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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Purified influenza virus contains ribonuclease activity. The enzyme does not hydrolyze viral RNA but both 28 S and 18 S host cell RNA are degraded forming large (about 16 S) and small (about 5 S) fragments with the release of the acid-soluble material. It has an optimum temperature of 37 degrees C, requires no divalent ions, and is inhibited by 0.1 M EDTA and 1% SDS. Treatment with 4 M urea increases enzymatic activity considerably (42%) but is not a prerequisite for eliciting ribonuclease activity suggesting that the enzyme is probably located near the surface of the virus particle. Results show that the observed enzyme activity is virus-associated as no host cell protein is detectable in the purified virus.
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PMID:Association of a ribonuclease with the purified influenza virus. 81 84

The nucleoprotein of the WSN strain of influenza was found to be phosphorylated in vitro. The phosphate-protein bond was stable to hot trichloroacetic acid, RNase, DNase, succinic acid, and succinic acid-hydroxylamine, but sensitive to hydrolysis by bacterial alkaline phosphatase. This suggested that the nucleoprotein is in the form of a phosphomonoester. Acid hydrolysis of the isolated nucleoprotein followed by thin-layer electrophoresis identified the phosphorylated amino acid residue as phosphoserine.
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PMID:Phosphorylated protein component present in influenza virions. 90 30

Chick embryo cells infected with an influenza A (fowl plague) virus have been labelled with (3H)-uridine for different lengths of time. Virion RNA and cellular RNA have been separated by specific hybridization with a surplus of unlabelled viral complementary RNA and RNase digestion. The ratio of the specific radioacticity in the UMP and CMP moieties of both types of RNA has been determined. Since the rate of approach to equilibrium of CMP to UMP labelling of both types of RNA is completely different it is concluded that cellular and virion RNA are synthesized using different pyrimidine nucleoside triphosphate pools.
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PMID:Cellular RNA and influenza-virion RNA are synthesized from different pyrimidine-nucleoside-triphosphate pools in chick-embryo cells. 123 79

The antiviral activity of a bacterial ribonuclease conjugate with chitosane of Kamchatka crab (in a form of water soluble chito-oligosaccharides) has been studied. The conjugate inhibitory activity for A and B viruses as well as to Sindbis arbovirus in tissue cultures is shown. The preparation efficiency at intramuscular and intranasal administration was observed at experimental influenza infection of white mice.
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PMID:[The antiviral action of a modified bacterial ribonuclease]. 130 13

Influenza A and B are RNA-containing viruses that frequently infect humans. Currently, sensitive detection of these viruses requires fresh respiratory secretions and special facilities for culture. To facilitate diagnosis of influenza, the polymerase chain reaction (PCR) was used in the present studies to detect DNA produced by reverse transcription of influenzal RNA in vaccines, tissue culture fluids, and stored respiratory secretions. Primers were directed at targets on the highly conserved segment 7 (matrix gene) of influenza A (212-bp product) and B (365-bp product). The primers were completely type specific. Critical variables in the assay were the concentration of pleotropic salts used during preparation of samples, the use of carrier RNA and RNase inhibitors during sample preparation, and the use of optimum K+ and Mg2+ levels at each step. Studies of 33 patients with symptoms of viral respiratory infection whose nasal washes had been cultured and frozen for up to 1 year before assay showed that PCR provided type-specific detection of influenza with a sensitivity comparable to that of culture of the fresh secretions. The assay offers a powerful test for detection of devitalized influenza viruses and may be useful in both diagnostic work and epidemiological studies of influenza.
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PMID:Detection of influenza A and B in respiratory secretions with the polymerase chain reaction. 147 62

DNA-directed RNA polymerase is responsible for gene expression. Despite its importance, many details of its function and higher-order structure still remain unknown. We report here a local sequence similarity between the second largest subunit of RNA polymerase II and bacterial RNases Ba (barnase), Bi, and St. The most remarkable similarity is that the catalytic sites of the RNases are shared with the eukaryotic RNA polymerase II subunits of Drosophila melanogaster and Saccharomyces cerevisiae. Several amino acids conserved among the RNases and the RNase-like domains of the RNA polymerase subunits are located in the neighborhood of the catalytic sites of barnase, whose three-dimensional structure has been resolved. This observation suggests the functional importance of the RNase-like domain of the RNA polymerase subunits and indicates that the RNase-like domain may have RNase activity. The location of the RNase-like domain relative to the region necessary for RNA polymerization is similar to the relative proximity of 5'----3' or 3'----5' exonuclease and the region of polymerase activity of DNA polymerase I. The RNase-like domain might work in proofreading, as in RNA-directed RNA polymerase of influenza virus, or it may contribute to RNA binding through an unknown function.
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PMID:RNase-like domain in DNA-directed RNA polymerase II. 192 68

Reconstitution of influenza virus nucleoprotein (NP)-RNA complexes was performed with segment 8 RNA, which was synthesized in vitro from cDNA, and NP purified from virions. Under optimum conditions established using a filter binding assay and a gel retardation assay, NP was found to bind any RNA longer than 15 nucleotides. NP-RNA complexes formed at 30 degrees C are more resistant to high concentrations of NaCl than those formed at 0 degrees C. Treatment of NP with N-ethylmaleimide gave no effect on its RNA binding activity, whereas treatment with alkaline phosphatase enhanced its RNA binding activity. The newly developed "reverse-printing" method of RNase V1-treated complexes revealed that reconstituted NP-RNA complexes carry RNase V1-sensitive sites as do native ribonucleoprotein (RNP) cores (RNA polymerase-NP-RNA complexes), implying that RNA-NP complexes structurally similar to native RNP cores are reconstituted from isolated components.
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PMID:Reconstitution of influenza virus RNA-nucleoprotein complexes structurally resembling native viral ribonucleoprotein cores. 235 55

The replication of influenza virus RNA in vitro has been studied by cell fractionation of MDCK-infected cells and characterization of in vitro synthesized RNA. Analysis of the RNA product polarity by liquid hybridization to excess single-stranded DNA probes shows that only the RNP complexes present in the nuclear matrix fraction are able to synthesize negative-polarity RNA. This RNA product has been characterized as authentic vRNA by size analysis, RNase-protection by unlabelled, positive-polarity riboprobes and T1-fingerprinting. Priming the in vitro reaction with ApG stimulates preferentially the synthesis of positive-polarity RNA, while ApGpU stimulates both positive and negative-polarity RNA synthesis.
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PMID:The synthesis of influenza virus negative-strand RNA takes place in insoluble complexes present in the nuclear matrix fraction. 239 81

Even when neutralized by saturating amounts of monoclonal IgG directed against the haemagglutinin, influenza virus attaches to cells with kinetics similar to those of infectious virus. It then enters those cells and is uncoated; its RNA becomes localized within the nucleus and its lipid envelope and associated proteins remain in the cytoplasm. In this report we show that despite the apparent normality of these early stages of virus-cell interaction, neutralized virus underwent no detectable primary transcription. In contrast, there was only a slight inhibition of transcription by neutralized virus in vitro which was insufficient to account for the loss in infectivity, despite using mRNA to measure the production of capped oligonucleotides or to prime the elongation step. To test whether the absence of primary transcription in vivo resulted from non-accessibility of the genome rather than an effect on the transcriptase complex itself, we examined the susceptibility to RNase of virion RNA after inoculation of cells with neutralized virus. Data clearly show that, unlike RNA of infectious virus, RNA of neutralized virus did not become sensitive to RNase and we conclude that neutralization of influenza virus by IgG results in failure of virus to undergo a secondary uncoating process which is necessary for the activity of the virion transcriptase complex. Finally we show that by treatment of virions in vitro with detergent it is possible to produce a core structure which is stable and has some of the properties expected of a structure resulting from primary uncoating.
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PMID:IgG-neutralized influenza virus undergoes primary, but not secondary uncoating in vivo. 276 31

There is a significant difference in the ability of human influenza A virus H1N1 strains isolated up to 1977 and those isolated later to rescue temperature-sensitive mutants of fowl plague virus with a defect in the nucleoprotein (NP) gene. Therefore the NP genes of five human H1N1 and H3N2 influenza A virus strains, isolated between 1950 and 1978, have been sequenced. By comparison with previous and more recent isolates, an evolutionary pathway has been established. Three amino acid replacements were found which might be responsible for the functional difference between the USSR (1977) and the Brazil (1978) strains. The California (H1N1) strain isolated in 1978 had acquired by reassortment the NP gene of a human H3N2 virus circulating at about 1977 as had been previously suggested by investigations involving RNase fingerprint or hybridization techniques.
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PMID:Biological and genetic evolution of the nucleoprotein gene of human influenza A viruses. 276 32


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