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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An RNA-dependent RNA polymerase has been completely purified from Cauliflower inflorescences. Analysis of the purified enzyme on SDS-polyacrylamide gels showed one polypeptide chain with a molecular weight of 140,000 dalton. The enzyme is monomeric in its native state. The in vitro activity was completely dependent on added RNA, the most efficient templates being poly (U), poly (U, C), poly (I) and viral RNA.
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PMID:[Purfication and molecular weight of an RNA-dependant RNA polymerase from Brassicae oleracea var. Botrytis]. 10 17

Two newly synthesized pyrimidine derivatives were found to possess antiviral activity against Mengovirus in Fogh and Lund (FL) cells and in a cell-free system. The inhibitory effect on RNA-dependent RNA polymerase of Mengovirus-infected FL cells was assayed using 14C-UTP as precursor. Addition of 50 or 100 muM of the inhibitors in a cell-free system of crude enzyme and nucleoside triphosphate medium for 60 min incubation at 37 degrees C resulted in about 40 to 60% lower counting rates for drug-treated reaction mixtures. The analysis of the polymerase synthesis product (virus RNA extracted from the cell-free reaction mixture and deproteinized by the phenol-SDS method) was carried out by means of agarose-acrylamide gel electrophoresis. The main finding was a reduction of single-stranded Mengovirus RNA (RNase-sensitive and LiCl-precipitable). The rates of synthesis of the replicative intermediate (LiCl-precipitable) and the replicative form of RNA (LiCl-soluble) were not significantly influenced.
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PMID:Effects of pyrimidine derivatives on RNA-dependent RNA polymerase of mengovirus-infected Fogh and Lund (FL) cells. 18 80

Phage SP RNA-dependent RNA polymerase (SP replicase) was purified from Escherichia coli infected with RNA phage SP. The enzyme was found to be composed of four non-identical polypeptides, i.e. subunits I, II, III, and IV and molecular weights of 74,000, 69,000, 47,000, and 36,000 daltons, respectively. As in the case of phage Qbeta replicase, the largest polypeptide is identical with the ribosomal protein S1, and subunits III and IV with polypeptide chain elongation factors EF-Tu and EF-ts, respectively.. This is based on the behaviour of the subunits on SDS-polyacrylamide gel electrophoresis, isoelectric focusing and immunological cross-reaction. Subunits I, III, and IV of SP replicase are derived from the host cell, while subunit II is coded by phage RNA genome. The striking coincidence of the composition and entity of the structural components of SP replicase with those of Qbeta replicase may indicate the structural and functional requirements of host-derived polypeptides in RNA replicase. The binding activity of S1 (in 70S ribosome comples) to poly (U) is retained in SP replicase complex. In contrast, the GDP binding activity of EF-Tu is masked in SP replicase. It is concluded that S1 is required functionally whereas EF-Tu.EF-Ts are required structurally in RNA replicase.
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PMID:Identification of host-derived subunits of phage SP RNA-dependent RNA polymerase (SP replicase). 36 4

1. Foot-and-mouth disease virus replicase was expressed by fusing its cDNA to the OmpA signal peptide coding sequence present in the pIN-III ompA series vectors. 2. Two constructions were developed to express either a full-length or truncated enzyme lacking the 20 amino acids at the N-terminal end. Bacterial extracts expressing the recombinant proteins were submitted to SDS-PAGE and the presence of the replicase was revealed by immunoblotting. The truncated form exhibited a higher mobility and the relative positions of the proteins show that the signal peptide was removed. 3. The biological activity of these two molecules was tested using a poly(A)-dependent oligo(U)-primed poly(U)-polymerase assay. The full-length replicase is active. The aminoterminal truncated enzyme had 0.02% activity of the intact one. 4. This result indicates the importance of the twenty N-terminal amino acids for the activity of FMDV RNA-dependent RNA polymerase.
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PMID:The N-terminal amino acid sequence is essential for foot-and-mouth disease virus replicase activity. 134 96

We have determined the complete nucleotide sequence of the largest segment S1 of rice dwarf phytoreovirus (RDV), a member of the family Reoviridae. S1 is 4423 nucleotides long with a segment-specific inverted repeat located adjacent to the conserved termini (5'GGCAAA---UGAU3'). A major open reading frame (bases 36 to 4367) on the S1 plus strand, which is preceded by a minicistron (bases 6 to 29), encodes the polypeptide (P1) consisting of 1444 amino acids with a M(r) of 164, 142. The sense-strand transcript derived from the full-length S1 cDNA, the minicistron of which was abolished, directed the synthesis of a polypeptide of 170 kDa in addition to smaller polypeptides in wheat germ extracts, and the 170-kDa product comigrated with the minor core protein in SDS-polyacrylamide gel. Thus, P1 is assumed to be localized in the viral core particle. The consensus sequence element conserved in RNA-dependent RNA polymerase is observed in the P1 amino acid sequence predicted from the nucleotide sequence. Based on the dendrogram established from the sequence alignment around the polymerase module region, and sequence identity within the alignment, P1 of plant-infecting RDV was evolutionarily compared with VP1, lambda 3, and VP1 of three other animal-infecting members of the family, rota-, reo-, and bluetongue viruses. Consequently, RDV S1 was shown to be more closely related to the rotavirus gene segment 1, in terms of molecular evolution, than the animal-infecting members are to one another.
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PMID:Molecular analysis of rice dwarf phytoreovirus segment S1: interviral homology of the putative RNA-dependent RNA polymerase between plant- and animal-infecting reoviruses. 152 32

Nonstructural proteins of plum pox potyvirus were partially purified following a procedure described for the isolation of tobacco etch virus nuclear inclusion proteins. Plum pox virus proteins with electrophoretic mobilities corresponding to 49, 59 and 68 kDa reacted with antibodies against the 49 kDa and 54 kDa components of the nuclear inclusions and the 70 kDa component of the cylindrical inclusions of tobacco etch virus, respectively. Further purification by size exclusion high performance liquid chromatography or SDS-polyacrylamide gel electrophoresis, and amino terminal amino acid sequencing permitted the location in the plum pox virus polyprotein of the cleavage sites from which the 49 kDa (NIa-type, protease), 59 kDa (NIb-type, putative RNA replicase), and 68 kDa (CI-type) proteins originate. A 110 kDa protein which copurified with the plum pox virus inclusion proteins reacted with both anti-NIa and anti-NIb sera and had the same amino terminus as the plum pox virus 49 kDa protein, indicating that it is a non-processed 49-59 kDa polypeptide.
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PMID:Determination of polyprotein processing sites by amino terminal sequencing of nonstructural proteins encoded by plum pox potyvirus. 213 35

Two-dimensional gel electrophoresis (IEF and SDS-PAGE) was used to examine virion polypeptide changes associated with switch-on of transcriptase function in reovirus. Results reveal that switch-on is correlated with altered electrophoretic behavior of a specific minor polypeptide (delta 1) which is present in intermediate subviral particles. A second finding is that each of the molecular weight classes of viral polypeptides exists as a series of subspecies with different isoelectric points. This suggests that extensive posttranslational modification of progeny viral polypeptides occurs during particle morphogenesis. These findings have important theoretical and practical implications.
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PMID:Switch-on of transcriptase function in reovirus: analysis of polypeptide changes using 2-D gels. 406 May 93

An RNA replicase of GA phage, one of the Group II RNA phages, was isolated and purified to a homogeneous state. By SDS polyacrylamide gel analysis, the purified GA replicase was found to contain four different subunits, numbered I, II, III, and IV, the molecular weights of which were 74,000, 60,000, 47,000, and 36,000, respectively. Three of them, I, III, and IV, proved to be host-coded proteins, ribosomal protein S1 (I), and elongation factors Tu (III) and Ts (IV) of protein biosynthesis, respectively. On a phosphocellulose column, the RNA replicase was separated into two components: One composed of subunits I and II, and the other composed of subunits III and IV. Each component alone had no replicase activity. However, when the two components were combined at 0 degree C, 60% of the replicase activity was restored within 10 min. The purified GA replicase catalyzed the GA phage RNA-directed synthesis of template-size RNA. However, the maximum level of product RNA synthesized was less than 20% of the amount of template RNA added. RNA-RNA hybridization experiments indicated that the product RNA included only the RNA strand complementary to the template RNA, and not the viral strand.
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PMID:In vitro replication of bacteriophage GA RNA. Subunit structure and catalytic properties of GA replicase. 689 19

A cell-free extract containing TMV-RNA replicase was prepared from TMV-infected tobacco leaves. It could synthesize double-stranded RNAs in the presence of four nucleoside triphosphates (among them, UTP was tritium-labelled), magnesium ion and actinomycin D. It was confirmed by polyacrylamide-agarose gel electrophoresis, RNase treatment, thermal denaturation and self annealing that 3H-ds RNAs, obtained from phenol-SDS extraction and Serva cellulose column chromatography, consisted of replicative form (RF) and replicative intermediate (RI) of TMV-RNA, with molecular weights of 40 X 10(6) and 5.0 X 10(6), respectively. Molecular hybridization competition experiment showed that 60-70% of the nascent RNAs in the 3H-ds RNA were plus strand of tMV-RNA.
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PMID:The nature of the RNA products synthesized in vitro with a cell-free extract from TMV-infected tobacco leaves. 723 51

Two paramyxovirus isolates recovered from the peripheral blood leukocytes of a patient with subacute sclerosing panencephalitis were characterized by biological, immunological, and molecular techniques. Both virus isolates possessed neuraminidase activity but demonstrated reduced hemagglutination potential. Neutralization titrations showed that the viruses were clearly related to, but were distinct from, simian virus 5. Characterization of purified virus preparations by SDS-PAGE showed that the structural polypeptides of the viruses were similar to those of simian virus 5, but distinct differences were noted as well. In addition, the virus isolates were found to differ from one another, particularly with regard to the major putative transcriptase protein (L).
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PMID:Characterization of nonmeasles paramyxovirus isolates from a patient with subacute sclerosing panencephalitis. 733 93


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