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

---

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

Pure yeast RNA polmymerase B (II) can selectively initiate abortive transcription on a supercoiled recombinant plasmid DNA carrying yeast DNA in the presence of low concentrations of ribonucleoside triphosphates and Mn2+. Five major products ranging between 60 and 150 nucleotides were characterized by hybridization. Three of them originate from the vector pBR322 and two from the yeast DNA insert. Based on a RNA primer extension reaction with recombinant M13 DNAs as template, a method allowing the mapping of the short abortive RNA products has been developed. An initiation site within the yeast DNA insert has thus precisely been mapped. The DNA sequence in this region was determined and showed several relevant features. The in vitro initiation site is preceded by a potential TATATATA box at -40 base pairs and at -105 by the sequence GTTAATCT similar to the consensus sequence GCTCAATCT usually found around 80 base pairs upstream from the cap site. Large blocks of alternated purine pyrimidine residues are found in this region as for several known yeast promotors. The 5' end of the RNA initiated from this site contains several potential signals for the initiation of translation. The possibility that a B to Z transition of DNA could be important for the interaction of the RNA polymerase with its template is discussed.
...
PMID:Pure yeast RNA polymerase B (II) initiates transcription at specific points on supercoiled yeast DNA. 629 90

The alpha and beta subunits of phenylalanyl-tRNA synthetase are encoded by the pheS and pheT genes, respectively. These genes are clustered closely together with the genes for threonyl-tRNA synthetase (thrS) and translation initiation factor IF3 (infC); the gene order is thrS infC pheS pheT. We have used two methods to study the transcription pattern within this cluster. The first was the in vitro transcription of DNA restriction fragments with purified RNA polymerase, followed by fractionation of the RNA products by polyacrylamide gel electrophoresis. The second method was the mapping of promoters by means of the "abortive initiation" reaction of McClure and co-workers. This procedure consists of the incubation of RNA polymerase with DNA restriction fragments plus one nucleoside monophosphate and one [alpha-32P]nucleoside triphosphate; the polymerase synthesizes dinucleotide products of known sequence at promoter sites in the DNA. We found that transcription initiated at an internal site within infC (designated P1), and at two promoter sites between infC and pheS (designated P2 and P3). Transcription terminated at two sites about 200 nucleotides apart, located just before pheS. The initiation and termination signals were arranged so as to yield a nested set of overlapping transcripts. At the P1 promoter, transcription initiated with G-C, at P2 with A-C and sometimes A-G, and at P3 with G-U. Promoter activity was also found in a 3000-base interval that includes the start of the thrS gene; eight or nine transcripts (not mapped in detail) were observed, which started with at least four different dinucleotides. All major initiation sites in the gene cluster represented purine starts, although some pyrimidine initiation was observed in trace amounts. No promoter activity was found between pheS and pheT with either of the two techniques; this observation supports the conclusion that these genes are co-transcribed. No evidence was found for any promoter between the termination sites and the beginning of the pheS gene. It is suggested that one of the terminators is an attenuation site controlling the extension of transcription into pheS and pheT. Attenuation may explain the observed regulation of phenylalanyl-tRNA synthetase by the amino acid supply.
...
PMID:Transcription of a gene cluster coding for two aminoacyl-tRNA synthetases and an initiation factor in Escherichia coli. 636 38

In the initial stages of Reye's Syndrome, following an influenza infection, the viral RNA polymerase activates liver host cell ornithine decarboxylase by combining with this enzyme. Once the reaction has occurred, ornithine decarboxylase is no longer available to combine with and to activate host cell RNA polymerase. The virally activated ornithine decarboxylase removes ornithine from participation in the urea cycle by metabolizing ornithine to putrescine which, in turn, is metabolized to spermidine. Once ornithine has been removed from participation in the urea cycle, mitochondrial carbamoyl phosphate levels increase until the carbamoyl phosphate passes from the mitochondria into the cytosol where it is metabolized by the de novo pyrimidine synthesis pathway. Through the implementation of this process, the virus has insured that: host cell RNA polymerase in liver cells is inactivated, viral RNA polymerase has complete access to newly synthesized pyrimidines, production of pyrimidines for the synthesis of viral messenger RNA is initiated, spermidine, a mRNA stabilizer is produced, many of the components necessary for viral mRNA synthesis are provided by the host cell's RNA synthesizing mechanism.
...
PMID:The viral mechanism of Reye's syndrome. 637 95

A 2.56-kbp fragment containing genes coding for histones H2A and H3 that forms a portion of the 10.2-kbp cluster containing all five histone genes isolated from a lambda-Charon 4A library of rainbow trout genomic DNA has been characterized in detail and its complete nucleotide sequence determined. The genes are arranged in tandem, being encoded on the same DNA strand. They are separated by 380 bp of intergenic spacer DNA that contains an alternating purine-pyrimidine stretch of 20 bp and a 46-bp stretch that has the potential of forming a triple cruciform structure. The histone genes contain no introns, have the RNA polymerase II promoter-associated signals known as CAAT and TATA boxes in their 5' flanking regions and contain a conserved inverted repeat sequence, similar to that found in histone genes of other species, capable of forming a hairpin structure at the 3' end of the transcription unit.
...
PMID:Organization and nucleotide sequence of rainbow trout histone H2A and H3 genes. 643 79

The synthesis of RNA catalysed by RNA polymerase from Escherichia coli is terminated at specific sites on DNA templates through the action of a multimeric basic protein known as rho (refs 1, 2). Three lines of evidence suggest that an interactions of rho with the nascent RNA is important for this termination. First, rho binds strongly to RNA; second, rho expresses an RNA-dependent ATPase activity which is essential for termination; third, RNA polymerase does not terminate RNA synthesis at rho-dependent sites when the nascent RNA is digested by ribonuclease during transcription. From the fact that certain RNAs, particularly single-stranded, pyrimidine-rich polymers containing at least 10% cytidylate residues, are more effective than other RNAs at promoting rho-ATPase, it has been proposed that rho recognises specific sites oion on a mRNA transcribed from bacteriophage lambda DNA.
...
PMID:A rho-recognition site on phage lambda cro-gene mRNA. 644 43

The non-transcribed spacers (NTS) of the ribosomal genes of a number of organisms have been studied and were found to contain repetitive sequences. In these studies with plasmid subclones of NTS, designated p3.4, p2.6 and p1.7, which come from both 5' and 3' flanking regions of the rat ribosomal genes, respectively, it has been determined that these sequences are found elsewhere within the genome. Southern hybridization analysis has demonstrated that the 5' and 3' NTS subclones cross-hybridize, and that the cross-hybridizing regions are synonymous with the highly repetitive regions. Sequences homologous to the rat NTS were specifically localized to both 5' and 3' flanking regions as well as to a number of the introns of cloned genes including rat serum albumin, rat alpha-fetoprotein, rat casein and human serum albumin. No hybridization was detected of the 5' NTS subclone to the human Alu sequence clone, Blur 8, or to the rodent equivalent, a clone containing Chinese hamster ovary type I and II Alu sequences. However, as reported for type II Alu sequences, the subcloned rat NTS sequences contain RNA polymerase III initiation sites and also hybridize to a number of small RNAs, but not 4.5 S or 7 S RNA. Sequence analysis of two distinct repetitive regions in p1.7 has revealed a region of alternating purine-pyrimidine nucleotides, potentially of Z DNA, and stretches of repetitive sequences. The possible roles for these repetitive sequences in recombination and in maintaining a hierarchical structure for the ribosomal genes are discussed.
...
PMID:Characterization of rat ribosomal DNA. The highly repetitive sequences that flank the ribosomal RNA transcription unit are homologous and contain RNA polymerase III transcription initiation sites. 671 75

A mutant of Salmonella typhimurium with a defect in the regulation of pyr-gene expression was obtained during a selection for mutants resistant to a combination of the two pyrimidine analogs, 5-fluorouracil and 5-fluorouridine. The mutant possesses 4-fold elevated pools of the pyrimidine nucleoside triphosphatases, UTP and CTP. The specific activities of aspartate transcarbamylase and orotate phosphoribosyltransferase are 40-fold and 7-fold higher in the mutant than in the parent strain when grown in minimal media. Furthermore, the synthesis of the two enzymes in the mutant is not repressed following addition of exogenous pyrimidines. The levels of carbamoylphosphate synthase and orotidine 5'-monophosphate decarboxylase are approximately 3-fold enhanced, while the activities of dihydroorotase and dihydroorotate oxidase appear largely unaffected by the mutation. The mutation responsible for these effects was shown to map between two known point mutations in the rpoBC gene cluster encoding the beta and beta' subunits of RNA polymerase. These observations indicate a regulatory function of RNA polymerase in the control of pyr-gene expression in S. typhimurium.
...
PMID:RNA polymerase involvement in the regulation of expression of Salmonella typhimurium pyr genes. Isolation and characterization of a fluorouracil-resistant mutant with high, constitutive expression of the pyrB and pyrE genes due to a mutation in rpoBC. 676 70

Rifampicin-resistant mutants of Salmonella typhimurium were isolated and tested for pleiotropic defects in the regulation of pyr gene expression. Seven per cent of all the Rifr mutants were inhibited in growth by addition of uracil (uracil-sensitive). The uracil-sensitive phenotype ( UraS ) was reversed by arginine or citrulline, but not by ornithine, and it was suppressed by mutations in either argR or pyrH , which causes increased expression of pyrA . It was shown that the basal levels of carbamoylphosphate synthase (the pyrA gene product) was reduced to approximately 60% in the mutants, and that addition of arginine and/or uracil to the growth medium caused hyperrepression of pyrA expression. The expression of other genes of the arginine and pyrimidine biosynthetic pathways was not affected significantly in the mutants. The mutations were located in the rpoB gene coding for the beta-subunit of RNA polymerase, suggesting a regulatory function of RNA polymerase in the control of pyrA expression.
...
PMID:Salmonella typhimurium mutants with altered expression of the pyrA gene due to changes in RNA polymerase. 676 40

The nucleotide sequence of the 5'-terminal oligonucleotides produced by pancreatic RNase digestion of bacteriophage T3 RNA polymerase (EC 2.7.7.6) transcripts of T3 DNA has been determined. The sequence determination is based upon a simple isolation procedure for the 5'-terminal oligonucleotides. This procedure involves treatment of pancreatic RNase digests of alpha 32P-labeled T3 RNA polymerase transcripts with bovine brain exoribonuclease to remove oligonucleotides with free 5'-hydroxyl termini and then chromatographing the products on hydroxylapatite to resolve the remaining oligonucleotides having 5'-phosphate termini. By application of standard two-dimensional separation and sequence techniques, the major 5'-end sequences deduced were pppGpGpGpApGpApGpApY(Y = pyrimidine nucleoside) and pppGpGpGpApGpApCp. In addition, the sequences of other minor 5'-terminal oligonucleotides observed on homochromatograms were also determined. The sequences of these 5'-oligonucleotides were pppGpGpGpApApCpY, pppGpGpGpApApUpY, pppGpGp(2-4 Gp, 2-3 ApGp)..., and pppGpGpGp.... These results demonstrate that T3 phage-induced RNA polymerase possesses a high degree of specificity in the initiation of RNA chains.
...
PMID:Isolation and sequence determination of 5'-terminal oligonucleotide fragments of RNA transcripts synthesized by bacteriophage T3-induced RNA polymerase from T3 DNA. 693 43

The mechanism of preferential transcription on poly[d(purine)] . poly[d(pyrimidine)] was investigated using RNA polymerase of T. thermophilus HB8. Though the machinery for initiation is lacking, the core enzyme has the latent ability to synthesize poly[r(pyrimidine)] as well as poly[r(purine)]. The holoenzyme can synthesize poly[r(purine)] in the usual manner. Poly[r(pyrimidine)] synthesis by the holoenzyme is, however, forbidden. These results suggest that the sigma factor plays a crucial role in this preferential transcription, and that this preferential transcription may be useful as a model for the sense strand recognition. Various results led us to the hypothesis that the high affinity site for the poly[d(pyrimidine)] strands on the enzyme plays a very important role.
...
PMID:The mechanism of preferential synthesis of poly[r(purine)] in the transcription of poly[d(purine)] . poly[d(pyrimidine)] by T. thermophilus RNA polymerase. 694 7


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---