Role of Ebola virus VP30 in transcription reinitiation.

INSERM, U758, Filovirus Laboratory, 21 Av. Tony Garnier, 69365 Lyon, Cedex 07, France.
Journal of Virology (Impact Factor: 4.65). 11/2008; 82(24):12569-73. DOI: 10.1128/JVI.01395-08
Source: PubMed

ABSTRACT VP30 is a phosphoprotein essential for the initiation of Ebola virus transcription. In this work, we have studied the effect of mutations in VP30 phosphorylation sites on the ebolavirus replication cycle by using a reverse genetics system. We demonstrate that VP30 is involved in reinitiation of gene transcription and that this activity is affected by mutations at the phosphorylation sites.

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    ABSTRACT: The recent outbreak of the human Zaire ebolavirus (EBOV) epidemic is spiraling out of control in West Africa. Human EBOV hemorrhagic fever has a case fatality rate of up to 90%. The EBOV is classified as a biosafety level 4 pathogen and is considered a category A agent of bioterrorism by Centers for Disease Control and Prevention, with no approved therapies and vaccines available for its treatment apart from supportive care. Although several promising therapeutic agents and vaccines against EBOV are undergoing the Phase I human trial, the current epidemic might be outpacing the speed at which drugs and vaccines can be produced. Like all viruses, the EBOV largely relies on host cell factors and physiological processes for its entry, replication, and egress. We have reviewed currently available therapeutic agents that have been shown to be effective in suppressing the proliferation of the EBOV in cell cultures or animal studies. Most of the therapeutic agents in this review are directed against non-mutable targets of the host, which is independent of viral mutation. These medications are approved by the Food and Drug Administration (FDA) for the treatment of other diseases. They are available and stockpileable for immediate use. They may also have a complementary role to those therapeutic agents under development that are directed against the mutable targets of the EBOV.
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    ABSTRACT: The ebolaviruses can cause severe hemorrhagic fever. Essential to the ebolavirus life cycle is the protein VP30, which serves as a transcriptional cofactor. Here, the crystal structure of the C-terminal, NP-binding domain of VP30 from Reston ebolavirus is presented. Reston VP30 and Ebola VP30 both form homodimers, but the dimeric interfaces are rotated relative to each other, suggesting subtle inherent differences or flexibility in the dimeric interface.
    04/2014; 70(Pt 4):457-60. DOI:10.1107/S2053230X14003811
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    ABSTRACT: The filovirus Ebola (EBOV) causes the most severe hemorrhagic fever known. The EBOV RNA-dependent polymerase complex includes a filovirus-specific VP30, which is critical for the transcriptional, but not replication activity of EBOV polymerase; to support transcription, VP30 must be in a dephosphorylated form. Here we show that EBOV VP30 is phosphorylated not only at the N-terminal serine clusters identified previously, but also at the threonine residues at positions 143 and 146. We also show that host cell protein phosphatase 1 (PP1) controls VP30 dephosphorylation as expression of a PP1-binding peptide cdNIPP1 increased VP30 phosphorylation. Moreover, targeting PP1 mRNA by shRNA resulted in the overexpression of SIPP1, a cytoplasm shuttling regulatory subunit of PP1, and increased EBOV transcription, suggesting that cytoplasmic accumulation of PP1 induces EBOV transcription. Furthermore, we developed a small molecule compound, 1E7-03 that targeted a non-catalytic site of PP1 and increased VP30 dephosphorylation. The compound inhibited the transcription but increased replication of the viral genome, and completely suppressed replication of EBOV in cultured cells. Finally, mutations of VP30's Thr143 and Thr146 significantly inhibited EBOV transcription and strongly induced VP30 phosphorylation in the N-terminal Ser residues 29-46 suggesting a novel mechanism of regulation of VP30 phosphorylation. Our findings suggest that targeting PP1 with small molecules is a feasible approach to achieve dysregulation of the EBOV polymerase activity. This novel approach may be used for development of antivirals against EBOV and other filovirus species.
    Journal of Biological Chemistry 06/2014; 289(33). DOI:10.1074/jbc.M114.575050 · 4.60 Impact Factor

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Nadine Biedenkopf