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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By serial subculture of MDCK cells which survived high multiplicity infections with AWBY-140, a weakly cytolytic mutant of influenza virus A/WSN (H1N1), we established a variant cell line (MDCK-L cells) that was uniquely resistant to infection with influenza A and B viruses, yielding 3 to 4 orders lower amount of progeny virus compared with MDCK cells. Competitive polymerase chain reaction revealed that the amount of primary transcript produced in MDCK-L cells infected with 10 PFU/cell of influenza virus A/Aichi was suppressed to 1/100 of that in MDCK cells similarly infected, although the amount of virus adsorbed to MDCK-L cells was 1/4 of MDCK cells. Even when MDCLK-L cells were infected with 40 PFU/cell of Aichi to overcome the lower amount of internalized virus in those cells, the results were the same. The synthesis of v-, c- and mRNAs, as well as proteins of infected A/Aichi was below detectable level in MDCK-L cells, in contrast with MDCK cells, where they were clearly demonstrable by ribonuclease protection assay or polyacrylamide gel electrophoresis.
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PMID:A variant of MDCK cell line which restricted growth of influenza viruses mainly through suppression of viral primary transcription. 867 37

We have investigated the endonuclease activity of the influenza A virus RNA polymerase in an in vitro assay with an artificial influenza-like mRNA containing a cap structure at its 5' terminus, followed by a 10 nt beta-globin mRNA sequence, and the 5' and 3' conserved termini of a truncated nucleoprotein (NP) cRNA influenza sequence. Results showed that partially purified virion ribonucleoprotein complexes (RNPs) and micrococcal nuclease treated RNPs cleaved the artificial influenza-like mRNA substrate specifically at positions near the 5' terminus to generate capped 14 and 15 nucleotide long RNA fragments which subsequently served as primers to initiate transcription. The endonuclease activity was completely blocked by addition of cap analog and competitively inhibited by added globin mRNA. Furthermore, an in vitro reconstituted influenza RNA transcription reaction containing a truncated NP vRNA as template, micrococcal nuclease treated RNPs and globin mRNA as primer, synthesized capped and uncapped full length (+) sense products. Enzyme kinetics showed that capped RNA was made earlier in the reaction; it reached a peak at 120 min and then declined. However, uncapped cRNA synthesis appeared later and remained as the dominant product later in the reaction. The nature of these products was confirmed by ribonuclease protection assays and by primer extension.
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PMID:Influenza A virus RNA-dependent RNA polymerase cleaves influenza mRNA in vitro. 880 82

A Chinese hamster alpha-tubulin cDNA was modified to encode an 11-amino acid carboxyl-terminal extension containing the immunodominant epitope from influenza hemagglutinin antigen (to create HA alpha 1-tubulin) and was cloned into a vector for expression in mammalian cells. 12 stable CHO cell lines expressing this HA alpha 1-tubulin were isolated and characterized. HA alpha 1-tubulin incorporated into all classes of microtubules, assembled to the same extent as the endogenous tubulin, and did not perturb the growth of the cells in which it was expressed. However, overexpression of HA alpha 1-tubulin strongly repressed the synthesis of endogenous alpha-tubulin while having little or no effect on the synthesis of beta-tubulin. Treatment of transfected cells with sodium butyrate to induce even greater expression of HA alpha 1-tubulin led to a further decrease in synthesis of endogenous alpha-tubulin that was fully reversible upon removal of the inducer. Decreased synthesis of alpha-tubulin in transfected cells did not result from decreased levels of alpha-tubulin mRNA, as demonstrated by ribonuclease protection assays. On the other hand, colchicine, a drug previously shown to destabilize the tubulin message, caused a clear reduction in both protein synthesis and mRNA levels for transfected HA alpha 1-tubulin and endogenous alpha-tubulin, thus indicating that the decreased alpha-tubulin synthesis observed as a result of HA alpha 1-tubulin overexpression is distinct from the previously described autoregulation of tubulin. The results are consistent with a mechanism in which free alpha-tubulin inhibits the translation of its own message as a way of ensuring stoichiometric synthesis of alpha- and beta-tubulin.
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PMID:alpha-Tubulin limits its own synthesis: evidence for a mechanism involving translational repression. 897 20

The transcription and replication of influenza virus RNA (vRNA) were reconstituted in vivo. The experimental approach involved the transfection of plasmids encoding the viral subunits of the polymerase and the nucleoprotein into cells infected with a vaccinia virus recombinant virus expressing the T7 RNA polymerase. As templates, one of two model RNAs was transfected: vNSZ or cNSZ RNA. The RNAs were 240 nucleotides in length, contained the terminal sequences of the NS viral segment, and were of negative or positive polarity, respectively. The accumulation of cRNA and mRNA in cells transfected with vNSZ RNA and the accumulation of vRNA and mRNA in cells transfected with cNSZ RNA were determined by RNase protection assays with labeled vNSZ-L or cNSZ-L probes. The patterns of protected bands obtained indicated that both cRNA replication intermediate and mRNA accumulated when the system was reconstituted with vNSZ RNA. Likewise, both vRNA and mRNA accumulated after reconstitution with cNSZ RNA. The reconstitution of incomplete systems in which any of the subunits of the polymerase or the model RNA were omitted was completely negative for the accumulation of cRNA or vRNA, indicating that the presence of the PB2 subunit in the polymerase is required for replication of vRNA.
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PMID:The influenza A virus PB2 polymerase subunit is required for the replication of viral RNA. 899 63

When MDCK cells in a semiconfluent monolayer were infected with 5 p.f.u. per cell of influenza virus A/PR/8/34 (H1N1), a majority of the cells continued to grow stably upon subsequent cultivation with a growth medium containing 50% foetal calf serum. While growing, the cells spontaneously excreted virus, the amount of which declined gradually as the passage number of the cells increased. The extent of virus shedding was significantly increased when the cells were subsequently maintained in a medium containing 0.2% bovine serum albumin. Within the cells, viral messenger RNAs for all eight genes of A/PR/8 were demonstrated by PCR indicating that endogenous viral genes were constitutively transcribed. However, viral proteins as well as viral genes were not demonstrable by radioimmunoprecipitation or ribonuclease protection assays, respectively.
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PMID:Spontaneous excretion of virus from MDCK cells persistently infected with influenza virus A/PR/8/34. 904 5

Glycoproteins generally exist as populations of glycosylated variants (glycoforms) of a single polypeptide. Although the same glycosylation machinery is available to all proteins that enter the secretory pathway in a given cell, most glycoproteins emerge with characteristic glycosylation patterns and heterogeneous populations of glycans at each glycosylation site. The factors that control the composition of the glycoform populations and the role that heterogeneity plays in the function of glycoproteins are important questions for glycobiology. A full understanding of the implications of glycosylation for the structure and function of a protein can only be reached when a glycoprotein is viewed as a single entity. Individual glycoproteins, by virtue of their unique structures, can selectively control their own glycosylation by modulating interactions with the glycosylating enzymes in the cell. Examples include protein-specific glycosylation within the immunoglobulins and immunoglobulin superfamily and site-specific processing in ribonuclease, Thy-1, IgG, tissue plasminogen activator, and influenza A hemagglutinin. General roles for the range of sugars on glycoproteins such as the leukocyte antigens include orientating the molecules on the cell surface. A major role for specific sugars is in recognition by lectins, including chaperones involved in protein folding. In addition, the recognition of identical motifs in different glycans allows a heterogeneous population of glycoforms to participate in specific biological interactions.
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PMID:Glycosylation: heterogeneity and the 3D structure of proteins. 906 19

The interaction of influenza virus NS1 protein with other viral products in the infected cell was analysed by co-immunoprecipitation studies. The three subunits of the polymerase and the nucleoprotein, but not M1 protein, were co-immunoprecipitated by NS1-specific serum but not when control serum was used. Such co-immunoprecipitation was not sensitive to RNase treatment of the immunoprecipitates. Co-immunoprecipitation was also obtained when the viral transcription-replication system was reconstituted in vivo by transfection of cDNAs and model vRNA template into vaccinia virus-T7-infected cells. Analysis of the RNA pulled-down in the NS1-specific precipitates indicated the presence of both vRNA and mRNA. These results are discussed in the context of the phenotype of virus temperature-sensitive mutants affected in the NS1 gene.
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PMID:Influenza virus NS1 protein interacts with viral transcription-replication complexes in vivo. 934 63

Antibodies (Abs) hydrolyzing proteins, DNA, and RNA are detected in the blood of patients with various autoimmune diseases. In the present work, homogeneous preparations of IgG Abs from the blood of the healthy donors as well as patients with A, B, C, and delta types of viral hepatitis, influenza, pneumonia, tuberculosis, tonsillitis, duodenal ulcer, and some types of cancer were purified. For the first time, the fraction of IgG and its Fab fragments of patients with viral hepatitis were shown to have high DNA- and RNA-hydrolyzing activity. In case of Abs from the healthy donors and patients with other diseases, high activity of Abs was not detected. The data obtained by various methods indicate that the activity of hepatitis Abs is an intrinsic property of the immunoglobulins. The relative rates of hydrolysis of cCMP, poly(U), poly(A), poly(C), and tRNA(Phe) by hepatitis Abs were compared with those of RNase A and other RNases from human blood. Significant differences in activities of Abs and nucleases in hydrolysis of model substrates were demonstrated. Thus, catalytically active Abs can appear in the blood of patients not only with autoimmune disorders, but with viral diseases as well.
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PMID:DNA- and RNA-hydrolyzing antibodies from the blood of patients with various forms of viral hepatitis. 948 69

The M1 protein of influenza virus inhibits the in vitro transcriptase activity of ribonucleoprotein cores from virions. This inhibitory activity is thought to be relevant in vivo because accumulation of M1 at the late stages of viral replication may be the cue to halt viral mRNA production. A model influenza reporter genome was used to explore the effect of M1 on the activity of the influenza virus transcriptase complex within cultured cells. Expression of M1 in cells bearing the model influenza virus reporter genome was accompanied by a reduction of CAT gene expression to 12% of control levels. Quantification of RNA by ribonuclease protection assay revealed that the influenza reporter genome mRNA levels in M1-expressing cells were reduced by approximately 74% compared with those of cells expressing a control protein. These findings are consistent with the proposed model in which M1 is responsible for limiting viral transcription during late stages of infection. By expressing truncated forms of M1, the inhibitory activity was found to reside within the amino-terminal half of the M1 protein. Two independent inhibitory domains were identified in this region: one between amino acid residues 1-90 and the other spanning residues 91-127.
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PMID:The matrix 1 protein of influenza A virus inhibits the transcriptase activity of a model influenza reporter genome in vivo. 974 Jul 76

The viral factor responsible for triggering the acute phase response, or 'flu' syndrome, associated with many acute viral infections is not defined. One candidate viral factor is double-stranded RNA (dsRNA) generated during viral replication. In this report we demonstrate by reverse-transcriptase polymerase-chain reaction that nuclease-stable viral RNA was released from influenza-infected MDCK epithelial cells at the time of cell lysis. Removal of virion-associated RNA by ultracentrifugation left equal amounts of positive- and negative-strand viral RNA in the medium that resisted degradation by endogenous RNase in the medium and by exogenous RNase added prior to phenol extraction. These data are the first demonstration that viral RNA with characteristics of dsRNA is spontaneously released from dying influenza virus-infected cells, and thus is available to amplify cytokine induction and contribute to systemic disease.
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PMID:Spontaneous release of stable viral double-stranded RNA into the extracellular medium by influenza virus-infected MDCK epithelial cells: implications for the viral acute phase response. 993 Jan 93


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