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Vaccinia virus entry is followed by core activation and proteasome-mediated release of the immunomodulatory effector VH1 from lateral bodies


Schmidt, Florian Ingo; Bleck, Christopher Karl Ernst; Reh, Lucia; Novy, Karel; Wollscheid, Bernd; Helenius, Ari; Stahlberg, Henning; Mercer, Jason (2013). Vaccinia virus entry is followed by core activation and proteasome-mediated release of the immunomodulatory effector VH1 from lateral bodies. Cell Reports, 4(3):464-476.

Abstract

Host cell entry of vaccinia virus, the prototypic poxvirus, involves a membrane fusion event delivering the viral core and two proteinaceous lateral bodies (LBs) into the cytosol. Uncoating of viral cores is poorly characterized, and the composition and function of LBs remains enigmatic. We found that cytosolic cores rapidly dissociated from LBs and expanded in volume, which coincided with reduction of disulfide-bonded core proteins. We identified the abundant phosphoprotein F17, the dual-specificity phosphatase VH1, and the oxidoreductase G4 as bona fide LB components. After reaching the cytosol, F17 was degraded in a proteasome-dependent manner. Proteasome activity, and presumably LB disassembly, was required for the immediate immunomodulatory activity of VH1: dephosphorylation of STAT1 to prevent interferon-γ-mediated antiviral responses. These results reveal a mechanism used by poxviruses to deliver viral enzymes to the host cell cytosol and are likely to facilitate the identification of additional LB-resident viral effectors.

Abstract

Host cell entry of vaccinia virus, the prototypic poxvirus, involves a membrane fusion event delivering the viral core and two proteinaceous lateral bodies (LBs) into the cytosol. Uncoating of viral cores is poorly characterized, and the composition and function of LBs remains enigmatic. We found that cytosolic cores rapidly dissociated from LBs and expanded in volume, which coincided with reduction of disulfide-bonded core proteins. We identified the abundant phosphoprotein F17, the dual-specificity phosphatase VH1, and the oxidoreductase G4 as bona fide LB components. After reaching the cytosol, F17 was degraded in a proteasome-dependent manner. Proteasome activity, and presumably LB disassembly, was required for the immediate immunomodulatory activity of VH1: dephosphorylation of STAT1 to prevent interferon-γ-mediated antiviral responses. These results reveal a mechanism used by poxviruses to deliver viral enzymes to the host cell cytosol and are likely to facilitate the identification of additional LB-resident viral effectors.

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Item Type:Journal Article, refereed, original work
Communities & Collections:Special Collections > SystemsX.ch
Special Collections > SystemsX.ch > Research, Technology and Development Projects > CINA
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:2013
Deposited On:24 Sep 2013 10:20
Last Modified:07 Dec 2017 22:38
Publisher:Cell Press (Elsevier)
ISSN:2211-1247
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.celrep.2013.06.028
PubMed ID:23891003

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