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Palmitoylation of Hepatitis C Virus NS2 Regulates Its Subcellular Localization and NS2-NS3 Autocleavage. J Virol 2019; 94:JVI.00906-19. [PMID: 31597774 PMCID: PMC6912101 DOI: 10.1128/jvi.00906-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/02/2019] [Indexed: 12/16/2022] Open
Abstract
Chronic infection with hepatitis C virus (HCV) is a major cause of severe liver diseases responsible for nearly 400,000 deaths per year. HCV NS2 protein is a multifunctional regulator of HCV replication involved in both viral-genome replication and infectious-virus assembly. However, the underlying mechanism that enables the protein to participate in multiple steps of HCV replication remains unknown. In this study, we discovered that NS2 palmitoylation is the master regulator of its multiple functions, including NS2-mediated self-cleavage and HCV envelope protein recruitment to the virus assembly sites, which in turn promote HCV RNA replication and infectious-particle assembly, respectively. This newly revealed information suggests that NS2 palmitoylation could serve as a promising target to inhibit both HCV RNA replication and virus assembly, representing a new avenue for host-targeting strategies against HCV infection. Hepatitis C virus (HCV) nonstructural protein 2 (NS2) is a multifunctional protein implicated in both HCV RNA replication and virus particle assembly. NS2-encoded cysteine protease is responsible for autoprocessing of NS2-NS3 precursor, an essential step in HCV RNA replication. NS2 also promotes HCV particle assembly by recruiting envelope protein 2 (E2) to the virus assembly sites located at the detergent-resistant membranes (DRM). However, the fundamental mechanism regulating multiple functions of NS2 remains unclear. In this study, we discovered that NS2 is palmitoylated at the position 113 cysteine residue (NS2/C113) when expressed by itself in cells and during infectious-HCV replication. Blocking NS2 palmitoylation by introducing an NS2/C113S mutation reduced NS2-NS3 autoprocessing and impaired HCV RNA replication. Replication of the NS2/C113S mutant was restored by inserting an encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) between NS2 and NS3 to separate the two proteins independently of NS2-mediated autoprocessing. These results suggest that NS2 palmitoylation is critical for HCV RNA replication by promoting NS2-NS3 autoprocessing. The NS2/C113S mutation also impaired infectious-HCV assembly, DRM localization of NS2 and E2, and colocalization of NS2 with Core and endoplasmic reticulum lipid raft-associated protein 2 (Erlin-2). In conclusion, our study revealed that two major functions of NS2 involved in HCV RNA replication and virus assembly, i.e., NS2-NS3 autoprocessing and E2 recruitment to the DRM, are regulated by palmitoylation at NS2/C113. Since S-palmitoylation is reversible, NS2 palmitoylation likely allows NS2 to fine tune both HCV RNA replication and infectious-particle assembly. IMPORTANCE Chronic infection with hepatitis C virus (HCV) is a major cause of severe liver diseases responsible for nearly 400,000 deaths per year. HCV NS2 protein is a multifunctional regulator of HCV replication involved in both viral-genome replication and infectious-virus assembly. However, the underlying mechanism that enables the protein to participate in multiple steps of HCV replication remains unknown. In this study, we discovered that NS2 palmitoylation is the master regulator of its multiple functions, including NS2-mediated self-cleavage and HCV envelope protein recruitment to the virus assembly sites, which in turn promote HCV RNA replication and infectious-particle assembly, respectively. This newly revealed information suggests that NS2 palmitoylation could serve as a promising target to inhibit both HCV RNA replication and virus assembly, representing a new avenue for host-targeting strategies against HCV infection.
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Gadalla MR, Veit M. Toward the identification of ZDHHC enzymes required for palmitoylation of viral protein as potential drug targets. Expert Opin Drug Discov 2019; 15:159-177. [PMID: 31809605 DOI: 10.1080/17460441.2020.1696306] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Introduction: S-acylation is the attachment of fatty acids not only to cysteines of cellular, but also of viral proteins. The modification is often crucial for the protein´s function and hence for virus replication. Transfer of fatty acids is mediated by one or several of the 23 members of the ZDHHC family of proteins. Since their genes are linked to various human diseases, they represent drug targets.Areas covered: The authors explore whether targeting acylation of viral proteins might be a strategy to combat viral diseases. Many human pathogens contain S-acylated proteins; the ZDHHCs involved in their acylation are currently identified. Based on the 3D structure of two ZDHHCs, the regulation and the biochemistry of the palmitolyation reaction and the lipid and protein substrate specificities are discussed. The authors then speculate how ZDHHCs might recognize S-acylated membrane proteins of Influenza virus.Expert opinion: Although many viral diseases can now be treated, the available drugs bind to viral proteins that rapidly mutate and become resistant. To develop inhibitors for the genetically more stable cellular ZDHHCs, their binding sites for viral substrates need to be identified. If only a few cellular proteins are recognized by the same binding site, development of specific inhibitors may have therapeutic potential.
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Affiliation(s)
- Mohamed Rasheed Gadalla
- Institute of Virology, Free University Berlin, Berlin, Germany.,Department of Virology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
| | - Michael Veit
- Institute of Virology, Free University Berlin, Berlin, Germany
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Scaturro P, Stukalov A, Haas DA, Cortese M, Draganova K, Płaszczyca A, Bartenschlager R, Götz M, Pichlmair A. An orthogonal proteomic survey uncovers novel Zika virus host factors. Nature 2018; 561:253-257. [PMID: 30177828 DOI: 10.1038/s41586-018-0484-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/20/2018] [Indexed: 11/09/2022]
Abstract
Zika virus (ZIKV) has recently emerged as a global health concern owing to its widespread diffusion and its association with severe neurological symptoms and microcephaly in newborns1. However, the molecular mechanisms that are responsible for the pathogenicity of ZIKV remain largely unknown. Here we use human neural progenitor cells and the neuronal cell line SK-N-BE2 in an integrated proteomics approach to characterize the cellular responses to viral infection at the proteome and phosphoproteome level, and use affinity proteomics to identify cellular targets of ZIKV proteins. Using this approach, we identify 386 ZIKV-interacting proteins, ZIKV-specific and pan-flaviviral activities as well as host factors with known functions in neuronal development, retinal defects and infertility. Moreover, our analysis identified 1,216 phosphorylation sites that are specifically up- or downregulated after ZIKV infection, indicating profound modulation of fundamental signalling pathways such as AKT, MAPK-ERK and ATM-ATR and thereby providing mechanistic insights into the proliferation arrest elicited by ZIKV infection. Functionally, our integrative study identifies ZIKV host-dependency factors and provides a comprehensive framework for a system-level understanding of ZIKV-induced perturbations at the levels of proteins and cellular pathways.
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Affiliation(s)
- Pietro Scaturro
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany. .,Technical University of Munich, School of Medicine, Institute of Virology, Munich, Germany.
| | - Alexey Stukalov
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany.,Technical University of Munich, School of Medicine, Institute of Virology, Munich, Germany
| | - Darya A Haas
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Kalina Draganova
- Institute of Stem Cell Research, Helmholtz Center Munich, Neuherberg, Germany.,Physiological Genomics, Biomedical Center, Ludwig-Maximilians-Universitaet, Munich, Germany
| | - Anna Płaszczyca
- 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 (DZIF), Heidelberg partner site, Heidelberg, Germany
| | - Magdalena Götz
- Institute of Stem Cell Research, Helmholtz Center Munich, Neuherberg, Germany.,Physiological Genomics, Biomedical Center, Ludwig-Maximilians-Universitaet, Munich, Germany.,Synergy, Excellence Cluster for Systems Neurology, Biomedical Center, Ludwig-Maximilians-Universitaet, Munich, Germany
| | - Andreas Pichlmair
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany. .,Technical University of Munich, School of Medicine, Institute of Virology, Munich, Germany. .,German Center for Infection Research (DZIF), Munich partner site, Munich, Germany.
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Zaghloul H, El Morsi AA, Soweha HE, Elsayed A, Seif S, El-Sharawy H. A simple real-time polymerase chain reaction assay using SYBR Green for hepatitis C virus genotyping. Arch Virol 2016; 162:57-61. [PMID: 27664028 DOI: 10.1007/s00705-016-3059-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/09/2016] [Indexed: 01/25/2023]
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Narayanan S, Nieh AH, Kenwood BM, Davis CA, Tosello-Trampont AC, Elich TD, Breazeale SD, Ward E, Anderson RJ, Caldwell SH, Hoehn KL, Hahn YS. Distinct Roles for Intracellular and Extracellular Lipids in Hepatitis C Virus Infection. PLoS One 2016; 11:e0156996. [PMID: 27280294 PMCID: PMC4900644 DOI: 10.1371/journal.pone.0156996] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/23/2016] [Indexed: 12/20/2022] Open
Abstract
Hepatitis C is a chronic liver disease that contributes to progressive metabolic dysfunction. Infection of hepatocytes by hepatitis C virus (HCV) results in reprogramming of hepatic and serum lipids. However, the specific contribution of these distinct pools of lipids to HCV infection remains ill defined. In this study, we investigated the role of hepatic lipogenesis in HCV infection by targeting the rate-limiting step in this pathway, which is catalyzed by the acetyl-CoA carboxylase (ACC) enzymes. Using two structurally unrelated ACC inhibitors, we determined that blockade of lipogenesis resulted in reduced viral replication, assembly, and release. Supplementing exogenous lipids to cells treated with ACC inhibitors rescued HCV assembly with no effect on viral replication and release. Intriguingly, loss of viral RNA was not recapitulated at the protein level and addition of 2-bromopalmitate, a competitive inhibitor of protein palmitoylation, mirrored the effects of ACC inhibitors on reduced viral RNA without a concurrent loss in protein expression. These correlative results suggest that newly synthesized lipids may have a role in protein palmitoylation during HCV infection.
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Affiliation(s)
- Sowmya Narayanan
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, United States of America
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States of America
| | - Albert H. Nieh
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, United States of America
| | - Brandon M. Kenwood
- Department of Pharmacology, University of Virginia, Charlottesville, United States of America
| | - Christine A. Davis
- Department of Biology, University of Richmond, Richmond, United States of America
| | | | - Tedd D. Elich
- Cropsolution Inc., Morrisville, United States of America
| | | | - Eric Ward
- Cropsolution Inc., Morrisville, United States of America
| | | | - Stephen H. Caldwell
- Division of Gastroenterology and Hepatology, University of Virginia, Charlottesville, United States of America
| | - Kyle L. Hoehn
- Department of Pharmacology, University of Virginia, Charlottesville, United States of America
| | - Young S. Hahn
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, United States of America
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, United States of America
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