Nucleotide phosphotransferase, nucleotide kinase and inorganic pyrophosphatase activities of killer virions of yeast

Georgopoulos, Denise E.; Leibowitz, Michael J.

doi:10.1002/yea.320030208

Cited by 10 publications

(6 citation statements)

References 31 publications

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“…It is thus conceivable that the GDP produced in this process was incorporated at the 5Ј-end of the viral RNA during transcription initiation. Georgopoulos et al (36) has observed that L-A virions are associated with numerous nucleotide-metabolizing enzyme activities, including nucleoside triphosphate phosphotransferase, nucleoside diphosphate and monophosphate kinases, in addition to inorganic pyrophosphatase activity, and speculated that these enzymes may allow the virus to utilize nucleotide pools distinct from those used in host cell transcription. However, the results shown in this work raise the possibility that some of the enzymatic activities associated with the virion are directly involved in the metabolism of phosphate group at the 5Ј termini of viral transcripts.…”

Section: Discussionmentioning

confidence: 99%

“…1S, A and B). A potent inorganic pyrophosphatase activity has been observed to be associated with L-A virions (36). It is likely that the enhanced release of P i was not caused by nucleoside triphosphatase activity per se but by hydrolysis of inorganic pyrophosphate generated as a byproduct from polymerization of the 6-nt transcript (5Ј-GAAAAA).…”

Section: Volume 285 • Number 30 • July 23 2010mentioning

confidence: 99%

“…Because CTP cannot support polymerization of even short transcripts without ATP and UTP, the results suggest that the decrease of GDP was not caused by its incorporation into RNA transcripts but by the competitive inhibition of the triphosphatase activity by ATP or CTP. It is also possible that unincorporated GDP was reconverted to GTP by virionassociated nucleoside diphosphate kinase (36).…”

Section: Volume 285 • Number 30 • July 23 2010mentioning

confidence: 99%

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Yeast Double-stranded RNA Virus L-A Deliberately Synthesizes RNA Transcripts with 5′-Diphosphate

Fujimura

Esteban

2010

Journal of Biological Chemistry

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L-A is a persistent double-stranded RNA virus commonly found in the yeast Saccharomyces cerevisiae. Isolated L-A virus synthesizes positive strand transcripts in vitro. We found that the 5 termini of the transcripts are diphosphorylated. The 5-terminal nucleotide is G, and GDP was the best substrate among those examined to prime the reaction. When GTP was used, the triphosphate of GTP incorporated into the 5-end was converted to diphosphate. This activity was not dependent on host CTL1 RNA triphosphatase. The 5-end of the GMP-primed transcript also was converted to diphosphate, the ␤-phosphate of which was derived from the ␥-phosphate of ATP present in the polymerization reaction. These results demonstrate that L-A virus commands elaborate enzymatic systems to ensure its transcript to be 5-diphosphorylated. Transcripts of M1, a satellite RNA of L-A virus, also had diphosphate at the 5 termini. Because viral transcripts are released from the virion into the cytoplasm to be translated and encapsidated into a new viral particle, a stage most vulnerable to degradation in the virus replication cycle, our results suggest that the 5-diphosphate status is important for transcript stability. Consistent with this, L-A transcripts made in vitro are resistant to the affinity-purified Ski1p 5-exonuclease. We also discuss the implication of these findings on translation of viral RNA. Because the viral transcript has no conventional 5-cap structure, this work may shed light on the metabolism of non-self-RNA in yeast.The 5Ј-cap (m 7 GpppXp) and 3Ј-poly(A) tail structures are the hallmark of eukaryotic mRNAs and have important biological functions in promoting stability in the nucleus, transport to the cytoplasm, and translation and stability in the cytoplasm. Therefore, many viruses furnish their transcripts with the 5Ј-cap structure utilizing their own or cellular enzymes or even by snatching the structure from cellular mRNAs (1-3). Transcripts made by T7 RNA polymerase are recognized as foreign and induce innate immune responses in animal cells. Recent studies suggest that the 5Ј-triphosphate of the transcripts as well as secondary structure, are involved in these responses (4, 5). Therefore, the 5Ј-end of RNA bears important information concerning on self or non-self for the host cells.L-A is a persistent double-stranded RNA (dsRNA) 2 virus commonly found in the laboratory strains of the yeast Saccharomyces cerevisiae (6). The virus has no extracellular transmission pathway. The viral genome is 4.6-kb-long, and only one strand (the positive strand) encodes proteins; the major 76-kDa coat protein Gag and a minor 170-kDa Gag-Pol (7, 8). The minor protein is made from the two overlapping genes by a Ϫ1 ribosomal frameshifting mechanism (9). The Pol domain of the fusion protein has consensus motifs for RNA-dependent RNA polymerases. The RNA genome is packed inside of a 39-nm icosahedral shell consisting of 60 Gag asymmetric dimers (10, 11). One molecule or two of Gag is replaced by Gag-Pol because the fusion protein is essential ...

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Section: Discussionmentioning

confidence: 99%

Section: Volume 285 • Number 30 • July 23 2010mentioning

confidence: 99%

Section: Volume 285 • Number 30 • July 23 2010mentioning

confidence: 99%

See 1 more Smart Citation

Yeast Double-stranded RNA Virus L-A Deliberately Synthesizes RNA Transcripts with 5′-Diphosphate

Fujimura

Esteban

2010

Journal of Biological Chemistry

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“…The bold regions are the two 11-base repeats that fall in the loops of the predicted stem-loop structures. [Adapted from Huan et al (19911.1 Ghabrial and Havens, 19891, a replicase Nemeroff and Bruenn, 19861, a protein kinase (Ghabrial and Havens, 19921, a nucleotide phosphohydrolase (Dowhanick et al, 19941, a nucleotide phosphotransferase, a nucleotide kinase, and an inorganic pyrophosphatase (Georgopoulos and Leibowitz, 1987). Furthermore, the pol domain of the 170-kDa CP-RDRP fusion protein of the yeast L-A virus has a n ssRNA binding activity (Fujimura and Wickner, 1988a).…”

Section: F Functional Domains In Proteins Of Totiuirusesmentioning

confidence: 99%

New Developments in Fungal Virology

Ghabrial

1994

Advances in Virus Research

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“…The latter two appear to have incorporated one and two C residues respectively. Because L‐A virions are associated with nucleoside mono‐ and diphosphate kinase activities (Georgopoulos and Leibowitz, ), empty particles may incorporate a couple of Cs if CMP is generated by minor degradation of the template RNA during incubation. 11‐ and 14‐mers were isolated from the gel, digested with S1 nuclease, and analyzed on TLC.…”

Section: Resultsmentioning

confidence: 99%

Diphosphates at the 5′ end of the positive strand of yeast L‐A double‐stranded RNA virus as a molecular self‐identity tag

Fujimura

Esteban

2016

Molecular Microbiology

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The 5'end of RNA conveys important information on self-identity. In mammalian cells, double-stranded RNA (dsRNA) with 5'di- or triphosphates generated during virus infection is recognized as foreign and elicits the host innate immune response. Here, we analyze the 5' ends of the dsRNA genome of the yeast L-A virus. The positive strand has largely diphosphates with a minor amount of triphosphates, while the negative strand has only diphosphates. Although the virus can produce capped transcripts by cap snatching, neither strand carried a cap structure, suggesting that only non-capped transcripts serve as genomic RNA for encapsidation. We also found that the 5' diphosphates of the positive but not the negative strand within the dsRNA genome are crucial for transcription in vitro. Furthermore, the presence of a cap structure in the dsRNA abrogated its template activity. Given that the 5' diphosphates of the transcripts are also essential for cap acquisition and that host cytosolic RNAs (mRNA, rRNA, and tRNA) are uniformly devoid of 5' pp-structures, the L-A virus takes advantage of its 5' terminal diphosphates, using them as a self-identity tag to propagate in the host cytoplasm.

show abstract

Nucleotide phosphotransferase, nucleotide kinase and inorganic pyrophosphatase activities of killer virions of yeast

Cited by 10 publications

References 31 publications

Yeast Double-stranded RNA Virus L-A Deliberately Synthesizes RNA Transcripts with 5′-Diphosphate

Yeast Double-stranded RNA Virus L-A Deliberately Synthesizes RNA Transcripts with 5′-Diphosphate

New Developments in Fungal Virology

Diphosphates at the 5′ end of the positive strand of yeast L‐A double‐stranded RNA virus as a molecular self‐identity tag

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