RNA triphosphatase component of the mRNA capping apparatus of Paramecium bursaria Chlorella virus 1 Journal Article
| Authors: | Ho, C. K.; Gong, C.; Shuman, S. |
| Article Title: | RNA triphosphatase component of the mRNA capping apparatus of Paramecium bursaria Chlorella virus 1 |
| Abstract: | Paramecium bursaria chlorella virus 1 (PBCV-1) elicits a lytic infection of its unicellular green alga host. The 330-kbp viral genome has been sequenced, yet little is known about how viral mRNAs are synthesized and processed. PBCV-1 encodes its own mRNA guanylyltransferase, which catalyzes the addition of GMP to the 5′ diphosphate end of RNA to form a GpppN cap structure. Here we report that PBCV-1 encodes a separate RNA triphosphatase (RTP) that catalyzes the initial step in cap synthesis: hydrolysis of the γ-phosphate of triphosphate-terminated RNA to generate an RNA diphosphate end. We exploit a yeast-based genetic system to show that Chlorella virus RTP can function as a cap-forming enzyme in vivo. The 193-amino-acid Chlorella virus RTP is the smallest member of a family of metal-dependent phosphohydrolases that includes the RNA triphosphatases of fungi and other large eukaryotic DNA viruses (poxviruses, African swine fever virus, and baculoviruses). Chlorella virus RTP is more similar in structure to the yeast RNA triphosphatases than to the enzymes of metazoan DNA viruses. Indeed, PBCV-1 is unique among DNA viruses in that the triphosphatase and guanylyltransferase steps of cap formation are catalyzed by separate viral enzymes instead of a single viral polypeptide with multiple catalytic domains. |
| Keywords: | controlled study; unclassified drug; nonhuman; protein domain; amino acid substitution; phosphatase; rna triphosphatase; enzyme activity; acid anhydride hydrolases; methyltransferases; amino acid sequence; kinetics; messenger rna; rna synthesis; saccharomyces cerevisiae; rna caps; rna, messenger; recombinant proteins; species difference; catalysis; adenosine triphosphate; rna structure; rna processing; glutamates; virus genome; genetic code; hydrolysis; amino acid motifs; gene structure; host; paramecium bursaria chlorella virus 1; virus protein; poxvirus; virus dna; capped rna; rna capping; nucleotidyltransferases; virus infectivity; transferase; guanylyltransferase; baculovirus; virus enzyme; dna virus; chlorella; guanosine phosphate; priority journal; article; phycodnaviridae; metals, heavy; african swine fever virus; green alga |
| Journal Title: | Journal of Virology |
| Volume: | 75 |
| Issue: | 4 |
| ISSN: | 0022-538X |
| Publisher: | American Society for Microbiology |
| Date Published: | 2001-02-01 |
| Start Page: | 1744 |
| End Page: | 1750 |
| Language: | English |
| DOI: | 10.1128/jvi.75.4.1744-1750.2001 |
| PUBMED: | 11160672 |
| PROVIDER: | scopus |
| PMCID: | PMC114083 |
| DOI/URL: | |
| Notes: | Export Date: 21 May 2015 -- Source: Scopus |
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