NS5A domain I antagonises PKR to facilitate the assembly of infectious hepatitis C virus particles. 2023

Shucheng Chen, and 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.

Hepatitis C virus NS5A is a multifunctional phosphoprotein comprised of three domains (DI, DII and DIII). DI and DII have been shown to function in genome replication, whereas DIII has a role in virus assembly. We previously demonstrated that DI in genotype 2a (JFH1) also plays a role in virus assembly, exemplified by the P145A mutant which blocked infectious virus production. Here we extend this analysis to identify two other conserved and surface exposed residues proximal to P145 (C142 and E191) that exhibited no defect in genome replication but impaired virus production. Further analysis revealed changes in the abundance of dsRNA, the size and distribution of lipid droplets (LD) and the co-localisation between NS5A and LDs in cells infected with these mutants, compared to wildtype. In parallel, to investigate the mechanism(s) underpinning this role of DI, we assessed the involvement of the interferon-induced double-stranded RNA-dependent protein kinase (PKR). In PKR-silenced cells, C142A and E191A exhibited levels of infectious virus production, LD size and co-localisation between NS5A and LD that were indistinguishable from wildtype. Co-immunoprecipitation and in vitro pulldown experiments confirmed that wildtype NS5A domain I (but not C142A or E191A) interacted with PKR. We further showed that the assembly phenotype of C142A and E191A was restored by ablation of interferon regulatory factor-1 (IRF1), a downstream effector of PKR. These data suggest a novel interaction between NS5A DI and PKR that functions to evade an antiviral pathway that blocks virus assembly through IRF1.

UI MeSH Term Description Entries
D006506 Hepatitis A INFLAMMATION of the LIVER in humans caused by a member of the HEPATOVIRUS genus, HUMAN HEPATITIS A VIRUS. It can be transmitted through fecal contamination of food or water. Hepatitis, Infectious,Infectious Hepatitis,Hepatitides, Infectious,Infectious Hepatitides
D006526 Hepatitis C INFLAMMATION of the LIVER in humans caused by HEPATITIS C VIRUS, a single-stranded RNA virus. Its incubation period is 30-90 days. Hepatitis C is transmitted primarily by contaminated blood parenterally and is often associated with transfusion and intravenous drug abuse. However, in a significant number of cases, the source of hepatitis C infection is unknown. Hepatitis, Viral, Non-A, Non-B, Parenterally-Transmitted,Parenterally-Transmitted Non-A, Non-B Hepatitis,PT-NANBH,Parenterally Transmitted Non A, Non B Hepatitis
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D014771 Virion The infective system of a virus, composed of the viral genome, a protein core, and a protein coat called a capsid, which may be naked or enclosed in a lipoprotein envelope called the peplos. Virus Particle,Viral Particle,Viral Particles,Particle, Viral,Particle, Virus,Particles, Viral,Particles, Virus,Virions,Virus Particles
D014779 Virus Replication The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle. Viral Replication,Replication, Viral,Replication, Virus,Replications, Viral,Replications, Virus,Viral Replications,Virus Replications
D016174 Hepacivirus A genus of FLAVIVIRIDAE causing parenterally-transmitted HEPATITIS C which is associated with transfusions and drug abuse. Hepatitis C virus is the type species. Hepatitis C virus,Hepatitis C-Like Viruses,Hepaciviruses,Hepatitis C Like Viruses,Hepatitis C viruses,Hepatitis C-Like Virus
D017361 Viral Nonstructural Proteins Proteins encoded by a VIRAL GENOME that are not structural components of VIRUS PARTICLES. Some of these proteins may play roles within the infected cell during VIRUS REPLICATION or act in regulation of virus replication or VIRUS ASSEMBLY. Nonstructural Proteins, Viral,NS Proteins, Viral,Viral NS Proteins,Viral Non-Structural Proteins,Viral Nonstructural Protein,Viral Nonstructural Proteins NS1,Viral Nonstructural Proteins NS2,Nonstructural Protein, Viral,Viral Non Structural Proteins
D019065 Virus Assembly The assembly of VIRAL STRUCTURAL PROTEINS and nucleic acid (VIRAL DNA or VIRAL RNA) to form a VIRUS PARTICLE. Viral Assembly,Assembly, Viral,Assembly, Virus

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