Vaccinia virus RNA helicase: An essential enzyme related to the DE-H family of RNA-dependent NTPases Journal Article
| Author: | Shuman, S. |
| Article Title: | Vaccinia virus RNA helicase: An essential enzyme related to the DE-H family of RNA-dependent NTPases |
| Abstract: | Three distinct nucleic acid-dependent ATPases are packaged within infectious vaccinia virus particles; one of these enzymes (nucleoside triphosphate phosphohydrolase II or NPH-II) is activated by single-stranded RNA. Purified NPH-II is now shown to be an NTP-dependent RNA helicase. RNA unwinding requires a divalent cation and any one of the eight common ribo- or deoxyribonucleoside triphosphates. The enzyme acts catalytically to displace an estimated 10-fold molar excess of duplex RNA under in vitro reaction conditions. NPH-II binds to single-stranded RNA. Turnover of the bound enzyme is stimulated by and coupled to hydrolysis of NTP. Photocrosslinking of radiolabeled RNA to NPH-II results in label transfer to a single 73-kDa polypeptide. The sedimentation properties of the helicase are consistent with NPH-II being a monomer of this protein. Immunoblotting experiments identify NPH-II as the product of the vaccinia virus 18 gene. The 18-encoded protein displays extensive sequence similarity to members of the DE-H family of RNA-dependent NTPases. Mutations in the NPH-II gene [Fathi, Z. & Condit, R. C. (1991) Virology 181, 258-272] define the vaccinia helicase as essential for virus replication in vivo. Encapsidation of NPH-II in the virus particle suggests a role for the enzyme in synthesis of early messenger RNAs by the virion-associated transcription machinery. |
| Keywords: | nonhuman; comparative study; animal; cells, cultured; enzyme activation; nucleoside triphosphatase; enzyme activity; time factors; amino acid sequence; molecular sequence data; sequence homology, amino acid; kinetics; messenger rna; virus rna; rna viruses; substrate specificity; immunoblotting; vaccinia virus; base sequence; helicase; sequence homology; rna helicases; molecular weight; phosphoric monoester hydrolases; enzyme purification; rna, double-stranded; vaccinia; nucleoside triphosphate; open reading frames; virion; chromatography, affinity; genes, viral; messenger rna synthesis; chromatography, ion exchange; virus transcription; rna nucleotidyltransferases; priority journal; article; chromatography, deae-cellulose |
| Journal Title: | Proceedings of the National Academy of Sciences of the United States of America |
| Volume: | 89 |
| Issue: | 22 |
| ISSN: | 0027-8424 |
| Publisher: | National Academy of Sciences |
| Date Published: | 1992-11-15 |
| Start Page: | 10935 |
| End Page: | 10939 |
| Language: | English |
| DOI: | 10.1073/pnas.89.22.10935 |
| PUBMED: | 1332061 |
| PROVIDER: | scopus |
| PMCID: | PMC50457 |
| DOI/URL: | |
| Notes: | Source: Scopus |
