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Title: Dimerization Controls Marburg Virus VP24-dependent Modulation of Host Antioxidative Stress Responses

Abstract

Marburg virus (MARV), a member of the Filoviridae family that also includes Ebola virus (EBOV), causes lethal hemorrhagic fever with case fatality rates that have exceeded 50% in some outbreaks. Within an infected cell, there are numerous host-viral interactions that contribute to the outcome of infection. Recent studies identified MARV protein 24 (mVP24) as a modulator of the host antioxidative responses, but the molecular mechanism remains unclear. Using a combination of biochemical and mass spectrometry studies, we show that mVP24 is a dimer in solution that directly binds to the Kelch domain of Kelch-like ECH-associated protein 1 (Keap1) to regulate nuclear factor (erythroid-derived 2)-like 2 (Nrf2). This interaction between Keap1 and mVP24 occurs through the Kelch interaction loop (K-Loop) of mVP24 leading to upregulation of antioxidant response element transcription, which is distinct from other Kelch binders that regulate Nrf2 activity. N-terminal truncations disrupt mVP24 dimerization, allowing monomeric mVP24 to bind Kelch with higher affinity and stimulate higher antioxidative stress response element (ARE) reporter activity. Mass spectrometry-based mapping of the interface revealed overlapping binding sites on Kelch for mVP24 and the Nrf2 proteins. Substitution of conserved cysteines, C209 and C210, to alanine in the mVP24 K-Loop abrogates Kelch binding and AREmore » activation. Our studies identify a shift in the monomer-dimer equilibrium of MARV VP24, driven by its interaction with Keap1 Kelch domain, as a critical determinant that modulates host responses to pathogenic Marburg viral infections.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
National Institutes of Health (NIH)
OSTI Identifier:
1351397
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Molecular Biology; Journal Volume: 428; Journal Issue: 17
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES

Citation Formats

Johnson, Britney, Li, Jing, Adhikari, Jagat, Edwards, Megan R., Zhang, Hao, Schwarz, Toni, Leung, Daisy W., Basler, Christopher F., Gross, Michael L., and Amarasinghe, Gaya K. Dimerization Controls Marburg Virus VP24-dependent Modulation of Host Antioxidative Stress Responses. United States: N. p., 2016. Web. doi:10.1016/j.jmb.2016.07.020.
Johnson, Britney, Li, Jing, Adhikari, Jagat, Edwards, Megan R., Zhang, Hao, Schwarz, Toni, Leung, Daisy W., Basler, Christopher F., Gross, Michael L., & Amarasinghe, Gaya K. Dimerization Controls Marburg Virus VP24-dependent Modulation of Host Antioxidative Stress Responses. United States. doi:10.1016/j.jmb.2016.07.020.
Johnson, Britney, Li, Jing, Adhikari, Jagat, Edwards, Megan R., Zhang, Hao, Schwarz, Toni, Leung, Daisy W., Basler, Christopher F., Gross, Michael L., and Amarasinghe, Gaya K. Thu . "Dimerization Controls Marburg Virus VP24-dependent Modulation of Host Antioxidative Stress Responses". United States. doi:10.1016/j.jmb.2016.07.020.
@article{osti_1351397,
title = {Dimerization Controls Marburg Virus VP24-dependent Modulation of Host Antioxidative Stress Responses},
author = {Johnson, Britney and Li, Jing and Adhikari, Jagat and Edwards, Megan R. and Zhang, Hao and Schwarz, Toni and Leung, Daisy W. and Basler, Christopher F. and Gross, Michael L. and Amarasinghe, Gaya K.},
abstractNote = {Marburg virus (MARV), a member of the Filoviridae family that also includes Ebola virus (EBOV), causes lethal hemorrhagic fever with case fatality rates that have exceeded 50% in some outbreaks. Within an infected cell, there are numerous host-viral interactions that contribute to the outcome of infection. Recent studies identified MARV protein 24 (mVP24) as a modulator of the host antioxidative responses, but the molecular mechanism remains unclear. Using a combination of biochemical and mass spectrometry studies, we show that mVP24 is a dimer in solution that directly binds to the Kelch domain of Kelch-like ECH-associated protein 1 (Keap1) to regulate nuclear factor (erythroid-derived 2)-like 2 (Nrf2). This interaction between Keap1 and mVP24 occurs through the Kelch interaction loop (K-Loop) of mVP24 leading to upregulation of antioxidant response element transcription, which is distinct from other Kelch binders that regulate Nrf2 activity. N-terminal truncations disrupt mVP24 dimerization, allowing monomeric mVP24 to bind Kelch with higher affinity and stimulate higher antioxidative stress response element (ARE) reporter activity. Mass spectrometry-based mapping of the interface revealed overlapping binding sites on Kelch for mVP24 and the Nrf2 proteins. Substitution of conserved cysteines, C209 and C210, to alanine in the mVP24 K-Loop abrogates Kelch binding and ARE activation. Our studies identify a shift in the monomer-dimer equilibrium of MARV VP24, driven by its interaction with Keap1 Kelch domain, as a critical determinant that modulates host responses to pathogenic Marburg viral infections.},
doi = {10.1016/j.jmb.2016.07.020},
journal = {Journal of Molecular Biology},
number = 17,
volume = 428,
place = {United States},
year = {Thu Aug 04 00:00:00 EDT 2016},
month = {Thu Aug 04 00:00:00 EDT 2016}
}
  • Suppression of innate immune responses during filoviral infection contributes to disease severity. Ebola (EBOV) and Marburg (MARV) viruses each encode a VP35 protein that suppresses RIG-I-like receptor signaling and interferon-α/β (IFN-α/β) production by several mechanisms, including direct binding to double stranded RNA (dsRNA). Here, we demonstrate that in cell culture, MARV infection results in a greater upregulation of IFN responses as compared to EBOV infection. This correlates with differences in the efficiencies by which EBOV and MARV VP35s antagonize RIG-I signaling. Furthermore, structural and biochemical studies suggest that differential recognition of RNA elements by the respective VP35 C-terminal IFN inhibitorymore » domain (IID) rather than affinity for RNA by the respective VP35s is critical for this observation. Our studies reveal functional differences in EBOV versus MARV VP35 RNA binding that result in unexpected differences in the host response to deadly viral pathogens.« less
  • The aim of the present study was to investigate the effects of an enhanced CO{sub 2} concentration alone or in combination with drought stress on antioxidative systems of a deciduous (oak; Quercus robur) and an evergreen (pine; Pinus pinaster) tree species. The seedlings were grown for one season in a greenhouse in tunnels supplied with 350 or 700 {mu}L L{sup {minus}1} CO{sub 2}. The experiment was repeated in a second year. Antioxidants, protective enzymes, soluble protein, and pigments showed considerable fluctuations in different years. Elevated CO{sub 2}, caused significant reductions in the activities of superoxide dismutases in both oak andmore » pine. The activities of ascorbate peroxidase and catalase were also reduced in most cases. The activities of dehydroascorbate reductase, monodehydroascorbate radical reductase, glutathione reductase, and guaiacol peroxidase were affected little or not at all by elevated CO{sub 2}. When the trees were subjected in drought stress by withholding water, the activities of antioxidative enzymes decreased in leaves of pine and oak grown at ambient CO{sub 2} and increased in plants grown at elevated CO{sub 2} concentrations. The present results suggest that growth in elevated CO{sub 2} might reduce oxidative stress to which leaf tissues are normally exposed and enhance metabolic flexibility to encounter increased stress by increases in antioxidative capacity. 48 refs., 2 figs., 4 tabs.« less
  • Ebola viruses and Marburg viruses, members of the filovirus family, are zoonotic pathogens that cause severe disease in people, as highlighted by the latest Ebola virus epidemic in West Africa. Filovirus disease is characterized by uncontrolled virus replication and the activation of host responses that contribute to pathogenesis. Underlying these phenomena is the potent suppression of host innate antiviral responses, particularly the type I interferon response, by viral proteins, which allows high levels of viral replication. In this Review, we describe the mechanisms used by filoviruses to block host innate immunity and discuss the links between immune evasion and filovirusmore » pathogenesis.« less