Characterization and modification of the carboxy-terminal sequences of bluetongue virus type 10 NS1 protein in relation to tubule formation and location of an antigenic epitope in the vicinity of the carboxy terminus of the protein

Monastyrskaya, Katia; Gould, Ernest A.; Roy, Polly

doi:10.1128/jvi.69.5.2831-2841.1995

Cited by 18 publications

(8 citation statements)

References 26 publications

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“…This ability to form tubules of variable helical forms and diameter suggests that tubule formation is a robust process capable of initiating in various configurations. The helical reconstruction shows that the immunogenic carboxyl terminus is located along the tubule surface, consistent with several previous studies, which indicated to this localization 12 , 15 . The location of the carboxyl terminus rationalizes the ability of NS1 tubules to serve as effective immunogen delivery vehicles, capable of carrying large peptides without disrupting the tubular structure 15 – 17 .…”

Section: Discussionsupporting

confidence: 91%

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Atomic structure of the translation regulatory protein NS1 of bluetongue virus

Kerviel

Lai

et al. 2019

Nat Microbiol

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Bluetongue virus (BTV) non-structural protein 1 (NS1) regulates viral protein synthesis and exists as tubular and non-tubular forms in infected cells but how tubules assemble and how protein synthesis is regulated are unknown. Here, we report near-atomic resolution structures of two NS1 tubular forms determined by cryo-electron microscopy. The two tubular forms are different helical assemblies of the same NS1 monomer, consisting of an N-terminal foot-, a head-and body domains connected to an extended C-terminal arm, which wraps atop the head domain of another NS1 subunit through hydrophobic interactions. Deletion of the C-terminus prevents tubule formation but not viral replication, suggesting an active non-tubular form. Two zinc finger-like motifs are present in each NS1 monomer and tubules are disrupted by divalent cation chelation and restored by cation addition, including Zn 2+ , suggesting a regulatory role of divalent cations in tubule formation. In vitro luciferase assays show that the NS1 non-tubular form upregulates BTV mRNA translation, while zinc-finger disruption decreases viral mRNA translation, tubule formation and virus replication, confirming a functional role. Thus, the non-tubular form of NS1 is sufficient for viral protein synthesis and infectious virus replication and the regulatory mechanism involved operates through divalent cation-dependent conversion between the non-tubular and tubular forms. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

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Section: Discussionsupporting

confidence: 91%

“…Previous biochemical studies 12 have shown that the C-terminal 10 amino acids are essential for tubule formation, suggesting that the C-terminal helix is involved in tubule formation. To investigate this, two C-terminal deletion mutants, Δ20 (Δ532–552) and Δ30 (Δ522–552) were generated using NS1-encoding gene S5 ( Fig.…”

Section: Resultsmentioning

confidence: 93%

Atomic structure of the translation regulatory protein NS1 of bluetongue virus

Kerviel

Lai

et al. 2019

Nat Microbiol

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“…The BTV nonstructural proteins play fundamental roles in virus replication. NS1 forms tubules in the cytoplasm of BTV-infected cells and favors viral protein synthesis ( 20 – 22 ). NS2 is the major component of viral inclusion bodies ( 23 – 25 ), while NS3/NS3A play a critical role in virus intracellular trafficking and egress ( 26 , 27 ).…”

Section: Introductionmentioning

confidence: 99%

Bluetongue Virus NS4 Protein Is an Interferon Antagonist and a Determinant of Virus Virulence

Ratinier

Shaw

Barry

et al. 2016

J Virol

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Bluetongue virus (BTV) is the causative agent of bluetongue, a major infectious disease of ruminants with serious consequences to both animal health and the economy. The clinical outcome of BTV infection is highly variable and dependent on a variety of factors related to both the virus and the host. In this study, we show that the BTV nonstructural protein NS4 favors viral replication in sheep, the animal species most affected by bluetongue. In addition, NS4 confers a replication advantage on the virus in interferon (IFN)-competent primary sheep endothelial cells and immortalized cell lines. We determined that in cells infected with an NS4 deletion mutant (BTV8ΔNS4), there is increased synthesis of type I IFN compared to cells infected with wild-type BTV-8. In addition, using RNA sequencing (RNA-seq), we show that NS4 modulates the host IFN response and downregulates mRNA levels of type I IFN and interferon-stimulated genes. Moreover, using reporter assays and protein synthesis assays, we show that NS4 downregulates the activities of a variety of promoters, such as the cytomegalovirus immediate-early promoter, the IFN-β promoter, and a promoter containing interferon-stimulated response elements (ISRE). We also show that the NS4 inhibitory activity on gene expression is related to its nucleolar localization. Furthermore, NS4 does not affect mRNA splicing or cellular translation. The data obtained in this study strongly suggest that BTV NS4 is an IFN antagonist and a key determinant of viral virulence. IMPORTANCE Bluetongue is one of the main infectious diseases of ruminants and is caused by bluetongue virus (BTV), an arthropod-borne virus transmitted from infected to susceptible animals by Culicoides biting midges. Bluetongue has a variable clinical outcome that can be related to both virus and host factors. It is therefore critical to understand the interplay between BTV and the host immune responses. In this study, we show that a nonstructural protein of BTV (NS4) is critical to counteract the innate immune response of the host. Infection of cells with a BTV mutant lacking NS4 results in increased synthesis of IFN-β and upregulation of interferon-stimulated genes. In addition, we show that NS4 is a virulence factor for BTV by favoring viral replication in sheep, the animal species most susceptible to bluetongue.

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“…NS1 enhances viral protein synthesis and forms tubules in the cytoplasm of infected cells ( Boyce et al , 2012 ; Monastyrskaya et al , 1995 ; Owens et al , 2004 ). NS2 is the major component of viral inclusion bodies that are readily observed in BTV-infected cells ( Butan & Tucker, 2010 ; Kar et al , 2007 ; Lymperopoulos et al , 2006 ).…”

Section: Introductionmentioning

confidence: 99%

Characterization of a second open reading frame in genome segment 10 of bluetongue virus

Stewart

Hardy

Barry

et al. 2015

Journal of General Virology

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Viruses have often evolved overlapping reading frames in order to maximize their coding capacity. Until recently, the segmented dsRNA genome of viruses of the Orbivirus genus was thought to be monocistronic, but the identification of the bluetongue virus (BTV) NS4 protein changed this assumption. A small ORF in segment 10, overlapping the NS3 ORF in the +1 position, is maintained in more than 300 strains of the 27 different BTV serotypes and in more than 200 strains of the phylogenetically related African horse sickness virus (AHSV). In BTV, this ORF (named S10-ORF2 in this study) encodes a putative protein 50–59 residues in length and appears to be under strong positive selection. HA- or GFP-tagged versions of S10-ORF2 expressed from transfected plasmids localized within the nucleoli of transfected cells, unless a putative nucleolar localization signal was mutated. S10-ORF2 inhibited gene expression, but not RNA translation, in transient transfection reporter assays. In both mammalian and insect cells, BTV S10-ORF2 deletion mutants (BTV8ΔS10-ORF2) displayed similar replication kinetics to wt virus. In vivo, S10-ORF2 deletion mutants were pathogenic in mouse models of disease. Although further evidence is required for S10-ORF2 expression during infection, the data presented provide an initial characterization of this ORF.

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Characterization and modification of the carboxy-terminal sequences of bluetongue virus type 10 NS1 protein in relation to tubule formation and location of an antigenic epitope in the vicinity of the carboxy terminus of the protein

Cited by 18 publications

References 26 publications

Atomic structure of the translation regulatory protein NS1 of bluetongue virus

Atomic structure of the translation regulatory protein NS1 of bluetongue virus

Bluetongue Virus NS4 Protein Is an Interferon Antagonist and a Determinant of Virus Virulence

Characterization of a second open reading frame in genome segment 10 of bluetongue virus

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