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 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.
authors: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA.
authors: Britney
authors: B
authors: Johnson
authors: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
authors: Jing
authors: J
authors: Li
authors: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
authors: Jagat
authors: J
authors: Adhikari
authors: 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.
authors: Megan R
authors: MR
authors: Edwards
authors: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA.
authors: Hao
authors: H
authors: Zhang
authors: Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
authors: Toni
authors: T
authors: Schwarz
authors: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA.
authors: Daisy W
authors: DW
authors: Leung
authors: 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.
authors: Christopher F
authors: CF
authors: Basler
authors: Department of Chemistry, Box 1134, Washington University, One Brookings Drive, St. Louis, Mo, 63130, USA. Electronic address: mgross@wustl.edu.
authors: Michael L
authors: ML
authors: Gross
authors: Department of Pathology and Immunology, Washington University School of Medicine in St Louis, St Louis, MO 63110, USA. Electronic address: gamarasinghe@path.wustl.edu.
authors: Gaya K
authors: GK
authors: Amarasinghe
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D001669:Biochemical Phenomena; D002460:Cell Line; D004252:DNA Mutational Analysis; D004847:Epithelial Cells / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D007113:Immunity, Innate; D000072019:Kelch-Like ECH-Associated Protein 1 / Q000378:metabolism*; D029024:Marburgvirus / Q000276:immunology / Q000472:pathogenicity*; D013058:Mass Spectrometry; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D017384:Sequence Deletion; D013312:Stress, Physiological; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*; D037521:Virulence Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C094002:VP24 protein, Marburg virus; D014764:Viral Proteins; D037521:Virulence Factors
keywords: Marburg virus; VP24; antioxidative stress; hydrogen deuterium exchange mass spectrometry; viral subversion