Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP

ABSTRACT   NF-κB plays a critical role in the induction and maintenance of innate and adaptive immune transcriptional programs. An associated inhibitor of κB protein (IκB) regulates NF-κB activation and contains a degron motif (DSGΦxS) that undergoes phosphorylation following pathogen recognition or...

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Autores principales: Marco Morelli, Allison F. Dennis, John T. Patton
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Publicado: American Society for Microbiology 2015
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spelling oai:doaj.org-article:4b88cd1bab5144a2ae6cd96cc7cccc8d2021-11-15T15:41:19ZPutative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP10.1128/mBio.02490-142150-7511https://doaj.org/article/4b88cd1bab5144a2ae6cd96cc7cccc8d2015-02-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02490-14https://doaj.org/toc/2150-7511ABSTRACT   NF-κB plays a critical role in the induction and maintenance of innate and adaptive immune transcriptional programs. An associated inhibitor of κB protein (IκB) regulates NF-κB activation and contains a degron motif (DSGΦxS) that undergoes phosphorylation following pathogen recognition or other proinflammatory signals. The E3 ubiquitin ligase SCFβ-TrCP recognizes this phosphodegron through its β-transducin repeat-containing protein (β-TrCP) subunit and induces IκB degradation, allowing NF-κB to translocate to the nucleus and modulate gene expression. Rotavirus (RV), a major cause of pediatric gastroenteritis, can block NF-κB activation through the action of its nonstructural protein NSP1, a putative E3 ubiquitin ligase that mediates the degradation of β-TrCP or other immunomodulatory proteins in a virus strain-specific manner. Here, we show that NSP1 targets β-TrCP by mimicking the IκB phosphodegron. The NSP1 proteins of most human and porcine RV strains conserve a C-terminal phosphodegron-like (PDL) motif, DSGΦS. Deletion of this motif or mutation of its serine residues disrupts NSP1-mediated degradation of β-TrCP and inhibition of NF-κB activation. Additionally, a point mutation within the phosphodegron-binding pocket protects β-TrCP from NSP1-mediated turnover. Fusion of the PDL motif to an NSP1 protein known to target other immunomodulatory proteins generates a chimeric NSP1 protein that can induce β-TrCP degradation and block NF-κB activation. Other viral proteins (Epstein-Barr virus LMP1, HIV-1 Vpu, and vaccinia virus A49) also contain a PDL motif and interact with β-TrCP to inhibit NF-κB activation. Taken together, these data suggest that targeting β-TrCP by molecular mimicry may be a common strategy used by human viruses to evade the host immune response. IMPORTANCE   The transcription factor NF-κB, a central regulator of the host response to infection, is a frequent target of viral antagonism. Pathogen detection activates NF-κB by inducing the phosphorylation of an associated inhibitor protein (IκB), which targets IκB for degradation by the E3 ubiquitin ligase β-TrCP. Rotavirus, a significant cause of childhood gastroenteritis, antagonizes NF-κB through the activity of its NSP1 protein, a putative E3 ubiquitin ligase that mediates β-TrCP turnover. Here, we show that NSP1 functions by mimicking the IκB phosphodegron recognized by β-TrCP. Nearly all human rotavirus strains conserve this motif at the NSP1 C terminus, and its removal disrupts NSP1 antagonist activity. This sequence conserves the biochemical properties of the IκB phosphodegron and can rescue antagonist activity when fused to an NSP1 protein otherwise inactive against β-TrCP. Other viral proteins also mimic IκB to disrupt NF-κB activation, indicating that this is an important immune evasion strategy.Marco MorelliAllison F. DennisJohn T. PattonAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 6, Iss 1 (2015)
institution DOAJ
collection DOAJ
language EN
topic Microbiology
QR1-502
spellingShingle Microbiology
QR1-502
Marco Morelli
Allison F. Dennis
John T. Patton
Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
description ABSTRACT   NF-κB plays a critical role in the induction and maintenance of innate and adaptive immune transcriptional programs. An associated inhibitor of κB protein (IκB) regulates NF-κB activation and contains a degron motif (DSGΦxS) that undergoes phosphorylation following pathogen recognition or other proinflammatory signals. The E3 ubiquitin ligase SCFβ-TrCP recognizes this phosphodegron through its β-transducin repeat-containing protein (β-TrCP) subunit and induces IκB degradation, allowing NF-κB to translocate to the nucleus and modulate gene expression. Rotavirus (RV), a major cause of pediatric gastroenteritis, can block NF-κB activation through the action of its nonstructural protein NSP1, a putative E3 ubiquitin ligase that mediates the degradation of β-TrCP or other immunomodulatory proteins in a virus strain-specific manner. Here, we show that NSP1 targets β-TrCP by mimicking the IκB phosphodegron. The NSP1 proteins of most human and porcine RV strains conserve a C-terminal phosphodegron-like (PDL) motif, DSGΦS. Deletion of this motif or mutation of its serine residues disrupts NSP1-mediated degradation of β-TrCP and inhibition of NF-κB activation. Additionally, a point mutation within the phosphodegron-binding pocket protects β-TrCP from NSP1-mediated turnover. Fusion of the PDL motif to an NSP1 protein known to target other immunomodulatory proteins generates a chimeric NSP1 protein that can induce β-TrCP degradation and block NF-κB activation. Other viral proteins (Epstein-Barr virus LMP1, HIV-1 Vpu, and vaccinia virus A49) also contain a PDL motif and interact with β-TrCP to inhibit NF-κB activation. Taken together, these data suggest that targeting β-TrCP by molecular mimicry may be a common strategy used by human viruses to evade the host immune response. IMPORTANCE   The transcription factor NF-κB, a central regulator of the host response to infection, is a frequent target of viral antagonism. Pathogen detection activates NF-κB by inducing the phosphorylation of an associated inhibitor protein (IκB), which targets IκB for degradation by the E3 ubiquitin ligase β-TrCP. Rotavirus, a significant cause of childhood gastroenteritis, antagonizes NF-κB through the activity of its NSP1 protein, a putative E3 ubiquitin ligase that mediates β-TrCP turnover. Here, we show that NSP1 functions by mimicking the IκB phosphodegron recognized by β-TrCP. Nearly all human rotavirus strains conserve this motif at the NSP1 C terminus, and its removal disrupts NSP1 antagonist activity. This sequence conserves the biochemical properties of the IκB phosphodegron and can rescue antagonist activity when fused to an NSP1 protein otherwise inactive against β-TrCP. Other viral proteins also mimic IκB to disrupt NF-κB activation, indicating that this is an important immune evasion strategy.
format article
author Marco Morelli
Allison F. Dennis
John T. Patton
author_facet Marco Morelli
Allison F. Dennis
John T. Patton
author_sort Marco Morelli
title Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
title_short Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
title_full Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
title_fullStr Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
title_full_unstemmed Putative E3 Ubiquitin Ligase of Human Rotavirus Inhibits NF-κB Activation by Using Molecular Mimicry To Target β-TrCP
title_sort putative e3 ubiquitin ligase of human rotavirus inhibits nf-κb activation by using molecular mimicry to target β-trcp
publisher American Society for Microbiology
publishDate 2015
url https://doaj.org/article/4b88cd1bab5144a2ae6cd96cc7cccc8d
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AT johntpatton putativee3ubiquitinligaseofhumanrotavirusinhibitsnfkbactivationbyusingmolecularmimicrytotargetbtrcp
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