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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.. 2016. "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 = 2016,
month = 8
}
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  • Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/foundermore » (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of T cell responses to conserved viral epitopes.« less