Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The RNA-dependent RNA polymerase associated with vesicular stomatitis virus has been found to be markedly inhibited at high concentrations of virus. This endogenous inhibitor of the virion transcriptase was completely reversed by the action of two negatively charged polyamino acids: poly(L-glutamic acid) and pepsin (EC 3.4.23.1). Two other polyanions, heparin and polyethylene sulfonate, strongly inhibited the activity of the virion transcriptase even at low virus concentrations. Poly (L-glutamic acid) rapidly released the block in transcription of concentrated vesicular stomatitis virus, possibly owing to competition for binding sites of the inhibitor on the virion nucleocapsid transcription complex.
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PMID:Reversal by certain polyanions of an endogenous inhibitor of the vesicular stomatitis virus-associated transcriptase. 20 38

The L and NS proteins of vesicular stomatitis virions (New Jersey serotype) were solubilized with Triton X-100 and high-salt buffer and recombined with purified nucleocapsids under conditions similar to those used to reconstitute transcriptase activity in vitro. The nucleocapsid-bound L and NS proteins were separated from unbound proteins on a glycerol gradient. The rebinding of L and NS proteins mimics the in vivo binding in that at saturation the ratio of L and NS molecules to N molecules is approximately the same as observed in the intact virion. L and NS proteins were separated and added back independently and in combination to the template. The purified NS protein bound to the template in the absence of L protein. However, the L protein binding appeared to depend on the presence of NS protein. The presence of Mg2+ and nucleotides, which is required for transcription, was not necessary for the rebinding of L and NS proteins.
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PMID:Rebinding of transcriptase components (L and NS proteins) to the nucleocapsid template of vesicular stomatitis virus. 21 81

The free 4S RNA of avian RNA tumor viruses is greatly enriched in one of the four methionine tRNAs of the host cells, tRNA4Met. On the assumption that viral tRNAMet forms are identical to the corresponding tRNAs of mouse or chick cells, the following conclusions were drawn concerning the tRNAMet content of oncornaviruses: (1) tRNAMet species may be compartmentalised within the host cells, and the viral tRNA pool could reflect the cellular compartment in which viral maturation takes place since tRNAMet forms distribute unevenly between different fractions of a cell homogenate. (2) tRNA4Met appears to have no special role in the modulation of protein synthesis in as much as no functional difference between tRNA2Met and tRNA3Met, tRNA4Met could be demonstrated in in vitro protein synthesising systems. (3) tRNA4Met differs in nucleotide sequence from all other host cell tRNAMet forms except possibly tRNA2Met. The nucleotide sequences of two tRNAMet species, tRNA1Met and tRNA4Met, have already been determined and the sequence of another host cell tRNAMet, tRNA3Met, was derived from the analogy of its sequence to that of tRNA4Met since the two molecules differ in only 6 nucleotides out of 76. (4) Avian myeloblastosis virus reverse transcriptase has been shown to bind specifically tRNA4Met and tRNATrp in whole cell tRNA and therefore the free tRNA4Met in the virion particle may exist substantially bound to virion-associated transcriptase.
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PMID:Selection of methionine tRNAs by avian oncornaviruses. 21 69

An endogenous transcriptase inhibitor active at high concentrations of vesicular stomatitis (VS) virus was present in trypsinized whole virions but was absent from ribonucleoprotein cores containing only the L, N, and NS proteins. Poly(L-glutamic acid) effectively reversed the transcriptase inhibition. Transcription under noninhibited, inhibited, and poly(L-glutamic acid)-reversed conditions did not appear to greatly affect the nature of the RNA transcription product. The VS virion matrix (M) protein was purified to greater than 98% homogeneity and was found to have an isoelectric point of approximately 9.0. Purified M protein inhibited transcription by ribonucleoprotein cores, an effect that was partially reversed by poly(L-glutamic acid). Two group III temperature-sensitive (ts) mutants of VS virus (tsO23 and ts G31) with lesions in the M protein exhibited little or no endogenous inhibitor activity compared with two wild-type strains and a group V mutant (tsO45) with a lesion in the G protein. The data presented strongly suggest that the virion M protein is responsible for the endogenous inhibition of in vitro RNA synthesis seen at high concentrations of VS virus.
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PMID:Role of the membrane (M) protein in endogenous inhibition of in vitro transcription by vesicular stomatitis virus. 21 13

Three RNA polymerase activities were found and associated with purified Pichinde virus, a member of the Arenaviridae. A heat-labile polymerase activity which required all four ribonucleoside triphosphates for optimal activity co-sedimented on sucrose gradient centrifugation with the viral ribonucleoprotein complex from detergent-disrupted virus preparations. This enzyme synthesized heteropolymers which represented about 23% of the genome RNA as determined by nucleic acid hybridization. Two relatively heat-stable polymerase activities which differed in their cation requirement and substrate specificity were recovered with the virus-associated ribosomes. These polymerase activities synthesized homopolymers of limited chain length: in the presence of 10 mM Mg2%, polyuridylic acid was made, whereas in the presence of 1 mM Mn2%, polyadenylic acid was made. The addition of complementary RNA synthesized with the viral transcriptase in vitro to the reaction mixture containing the polyadenylic acid polymerase activity resulted in the terminal addition of polyadenylic acid to the complementary RNA. The possible function of the ribosome-associated polymerase activities in the replication of the virus is discussed.
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PMID:Distinctive RNA transcriptase, polyadenylic acid polymerase, and polyuridylic acid polymerase activities associated with Pichinde virus. 22 33

The virion-associated RNA transcriptase activity of vesicular stomatitis virus New Jersey temperature-sensitive (ts) mutants was assayed in vitro at the permissive (31 degrees C) and restrictive (39 degrees C) temperatures. RNA synthesis at 39 degrees C by the RNA-negative ts A1 and the RNA-positive ts C1 and ts D1 mutants was similar to that of wild-type virus. The RNA-negative ts B1 synthesized only small amounts of RNA in vitro at 39 degrees C. The three mutants of complementation group E were dissimilar in the amounts of RNA they synthesized at 39 degrees C: ts E1 synthesized very little RNA, ts E2 synthesized moderate amounts, and RNA synthesis by ts E3 was not inhibited. The two mutants of group F were also dissimilar, since ts F1 synthesized very little RNA at 39 degrees C, whereas ts F2 synthesized as much RNA as wild-type virus. The revertant clones ts B1/R1, ts E1/R1, and ts F1/R1 synthesized RNA at 39 degrees C in amounts comparable to wild-type virus, indicating that the heat sensitivity of the transcriptase activity of the mutants ts B1, ts E1, and ts F1 was associated with temperature sensitivity. Similar heat sensitivities were observed when transcribing nucleoprotein complexes were used in the assays, showing that the mutated polypeptides were part of the viral core. The heat stability of the mutant ts B1 was similar to that of wild-type virus, and in vitro RNA synthesis was fully restored when the temperature was lowered to 31 degrees C after 30 min of preincubation at 39 degrees C, showing that the inhibition was due to reversible configurational change of the mutated polypeptide. When virions of the mutant ts E1 were heated for 5 h at 39 degrees C, their infectivity and transcriptase activity were as stable as those of the wild-type virus, whereas transcriptase activity became very heat labile after disruption of the viral coat with a neutral detergent. This suggests an interaction between the mutated polypeptide and a coat polypeptide which stabilizes the activity of the transcriptase. The RNA transcriptase activity of the mutant ts F1 was also heat labile, although to a lesser extent than that of ts E1. Thus, the defects in transcriptase activity of groups B, E, and F suggest that all three polypeptides of the virus core, polypeptides L, N, and NS, are involved in the transcription. In addition, we postulate that the mutated gene products of groups E and F are multifunctional, being required both in transcription and replication, and that the gene product of group E may also be involved in some late stage of virus development.
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PMID:Effect of temperature-sensitive mutation on activity of the RNA transcriptase of vesicular stomatitis virus New Jersey. 22 38

In cultures of Ly cells treated with 10 or 30 reference units/ml of mouse interferon there was a 30 to 200 times reduction in the production of infectious vesicular stomatitis virus (VSV); virus particle production, as measured by VSV particle associated virus RNA, virus protein, and virus transcriptase, was inhibited by, at most, six times. These results suggested that interferon-treated cells produce VSV particles with low infectivity and resemble the findings in interferon-treated cells infected with murine leukaemia viruses.
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PMID:Production of vesicular stomatitis virus with low infectivity by interferon-treated cells. 22 98

Sendai virus and VSV minus strand genome RNAs, labeled specifically at their 3' ends with RNA ligase, were used as probes to detect leader RNA--that is, short transcripts (approximately 50 nucleotides) complementary to the exact 3' end of the minus strand genome. These probes have allowed the detection of plus strand leader RNAs in both Sendai virus and VSV-infected cells as well as in the virion transcriptase reactions. The use of a similar probe, prepared from the self-complementary ends of DI genome RNA and containing the 3' end of the plus strand antigenome RNA, has allowed the detection of a minus strand leader RNA of identical size in VSV-infected cells. Since the presence of DI genomes could not be detected by analytical sucrose gradient centrifugation in these VSV-infected cells, this minus strand leader RNA is apparently synthesized on the template formed by the exact 3' end of the antigenome RNA.
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PMID:Plus and minus strand leader RNAs in negative strand virus-infected cells. 22 62

The RNA-dependent RNA polymerase induced in BHK 21 cells by infection with foot-and-mouth disease virus has been isolated from the replication complex. It contains a major, virus-coded protein with mol. wt. 56 000 which appears from serological studies and tryptic peptide mapping to be the same as the virus infection associated (VIA) antigen and the protein P56 found in cells infected with the virus. Other virus coded proteins and a host cell protein were present in the partially purified replication complex but were removed by digestion with ribonuclease T1, leaving only the major virus coded protein. The tryptic peptide maps of the VIA antigen of the seven serotypes of the virus were similar, suggesting a high level of conservation in that region of the genome coding for the RNA polymerase of each type.
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PMID:Purification and identification of the RNA-dependent RNA polymerase of foot-and-mouth disease virus. 23 34

Pulse-chase labeling and cell fractionation were used to examine the pathways taken by the three nucleocapsid polypeptide species of vesicular stomatitis virus into nucleocapsids and then into virions. An improved method of polyacrylamide gel electrophoresis resolved nucleocapsid polypeptides N and NS from cellular actin, facilitating accurate quantitation of the viral polypeptides. Contrary to previous belief, the rate of NS synthesis was found to be a constant fraction of total virus protein synthesis throughout infection, indicating a consistent mechanism of virus protein synthesis regulation. In the kinetic studies, each polypeptide species displayed the following characteristic behavior. (i) Structural polypeptide N was the only species that entered a metabolically active soluble pool before assembly into nucleocapsids. The size of this pool increased with time after infection, causing an increasing delay in the appearance of pulse-labeled N molecules in nucleocapsids. (ii) Throughout infection, the entire complement of L molecules entered nucleocapsids immediately after their synthesis, without diversion through a soluble pool. (iii) Although 75% of newly synthesized molecules of the transcriptase-associated protein NS entered a soluble pool, they never emerged from the compartment. At all times after infection, about 25% of the NS molecules bypassed the soluble pool and entered nucleocapsids directly after their synthesis, as if in concert with L. These results indicate that VSV nucleocapsid assembly in vivo is a stepwise process, comprising an initial condensation of N with the viral RNA, followed by attachment of L and NS, analogous to the stepwise assembly of Sendai virus nucleocapsids. (D. W. Kingsbury, C.-H. Hsu, and K. G. Murti. Virology 91:86-94, 1978). About half of the intracellular nucleocapsids were recovered in a form that sedimented at anomalously low centrifugal forces, reflecting an association with large cellular organelles. This attachment was mediated mainly by electrostatic forces, since these "bound" nucleocapsids were released by elevated salt concentrations. The kinetic behavior of nucleocapsid polypeptides was the same in both fractions, providing no evidence for a division of nucleocapsid functions between cellular compartments.
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PMID:Assembly of vesicular stomatitis virus nucleocapsids in vivo: a kinetic analysis. 23 81


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