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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influenza virus-associated RNA polymerase cleaves capped RNA in an endonucleolytic manner and the transcription is initiated by the addition of GMP, the first substrate to be polymerized under the direction of viral RNA template, onto 3'-termini of resulting capped RNA fragments. In the presence of high concentrations of GTP as a sole substrate, multiple GMP residues were polymerized onto the primers. By the addition of the second substrate CTP, excess GMP residues, other than the 1st residue, were removed prior to elongation. The result may suggest that the RNA-dependent RNA polymerase carries a proofreading function.
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PMID:Proofreading function associated with the RNA-dependent RNA polymerase from influenza virus. 301 29

The virion-associated RNA polymerase and the structural nucleoprotein of influenza A virus were separated by sodium dodecyl sulfate/PAGE, electroblotted to a polyvinylidine membrane, and eluted with good recovery from the membrane. After renaturation by incubating with Escherichia coli thioredoxin, these proteins were active in a reconstituted in vitro transcription reaction with purified genomic RNAs. All four proteins (i.e., the three subunits of the RNA polymerase as well as the structural nucleoprotein) were required for activity. The RNA products were plus-strand, mRNA-sized species.
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PMID:Purification, thioredoxin renaturation, and reconstituted activity of the three subunits of the influenza A virus RNA polymerase. 305 75

Ribonucleoprotein (RNP) cores of influenza virus A/PR/8/34 were dissociated into RNA polymerase (PB1-PB2-PA complex)-associated genome RNA and nuclear protein (NP) fractions by CsCl centrifugation. The RNA polymerase-RNA complexes were capable of catalyzing the endonucleolytic cleavage of capped RNA, the initiation of primer-dependent RNA synthesis, and the synthesis of small-sized RNA, but were unable to synthesize template-sized RNA. By adding the NP protein to the RNA polymerase-RNA complexes, RNP (RNA polymerase-RNA-NP) complexes were reconstituted; they synthesized template-sized transcripts as did native RNP cores. These observations are consistent with the model where viral RNA polymerase is composed of the three P proteins while NP is essential for the elongation of RNA chains. RNP was completely dissociated into RNA-free proteins (PB1, PB2, PA, and NP) and a protein-free genome RNA fraction by centrifugation in cesium trifluoroacetate (CsTFA) and glycerol. By mixing the protein and RNA fractions, primer-dependent RNA-synthesizing activity was regained. These complexes, however, produced only small-sized RNA, presumably due to incorrect assembly of NP on viral RNA.
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PMID:RNA polymerase of influenza virus: role of NP in RNA chain elongation. 324 63

Influenza virus cap-binding protein (PB2; Mr 85,000) is made in Escherichia coli when the cloned cDNA is transcribed by T7 RNA polymerase. Translation begins at the probable natural start codon and also from at least five internal sites in the same reading frame. The eukaryotic initiation site is not typical of protein initiation sites of E. coli, in that the closest potential Shine-Dalgarno sequence is far (15 nucleotides) from the start codon. Nevertheless, protein synthesis initiates efficiently at this site even in competition with a strong upstream prokaryotic initiation site. PB2 is somewhat unstable in the cell, but accumulates to a level where it is easily detectable in electrophoresis patterns of total cell protein. The full-length protein and various subfragments of it are insoluble in crude extracts, but have been useful for producing antibodies.
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PMID:T7 RNA polymerase can direct expression of influenza virus cap-binding protein (PB2) in Escherichia coli. 332 38

A cDNA encoding the entire amino acid sequence of the matrix (M1) protein of influenza A/WSN/33 virus was cloned, sequenced, and expressed in a vaccinia virus system consisting of the T7 bacteriophage RNA polymerase and a plasmid carrying the M1 gene flanked by T7 polymerase promoter and terminator sequences. The transiently expressed M1 gene product comigrated on SDS-polyacrylamide gels with the endogenous WSN virus M1 protein and was recognized in Western blot analysis by three epitope-specific monoclonal antibodies directed to the M1 protein. The nucleotide sequence and the predicted amino acid sequence of the cloned WSN virus M1 coding region was found to be more than 97% homologous to that of the M1 gene of influenza virus A/PR/8/34 reported by G. Winter and S. Fields (Nucleic Acids Res. 8, 1965-1974, 1980).
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PMID:Transient expression and sequence of the matrix (M1) gene of WSN influenza A virus in a vaccinia vector. 335 9

This communication presents our recent studies on the biosynthesis of influenza virus hemagglutinin (HA) in a mammalian-cell-free system and its translocation across microsomal membranes. RNAs coding for wild-type (full-length) and mutant (truncated) forms of HA were generated by in vitro transcription by using bacteriophage T7 DNA-dependent RNA polymerase. These RNAs were translated in a rabbit reticulocyte system that was supplemented with dog pancreas membranes, either before translation was initiated or after it had been artificially terminated with the antibiotic cycloheximide. All forms of HA could be cotranslationally translocated. However, only truncated molecules (83% of full length) could translocate after protein synthesis had been terminated. Posttranslational translocation was dependent on the presence of a functional N-terminal signal sequence and occurred only in the presence of ribosomes. The molecular mechanism of protein targeting and translocation across the membrane of the endoplasmic reticulum is discussed based on the signal hypothesis.
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PMID:Uncoupling of translocation across microsomal membranes from biosynthesis of influenza virus hemagglutinin. 337 4

The binding sites for influenza viral RNA polymerase on genome RNA segments were investigated. Ribonucleoprotein (RNP) cores containing the RNA polymerase were isolated from detergent-treated virions by glycerol gradient centrifugation. On ApG-primed in vitro transcription by the isolated RNP cores, different levels of RNA transcripts were synthesized for the eight RNP cores, suggesting an uneven distribution of the RNA polymerase. 3'-Terminal labeling of the RNP cores with the use of [32P]pCp and T4-RNA ligase indicated a reciprocal correlation between the levels of the RNA-3' label and RNA synthesis. Centrifugation of detergent-treated virions in a double gradient of cesium trifluoroacetate (or cesium chloride) and glycerol yielded RNA polymerase-RNA complexes devoid of NP, the major RNA-bound protein, but the pattern of RNA-3' labeling remained virtually unaffected. All these observations together indicated that the RNA polymerase is associated near the 3' termini of some viral RNA segments, thereby preventing the in vitro labeling of the RNA-3' ends. The results of foot-printing experiments using RNase V1 and RNase T2 were in agreement with this model.
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PMID:Identification of the RNA polymerase-binding site on genome RNA of influenza virus. 343 66

The combined effect of sodium selenite and remantadine on influenza A virus reproduction in vitro and in vivo is described. The effect of sodium selenite on influenza virus transcriptase was studied. Inoculation of remantadine in combination with nontoxic concentrations of sodium selenite was found to be a promising combination for inhibition of experimental influenza infection.
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PMID:[Antiviral action of sodium selenite and its combination with remantadine]. 344 84

The priming activities of dinucleotides of all possible base sequences as to the transcription initiation by influenza virus-associated RNA polymerase were investigated. Dinucleotide ApG, complementary to positions 1-2 from the 3' termini of viral RNA segments, was the most active primer and directed the formation of ApGpC; dinucleotide GpC, complementary to positions 2-3, was also an active primer and directed the formation of either GpCpG or GpCpA; but both dinucleotides CpG and CpU, complementary to positions 3-4, were virtually inactive. These results indicate that the transcription is initiated within the first four nucleotides at the 3' termini of viral RNA. Among other dinucleotides, only those hybridizable to viral sequences at their 3'-proximal bases were partially active, implying the essential role of base pairing immediately next to the first phosphodiester bond.
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PMID:RNA polymerase of influenza virus. Dinucleotide-primed initiation of transcription at specific positions on viral RNA. 345 92

Polynucleotide inhibitors of the influenza virion transcriptase, which is activated in vitro by detergent, can be divided into two categories. Polyribonucleotides comprised of adenine and guanine bases or adenine and uracil bases inhibit initiation but not elongation events of transcription. In contrast, polyribonucleotides containing cytidine and uracil or inosine and uracil block both initiation and elongation. Effects on elongation are apparent on addition of polynucleotides at either 5 or 10 min post-initiation. Dose-response studies with these and other polynucleotides have shown that the concentrations causing 50% inhibition of transcription vary considerably with the most potent inhibitor being the modified polymer, poly(C,S4U10).
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PMID:Effects of polynucleotide inhibitors on transcriptional events of influenza virions. 350 18


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