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)

Carrier cultures of L cells infected with wild-type vesicular stomatitis virus (VSV0) were initiated without the use of defective-interfering particles or homologous interferon. The cloned viruses recovered from such carrier cultures after passage 21 were characterized as temperature-sensitive. Furthermore, these clones of the mutant showed restricted replication at permissive temperature in HEp-2 cell cultures as compared to the wild-type VSV0. This restrictive replication of the mutant in HEp-2 cells was not due to a defect in the expression of virion-associated primary transcriptase activity in vivo, but due to the marked reduction in virus-specific characterized may govern the synthesis of mutant virus-specific amplified RNA in HEp-2 cells.
J Gen Virol 1981 Jun
PMID:Host restriction property of a vesicular stomatitis virus mutant isolated from carrier cultures. 627 Feb 62

The kinetics of synthesis and the metabolic stability of uncapped vesicular stomatitis virus (VSV) mRNA transcripts have been studied using techniques which clearly differentiate them from other RNA species. The triphosphate-initiating mRNA transcripts accumulate for at least 5 h during a typical in vitro transcription reaction. The great majority of these transcripts are smaller than a functional message and have been released from the template-transcriptase complex. Label that accumulates in them is stable and is not detectably diminished after a 1 h chase with unlabelled precursor. These kinetic properties are not these expected for active intermediates in mRNA synthesis and suggest that the uncapped transcripts are products of aborted transcription that accumulate during the transcriptive process. However, we cannot rule out that a small subset of these transcripts may be elongated into mature mRNA. Initiation of transcription at internal positions along the VSV genome is both frequent (one-half to one-sixth as frequent as initiations at the leader RNA gene) and site-specific (occurring only at the beginning of cistrons). The relevance of these results to the models for VSV transcription is discussed.
J Gen Virol 1982 Feb
PMID:The metabolic fate of independently initiated VSV mRNA transcripts. 627 64

The multiplication of murine coronavirus strains A59 or JHM in Sac(-) cells was unaffected by the presence of alpha-amanitin at concentrations which inhibited the host cell DNA-dependent RNA polymerase activity. In cells infected with the A59 virus strain, actinomycin D-resistant RNA synthesis could readily be detected by pulse-labelling with [3H]uridine; this virus-specific RNA synthesis was not induced in the presence of the protein synthesis inhibitor anisomycin. A new RNA-dependent RNA polymerase activity was detected in the large particle fraction of A59 virus-infected cells. Optimal conditions for enzyme activity in vitro were established. Maximum activity occurred 5 h after infection, coincident with the peak of virus-specific RNA synthesis detected by pulse-labelling in vivo.
J Gen Virol 1983 Jan
PMID:RNA-dependent RNA polymerase activity in murine coronavirus-infected cells. 629 95

The effect of proteins soluble in acidic chloroform-methanol (ACMS proteins) on the transcriptase activity of virus ribonucleoproteins (RNPs) in vitro has been studied. Experiments with ACMS membrane (M) proteins from type A and B orthomyxoviruses, as well as from vesicular stomatitis virus, showed that inhibition of the viral RNP transcriptase activity occurred when they interacted with M proteins isolated from viruses of a different serotype, or even of a different family. The presence of ACMS proteins capable of inhibiting the transcriptase activity of orthomyxovirus RNP in vitro was also detected in human blood plasma and among proteins produced by human leukocytes. Determination of the minimum concentration of M protein inhibiting the RNP transcriptase activity, and analysis of the fowl plague virus M protein-RNP complex formed in the in vitro system, showed that the M protein was capable of inhibiting RNP transcriptase activity at a M:RNP ratio of 0.1 to 0.2:1.
J Gen Virol 1983 Feb
PMID:In vitro inhibition of negative strand virus transcriptase activity by proteins soluble in acidic chloroform-methanol. 630 Feb 85

Eleven temperature-sensitive (ts) mutants of influenza A (fowl plague, Rostock) virus were analysed for in vitro RNA transcriptase activity in reactions primed by ApG or globin mRNA at 31 degrees C or at 40.5 degrees C, the restrictive temperature for ts mutant growth. Only those ts mutants studied which were defective in RNA segment 1, coding for the virion P2 protein, were defective in RNA transcriptase activity when compared to wild-type virus. Mutants having a defect in the P2 protein had no significant RNA transcriptase activity in reactions at 40.5 degrees C primed by globin mRNA. However, one mutant showed RNA transcriptase activity similar to wild-type virus at 40.5 degrees C when ApG (0.3 mM) was used as primer. The results suggest that influenza (fowl plague, Rostock) P2 protein is directly involved in the mRNA priming reaction, as well as in the RNA transcription reaction in vitro.
J Gen Virol 1981 Dec
PMID:Evidence for the involvement of influenza A (fowl plague Rostock) virus protein P2 in ApG and mRNA primed in vitro RNA synthesis. 689 49

Influenza viruses, which had lost up to 99.999% infectivity by incubation with antibody (a) specific for the haemagglutinin (HA) or with monoclonal alpha-HA, attached on to and penetrated chick embryo fibroblast (CEF) cells to the same extent as non-neutralized virus. Neutralized virus was also uncoated efficiently as shown by the accumulation of virion RNA in the nucleus and virion envelope in the cytoplasm. Polyacrylamide gel electrophoresis of virion RNA segments recovered from the nucleus or cytoplasm of cells inoculated with neutralized or non-neutralized virus showed that antibody did not potentiate degradation of RNA. However, these RNAs were not expressed since virus-induced proteins were not detected in cells to which neutralized virus had been added. Assay of virion transcriptase of neutralized virus in vitro showed that its activity was reduced up to sevenfold compared with non-neutralized virus, and annealing studies showed that no detectable transcription took place in vivo with neutralized virus. These studies support the conclusion that antibody directed specifically against the HA protein on the outer surface of the influenza virus particle neutralizes infectivity by inactivating virion transcriptase activity and it is suggested that antibody to HA brings about allosteric rearrangements in the HA molecule which are transmitted across the virus envelope to the interior of the particle.
J Gen Virol 1982 Feb
PMID:Studies on the mechanism of neutralization of influenza virus by antibody: evidence that neutralizing antibody (anti-haemagglutinin) inactivates influenza virus in vivo by inhibiting virion transcriptase activity. 706 92

S-Adenosyl-L-methionine (SAM), a methyl donor, and its analogue S-adenyl-L-homocysteine (SAH), an inhibitor of methylation, stimulate the activity of spring viraemia of carp virus (SVCV) virion transcriptase. The stimulation observed for SVCV is analogous to that observed previously (Furuichi, 1974, 1978) for a totally unrelated virus, cytoplasmic polyhedrosis virus (CPV). In the absence of exogenous SAM, RNA with 5'-methylated termini (presumptive GpppAmpAp) was produced, indicating that SVCV has an endogenous methyl donor. Significantly less methylated termini were produced when SVCV nucleocapsids were used to prime in vitro transcription reactions, suggesting that the majority of the endogenous methyl donor is not associated with the nucleocapsid. Partial removal of endogenous methyl donor by preparing nucleocapsids did not have any effect on the degree of stimulation by exogenous SAM or SAH. We conclude from this study that SAH has two effects on SVCV transcription, inhibition of methylation and stimulation of transcription.
J Gen Virol 1981 Mar
PMID:Stimulation of transcription by S-adenosyl-L-homocysteine and virion-encapsidated methyl donor in spring viraemia of carp virus. 727 15

Monoclonal antibodies were produced using a purified cucumber mosaic virus (CMV) replicase complex, and Escherichia coli-expressed CMV 1a and 2a proteins, as immunogens. Five out of eight monoclonal antibodies, which bound to the 1a and 2a proteins in immunoblots, inhibited the RNA-dependent RNA polymerase (RdRp) activity of the purified replicase complex in vitro. Epitope mapping showed that two of the inhibitory antibodies interacted with regions of the 1a protein containing putative helicase and methyltransferase domains respectively. Two other inhibitory antibodies mapped to a region of the 2a protein containing the GDD motif which is highly conserved in RdRps. Prior interaction of the latter antibodies with a peptide containing the GDD motif prevented the antibody-mediated inhibition of the replicase. Polyclonal antibodies which inhibited the RdRp activity of the replicase complex were also produced using peptides corresponding to conserved helicase and polymerase motifs in the 1a and 2a proteins. The greatest inhibition was shown by antibodies to a peptide containing the GDD motif. These results demonstrate the functional importance of the identified sequence motifs in CMV RNA replication and indicate that the motifs are located in the replicase complex at positions accessible to antibodies, consistent with roles in interacting with the RNA template, RNA primer and enzyme substrates.
J Gen Virol 1994 Nov
PMID:Localization of functional regions of the cucumber mosaic virus RNA replicase using monoclonal and polyclonal antibodies. 752 62

The entire sequence of 13952 nucleotides of a plasmid-like, double-stranded RNA (dsRNA) from rice was assembled from more than 50 independent cDNA clones. The 5' non-coding region of the coding (sense) strand spans over 166 nucleotides, followed by one long open reading frame (ORF) of 13716 nucleotides that encodes a large putative polyprotein of 4572 amino acid residues, and by a 70-nucleotide 3' non-coding region. This ORF is apparently the longest reported to date in the plant kingdom. Amino acid sequence comparisons revealed that the large putative polyprotein includes an RNA helicase-like domain and an RNA-dependent RNA polymerase (replicase)-like domain. Comparisons of the amino acid sequences of these two domains and of the entire genetic organization of the rice dsRNA with those found in potyviruses and the CHV1-713 dsRNA of chestnut blight fungus suggest that the rice dsRNA is located evolutionarily between potyviruses and the CHV1-713 dsRNA. This plasmid-like dsRNA in rice seems to constitute a novel RNA replicon in plants.
Mol Gen Genet 1995 Aug 21
PMID:Double-stranded RNA in rice: a novel RNA replicon in plants. 756 98

The genome of cowpea mottle virus (CPMoV) is a positive ssRNA of 4029 nucleotides with six major open reading frames (ORFs). A non-coding region of 34 nucleotides precedes the first AUG. ORF1 encodes a 25 kDa polypeptide of unknown function and ORF2 encodes a 56 kDa putative RNA replicase. Like other members of carmoviruses, suppression of the amber termination codon of ORF1 would produce a readthrough polypeptide of 83 kDa. ORF3 and ORF4 encode two small proteins of 7.8 and 9.8 kDa, respectively. ORF5 encodes the 40 kDa capsid protein. ORF6 is located within ORF5 but is in a different frame and has no postulated function. CPMoV RNA is blocked at the 5' end and is not polyadenylated at the 3' end. Comparison of the physicochemical properties, genomic arrangement, and predicted amino acid sequences with those of other viruses justify the assignment of CPMoV to the genus Carmovirus, family Tombusviridae.
J Gen Virol 1995 Nov
PMID:The nucleotide sequence of cowpea mottle virus and its assignment to the genus Carmovirus. 759 92


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