scholarly journals A Second RNA-Binding Site in the NS1 Protein of Influenza B Virus

Structure ◽  
2016 ◽  
Vol 24 (9) ◽  
pp. 1562-1572 ◽  
Author(s):  
Li-Chung Ma ◽  
Rongjin Guan ◽  
Keith Hamilton ◽  
James M. Aramini ◽  
Lei Mao ◽  
...  
Keyword(s):  
Binding Site ◽  
Rna Binding ◽  
Influenza B Virus ◽  
Influenza B ◽  
Ns1 Protein ◽  
B Virus

scholarly journals Robust Lys63-Linked Ubiquitination of RIG-I Promotes Cytokine Eruption in Early Influenza B Virus Infection

2016 ◽  
Vol 90 (14) ◽  
pp. 6263-6275 ◽  
Author(s):  
Jingwen Jiang ◽  
Jing Li ◽  
Wenhui Fan ◽  
Weinan Zheng ◽  
Meng Yu ◽  
...  
Keyword(s):  
Virus Infection ◽  
Influenza A Virus ◽  
Influenza A ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Influenza B Virus ◽  
Influenza B ◽  
Type I ◽  
Ns1 Protein ◽  
B Virus

ABSTRACTInfluenza A and B virus infections both cause a host innate immunity response. Here, we report that the robust production of type I and III interferons (IFNs), IFN-stimulated genes, and proinflammatory factors can be induced by influenza B virus rather than influenza A virus infection in alveolar epithelial (A549) cells during early infection. This response is mainly dependent on the retinoic acid-inducible gene I (RIG-I)-mediated signaling pathway. Infection by influenza B virus promotes intense Lys63-linked ubiquitination of RIG-I, resulting in cytokine eruption. It is known that the influenza A virus NS1 protein (NS1-A) interacts with RIG-I and TRIM25 to suppress the activation of RIG-I-mediated signaling. However, the present results indicate that the influenza B virus NS1 protein (NS1-B) is unable to interact with RIG-I but engages in the formation of a RIG-I/TRIM25/NS1-B ternary complex. Furthermore, we demonstrate that the N-terminal RNA-binding domain (RBD) of NS1-B is responsible for interaction with TRIM25 and that this interaction blocks the inhibitory effect of the NS1-B C-terminal effector domain (TED) on RIG-I ubiquitination. Our findings reveal a novel mechanism for the host cytokine response to influenza B virus infection through regulatory interplay between host and viral proteins.IMPORTANCEInfluenza B virus generally causes local mild epidemics but is occasionally lethal to individuals. Existing studies describe the broad characteristics of influenza B virus epidemiology and pathology. However, to develop better prevention and treatments for the disease, determining the concrete molecular mechanisms of pathogenesis becomes pivotal to understand how the host reacts to the challenge of influenza B virus. Thus, we aimed to characterize the host innate immune response to influenza B virus infection. Here, we show that vigorous Lys63-linked ubiquitination of RIG-I and cytokine eruption dependent on RIG-I-mediated signal transduction are induced by virus infection. Additionally, TRIM25 positively regulates RIG-I-mediated signaling by ablating the inhibitory function of NS1-B on RIG-I ubiquitination.

scholarly journals The N- and C-Terminal Domains of the NS1 Protein of Influenza B Virus Can Independently Inhibit IRF-3 and Beta Interferon Promoter Activation

2004 ◽  
Vol 78 (21) ◽  
pp. 11574-11582 ◽  
Author(s):  
Nicola R. Donelan ◽  
Bianca Dauber ◽  
Xiuyan Wang ◽  
Christopher F. Basler ◽  
Thorsten Wolff ◽  
...  
Keyword(s):  
Amino Acids ◽  
Influenza A ◽  
Rna Binding ◽  
Nuclear Translocation ◽  
Influenza B Virus ◽  
Influenza B ◽  
Ns1 Protein ◽  
Promoter Activation ◽  
Beta Interferon ◽  
B Virus

ABSTRACT The NS1 proteins of influenza A and B viruses (A/NS1 and B/NS1 proteins) have only ∼20% amino acid sequence identity. Nevertheless, these proteins show several functional similarities, such as their ability to bind to the same RNA targets and to inhibit the activation of protein kinase R in vitro. A critical function of the A/NS1 protein is the inhibition of synthesis of alpha/beta interferon (IFN-α/β) during viral infection. Recently, it was also found that the B/NS1 protein inhibits IFN-α/β synthesis in virus-infected cells. We have now found that the expression of the B/NS1 protein complements the growth of an influenza A virus with A/NS1 deleted. Expression of the full-length B/NS1 protein (281 amino acids), as well as either its N-terminal RNA-binding domain (amino acids 1 to 93) or C-terminal domain (amino acids 94 to 281), in the absence of any other influenza B virus proteins resulted in the inhibition of IRF-3 nuclear translocation and IFN-β promoter activation. A mutational analysis of the truncated B/NS1(1-93) protein showed that RNA-binding activity correlated with IFN-β promoter inhibition. In addition, a recombinant influenza B virus with NS1 deleted induces higher levels of IRF-3 activation, as determined by its nuclear translocation, and of IFN-α/β synthesis than wild-type influenza B virus. Our results support the hypothesis that the NS1 protein of influenza B virus plays an important role in antagonizing the IRF-3- and IFN-induced antiviral host responses to virus infection.

scholarly journals Analysis of Influenza B Virus NS1 Protein Trafficking Reveals a Novel Interaction with Nuclear Speckle Domains

2008 ◽  
Vol 83 (2) ◽  
pp. 701-711 ◽  
Author(s):  
Jana Schneider ◽  
Bianca Dauber ◽  
Krister Melén ◽  
Ilkka Julkunen ◽  
Thorsten Wolff
Keyword(s):  
Gene Expression ◽  
Protein Domain ◽  
Replication Capacity ◽  
Influenza B Virus ◽  
Viral Gene ◽  
Influenza B ◽  
Ns1 Protein ◽  
Nuclear Speckles ◽  
Nuclear Speckle ◽  
B Virus

ABSTRACT Many proteins that function in the transcription, maturation, and export of metazoan mRNAs are concentrated in nuclear speckle domains, indicating that the compartment is important for gene expression. Here, we show that the NS1 protein of influenza B virus (B/NS1) accumulates in nuclear speckles and causes rounding and morphological changes of the domains, indicating a disturbance in their normal functions. This property was located within the N-terminal 90 amino acids of the B/NS1 protein and was shown to be independent of any other viral gene product. Within this protein domain, we identified a monopartite importin α binding nuclear localization signal. Reverse-genetic analysis of this motif indicated that nuclear import and speckle association of the B/NS1 protein are required for the full replication capacity of the virus. In the late phase of virus infection, the B/NS1 protein relocated to the cytoplasm, which occurred in a CRM1-independent manner. The interaction of the B/NS1 protein with nuclear speckles may reflect a recruitment function to promote viral-gene expression. To our knowledge, this is the first functional description of a speckle-associated protein that is encoded by a negative-strand RNA virus.

scholarly journals Molecular and biochemical characterization of the NS1 protein of non-cultured influenza B virus strains circulating in Singapore

2016 ◽  
Vol 2 (8) ◽  
Author(s):  
Muhammad Raihan Jumat ◽  
Puisan Wong ◽  
Raphael Tze Chuen Lee ◽  
Sebastian Maurer-Stroh ◽  
Boon Huan Tan ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Influenza B Virus ◽  
Influenza B ◽  
Ns1 Protein ◽  
B Virus ◽  
Virus Strains

scholarly journals The Influenza B Virus Nonstructural NS1 Protein Is Essential for Efficient Viral Growth and Antagonizes Beta Interferon Induction

2004 ◽  
Vol 78 (4) ◽  
pp. 1865-1872 ◽  
Author(s):  
Bianca Dauber ◽  
Gudrun Heins ◽  
Thorsten Wolff
Keyword(s):  
Mutant Virus ◽  
Lung Epithelial Cells ◽  
Influenza B Virus ◽  
Influenza B ◽  
Ns1 Protein ◽  
Viral Propagation ◽  
Culture Cells ◽  
B Virus ◽  
Protein Functions ◽  
Knockout Virus

ABSTRACT We analyzed the functions of the influenza B virus nonstructural NS1-B protein, both by utilizing a constructed mutant virus (ΔNS1-B) lacking the NS1 gene and by testing the activities of the protein when expressed in cells. The mutant virus replicated to intermediate levels in 6-day-old embryonated chicken eggs that contain an immature interferon (IFN) system, whereas older eggs did not support viral propagation to a significant extent. The ΔNS1-B virus was a substantially stronger inducer of beta IFN (IFN-β) transcripts in human lung epithelial cells than the wild type, and furthermore, transiently expressed NS1-B protein efficiently inhibited virus-dependent activation of the IFN-β promoter. Interestingly, replication of the ΔNS1-B knockout virus was attenuated by more than 4 orders of magnitude in tissue culture cells containing or lacking functional IFN-α/β genes. These findings show that the NS1-B protein functions as a viral IFN antagonist and indicate a further requirement of this protein for efficient viral replication that is unrelated to blocking IFN effects.

scholarly journals Species-Specific Antagonism of Host ISGylation by the Influenza B Virus NS1 Protein

2010 ◽  
Vol 84 (10) ◽  
pp. 5423-5430 ◽  
Author(s):  
Gijs A. Versteeg ◽  
Benjamin G. Hale ◽  
Sander van Boheemen ◽  
Thorsten Wolff ◽  
Deborah J. Lenschow ◽  
...  
Keyword(s):  
E3 Ligase ◽  
Influenza B Virus ◽  
Influenza B ◽  
Ns1 Protein ◽  
Expression Systems ◽  
B Virus ◽  
Bona Fide ◽  
Species Specific ◽  
Necessary And Sufficient ◽  
Human And Mouse

ABSTRACT Interferon-stimulated expression and conjugation of the ubiquitin-like modifier ISG15 restricts replication of several viruses. Here, we established complete E1-activating, E2-conjugating, and E3 ligase-dependent expression systems for assaying both human and mouse ISGylation. We confirm that human HerC5, but not human HerC6, has ISG15 E3 ligase activity and identify mouse HerC6 as a bona fide ISG15 E3 ligase. Furthermore, we demonstrate that influenza B virus NS1 protein potently antagonizes human but not mouse ISGylation, a property dependent on B/NS1 binding the N-terminal domain of human but not mouse ISG15. Using chimeric human/mouse ISG15 constructs, we show that the B/NS1:ISG15 interaction is both necessary and sufficient to inhibit ISGylation regardless of the ligation machinery used. Inability to block ISGylation in certain species may contribute to limiting influenza B virus host range.

scholarly journals The CPSF30 Binding Site on the NS1A Protein of Influenza A Virus Is a Potential Antiviral Target

2006 ◽  
Vol 80 (8) ◽  
pp. 3957-3965 ◽  
Author(s):  
Karen Y. Twu ◽  
Diana L. Noah ◽  
Ping Rao ◽  
Rei-Lin Kuo ◽  
Robert M. Krug
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Influenza B Virus ◽  
Influenza B ◽  
Influenza A Viruses ◽  
B Virus ◽  
Ns1a Protein

ABSTRACT The emergence of influenza A viruses resistant to the two existing classes of antiviral drugs highlights the need for additional antiviral drugs, particularly considering the potential threat of a pandemic of H5N1 influenza A viruses. Here, we determine whether influenza A virus replication can be selectively inhibited by blocking the ability of its NS1A protein to inhibit the 3′-end processing of cellular pre-mRNAs, including beta interferon (IFN-β) pre-mRNA. Pre-mRNA processing is inhibited via the binding of the NS1A protein to the cellular CPSF30 protein, and mutational inactivation of this NS1A binding site causes severe attenuation of the virus. We demonstrate that binding of CPSF30 is mediated by two of its zinc fingers, F2F3, and that the CPSF30/F2F3 binding site on the NS1A protein extends from amino acid 144 to amino acid 186. We generated MDCK cells that constitutively express epitope-tagged F2F3 in the nucleus, although at only approximately one-eighth the level of the NS1A protein produced during virus infection. Influenza A virus replication was inhibited in this cell line, whereas no inhibition was observed with influenza B virus, whose NS1B protein lacks a binding site for CPSF30. Influenza A virus, but not influenza B virus, induced increased production of IFN-β mRNA in the F2F3-expressing cells. These results, which indicate that F2F3 inhibits influenza A virus replication by blocking the binding of endogenous CPSF30 to the NS1A protein, point to this NS1A binding site as a potential target for the development of antivirals directed against influenza A virus.

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