| Structural highlights
Function
[VP35_EBOZM] Acsts as a polymerase cofactor in the RNA polymerase transcription and replication complex. Prevents establishment of cellular antiviral state by blocking virus-induced phosphorylation and activation of interferon regulatory factor 3 (IRF3), a transcription factor critical for the induction of interferons alpha and beta. The mechanism by which this blockage occurs remains incompletely defined, a hypothesis suggests that VP35 dsRNA-binding activity prevents activation of IRF3 by sequestering dsRNA. Also inhibits the antiviral effect mediated by the interferon-induced, double-stranded RNA-activated protein kinase EIF2AK2/PKR.[1] [2] [3] [4] [5]
Publication Abstract from PubMed
Ebola viruses (EBOVs) cause rare but highly fatal outbreaks of viral hemorrhagic fever in humans, and approved treatments for these infections are currently lacking. The Ebola VP35 protein is multifunctional, acting as a component of the viral RNA polymerase complex, a viral assembly factor, and an inhibitor of host interferon (IFN) production. Mutation of select basic residues within the C-terminal half of VP35 abrogates its dsRNA-binding activity, impairs VP35-mediated IFN antagonism, and attenuates EBOV growth in vitro and in vivo. Because VP35 contributes to viral escape from host innate immunity and is required for EBOV virulence, understanding the structural basis for VP35 dsRNA binding, which correlates with suppression of IFN activity, is of high importance. Here, we report the structure of the C-terminal VP35 IFN inhibitory domain (IID) solved to a resolution of 1.4 A and show that VP35 IID forms a unique fold. In the structure, we identify 2 basic residue clusters, one of which is important for dsRNA binding. The dsRNA binding cluster is centered on Arg-312, a highly conserved residue required for IFN inhibition. Mutation of residues within this cluster significantly changes the surface electrostatic potential and diminishes dsRNA binding activity. The high-resolution structure and the identification of the conserved dsRNA binding residue cluster provide opportunities for antiviral therapeutic design. Our results suggest a structure-based model for dsRNA-mediated innate immune antagonism by Ebola VP35 and other similarly constructed viral antagonists.
Structure of the Ebola VP35 interferon inhibitory domain.,Leung DW, Ginder ND, Fulton DB, Nix J, Basler CF, Honzatko RB, Amarasinghe GK Proc Natl Acad Sci U S A. 2009 Jan 2. PMID:19122151[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Muhlberger E, Weik M, Volchkov VE, Klenk HD, Becker S. Comparison of the transcription and replication strategies of marburg virus and Ebola virus by using artificial replication systems. J Virol. 1999 Mar;73(3):2333-42. PMID:9971816
- ↑ Basler CF, Wang X, Muhlberger E, Volchkov V, Paragas J, Klenk HD, Garcia-Sastre A, Palese P. The Ebola virus VP35 protein functions as a type I IFN antagonist. Proc Natl Acad Sci U S A. 2000 Oct 24;97(22):12289-94. PMID:11027311 doi:10.1073/pnas.220398297
- ↑ Basler CF, Mikulasova A, Martinez-Sobrido L, Paragas J, Muhlberger E, Bray M, Klenk HD, Palese P, Garcia-Sastre A. The Ebola virus VP35 protein inhibits activation of interferon regulatory factor 3. J Virol. 2003 Jul;77(14):7945-56. PMID:12829834
- ↑ Enterlein S, Warfield KL, Swenson DL, Stein DA, Smith JL, Gamble CS, Kroeker AD, Iversen PL, Bavari S, Muhlberger E. VP35 knockdown inhibits Ebola virus amplification and protects against lethal infection in mice. Antimicrob Agents Chemother. 2006 Mar;50(3):984-93. PMID:16495261 doi:10.1128/AAC.50.3.984-993.2006
- ↑ Feng Z, Cerveny M, Yan Z, He B. The VP35 protein of Ebola virus inhibits the antiviral effect mediated by double-stranded RNA-dependent protein kinase PKR. J Virol. 2007 Jan;81(1):182-92. Epub 2006 Oct 25. PMID:17065211 doi:JVI.01006-06
- ↑ Leung DW, Ginder ND, Fulton DB, Nix J, Basler CF, Honzatko RB, Amarasinghe GK. Structure of the Ebola VP35 interferon inhibitory domain. Proc Natl Acad Sci U S A. 2009 Jan 2. PMID:19122151
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