Britney Johnson, Jing Li, Jagat Adhikari, Megan R Edwards, Hao Zhang, Toni Schwarz, Daisy W Leung, Christopher F Basler, Michael L Gross, Gaya K Amarasinghe
Author Information
Britney Johnson: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA.
Jing Li: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
Jagat Adhikari: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
Megan R Edwards: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA; Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA.
Hao Zhang: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
Toni Schwarz: Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
Daisy W Leung: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA.
Christopher F Basler: Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
Michael L Gross: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA. Electronic address: mgross@wustl.edu.
Gaya K Amarasinghe: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA. Electronic address: gamarasinghe@path.wustl.edu.
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.
