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J Gen Virol. 2016 Sep 16. doi: 10.1099/jgv.0.000604. [Epub ahead of print]
DISRUPTION OF SRC HOMOLOGY 3 BINDING MOTIF WITHIN NS1 PROTEIN OF INFLUENZA B VIRUS UNEXPECTEDLY ENHANCES VIRAL REPLICATION IN HUMAN CELLS.
Sadewasser A1, Saenger S2, Paki K3, Schwecke T4, Wolff T5.
Author information
Abstract
The influenza virus non-structural protein 1 (NS1) is a multifunctional virulence factor that plays a crucial role during infection by blocking the innate antiviral immune response of infected cells. In contrast to the well-studied NS1 protein of influenza A virus, knowledge about structure and functions of the influenza B virus homologue B/NS1, which shares less than 25% sequence identity, is still limited. Here, we report on a reverse genetic analysis to study the role of a highly conserved class II SH3 binding motif (SH3-BM) matching the consensus P-x-x-P-x-(K/R) that we identified at positions 122-127 of the B/NS1 protein. Surprisingly, glycine substitutions in the SH3-BM increased virus replication up to three orders of magnitude in human lung cells. Enhanced mutant virus propagation was accompanied by increased gene expression and apoptosis induction linking this motif to the control of programmed cell death. A mass spectrometry based interactome study revealed that the glycine substitutions facilitate binding of B/NS1 to heat shock protein 90-beta (HSP90β). Moreover, recruitment of the viral polymerase PB2 to the B/NS1-HSP90β complex was observed. Pharmacological inhibition of HSP90 reduced mutant virus propagation suggesting that the mutation-induced involvement of HSP90β enhanced viral replication. This study not only functionally characterizes a conserved motif within the B/NS1 protein, but also illustrates a rare example in which mutation of a highly conserved sequence within a viral protein does not result in high fitness costs, but rather increases viral replication via recruitment of a host factor.
PMID: 27654951 DOI: 10.1099/jgv.0.000604
[PubMed - as supplied by publisher]
DISRUPTION OF SRC HOMOLOGY 3 BINDING MOTIF WITHIN NS1 PROTEIN OF INFLUENZA B VIRUS UNEXPECTEDLY ENHANCES VIRAL REPLICATION IN HUMAN CELLS.
Sadewasser A1, Saenger S2, Paki K3, Schwecke T4, Wolff T5.
Author information
Abstract
The influenza virus non-structural protein 1 (NS1) is a multifunctional virulence factor that plays a crucial role during infection by blocking the innate antiviral immune response of infected cells. In contrast to the well-studied NS1 protein of influenza A virus, knowledge about structure and functions of the influenza B virus homologue B/NS1, which shares less than 25% sequence identity, is still limited. Here, we report on a reverse genetic analysis to study the role of a highly conserved class II SH3 binding motif (SH3-BM) matching the consensus P-x-x-P-x-(K/R) that we identified at positions 122-127 of the B/NS1 protein. Surprisingly, glycine substitutions in the SH3-BM increased virus replication up to three orders of magnitude in human lung cells. Enhanced mutant virus propagation was accompanied by increased gene expression and apoptosis induction linking this motif to the control of programmed cell death. A mass spectrometry based interactome study revealed that the glycine substitutions facilitate binding of B/NS1 to heat shock protein 90-beta (HSP90β). Moreover, recruitment of the viral polymerase PB2 to the B/NS1-HSP90β complex was observed. Pharmacological inhibition of HSP90 reduced mutant virus propagation suggesting that the mutation-induced involvement of HSP90β enhanced viral replication. This study not only functionally characterizes a conserved motif within the B/NS1 protein, but also illustrates a rare example in which mutation of a highly conserved sequence within a viral protein does not result in high fitness costs, but rather increases viral replication via recruitment of a host factor.
PMID: 27654951 DOI: 10.1099/jgv.0.000604
[PubMed - as supplied by publisher]