cellular signalling and trafficking pathways. We have shown previously that NS5A impaired epidermal growth factor (EGF) receptor (EGFR) endocytosis, thereby inhibiting EGF-stimulated EGFR degradation by a mechanism that remained unclear. As EGFR has been implicated in HCV cell entry and trafficking of the receptor involves several SH3-domain containing proteins, we investigated in more detail the mechanisms by which NS5A perturbs EGFR trafficking. We demonstrated that the P2 motif was required for the NS5A-mediated disruption to EGFR trafficking. We further demonstrated that the P2 motif was required for an interaction between NS5A and CMS, a homologue of CIN85 that has previously been implicated in EGFR endocytosis. We provided evidence that CMS was involved in the NS5A-mediated perturbation of EGFR trafficking. We also showed that NS5A effected a loss of EGFR ubiquitination in a P2-motif-dependent fashion. These data provide clues to the mechanism by which NS5A regulates the trafficking of a key cellular receptor and demonstrate for the first time the ability of NS5A to regulate host cell ubiquitination pathways.
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Affiliation(s)
- Zsofia Igloi
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Arunas Kazlauskas
- Department of Virology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, Helsinki 00014, Finland
| | - Kalle Saksela
- Department of Virology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, Helsinki 00014, Finland
| | - Andrew Macdonald
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Jamel Mankouri
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Isken O, Langerwisch U, Jirasko V, Rehders D, Redecke L, Ramanathan H, Lindenbach BD, Bartenschlager R, Tautz N. A conserved NS3 surface patch orchestrates NS2 protease stimulation, NS5A hyperphosphorylation and HCV genome replication. PLoS Pathog 2015; 11:e1004736. [PMID: 25774920 PMCID: PMC4361677 DOI: 10.1371/journal.ppat.1004736] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/06/2015] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) infection is a leading cause of liver disease worldwide. The HCV RNA genome is translated into a single polyprotein. Most of the cleavage sites in the non-structural (NS) polyprotein region are processed by the NS3/NS4A serine protease. The vital NS2-NS3 cleavage is catalyzed by the NS2 autoprotease. For efficient processing at the NS2/NS3 site, the NS2 cysteine protease depends on the NS3 serine protease domain. Despite its importance for the viral life cycle, the molecular details of the NS2 autoprotease activation by NS3 are poorly understood. Here, we report the identification of a conserved hydrophobic NS3 surface patch that is essential for NS2 protease activation. One residue within this surface region is also critical for RNA replication and NS5A hyperphosphorylation, two processes known to depend on functional replicase assembly. This dual function of the NS3 surface patch prompted us to reinvestigate the impact of the NS2-NS3 cleavage on NS5A hyperphosphorylation. Interestingly, NS2-NS3 cleavage turned out to be a prerequisite for NS5A hyperphosphorylation, indicating that this cleavage has to occur prior to replicase assembly. Based on our data, we propose a sequential cascade of molecular events: in uncleaved NS2-NS3, the hydrophobic NS3 surface patch promotes NS2 protease stimulation; upon NS2-NS3 cleavage, this surface region becomes available for functional replicase assembly. This model explains why efficient NS2-3 cleavage is pivotal for HCV RNA replication. According to our model, the hydrophobic surface patch on NS3 represents a module critically involved in the temporal coordination of HCV replicase assembly.
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Affiliation(s)
- Olaf Isken
- Institute of Virology and Cell Biology, University of Lübeck, Germany
| | | | - Vlastimil Jirasko
- Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Dirk Rehders
- Joint Laboratory for Structural Biology of Infection and Inflammation of the University of Hamburg and the University of Lübeck, DESY, Hamburg, Germany
| | - Lars Redecke
- Joint Laboratory for Structural Biology of Infection and Inflammation of the University of Hamburg and the University of Lübeck, DESY, Hamburg, Germany
| | - Harish Ramanathan
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, United States of America
| | - Brett D. Lindenbach
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, United States of America
| | - Ralf Bartenschlager
- Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Norbert Tautz
- Institute of Virology and Cell Biology, University of Lübeck, Germany
- * E-mail:
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Jardim ACG, Igloi Z, Shimizu JF, Santos VAFFM, Felippe LG, Mazzeu BF, Amako Y, Furlan M, Harris M, Rahal P. Natural compounds isolated from Brazilian plants are potent inhibitors of hepatitis C virus replication in vitro. Antiviral Res 2015; 115:39-47. [PMID: 25557602 PMCID: PMC4329992 DOI: 10.1016/j.antiviral.2014.12.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 11/27/2014] [Accepted: 12/23/2014] [Indexed: 01/22/2023]
Abstract
Compounds extracted from plants can provide an alternative approach to new therapies. They present characteristics such as high chemical diversity, lower cost of production and milder or inexistent side effects compared with conventional treatment. The Brazilian flora represents a vast, largely untapped, resource of potential antiviral compounds. In this study, we investigate the antiviral effects of a panel of natural compounds isolated from Brazilian plants species on hepatitis C virus (HCV) genome replication. To do this we used firefly luciferase-based HCV sub-genomic replicons of genotypes 2a (JFH-1), 1b and 3a and the compounds were assessed for their effects on both HCV replication and cellular toxicity. Initial screening of compounds was performed using the maximum non-toxic concentration and 4 compounds that exhibited a useful therapeutic index (favourable ratio of cytotoxicity to antiviral potency) were selected for extra analysis. The compounds APS (EC50=2.3μM), a natural alkaloid isolated from Maytrenus ilicifolia, and the lignans 3(∗)43 (EC50=4.0μM), 3(∗)20 (EC50=8.2μM) and 5(∗)362 (EC50=38.9μM) from Peperomia blanda dramatically inhibited HCV replication as judged by reductions in luciferase activity and HCV protein expression in both the subgenomic and infectious systems. We further show that these compounds are active against a daclatasvir resistance mutant subgenomic replicon. Consistent with inhibition of genome replication, production of infectious JFH-1 virus was significantly reduced by all 4 compounds. These data are the first description of Brazilian natural compounds possessing anti-HCV activity and further analyses are being performed in order to investigate the mode of action of those compounds.
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Affiliation(s)
- A C G Jardim
- UFU - Federal University of Uberlândia, Institute of Biomedical Science - ICBIM, Uberlândia, MG, Brazil; UNESP - São Paulo State University, Institute of Bioscience, Language and Exact Science - IBILCE, Department of Biology, São José do Rio Preto, SP, Brazil.
| | - Z Igloi
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - J F Shimizu
- UNESP - São Paulo State University, Institute of Bioscience, Language and Exact Science - IBILCE, Department of Biology, São José do Rio Preto, SP, Brazil.
| | - V A F F M Santos
- UNESP - São Paulo State University, Institute of Chemistry, Department of Organic Chemistry, Araraquara, SP, Brazil.
| | - L G Felippe
- UNESP - São Paulo State University, Institute of Chemistry, Department of Organic Chemistry, Araraquara, SP, Brazil.
| | - B F Mazzeu
- UNESP - São Paulo State University, Institute of Bioscience, Language and Exact Science - IBILCE, Department of Biology, São José do Rio Preto, SP, Brazil.
| | - Y Amako
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
| | - M Furlan
- UNESP - São Paulo State University, Institute of Chemistry, Department of Organic Chemistry, Araraquara, SP, Brazil.
| | - M Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - P Rahal
- UNESP - São Paulo State University, Institute of Bioscience, Language and Exact Science - IBILCE, Department of Biology, São José do Rio Preto, SP, Brazil.
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Regulation and function of phosphorylation on VP8, the major tegument protein of bovine herpesvirus 1. J Virol 2015; 89:4598-611. [PMID: 25673708 DOI: 10.1128/jvi.03180-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
UNLABELLED The major tegument protein of bovine herpesvirus 1 (BoHV-1), VP8, is essential for virus replication in cattle. VP8 is phosphorylated in vitro by casein kinase 2 (CK2) and BoHV-1 unique short protein 3 (US3). In this study, VP8 was found to be phosphorylated in both transfected and infected cells but was detected as a nonphosphorylated form in mature virions. This suggests that phosphorylation of VP8 is strictly controlled during different stages of the viral life cycle. The regulation and function of VP8 phosphorylation by US3 and CK2 were further analyzed. An in vitro kinase assay, site-directed mutagenesis, and liquid chromatography-mass spectrometry were used to identify the active sites for US3 and CK2. The two kinases phosphorylate VP8 at different sites, resulting in distinct phosphopeptide patterns. S(16) is a primary phosphoreceptor for US3, and it subsequently triggers phosphorylation at S(32). CK2 has multiple active sites, among which T(107) appears to be the preferred residue. Additionally, CK2 consensus motifs in the N terminus of VP8 are essential for phosphorylation. Based on these results, a nonphosphorylated VP8 mutant was constructed and used for further studies. In transfected cells phosphorylation was not required for nuclear localization of VP8. Phosphorylated VP8 appeared to recruit promyelocytic leukemia (PML) protein and to remodel the distribution of PML in the nucleus; however, PML protein did not show an association with nonphosphorylated VP8. This suggests that VP8 plays a role in resisting PML-related host antiviral defenses by redistributing PML protein and that this function depends on the phosphorylation of VP8. IMPORTANCE The progression of VP8 phosphorylation over time and its function in BoHV-1 replication have not been characterized. This study demonstrates that activation of S(16) initiates further phosphorylation at S(32) by US3. Additionally, VP8 is phosphorylated by CK2 at several residues, with T(107) having the highest level of phosphorylation. Evidence for a difference in the phosphorylation status of VP8 in host cells and mature virus is presented for the first time. Phosphorylation was found to be a critical modification, which enables VP8 to attract and to redistribute PML protein in the nucleus. This might promote viral replication through interference with a PML-mediated antiviral defense. This study provides new insights into the regulation of VP8 phosphorylation and suggests a novel, phosphorylation-dependent function for VP8 in the life cycle of BoHV-1, which is important in view of the fact that VP8 is essential for virus replication in vivo.
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Serine phosphorylation of the hepatitis C virus NS5A protein controls the establishment of replication complexes. J Virol 2014; 89:3123-35. [PMID: 25552726 PMCID: PMC4337517 DOI: 10.1128/jvi.02995-14] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The hepatitis C virus (HCV) nonstructural 5A (NS5A) protein is highly phosphorylated and involved in both virus genome replication and virion assembly. We and others have identified serine 225 in NS5A to be a phosphorylation site, but the function of this posttranslational modification in the virus life cycle remains obscure. Here we describe the phenotype of mutants with mutations at serine 225; this residue was mutated to either alanine (S225A; phosphoablatant) or aspartic acid (S225D; phosphomimetic) in the context of both the JFH-1 cell culture infectious virus and a corresponding subgenomic replicon. The S225A mutant exhibited a 10-fold reduction in genome replication, whereas the S225D mutant replicated like the wild type. By confocal microscopy, we show that, in the case of the S225A mutant, the replication phenotype correlated with an altered subcellular distribution of NS5A. This phenotype was shared by viruses with other mutations in the low-complexity sequence I (LCS I), namely, S229D, S232A, and S235D, but not by viruses with mutations that caused a comparable replication defect that mapped to domain II of NS5A (P315A, L321A). Together with other components of the genome replication complex (NS3, double-stranded RNA, and cellular lipids, including phosphatidylinositol 4-phosphate), the mutation in NS5A was restricted to a perinuclear region. This phenotype was not due to cell confluence or another environmental factor and could be partially transcomplemented by wild-type NS5A. We propose that serine phosphorylation within LCS I may regulate the assembly of an active genome replication complex. IMPORTANCE The mechanisms by which hepatitis C virus replicates its RNA genome remain poorly characterized. We show here that phosphorylation of the viral nonstructural protein NS5A at serine residues is important for the efficient assembly of a complex that is able to replicate the viral genome. This research implicates cellular protein kinases in the control of virus replication and highlights the need to further understand the interplay between the virus and the host cell in order to develop potential avenues for future antiviral therapy.
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Ross-Thriepland D, Harris M. Hepatitis C virus NS5A: enigmatic but still promiscuous 10 years on! J Gen Virol 2014; 96:727-738. [PMID: 25481754 DOI: 10.1099/jgv.0.000009] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Since one of us co-authored a review on NS5A a decade ago, the hepatitis C virus (HCV) field has changed dramatically, primarily due to the advent of the JFH-1 cell culture infectious clone, which allowed the study of all aspects of the virus life cycle from entry to exit. This review will describe advances in our understanding of NS5A biology over the past decade, highlighting how the JFH-1 system has allowed us to determine that NS5A is essential not only in genome replication but also in the assembly of infectious virions. We shall review the recent structural insights - NS5A is predicted to comprise three domains; X-ray crystallography has revealed the structure of domain I but there is a lack of detailed structural information about the other two domains, which are predicted to be largely unstructured. Recent insights into the phosphorylation of NS5A will be discussed, and we shall highlight a few pertinent examples from the ever-expanding list of NS5A-binding partners identified over the past decade. Lastly, we shall review the literature showing that NS5A is a potential target for a new class of highly potent small molecules that function to inhibit virus replication. These direct-acting antivirals (DAAs) are now either licensed, or in the late stages of approval for clinical use both in the USA and in the UK/Europe. In combination with other DAAs targeting the viral protease (NS3) and polymerase (NS5B), they are revolutionizing treatment for HCV infection.
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Affiliation(s)
- Douglas Ross-Thriepland
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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Kim S, Jin B, Choi SH, Han KH, Ahn SH. Casein kinase II inhibitor enhances production of infectious genotype 1a hepatitis C virus (H77S). PLoS One 2014; 9:e113938. [PMID: 25464014 PMCID: PMC4252060 DOI: 10.1371/journal.pone.0113938] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 10/31/2014] [Indexed: 01/11/2023] Open
Abstract
Genotype 2a JFH1 virus has substantially contributed to the progress of HCV biology by allowing entire viral life cycle of HCV in cell culture. Using this genotype 2a virus, casein kinase II (CKII) was previously identified as a crucial host factor in virus assembly by phosphorylating NS5A. Since most of the prior studies employed genotype 2a JFH1 or JFH1-based intragenotypic chimera, we used genotype 1a H77S to study virus assembly. CKII inhibition by chemical inhibitors enhanced H77S virus production in contrast to that of JFH1 virus, but genetic inhibition of CKII by siRNA did not change H77S virus titer significantly. The different outcomes from these two approaches of CKII inhibition suggested that nonspecific target kinase of CKII inhibitors plays a role in increasing H77S virus production and both viral and host factors were investigated in this study. Our results emphasize substantial differences among the HCV genotypes that should be considered in both basic research and clinical practices.
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Affiliation(s)
- Seungtaek Kim
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
- Institute of Gastroenterology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- * E-mail:
| | - Bora Jin
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Sung Hoon Choi
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Kwang-Hyub Han
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
- Institute of Gastroenterology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Sang Hoon Ahn
- Institute of Gastroenterology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
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Eyre NS, Helbig KJ, Beard MR. Current and future targets of antiviral therapy in the hepatitis C virus life cycle. Future Virol 2014. [DOI: 10.2217/fvl.14.83] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
ABSTRACT Advances in our understanding of the hepatitis C virus (HCV) life cycle have enabled the development of numerous clinically advanced direct-acting antivirals. Indeed, the recent approval of first-generation direct-acting antivirals that target the viral NS3–4A protease and NS5B RNA-dependent RNA polymerase brings closer the possibility of universally efficacious and well-tolerated antiviral therapies for this insidious infection. However, the complexities of comorbidities, unforeseen side effects or drug–drug interactions, viral diversity, the high mutation rate of HCV RNA replication and the elegant and constantly evolving mechanisms employed by HCV to evade host and therapeutically implemented antiviral strategies remain as significant obstacles to this goal. Here, we review advances in our understanding of the HCV life cycle and associated opportunities for antiviral therapy.
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Affiliation(s)
- Nicholas S Eyre
- School of Molecular & Biomedical Science, The University of Adelaide & Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia
| | - Karla J Helbig
- School of Molecular & Biomedical Science, The University of Adelaide & Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia
| | - Michael R Beard
- School of Molecular & Biomedical Science, The University of Adelaide & Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia
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Eyre NS, Beard MR. HCV NS5A inhibitors disrupt replication factory formation: a novel mechanism of antiviral action. Gastroenterology 2014; 147:959-62. [PMID: 25265576 DOI: 10.1053/j.gastro.2014.09.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Nicholas S Eyre
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, Adelaide, Australia
| | - Michael R Beard
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia; Centre for Cancer Biology, Adelaide, Australia.
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Cordek DG, Croom-Perez TJ, Hwang J, Hargittai MRS, Subba-Reddy CV, Han Q, Lodeiro MF, Ning G, McCrory TS, Arnold JJ, Koc H, Lindenbach BD, Showalter SA, Cameron CE. Expanding the proteome of an RNA virus by phosphorylation of an intrinsically disordered viral protein. J Biol Chem 2014; 289:24397-416. [PMID: 25031324 DOI: 10.1074/jbc.m114.589911] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The human proteome contains myriad intrinsically disordered proteins. Within intrinsically disordered proteins, polyproline-II motifs are often located near sites of phosphorylation. We have used an unconventional experimental paradigm to discover that phosphorylation by protein kinase A (PKA) occurs in the intrinsically disordered domain of hepatitis C virus non-structural protein 5A (NS5A) on Thr-2332 near one of its polyproline-II motifs. Phosphorylation shifts the conformational ensemble of the NS5A intrinsically disordered domain to a state that permits detection of the polyproline motif by using (15)N-, (13)C-based multidimensional NMR spectroscopy. PKA-dependent proline resonances were lost in the presence of the Src homology 3 domain of c-Src, consistent with formation of a complex. Changing Thr-2332 to alanine in hepatitis C virus genotype 1b reduced the steady-state level of RNA by 10-fold; this change was lethal for genotype 2a. The lethal phenotype could be rescued by changing Thr-2332 to glutamic acid, a phosphomimetic substitution. Immunofluorescence and transmission electron microscopy showed that the inability to produce Thr(P)-2332-NS5A caused loss of integrity of the virus-induced membranous web/replication organelle. An even more extreme phenotype was observed in the presence of small molecule inhibitors of PKA. We conclude that the PKA-phosphorylated form of NS5A exhibits unique structure and function relative to the unphosphorylated protein. We suggest that post-translational modification of viral proteins containing intrinsic disorder may be a general mechanism to expand the viral proteome without a corresponding expansion of the genome.
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Affiliation(s)
| | | | - Jungwook Hwang
- the Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimri-ro, Seongdong-gu, Seoul, 133-791, Korea
| | | | - Chennareddy V Subba-Reddy
- the Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, and
| | - Qingxia Han
- From the Department of Biochemistry and Molecular Biology
| | | | - Gang Ning
- the Huck Institutes of the Life Sciences, and
| | | | - Jamie J Arnold
- From the Department of Biochemistry and Molecular Biology
| | - Hasan Koc
- the Department of Pharmaceutical Science and Research, Marshall University School of Pharmacy, Huntington, West Virginia 25755
| | - Brett D Lindenbach
- the Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, and
| | - Scott A Showalter
- the Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
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Involvement of hepatitis C virus NS5A hyperphosphorylation mediated by casein kinase I-α in infectious virus production. J Virol 2014; 88:7541-55. [PMID: 24760886 DOI: 10.1128/jvi.03170-13] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED Nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) possesses multiple functions in the viral life cycle. NS5A is a phosphoprotein that exists in hyperphosphorylated and basally phosphorylated forms. Although the phosphorylation status of NS5A is considered to have a significant impact on its function, the mechanistic details regulating NS5A phosphorylation, as well as its exact roles in the HCV life cycle, are still poorly understood. In this study, we screened 404 human protein kinases via in vitro binding and phosphorylation assays, followed by RNA interference-mediated gene silencing in an HCV cell culture system. Casein kinase I-α (CKI-α) was identified as an NS5A-associated kinase involved in NS5A hyperphosphorylation and infectious virus production. Subcellular fractionation and immunofluorescence confocal microscopy analyses showed that CKI-α-mediated hyperphosphorylation of NS5A contributes to the recruitment of NS5A to low-density membrane structures around lipid droplets (LDs) and facilitates its interaction with core protein and the viral assembly. Phospho-proteomic analysis of NS5A with or without CKI-α depletion identified peptide fragments that corresponded to the region located within the low-complexity sequence I, which is important for CKI-α-mediated NS5A hyperphosphorylation. This region contains eight serine residues that are highly conserved among HCV isolates, and subsequent mutagenesis analysis demonstrated that serine residues at amino acids 225 and 232 in NS5A (genotype 2a) may be involved in NS5A hyperphosphorylation and hyperphosphorylation-dependent regulation of virion production. These findings provide insight concerning the functional role of NS5A phosphorylation as a regulatory switch that modulates its multiple functions in the HCV life cycle. IMPORTANCE Mechanisms regulating NS5A phosphorylation and its exact function in the HCV life cycle have not been clearly defined. By using a high-throughput screening system targeting host protein kinases, we identified CKI-α as an NS5A-associated kinase involved in NS5A hyperphosphorylation and the production of infectious virus. Our results suggest that the impact of CKI-α in the HCV life cycle is more profound on virion assembly than viral replication via mediation of NS5A hyperphosphorylation. CKI-α-dependent hyperphosphorylation of NS5A plays a role in recruiting NS5A to low-density membrane structures around LDs and facilitating its interaction with the core for new virus particle formation. By using proteomic approach, we identified the region within the low-complexity sequence I of NS5A that is involved in NS5A hyperphosphorylation and hyperphosphorylation-dependent regulation of infectious virus production. These findings will provide novel mechanistic insights into the roles of NS5A-associated kinases and NS5A phosphorylation in the HCV life cycle.
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