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)

1. Messenger activity of phage f2 RNA modified with methoxyamine under non-denaturing conditions was studied in E. coli-free system. The incorporation of amino acids into phage polypeptides was decreased, and the synthesis of phage-specific proteins was diminished. The RNA replicase synthesis was more affected than synthesis of coat protein. The impaired messenger activity of the methoxyamine-modified f2 RNA was due to the blocking of elongation process by modified cytosines present in RNA chain. 2. Specificity of f2 RNA to stimulate ribosomal binding predominantly at the coat protein initiation site was not affected by methoxyamine-treatment, as demonstrated by unchanged binding of f[3H]Met-tRNA and [14C]alanyl-tRNA to ribosomes. 3. Unfolding of f2 RNA molecule on treatment with methoxyamine in the presence of guanidine-HCl resulted in a significant increase of RNA capacity to direct fMet-tRNA binding to ribosomes. Sucrose-density gradient profiles revealed the formation of polysome-like initiation complexes indicating that ribosomes were able to bind at many hitherto inaccessible initiation codons in RNA molecules. fMet-tRNA bound to ribosomes in the presence of unfolded RNA was found to be fully reactive with puromycin.
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PMID:Activity of methoxyamine-modified f2 RNA in initiation and elongation steps of protein synthesis. 78 15

The putative viral transcriptase p90 in infectious bursal disease virus (IBDV) was shown to form an enzyme-guanylate intermediate which is indicative of guanylyl-transferase activity. The p90-nucleotide bond is most likely to be a phosphodiester linkage, as it resisted treatment with HCl and NH2OH but was sensitive to NaOH. This is in contrast to phosphoamide bonds formed by reovirus cores. Methyltransferase activity was also demonstrated in IBDV, and is closely associated with transcription, suggesting that p90 may be a multifunctional enzyme.
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PMID:Demonstration of enzyme activities required for cap structure formation in infectious bursal disease virus, a member of the birnavirus group. 215 6

Polyspermine-ribonuclease (Mr approximately 17 000) and the enzyme transcriptase from Rauscher-leukaemia virus (Mr approximately 70 000) form a complex Mr approx. 160 000) such that the molar ratio of polyspermine-ribonuclease to reverse transcriptase is 5:1. The most favourable condition for complex-formation is in a solution consisting of 0.01 M-Tris/HCl buffer, pH 7.5, 0.25 M-KCl and 1 mM-Mn2+ at 37 degrees C. The association of the two enzymes retains full RNAase activity, but reverse-transcriptase activity is completely inhibited when ribonuclease-sensitive polymers such as (dG)12 x (rC)n or viral 70S RNA are used as primer templates.
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PMID:Complexing reverse transcriptase with polyspermine-ribonuclease. 616 6

Administration of a single-stranded polynucleotide copolymer containing 9% cytidine residues and 91% 4-thiouridine residues [poly(C,S4U10)], a known potent inhibitor of the virion transcriptase of influenza viruses, suppressed the amount of virus recoverable from the nasal washes of influenza virus-infected hamsters and ferrets. The incidence of sneezing and nasal discharge in infected ferrets was also reduced. In hamsters, poly(C,S4U10) was more effective than amantadine-HCl or Virazole. Polyinosinic acid in combination with poly-5-hydroxy cytidylic acid also had anti-influenza effects. Poly(C,S4U10) annealed to polyadenylic acid was not effective, nor was the double-stranded polymer (polyinosinic acid) . (polycytidylic acid) even when complexed with carboxymethylcellulose and polylysine. No toxic effects of poly(C,S4U10) were apparent in the treated hamsters and ferrets, and high doses (greater than or equal to 2.86 g/kg) administered intraperitoneally to mice produced no adverse effects.
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PMID:Antiviral effects of single-stranded polynucleotide inhibitors of the influenza virion-associated transcriptase against influenza virus infection of hamsters and ferrets. 628 Jun 8

To estimate the polyamine distribution in Escherichia coli, the binding constants (K) for DNA, RNA, phospholipids, and ATP were calculated under the condition of 10 mM Tris-HCl, pH 7.5, 150 mM K+, and 10 mM Mg2+. The binding constants of spermidine for E. coli DNA, E. coli 16S rRNA, phospholipids in E. coli membrane, and ATP were 0.015, 0.066, 0.028, and 0.081 mM-1, respectively. Similarly, those of putrescine were 0.010, 0.010, 0.007, and 0.037 mM-1, respectively. The concentrations of putrescine, spermidine, and ATP and phosphates in DNA, RNA, and phospholipids in E. coli harvested at A600 = 0.3 were 32.2, 6.88, and 2.66 and 96.4, 436, and 57.2 mM, respectively. Accordingly, the percentage of spermidine bound to DNA, RNA, phospholipids, and ATP and that of free spermidine were 5.1, 90, 0.7, 0.8, and 3.8%, respectively. The percentage of putrescine bound to DNA, RNA, phospholipids, and ATP and that of free putrescine were 9.3, 48, 1.4, 2.6, and 39%, respectively. The results indicate that most spermidine exists as a spermidine--RNA complex, and about 40% and 50% of putrescine exists as a free form and a putrescine--RNA complex in cells, respectively. Under the conditions that the synthesis of specific proteins such as RNA replicase is stimulated by polyamines in a cell-free system, the amount of spermidine and putrescine bound to RNA was close to the value estimated in cells. Experiments to demonstrate the polyamine stimulation of MS2 RNA-directed RNA replicase synthesis in vivo were thus performed, and the results were confirmed.
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PMID:Estimation of polyamine distribution and polyamine stimulation of protein synthesis in Escherichia coli. 767 29

Protease-activated receptor-2 (PAR-2) is distributed throughout the gastrointestinal systems. The present study investigated the role for PAR-2 in the rat salivary glands. PAR-2 mRNA was detected in the sublingual, submaxillary, and parotid glands by a reverse-transcriptase polymerase chain reaction. In the isolated sublingual gland that exhibited the strongest signal for PAR-2, Ser-Leu-Ile-Gly-Arg-Leu-NH(2), a PAR-2-activating peptide, and trypsin, a PAR-2-activating enzyme, but not thrombin that can activate PARs 1, 3, and 4, triggered secretion of N-acetylneuraminic acid, an indicator of mucin, that was a unique major sialic acid detectable after hydrolysis of the sublingual mucin with 0.1 N HCl. The PAR-2-mediated secretion of mucin was attenuated by genistein, a tyrosine kinase inhibitor, but not by inhibitors of protein kinase C and phosphatidyl inositol 3'-kinase. Thus, PAR-2 is expressed by the three distinct salivary glands in the rat, and sublingual PAR-2 appears to play a role in triggering mucin secretion, at least in part, via activation of tyrosine kinase.
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PMID:Activation of protease-activated receptor-2 (PAR-2) triggers mucin secretion in the rat sublingual gland. 1073 43

There are two protein primers involved in picornavirus RNA replication, VPg, the viral protein of the genome, and VPgpUpU(OH). A cis-acting replication element (CRE) within the open reading frame of poliovirus (PV) RNA allows the viral RNA-dependent RNA polymerase 3D(Pol) to catalyze the conversion of VPg into VPgpUpU(OH). In this study, we used preinitiation RNA replication complexes (PIRCs) to determine when CRE-dependent VPg uridylylation occurs relative to the sequential synthesis of negative- and positive-strand RNA. Guanidine HCl (2 mM), a reversible inhibitor of PV 2C(ATPase), prevented CRE-dependent VPgpUpU(OH) synthesis and the initiation of negative-strand RNA synthesis. VPgpUpU(OH) and nascent negative-strand RNA molecules were synthesized coincident in time following the removal of guanidine, consistent with PV RNA functioning simultaneously as a template for CRE-dependent VPgpUpU(OH) synthesis and negative-strand RNA synthesis. The amounts of [(32)P]UMP incorporated into VPgpUpU(OH) and negative-strand RNA products indicated that 100 to 400 VPgpUpU(OH) molecules were made coincident in time with each negative-strand RNA. 3'-dCTP inhibited the elongation of nascent negative-strand RNAs without affecting CRE-dependent VPg uridylylation. A 3' nontranslated region mutation which inhibited negative-strand RNA synthesis did not inhibit CRE-dependent VPg uridylylation. Together, the data implicate 2C(ATPase) in the mechanisms whereby PV RNA functions as a template for reiterative CRE-dependent VPg uridylylation before and during negative-strand RNA synthesis.
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PMID:Conversion of VPg into VPgpUpUOH before and during poliovirus negative-strand RNA synthesis. 1981 61

Reverse transcriptase (RT) catalyzes the formation of dsDNA from single-stranded retroviral RNA genome. This enzyme is unique among DNA polymerases in its ability to use either RNA or DNA as a template. Moloney Murine Leukemia virus reverse transcriptase lacking RNase H activity (M-MLVH- RT) especially holds particular interest because of its ability to eliminate the deleterious effect of RNase H, which results in more efficient synthesis of full-length cDNA from mRNA. Therefore, the development of a simple purification method attracts the attention of retroviral drug and enzyme researchers and manufacturers. The present work is the first purification example of a non-tagged (native) RT by affinity chromatography using synthetic affinity ligands. In this study, the ligand was selected from a structure-biased combinatorial library of dNTP-mimetic ligands, and it was evaluated for its ability to bind and purify M-MLVH- RT from inclusion bodies of recombinant E. coli. The selected ligand (AEAd), bearing 9-aminoethyladenine and 1,6-diamine-hexane both linked on the same triazine scaffold, displayed the highest enzyme purifying ability after applying mild desorption conditions (6 mM MnCl(2) in 20 mM Tris-HCl buffer, pH 7.5). The binding capacity of immobilized AEAd with M-MLVH- RT was determined to be equal to approximately 1 mg enzyme/g moist weight gel. Adsorption studies with immobilized AEAd and soluble M-MLVH- RT demonstrated that the formation of the respective complex was perturbed by ATP. Quality control tests of the purified M-MLVH- RT essentially showed a single band (sodium dodecyl sulfate polyacrylamide gel electrophoresis) and absence of nucleic acids and contaminating nuclease activities.
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PMID:Purification of M-MLVH- RT on a 9-aminoethyladenine-(1,6-diamine-hexane)-triazine selected from a combinatorial library of dNTP-mimetic ligands. 2082 67