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Basic Characteristics of Mutations
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Mutation Site
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R312A |
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Mutation Site Sentence
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In contrast, two VP35 point mutants, R312A and K309A, were found to be greatly impaired in their dsRNA-binding activity. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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VP35 |
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Standardized Encoding Gene
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VP35
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Genotype/Subtype
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Zaire |
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Viral Reference
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-
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Functional Impact and Mechanisms
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Disease
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Cell line
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Immune
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- |
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Target Gene
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IFNB1
MAVS
RIGI
IKBKE
TBK1
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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16698997
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Title
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Ebola virus VP35 protein binds double-stranded RNA and inhibits alpha/beta interferon production induced by RIG-I signaling
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Author
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Cardenas WB,Loo YM,Gale M Jr,Hartman AL,Kimberlin CR,Martinez-Sobrido L,Saphire EO,Basler CF
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Journal
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Journal of virology
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Journal Info
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2006 Jun;80(11):5168-78
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Abstract
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The Ebola virus (EBOV) VP35 protein blocks the virus-induced phosphorylation and activation of interferon regulatory factor 3 (IRF-3), a transcription factor critical for the induction of alpha/beta interferon (IFN-alpha/beta) expression. However, the mechanism(s) by which this blockage occurs remains incompletely defined. We now provide evidence that VP35 possesses double-stranded RNA (dsRNA)-binding activity. Specifically, VP35 bound to poly(rI) . poly(rC)-coated Sepharose beads but not control beads. In contrast, two VP35 point mutants, R312A and K309A, were found to be greatly impaired in their dsRNA-binding activity. Competition assays showed that VP35 interacted specifically with poly(rI) . poly(rC), poly(rA) . poly(rU), or in vitro-transcribed dsRNAs derived from EBOV sequences, and not with single-stranded RNAs (ssRNAs) or double-stranded DNA. We then screened wild-type and mutant VP35s for their ability to target different components of the signaling pathways that activate IRF-3. These experiments indicate that VP35 blocks activation of IRF-3 induced by overexpression of RIG-I, a cellular helicase recently implicated in the activation of IRF-3 by either virus or dsRNA. Interestingly, the VP35 mutants impaired for dsRNA binding have a decreased but measurable IFN antagonist activity in these assays. Additionally, wild-type and dsRNA-binding-mutant VP35s were found to have equivalent abilities to inhibit activation of the IFN-beta promoter induced by overexpression of IPS-1, a recently identified signaling molecule downstream of RIG-I, or by overexpression of the IRF-3 kinases IKKepsilon and TBK-1. These data support the hypothesis that dsRNA binding may contribute to VP35 IFN antagonist function. However, additional mechanisms of inhibition, at a point proximal to the IRF-3 kinases, most likely also exist.
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Sequence Data
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-
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