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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The virion transcriptase (nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) of vesicular stomatitis virus was fully active when ribonucleoprotein cores from purified virions were added to cell-free protein synthesizing systems of eukaryotic origin. Synthesis of mRNA was linear for at least 3 hr and the newly synthesized viral mRNA was efficiently utilized for the synthesis of viral proteins N (nucleoprotein), NS, and M (matrix); small amounts of a putative G (glycoprotein protein precursor and several unidentified polypeptides were regularly synthesized. The ratio of the various newly synthesized viral proteins was identical after different periods of coupled mRNA and protein synthesis. Identical proteins were obtained when the cell-free protein synthesizing systems were programmed with purified VSV mRNA synthesized in vitro. No detectable L protein was synthesized, even though transcripts complementary to the complete viral genome were detectable in the mRNA preparation by hybridization.
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PMID:Coupled in vitro transcription and translation of vesicular stomatitis virus messenger RNA. 17 Jun 4

The in vitro activity of the ribonucleoprotein-dependent RNA transcriptase of vesicular stomatitis virions was found to be completely inhibited by low concentrations of aurintricarboxylic acid (ATA) and polyethylene sulfonic acid (PES) when these inhibitors were added before the start of the RNA polymerase reaction. However, if RNA synthesis was allowed to occur before ATA or PES was added, RNA synthesis continued for a short time (10 min or less) in the presence of either inhibitor at a concentration which completely inhibited uninitiated enzyme. The ability to continue to synthesize RNA in the presence of ATA or PES only developed if all four nucleoside triphosphates were present during the preincubation period prior to the addition of the inhibitors. The protection was apparently not due to the released products of RNA polymerization. The results are interpreted as indicating that ATA and PES probably inhibit some reaction other than elongation of RNA chains, and this reaction might be one involved at or near initiation sites.
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PMID:Inhibition by aurintricarboxylic acid and polyethylene sulfonate of RNA transcription of vesicular stomatitis virus. 17 45

We established previously that the temperature-dependent host range mutant, td CE 3, of vesicular stomatitis virus (VSV) New Jersey possesses temperature-sensitive RNA transcriptase activity. In this paper, we describe dissociation and reconstitution experiments designed to determine which VSV polypeptide is affected by the td CE 3 mutation. Wild-type VSV New Jersey (ts+), the temperature-dependent host range mutant (td CE 3), and the revertant of this mutant (td CE/R1) were used. Transcribing nucleoprotein preparations, isolated from purified virus particles, were treated in the presence of digitonin with either 0.9 M LiCl to produce supernatants containing virtually only the L polypeptide or 2.0 M LiCl to produce ribonucleoprotein pellets containing only the polypeptides N and NS. Supernatant and pellet fractions synthesized either no or only trace amounts of RNA in vitro. Reconstitution of the supernatants with the pellets in all combinations at 31 degrees C restored much of the transcriptase activity of the transcribing nucleoprotein preparations. RNA synthesis occurred at 39 degrees C when the three pellets were reconstituted with wild-type and revertant supernatants. However, supernatant of the mutant td CE 3 reconstituted with any of the three pellets resulted in little or no detectable transcriptase activity at 39 degrees C. This implies that the polypeptide affected by the td CE 3 mutation is the L polypeptide.
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PMID:Temperature-dependent host range mutation in vesicular stomatitis virus affecting polypeptide L. 19 60

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

We have developed an in vitro assay for the lymphocytic choriomeningitis virus (LCMV) RNA-dependent RNA polymerase with ribonucleoprotein complexes extracted from acutely infected tissue culture cells. The RNA products synthesized in vitro corresponded in size to the full-length genomic L and S RNAs and subgenomic NP and GP mRNAs normally produced in vivo during acute LCMV infection. In a temporal analysis spanning the first 72 h of acute infection, the in vitro polymerase activity of ribonucleoprotein complexes was maximal at 16 h and declined significantly at later times. In contrast, the intracellular levels of the viral L protein (the putative polymerase protein) appeared to be maximal at 48 to 72 h postinfection. Our results suggest that the accumulation of L protein correlates with reduced viral replication and transcription at later times in acute infection and may be involved in the transition from acute to persistent LCMV infection.
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PMID:Detection of virus-specific RNA-dependent RNA polymerase activity in extracts from cells infected with lymphocytic choriomeningitis virus: in vitro synthesis of full-length viral RNA species. 270 71

The complete RNA sequence of the L protein gene of lymphocytic choriomeningitis virus (LCMV) is presented. It is the first L protein sequence to be obtained for the Arenaviridae, a family of single-stranded RNA viruses which includes Lassa fever virus, and the Tacaribe complex viruses such as Pichinde and the Argentine and Bolivian hemorrhagic fever viruses. It is the largest open reading frame on the L RNA spanning 6633 nucleotides and coding for a 2210 amino acid protein with a calculated molecular weight of 254,529. Antipeptide sera identify a gene product encoded on the L RNA: it has a mass of approximately 200,000 Da and is found in virions and ribonucleoprotein complexes from infected cells (M. Singh, F. Fuller-Pace, M. J. Buchmeier, and P. J. Southern, 1987, Virology, 161, 448-456). Mutations mapped to the L gene affect plaque morphology (Kirk et al., 1980), the lethality of a virulent LCMV strain on guinea pigs (Y. Riviere, R. Ahmed, P. J. Southern, M. J. Buchmeier, and M. B. A. Oldstone, 1985, J. Virol., 55, 704-709), and the ability of a variant strain of LCMV to suppress the cytotoxic T-cell response and initiate persistent infection (M. Salvato, E. Shimomaye, P. Southern, and M. B. A. Oldstone, 1988, Virology, 164, 517-522; Ahmed et al., 1988). All of these phenotypes indicate that the viral genes on the L strand are critical elements controlling virus replication and the pattern of LCMV infection. The L gene sequence encodes a viral polymerase although this protein bears little resemblance to the published sequences of other RNA virus polymerases. Therefore the LCMV polymerase likely represents a distinct category of viral transcriptase.
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PMID:The primary structure of the lymphocytic choriomeningitis virus L gene encodes a putative RNA polymerase. 270 3

Using morphological and cell biological techniques, we have shown that the RNA replicase of Semliki Forest and Sindbis virus (two closely related alphaviruses) is located in complex ribonucleoprotein structures associated with the cytoplasmic surface of modified secondary lysosomes and endosomes. These nucleoprotein complexes often form a bridge between the membrane of the endocytic vacuole and the rough endoplasmic reticulum where the synthesis of the structural proteins of these viruses occurs. The results suggest that these cytopathic vacuoles constitute sites not only for viral RNA synthesis, but also for translation of structural proteins, and for the assembly of nucleocapsids.
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PMID:Alphavirus RNA replicase is located on the cytoplasmic surface of endosomes and lysosomes. 290 46

Immunogold labelling and in vitro transcription of influenza virus vRNA have been used to analyse the interaction of anti-influenza polymerase antibodies with influenza-ribonucleoprotein (RNP) complexes. The polymerase proteins (P proteins) were localized exclusively at one end of the RNP segments. In the course of transcription the amount of P protein decreased significantly. The in vitro transcriptase activity y of influenza A virus RNP complexes in the presence of anti-polymerase antibodies to the strain A/PR/8/34 was inhibited by 60%. In contrast, RNP transcriptase activity of influenza B virus was not inhibited by these antibodies.
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PMID:Interaction between anti-influenza viral polymerase antibodies and RNP particles using the in vitro transcription process and an immunogold labelling technique. 290 34

The arenavirus genomic L RNA segment represents approximately 70% of the viral genetic material but current understanding of the organization, regulation, and functioning of the viral L products remains limited. Biological studies with reassortant viruses have implicated the L RNA segment in the lethal infection of adult guinea pigs produced by LCMV-WE but no further explanation of the pathogenic process is presently available. We have initiated a detailed molecular analysis of LCMV L products based on construction and characterization of L-specific cDNA clones and synthesis of L-specific hybridization probes. Nucleotide sequencing studies have allowed the derivation of a partial amino acid sequence for a predicted L protein and antisera raised against synthetic peptides have demonstrated an L protein in Western blotting experiments. Using this approach we have identified a single high molecular weight protein (approximately 200,000 Da) in purified virions and in viral ribonucleoprotein complexes extracted from acutely infected tissue culture cells. This L protein is translated from a nonpolyadenylated, genomic complementary L mRNA and potentially represents part or all of the viral RNA-dependent RNA polymerase.
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PMID:Analysis of the genomic L RNA segment from lymphocytic choriomeningitis virus. 331 94


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