Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The roles of the L and NS polypeptides in transcription by vesicular stomatitis virus New Jersey were studied using a mutant, tsE1, which contains a temperature-sensitive transcriptase and an altered NS polypeptide, both phenotypic changes being the consequence of the ts mutation. Mutant tsE1, its revertant (tsE1/R1) and the wild-type virus were dissociated into sub-viral fractions and, after reconstitution of these fractions in all combinations, the transcriptase was assayed in vitro at the permissive (31 degrees C) and restrictive (39 degrees C) temperatures. Reconstitution of the pellet fractions (containing polypeptide N complexed with the virion RNA) and the supernatant fractions (containing polypeptides L and NS) restored transcriptase activity at 31 degrees C in all combinations, but at 39 degrees C transcription was observed only in the presence of the supernatant fractions of wild-type and revertant viruses but not in the presence of the supernatant fractions of tsE1. When the pellet fractions and the L fractions were reconstituted, the transcriptase activity was restored in all combinations both at 31 degrees C and 39 degrees C. However, in vitro transcription at 39 degrees C by reconstituted pellet and L fractions was strongly inhibited when the NS fraction of tsE1 was also added, while addition of the NS fractions of wild-type and revertant viruses had no effect. Since only traces of polypeptide NS were present in the L fractions and none in the pellet fractions, the results strongly suggest that polypeptide L is the transcriptase itself while polypeptide NS exerts some control over transcription.
J Gen Virol 1985 May
PMID:The role of polypeptides L and NS in the transcription process of vesicular stomatitis virus New Jersey using the temperature-sensitive mutant tsE1. 298 93

Two conditional transcriptase-negative mutants of vesicular stomatitis virus (VSV) serotype New Jersey, tsB1 and tsF1, their revertants tsB1/R1 and tsF1/R1 and the wildtype virus were dissociated into pellet, NS and L fractions and, after reconstitution of these in various combinations, the transcriptase activities were assayed in vitro at the permissive (31 degrees C) and restrictive (39 degrees C) temperatures. The pellet fractions contained the virion RNA-polypeptide N complexes, while the NS and L fractions were essentially pure preparations of these polypeptides. The synthesis of RNA by the reconstituted pellet and L fractions was inhibited at 39 degrees C only when the L fractions of tsB1 or tsF1 were used. Addition of the NS fractions to the reconstituted pellet and L fractions did not alter the rates of RNA synthesis. These results demonstrate that polypeptide L is the temperature-sensitive polypeptide of both mutants tsB1 and tsF1 and support previous observations that polypeptide L is the transcriptase itself. The fact that a second mutant of complementation group F, tsF2, is transcriptase-positive but replicase-negative suggests that polypeptide L is involved both in transcription and replication. Intracistronic complementations may account for the observation that the temperature-sensitive mutations affect polypeptide L in complementation groups B and F.
J Gen Virol 1985 Jul
PMID:Temperature sensitivity of the transcriptase of mutants tsB1 and tsF1 of vesicular stomatitis virus New Jersey is a consequence of mutation affecting polypeptide L. 299 27

Phosphorylation of rabies virus proteins was followed in vivo and in vitro. The N and M1 proteins were both found to be phosphorylated. The M1 protein was present in the virion in two phosphorylated states, but only the hypophosphorylated form of M1 was found in infected cells. The hypothesis that some of the M1 molecules become hyperphosphorylated during the maturation process by a membrane-bound kinase was examined. The phosphorylation of the viral proteins by the kinase present in purified rabies virions was studied using an in vitro transcriptase assay: under the conditions of the assay, additional phosphate groups were rapidly attached to the N protein. The M1 protein was similarly hyperphosphorylated although more slowly. Whether the hyperphosphorylation of the N protein is responsible for the poor efficiency of the in vitro transcriptase reaction is not clear. No detectable change in the phosphorylation of cellular proteins was observed in the course of rabies virus infection.
J Gen Virol 1985 Oct
PMID:Phosphorylation of the N and M1 proteins of rabies virus. 299 64

Flaviviruses encode seven non-structural proteins for which functions have not yet been described. The identification of the viral and possible host proteins which may be involved in flavivirus replication has been impeded by the fact that the viral replication complexes are tightly associated with endoplasmic reticular membranes within infected cells and that in vitro polymerase activity is associated with large membrane fragments. To facilitate further study of flavivirus replication complexes, selected ultrapure detergents were analysed for their effect on West Nile virus (WNV) in vitro RNA-dependent RNA polymerase activity and for their ability to release functional replication complexes from partially purified intracellular BHK-21 membrane fragments. A few previous reports indicated that flavivirus in vitro polymerase activity was sensitive to detergent treatment. The present study indicates that WNV polymerase activity is variably inhibited depending on the concentration and identity of the detergent used. Of the five detergents (Tween 20, maltoside, octylglucoside, lubrol PX and sodium deoxycholate) tested, sodium deoxycholate was the most efficient at releasing functional viral replication complexes from intracellular membranes.
J Gen Virol 1988 Dec
PMID:Separation of functional West Nile virus replication complexes from intracellular membrane fragments. 319 3

RNA polymerase activities in parental strains of influenza A and B viruses nonpathogenic for mice and their pathogenic variants have been studied. The parental strains are A/seal/Massachusetts 1/80, A/USSR 05/81, A/Philippines 2/82, B/Singapore 222/79. The RNA polymerase activity has been also studied in recombinant strains obtained by crossing various parental strains, one of which is pathogenic for mice (AR/PR 8/34), and having different degrees of pathogenicity. The nonpathogenic viruses had low transcriptase activity. RNA polymerase activity in pathogenic variants is shown to be 1.5-3 times higher than that in the parental strains. All the recombinants, whatever their pathogenicity, had approximately the same transcriptase activities which were 1.5-2 times higher than those registered in parental nonpathogenic strains.
Mol Gen Mikrobiol Virusol 1986 Dec
PMID:[Activity of virion RNA-polymerase in influenza A and B virus variants with different pathogenicities for mice]. 380 28

Six temperature-sensitive (ts) mutants of vesicular stomatitis virus (VSV) isolated from the central nervous system (CNS) following injection with ts G31 (III) all possessed a post-transcriptional defect, not found in the initial virus, that affects the stability of viral RNA transcripts. Examination of viral RNA metabolism in mouse neuroblastoma (N-18) cells revealed that RNA synthesis of the CNS isolates was decreased considerably at elevated temperatures (up to 80 or 90% at 39 degrees C). In addition, analysis of the RNA transcripts suggested that little if any normal-sized transcripts were made in cells infected with these CNS isolates at either 37 degrees C or 39 degrees C. The RNA deficiencies did not appear to be the result of a temperature-sensitive lability of virion transcriptase as examined by in vitro transcriptase assays. However, when N-18 cells infected with one of the CNS isolates, ts G31 BP, were first preincubated at the permissive temperature of 31 degrees C for 3 h and then shifted to 39 degrees C, RNA synthesis proceeded at a rate comparable to that of 31 degrees C. The viral mRNA species synthesized following the temperature shift also contained normal sized tracts of poly(A) RNA, suggesting that neither the viral transcriptase nor its polyadenylate synthetase was thermally labile. However, for any of the six CNS isolates, all species of viral RNA synthesized in cells that were first preincubated at 31 degrees C degraded rapidly when the cells were shifted to 39 degrees C. In contrast little or no RNA degradation of either 42S progeny RNA or mRNA species was detected in the wild-type VSV, ts G31 or three other VSV mutants that are defective in some aspect of viral RNA metabolism: [ts G11 (I), ts G22 (II), ts G41 (IV)]. The apparent phenotype alteration in the stability of viral RNA in all of these CNS isolates is discussed in terms of the possible genotypic changes that may have occurred as well a the unique CNS disease that accompanies infection by these viruses.
J Gen Virol 1981 Aug
PMID:RNA degradation defect in central nervous system isolates of vesicular stomatitis virus. 616 98

The relationship between the in vitro phosphorylation of vesicular stomatitis virus (VSV) proteins and virion uncoating was examined. Activation of the VSV virion kinase with low concentrations of melittin, the active peptide component of bee venom, in the presence of gamma-[32P] ATP resulted in the phosphorylation of virion proteins. Following the in vitro phosphorylation of VSV proteins in the presence of melittin and deoxyadenosine triphosphate, the virion envelope was disrupted based on the accessibility of the internal ribonucleoprotein core (RNP) to the heavy metal stain, uranyl acetate, as determined by electron microscopic observation. The RNP structure was not observed in unphosphorylated virions treated with melittin and uranyl acetate. Phosphorylated virions treated with uranyl acetate subsequently lost the capacity for transcription whereas unphosphorylated virions treated with the stain retained transcriptase activity. These observations suggest that phosphorylation of VSV proteins may contribute to virion uncoating by disrupting the virus envelope.
J Gen Virol 1981 Oct
PMID:Phosphorylation of vesicular stomatitis virus proteins as a possible contributing factor in virion uncoating. 617 11

The presence of an RNA-dependent RNA polymerase was demonstrated in purified infectious pancreatic necrosis virus (IPNV). The enzyme was active in vitro without any pretreatment of the virus. Optimum activity was shown at 30 degrees C, pH 8 and in the presence of 6 mM-magnesium ions. Approx. 50% of the polymerase product remained associated with the dsRNA template of the virions. The remainder was found as extravirion ssRNA broken down to 5S to 7S fragments by virus-associated RNase(s). Although the addition of bentonite considerably reduced the amount of RNA synthesized, it protected the ssRNA product from degradation. This, in turn, permitted the synthesis of small amounts of ssRNA, which when analysed by sucrose gradient centrifugation or polyacrylamide gel electrophoresis behaved identically to the 24S single-stranded virus mRNA produced in infected cells. The virion polymerase was not stimulated by S-adenosyl-L-methionine or the addition of cellular or capped reovirus ssRNA. Several other modifications of the assay system were tried in an attempt to increase 24S RNA synthesis, but with little success. When [3H]uridine-labelled virus was used in the polymerase reaction, some labelled 24S ssRNA was obtained, indicating that in vitro transcription may proceed by a semi-conservative (displacement) mechanism.
J Gen Virol 1982 Mar
PMID:In vitro RNA synthesis by infectious pancreatic necrosis virus-associated RNA polymerase. 617 31

Ibaraki virus core particles were purified from infected BHK-21 cells. The core particles displayed RNA transcriptase activity while the virion did not. The RNA transcriptase activity was stimulated about 15-fold by addition of S-adenosyl-L-methionine. The reaction product was single-stranded RNA which could be hybridized with heat-denatured Ibaraki virus RNA. The hybrids possessed the same electrophoretic mobility as Ibaraki virus double-stranded RNA.
J Gen Virol 1983 Jun
PMID:Characterization of ribonucleic acid transcriptase in Ibaraki virus core particles. 618 66

Soluble transcriptase containing the L and the NS proteins was isolated from purified vesicular stomatitis virus and its binding with the template ribonucleoprotein containing the N protein-RNA complex was studied with respect to its ability to initiate and synthesize RNA in vitro. By using u.v.-irradiated template reconstituted with soluble transcriptase, it was shown that the synthesis of leader RNA and other small initiated mRNA sequences continued while full-length mRNA synthesis decreased by 90%. In the presence of ATP and CTP, the reconstituted complex synthesized polyphosphorylated oligonucleotides which include AC, AAC and AACA which represent 5'-terminal sequences transcribed from the leader template and genes coding for mRNAs. In the presence of arabinosyl ATP, an inhibitor of RNA synthesis in vitro, the synthesis of leader RNA was found to be inhibited considerably more than other small initiated mRNA sequences. Reconstitution of RNA synthesis with soluble transcriptase and template in the presence of viral matrix (M) protein at low ionic condition resulted in virtual cessation of leader RNA synthesis, although the synthesis of small initiated N mRNA, 11 to 14 bases, continued. These results suggest that transcriptase can bind at multiple sites on the genome template and initiate RNA chains.
J Gen Virol 1984 Mar
PMID:Interaction of L and NS proteins of vesicular stomatitis virus with its template ribonucleoprotein during RNA synthesis in vitro. 619 59


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