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Crystal structure of the Zaire ebolavirus VP35 interferon inhibitory domain R312A/K319A/R322A mutantCrystal structure of the Zaire ebolavirus VP35 interferon inhibitory domain R312A/K319A/R322A mutant
Structural highlights
FunctionVP35_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 PubMedViral protein 35 (VP35), encoded by filoviruses, are multifunctional dsRNA binding proteins that play important roles in viral replication, innate immune evasion and pathogenesis. The multifunctional nature of these proteins also presents opportunities to develop countermeasures that target distinct functional regions. However, functional validation and the establishment of therapeutic approaches toward such multifunctional proteins, particularly for non-enzymatic targets, are often challenging. Our previous work on filoviral VP35 proteins defined conserved basic residues located within its C-terminal dsRNA binding interferon (IFN) inhibitory domain (IID) as important for VP35 mediated IFN antagonism and viral polymerase co-factor functions. In the current study, we used a combination of structural and functional data to determine regions of Ebola virus (EBOV) VP35 (eVP35) to target for aptamer selection using SELEX. Select aptamers, representing two distinct classes, were further characterized based on their interaction properties to eVP35 IID. These results revealed that the aptamers bind to distinct regions of eVP35 IID with high affinity (10-50 nM) and specificity. These aptamers can compete with dsRNA for binding to eVP35 and disrupt the eVP35-nucleoprotein (NP) interaction. Consistent with the ability to antagonize eVP35-NP interaction, select aptamers can inhibit the function of the EBOV polymerase complex reconstituted by expression of select viral proteins. Taken together, our results support the identification of two aptamers that bind filoviral VP35 proteins with high affinity and specificity and the capacity to potentially target filoviral VP35 proteins as a therapeutic target. Development of RNA aptamers targeting Ebola virus VP35.,Binning JM, Wang T, Luthra P, Shabman RS, Borek DM, Liu G, Xu W, Leung DW, Basler CF, Amarasinghe GK Biochemistry. 2013 Sep 26. PMID:24067086[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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