scholarly journals The Broad Spectrum Antiviral Nucleoside Ribavirin as a Substrate for a Viral RNA Capping Enzyme

2004 ◽  
Vol 279 (21) ◽  
pp. 22124-22130 ◽  
Author(s):  
Isabelle Bougie ◽  
Martin Bisaillon
Keyword(s):  
Broad Spectrum ◽  
Viral Rna ◽  
Capping Enzyme ◽  
Rna Capping ◽  
Antiviral Nucleoside

scholarly journals Helicase and Capping Enzyme Active Site Mutations in Brome Mosaic Virus Protein 1a Cause Defects in Template Recruitment, Negative-Strand RNA Synthesis, and Viral RNA Capping

2000 ◽  
Vol 74 (19) ◽  
pp. 8803-8811 ◽  
Author(s):  
Tero Ahola ◽  
Johan A. den Boon ◽  
Paul Ahlquist
Keyword(s):  
Mosaic Virus ◽  
Rna Synthesis ◽  
Rna Replication ◽  
Brome Mosaic Virus ◽  
Viral Rna ◽  
Negative Strand ◽  
Capping Enzyme ◽  
Low Levels ◽  
Positive Strand Rna ◽  
Rna Capping

ABSTRACT Brome mosaic virus (BMV) encodes two RNA replication proteins: 1a, which contains RNA capping and helicase-like domains, and 2a, which is related to polymerases. BMV 1a and 2a can direct virus-specific RNA replication in the yeast Saccharomyces cerevisiae, which reproduces the known features of BMV replication in plant cells. We constructed single amino acid point mutations at the predicted capping and helicase active sites of 1a and analyzed their effects on BMV RNA3 replication in yeast. The helicase mutants showed no function in any assays used: they were strongly defective in template recruitment for RNA replication, as measured by 1a-induced stabilization of RNA3, and they synthesized no detectable negative-strand or subgenomic RNA. Capping domain mutants divided into two groups. The first exhibited increased template recruitment but nevertheless allowed only low levels of negative-strand and subgenomic mRNA synthesis. The second was strongly defective in template recruitment, made very low levels of negative strands, and made no detectable subgenomes. To distinguish between RNA synthesis and capping defects, we deleted chromosomal geneXRN1, encoding the major exonuclease that degrades uncapped mRNAs. XRN1 deletion suppressed the second but not the first group of capping mutants, allowing synthesis and accumulation of large amounts of uncapped subgenomic mRNAs, thus providing direct evidence for the importance of the viral RNA capping function. The helicase and capping enzyme mutants showed no complementation. Instead, at high levels of expression, a helicase mutant dominantly interfered with the function of the wild-type protein. These results are discussed in relation to the interconnected functions required for different steps of positive-strand RNA virus replication.

scholarly journals Broad-Spectrum Antiviral Strategies and Nucleoside Analogues

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 667
Author(s):  
Robert J. Geraghty ◽  
Matthew T. Aliota ◽  
Laurent F. Bonnac
Keyword(s):  
Public Health ◽  
Severe Acute Respiratory Syndrome ◽  
Broad Spectrum ◽  
Vaccine Development ◽  
Fast Response ◽  
Mechanisms Of Action ◽  
Public Health Emergency ◽  
Nucleoside Analogues ◽  
The Family ◽  
Antiviral Nucleoside

The emergence or re-emergence of viruses with epidemic and/or pandemic potential, such as Ebola, Zika, Middle East Respiratory Syndrome (MERS-CoV), Severe Acute Respiratory Syndrome Coronavirus 1 and 2 (SARS and SARS-CoV-2) viruses, or new strains of influenza represents significant human health threats due to the absence of available treatments. Vaccines represent a key answer to control these viruses. However, in the case of a public health emergency, vaccine development, safety, and partial efficacy concerns may hinder their prompt deployment. Thus, developing broad-spectrum antiviral molecules for a fast response is essential to face an outbreak crisis as well as for bioweapon countermeasures. So far, broad-spectrum antivirals include two main categories: the family of drugs targeting the host-cell machinery essential for virus infection and replication, and the family of drugs directly targeting viruses. Among the molecules directly targeting viruses, nucleoside analogues form an essential class of broad-spectrum antiviral drugs. In this review, we will discuss the interest for broad-spectrum antiviral strategies and their limitations, with an emphasis on virus-targeted, broad-spectrum, antiviral nucleoside analogues and their mechanisms of action.

scholarly journals Thermodynamics of ligand binding by the yeast mRNA-capping enzyme reveals different modes of binding

2004 ◽  
Vol 384 (2) ◽  
pp. 411-420 ◽  
Author(s):  
Isabelle BOUGIE ◽  
Amélie PARENT ◽  
Martin BISAILLON
Keyword(s):  
Ligand Binding ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Mrna Capping ◽  
Capping Enzyme ◽  
Eukaryotic Mrnas ◽  
Entropic Effect ◽  
A Minor ◽  
Rna Capping ◽  
Capping Enzymes

RNA-capping enzymes are involved in the synthesis of the cap structure found at the 5′-end of eukaryotic mRNAs. The present study reports a detailed study on the thermodynamic parameters involved in the interaction of an RNA-capping enzyme with its ligands. Analysis of the interaction of the Saccharomyces cerevisiae RNA-capping enzyme (Ceg1) with GTP, RNA and manganese ions revealed significant differences between the binding forces that drive the interaction of the enzyme with its RNA and GTP substrates. Our thermodynamic analyses indicate that the initial association of GTP with the Ceg1 protein is driven by a favourable enthalpy change (ΔH=−80.9 kJ/mol), but is also clearly associated with an unfavourable entropy change (TΔS=−62.9 kJ/mol). However, the interaction between Ceg1 and RNA revealed a completely different mode of binding, where binding to RNA is clearly dominated by a favourable entropic effect (TΔS=20.5 kJ/mol), with a minor contribution from a favourable enthalpy change (ΔH=−5.3 kJ/mol). Fluorescence spectroscopy also allowed us to evaluate the initial binding of GTP to such an enzyme, thereby separating the GTP binding step from the concomitant metal-dependent hydrolysis of GTP that results in the formation of a covalent GMP–protein intermediate. In addition to the determination of the energetics of ligand binding, our study leads to a better understanding of the molecular basis of substrate recognition by RNA-capping enzymes.

scholarly journals Expression and characterization of an RNA capping enzyme encoded by Chlorella virus PBCV-1.

1996 ◽  
Vol 70 (10) ◽  
pp. 6658-6664 ◽  
Author(s):  
C K Ho ◽  
J L Van Etten ◽  
S Shuman
Keyword(s):  
Chlorella Virus ◽  
Capping Enzyme ◽  
Rna Capping

scholarly journals Identification of a Novel Antiviral Inhibitor of the Flavivirus Guanylyltransferase Enzyme

2012 ◽  
Vol 86 (16) ◽  
pp. 8730-8739 ◽  
Author(s):  
Hillary J. Stahla-Beek ◽  
Daniel G. April ◽  
Bejan J. Saeedi ◽  
Amanda M. Hannah ◽  
Susan M. Keenan ◽  
...  
Keyword(s):  
Dengue Virus ◽  
High Throughput Screening ◽  
Yellow Fever Virus ◽  
Subgenomic Replicon ◽  
Relationship Analysis ◽  
Gtp Binding ◽  
Capping Enzyme ◽  
Low Toxicity ◽  
Rna Capping ◽  
New Compounds

Arthropod-borne flavivirus infection causes serious morbidity and mortality worldwide, but there are currently no effective antiflaviviral chemotherapeutics available for human use. Therefore, it is critical that new therapeutics against virus-specific targets be developed. To identify new compounds that may be used as broadly active flavivirus therapeutics, we have performed a high-throughput screening of 235,456 commercially available compounds for small-molecule inhibitors of the dengue virus NS5 RNA capping enzyme. We identified a family of compounds, the 2-thioxothiazolidin-4-ones, that show potent biochemical inhibition of capping enzyme GTP binding and guanylyltransferase function. During the course of structure-activity relationship analysis, a molecule within this family, (E)-{3-[5-(4-tert-butylbenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]propanoic acid} (BG-323), was found to possess significant antiviral activity in a dengue virus subgenomic replicon assay. Further testing of BG-323 demonstrated that this molecule is able to reduce the replication of infectious West Nile virus and yellow fever virus in cell culture with low toxicity. The results of this study describe the first inhibitor that targets the GTP-binding/guanylyltransferase activity of the flavivirus RNA capping enzyme.

scholarly journals Vesicular Stomatitis Virus mRNA Capping Machinery Requires Specific cis-Acting Signals in the RNA

2007 ◽  
Vol 81 (20) ◽  
pp. 11499-11506 ◽  
Author(s):  
Jennifer T. Wang ◽  
Lauren E. McElvain ◽  
Sean P. J. Whelan
Keyword(s):  
Vesicular Stomatitis Virus ◽  
Rna Viruses ◽  
Translation Strategies ◽  
Cis Acting ◽  
Specific Manner ◽  
Mrna Capping ◽  
Capping Enzyme ◽  
Vesicular Stomatitis ◽  
Rna Capping ◽  
Negative Sense

ABSTRACT Many viruses of eukaryotes that use mRNA cap-dependent translation strategies have evolved alternate mechanisms to generate the mRNA cap compared to their hosts. The most divergent of these mechanisms are those used by nonsegmented negative-sense (NNS) RNA viruses, which evolved a capping enzyme that transfers RNA onto GDP, rather than GMP onto the 5′ end of the RNA. Working with vesicular stomatitis virus (VSV), a prototype of the NNS RNA viruses, we show that mRNA cap formation is further distinct, requiring a specific cis-acting signal in the RNA. Using recombinant VSV, we determined the function of the eight conserved positions of the gene-start sequence in mRNA initiation and cap formation. Alterations to this sequence compromised mRNA initiation and separately formation of the GpppA cap structure. These studies provide genetic and biochemical evidence that the mRNA capping apparatus of VSV evolved an RNA capping machinery that functions in a sequence-specific manner.

scholarly journals Conversion of a DNA ligase into an RNA capping enzyme

1999 ◽  
Vol 27 (16) ◽  
pp. 3253-3258 ◽  
Author(s):  
A. J. Doherty
Keyword(s):  
Dna Ligase ◽  
Capping Enzyme ◽  
Rna Capping
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