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 mobile element jockey is similar in structural organization and coding potential to the LINEs of various organisms. As demonstrated here, two polyadenylated jockey transcripts detected at different stages of Drosophila ontogenesis and in cell cultures have the same length as genomic copies of jockey and correspond to the strand containing ORFs. alpha-amanitin experiments indicate that jockey is transcribed by RNA polymerase II. Analysis of both expression of CAT constructions and initiation of transcription in jockey genomic and transfected copies has shown that jockey transcription is controlled by an internal promoter. Inward location of the promoter allows it to be preserved in the course of replication via reverse transcription and accounts for the distribution of jockey and probably other LINEs throughout the genome. This is the first case of an internal promoter described for RNA polymerase II. The comparison of sequences at the beginning of LINE elements in Drosophila allows one to detect possible core sequences.
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PMID:jockey, a mobile Drosophila element similar to mammalian LINEs, is transcribed from the internal promoter by RNA polymerase II. 284 63

Two polyadenylated transcripts of the jockey are detected at different stages of Drosophila melanogaster ontogenesis and in the cell culture. They have the same length as complete and deleted copies of jockey and correspond to the DNA strand containing open reading frames coding for polypeptides which are homologous to retroviral RNA-(DNA)-binding proteins and to their reverse transcriptases. The results of the experiments, where transcription was inhibited with alpha-amanitin in vivo, indicate that jockey is transcribed by RNA polymerase II. The analysis of expression of CAT constructions made on the basis of jockey, and the detection of a fixed site for transcription initiation in jockey genomic and transfected copies have shown that jockey transcription is controlled by an internal promoter located not farther than 12 nucleotides from the beginning of the element. Such an inward location of the promoter allows it to be preserved in replication via reverse transcription and accounts for the distribution of jockey and probably other LINEs throughout the genome. This is the case of the first internal promoter described for RNA polymerase II. The comparison of starting sequences of LINEs in Drosophila makes it possible to detect core sequences of such a promoter.
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PMID:[The Drosophila mobile element jockey, being a typical LINE, is transcribed from the internal promoter by RNA polymerase II]. 284 76

Bacillus mesentericus DNA fragments carrying promoters were cloned in Bacillus subtilis. The nucleotide sequences of four promoters, the sites of transcription initiation and the levels of promoter-mediated expression of pPL603 CAT gene at different stages of cell growth were determined. It was identified, that the two promoters (P435 and P442) are the typical sigma 43-RNA polymerase promoters. Promoter P462 possessed the unusual nucleotide sequence and induced the expression of indicator CAT gene at the middle of the stationary phase of cell growth. The next P428 promoter was found to be a complex promoter composed of three overlapping ones: P428-1, P428-2 and P428-3. P428-3 is the sigma 43-specific promoter which revealed the high degree of homology with Bacillus subtilis spoOB gene promoter. We suggest the promoters P428-1 and P428-2 to be sigma 43- and sigma 37-RNA polymerase specific, respectively.
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PMID:[Structural-functional characteristics of Bacillus mesentericus promoters cloned in Bacillus subtilis cells]. 311 Jun 6

To examine the RNA polymerase (EC 2.7.7.6) specificity of RNA maturation/utilization and transcriptional enhancement, we constructed a chimeric plasmid (pPolI-CAT) in which a promoter for mouse rRNA gene transcription was placed adjacent the coding sequences for chloramphenicol acetyltransferase (CAT; EC 2.3.1.28). A number of other constructs, including plasmids also containing a murine sarcoma virus enhancer or lacking any natural eukaryotic promoter sequences, were also prepared. In apparent agreement with earlier conclusions that an RNA polymerase I transcript can act as a messenger RNA, transient transfection of mouse L cells with pPolI-CAT yielded both high levels of transcription from the RNA polymerase I promoter and enzymatically active CAT protein. However, further examination revealed that CAT protein is not translated from RNA that begins at the normal rRNA transcription initiation site. Polysomal RNA is devoid of such RNA and instead consists of CAT-encoding transcripts that begin elsewhere in the mouse ribosomal DNA (rDNA) region. Since transcription of these aberrant RNAs is stimulated by the addition of a murine sarcoma virus enhancer segment, they are probably transcribed by RNA polymerase II. Transcripts that map to the authentic rRNA start site are not similarly enhanced. Moreover, unlike the RNAs deriving from the rRNA initiation site, these aberrant RNAs are more stable and the level of translatable CAT transcripts is suppressed by inclusion of larger segments of the rDNA promoter regions. Fortuitously initiated mRNAs are also formed in the absence of any natural eukaryotic promoter sequence. From these data we conclude that there is no evidence that normal RNA polymerase I transcription yields functional mRNA and that transcriptional enhancement appears to be RNA polymerase specific.
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PMID:RNA polymerase specificity of mRNA production and enhancer action. 346 18

The nucleotide sequence of the inducible chloramphenicol acetyltransferase gene (cat) of Staphylococcus aureus plasmid pC221 has been determined. The deduced primary structure for the 215 residue polypeptide (25.9 kDa) is in agreement with partial amino acid sequence data on the purified protein, previously designated as the type C variant of CAT. In common with the inducible cat elements of pC194 and B. pumilus, the 5' non-coding region of the cat of pC221 contains an inverted complementary repeat ('stem-loop' or 'hairpin') which may sequester the predicted ribosome bonding site of the mRNA. The likely transcription initiation site has been determined in vitro using purified B. subtilis RNA polymerase. Recombinant plasmids carrying the cat of pC221 on a 1156 bp TaqI fragment are expressed inefficiently in Escherichia coli, wherein induction is both poor and orientation-specific.
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PMID:Chloramphenicol acetyltransferase gene of staphylococcal plasmid pC221. Nucleotide sequence analysis and expression studies. 385 95

The morphology of Safferman's virus of blue-green algae (phycovirus LPP-1) has been studied by electron microscopy and physicochemical methods. The virion has a short (100 to 200 A long, 150 A in diameter) forked tail, with an outer sheath, an inner core, and a capital attached to one of the vertices of a polyhedral head. The head capsid edge-to-edge distance is 600 A, based upon internal calibration of the magnification in electron micrographs by use of the line-line spacing of catalase crystals. Measurements of absorbancy and infectivity, and electron microscopy across the band of virus after zone centrifugation on a sucrose gradient, indicated that infectivity was correlated with the short-tailed particles described. The viral deoxyribonucleic acid (DNA) is linear, with a contour length of 13.2 +/- 0.5 mu, measured by the Kleinschmidt method. Its sedimentation coefficient, S(0) (20, w), is 33.4 +/- 0.7 S. These values are consistent with a molecular weight of 27 x 10(6) for the viral DNA. Based upon buoyant density in CsCl and thermal denaturation, the guanine-cytosine content of the DNA is 53%. The viral DNA was used as template for in vitro ribonucleic acid (RNA) synthesis by Escherichia coli RNA polymerase. This RNA annealed to 18% of the sequences in the viral DNA, 0.5% of the sequences in bacteriophage T7 DNA, and 0.25% of the sequences in Plectonema boryanum DNA, at saturating levels of RNA in the Hall-Nygaard hybridization assay. The lack of homology with T7 DNA is of interest because the two viruses are very similar morphologically. The lack of homology with host DNA suggests that this algal virus is a poor candidate for transduction.
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PMID:Morphology of a virus of blue-green algae and properties of its deoxyribonucleic acid. 499 40

Nucleotide sequences of 188 promoter-containing DNA regions have been studied by the computer statistic analysis. Undecanucleotide NTT(G/C)TTGACA(A/T) or (G/C) X TT(G/C)A(G/C)A(A/T)TT(G/T) (recognition site) and heptanucleotide RTATATR or TATAATR (initiation site) separated by 12-19 base pairs are characteristic of a "generalized" promoter structure. Promoters can function if a minimal level of correspondence for their recognition and initiation sites to a generalized structure is attained (the correspondence function value for the whole structure is not lower than 0,61; for the most effective promoters it may be equal to 1). The transcription start is situated 3-9 base pairs after initiation site, 4-7 pairs distance being the most effective. Transcription can start from any nucleotide, preferably with A or G. The start from A is the most effective if it is contained within the CAC or CAT trinucleotides. The promoter efficiency is enhanced by some additional structural factors: the presence of an extended A-T rich region directly before the recognition site; availability of integral promoter structures or several RNA polymerase binding sites in the preceding nucleotide sequence. A characteristic feature of the promoter is the presence of either the dyadic axial symmetry elements in the initiation and recognition sites as well as in the intermediate region, or the A-T rich area in the latter.
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PMID:[Statistical study of the nucleotide sequence of a prokaryotic promoter. Structural elements determining the efficacy of the transcription initiation stages]. 623 57

Peptides of melanosomal proteins have recently been shown to be recognized in an HLA-restricted mode by specific cytolytic T lymphocytes in melanoma patients. Dendritic antigen-presenting cells (DC) are considered to be the most effective stimulators of T cell responses, and the use of these cells has therefore been proposed to generate therapeutic responses to tumor antigens in cancer patients. We, therefore, generated DC from peripheral blood of normal donors in the presence of granulocyte/macrophage colony-stimulating factor and interleukin-4. Flow cytometric analysis of the cells during a 2-week culture revealed a loss of CD14 and CD34 expression, a concomittent increase of CD1a, CD11a,b and c, CD44, CD45, CD54, HLA-class I and II, and intermediate levels of CD26, CD80 and CD86. Cultured DC stimulated proliferation of allogeneic T cells and induced a marked, up to 20-fold, stimulation of T cell proliferation after pulsing with tetanus toxoid. To achieve independence of already-identified antigenic peptides presented in HLA class I-restricted fashion, which limits the general applicability of such peptides for vaccination of melanoma patients, we tested whether DC are transfectable with eukaryotic expression plasmids. DC transfected with two reporter genes (CAT, beta-galactosidase) using a liposome-based transfection technique, exhibited only low levels of enzymatically active proteins, but were able to degrade rapidly intracellular proteins and to process peptides efficiently. Chloramphenicol acetyltransferase as well as tyrosinase mRNA were detectable after transfection by reverse-transcriptase-polymerase chain reaction, and enzyme activities became measurable. Furthermore, DC transfected with the tyrosinase gene were able to induce specific T cell activation in vitro, indicating appropriate peptide processing and presentation in DC after transfection. These data suggest new approaches to future tumor vaccination strategies.
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PMID:Dendritic cells generated from peripheral blood transfected with human tyrosinase induce specific T cell activation. 748 49

Sophisticated biochemical networks allow organisms such as bacteria and insects to switch from very rapid growth and development in ideal environments to dormancy during severely unfavorable conditions. These switches may be accompanied by abrupt changes in oxidation/reduction involving reactive oxygen species (ROS). ROS have the potential of damaging nucleic acids, proteins, and membranes. In Escherichia coli, certain genetically regulated circuits (regulons) turn on synthesis of anti-oxidant enzymes to protect against distinct ROS excesses (superoxide, hydrogen peroxide, organic or lipid peroxides, etc.). As examples, the soxRS regulon controls synthesis of Mn-superoxide dismutase, oxyR controls catalase HPI, rpoS positively regulates HPII, and fur regulates several oxidative reactions that involve iron uptake. Our studies have focused on the regulatory role of rpoS, known to be a sigma factor (sigma 38) that combines with RNA polymerase and is a regulator of those gene products needed to protect cells during dormancy. Since insect cells, during both active growth and dormancy, endure severe environments, analogous protective gene products may be induced. Examples are presented of insect anti-oxidant metabolism, including those involved in the aging process. In addition, we searched several DNA and protein sequence data banks to compare resemblances between anti-oxidant gene products of bacteria and insects.
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PMID:Genetic mechanisms involved in cellular recovery from oxidative stress. 760 42

An established cell line, clone 64, in which the expression of the RNA polymerase PB1 and PA subunit genes and the nucleoprotein (NP) gene but not the PB2 subunit gene of influenza virus can be induced by the addition of dexamethasone, was used to analyze the replication and transcription machineries of the influenza virus. Both NS-CATc and NS-CATv, the chimeric nonstructural protein chloramphenicol acetyltransferase (NS-CAT) RNAs in the sense and antisense orientations positioned between the 5'- and 3'-terminal sequences of influenza virus RNA segment 8 (the NS gene), respectively, can be transcribed into the corresponding complementary-strand RNA in clone 64 cells only when treated with dexamethasone. Although sense-strand poly(A)+ CAT RNA was detected in the dexamethasone-treated clone 64 cells transfected with NS-CATv RNA, CAT activity was not detected in these cells and the isolated poly(A)+ CAT RNA was inert in an in vitro translation system. However, when the poly(A)+ CAT RNA was capped by using a purified yeast mRNA capping enzyme (mRNA guanylyltransferase), the capped poly(A)+ CAT RNA became translatable in the in vitro translation system. These results indicated that PB1, PA, and NP can support the replication of the influenza virus genome as well as the transcription to yield uncapped poly(A)+ RNA and that PB2 is specifically required for the synthesis of capped RNA.
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PMID:The RNA polymerase PB2 subunit is not required for replication of the influenza virus genome but is involved in capped mRNA synthesis. 781 36


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