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

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

Research output: Contribution to journalArticle

17 Scopus citations

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.

Original languageEnglish
Pages (from-to)3483-3494
Number of pages12
JournalJournal of Molecular Biology
Volume428
Issue number17
DOIs
StatePublished - Aug 28 2016

Keywords

  • Marburg virus
  • VP24
  • antioxidative stress
  • hydrogen deuterium exchange mass spectrometry
  • viral subversion

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