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)

The major 5'-termini of human adenovirus type 2 early gene block 4 mRNA were sequenced. Poly(A+) polyribosomal RNA was isolated from Ad2 early infected cells, the 5'-terminal m7GPPP removed and the 5'-OH of the penultimate 2'-0-methylated nucleotide labeled with [gamma-32P]ATP using polynucleotide kinase. Ad2 E4 mRNA was purified by hybridization to the Ad2 EcoRI-C fragment and was digested with RNase T1. The resulting oligonucleotides were resolved by two dimensional paper electrophoresis-homochromatography. Four major and 3-4 minor 5'-terminal sequences were identified and characterized. The sequence of the 5'-terminal structures of the major four termini are: (1) m7GpppUmU(m)UUACACUGp, (2) m7GpppUmU(m)UACACUGp, (3) m7GpppUmU(m)ACACUGp, and (4) m7Gppp(m6)AmC(m)ACUGp. These major 5'-terminal sequences were aligned with nucleotide 325, 326, 327, and 329 from the righthand end of the known Ad2 DNA sequence (1) in the region mapped as the 5'-terminus of E4 mRNA by electron microscopy (2,3) and S1 nuclease-gel (4) mapping. Two potential ribosomal binding sites and an initiator codon were found at 40 to 65 nucleotides and about 80 nucleotides, respectively, from these heterogenous 5'-termini. Ad2 E4 major mRNA species appear to be unique since mRNA molecules initiate at a pyrimidine, perhaps by RNA polymerase stuttering, or they are products of an unusual type of RNA processing.
...
PMID:Nucleotide sequences and mapping of novel heterogenous 5'-termini of adenovirus 2 early region 4 mRNA. 616 92

Cloned DNA fragments form the human beta-like globin genomic region can be transcribed in vitro by RNA polymerase III. We have investigated the structure of two templates and their transcripts by DNA sequencing, size fractionation of ribonuclease T1 generated oligonucleotides, and ribonuclease H digestion of RNA : DNA duplexes. The data indicate the repetitive DNA sequences, members of the Alu family of interpersed 300 bp reiterated DNA, are imbedded in both templates. The RNAs transcribed from them are composed of an entire Alu family sequence at their 5' ends linked to 3' ends of non-repetitive sequence.
...
PMID:Structural analysis of templates and RNA polymerase III transcripts of Alu family sequences interspersed among the human beta-like globin genes. 616 49

Genomic DNA fragments containing sequences homologous to 5 S rRNA have been isolated from humans and mice. When transcribed in a cell-free system (S100) derived from human HeLa cells, these cloned fragments show qualitative and quantitative differences with respect to 5 S rRNA synthesis and with respect to the synthesis of larger RNA polymerase III transcripts in the 300-600-nucleotide range. One mouse and one human clone have been characterized in detail. The clone containing the mouse 5 S gene is active in an in vitro transcription system and generates a 5 S transcript which differs in five RNase T1 oligonucleotides from mouse 5 S rRNA. In contrast, the clone containing the human 5 S gene is transcriptionally inactive for a 5 S-sized RNA product in vitro. Both clones serve as active templates for multiple RNA transcripts which share sequence homology with the human Alu family. These transcripts, as well as cloned Alu sequences used as hybridization probes, map to sites within close proximity of the 5 S gene in both the mouse and human clones. These functionally heterogeneous 5 S genes are arranged in a manner similar to the bulk of 5 S rRNA genes within their respective genomes and may be interspersed among them. The repeat lengths for DNA fragments containing these genes are considerably longer (2.8 and 6 kilobases) than observed for 5 S genes in other organisms and may indicate that larger repeat units are a characteristic feature of mammalian 5 S genes.
...
PMID:Isolation and genomic arrangement of active and inactive forms of mammalian 5 S RNA genes. 620 99

RNA polymerase is known to undergo a cycling process during initiation of transcription in vitro in which large amounts of small oligonucleotides are released. We have used this cycling reaction to determine the 5' end of the RNA synthesized from the outer ends of the Tn5 inverted repeats. By analyzing the size of the radiolabeled oligonucleotides synthesized using different labeled nucleoside triphosphates and in reactions deficient for a particular nucleoside triphosphate, the partial 5' sequence was obtained. This sequence was correlated with the DNA sequence of the region and an unambiguous origin for the mRNA was determined. The start site for the RNA, which is located at 97 base pairs from the outer ends of the inverted repeats, was confirmed by digesting gamma-32 P-ATP labeled full length (run off) transcripts with ribonuclease T1. The resulting gamma-labeled T1 generated oligonucleotide corresponded to the predicted size determined using the cycling reaction. With the knowledge of the RNA start site, the probable translation start sites for the protein(s) known to be required for Tn5 transposition can be predicted. Possible implications of the DNA sequence with respect to the regulation of the transposase are also discussed.
...
PMID:Localization of the Tn5 transposase promoter using the cycling reaction of RNA polymerase. 626 98

The 6 S leader RNA transcript from the Escherichia coli threonine operon controlling region was synthesized in vitro using purified RNA polymerase and restriction fragment DNA templates. The terminated leader transcript was analyzed by RNase T1 digestion followed by electrophoresis on 20% polyacrylamide, 8 M urea gels. Oligonucleotides of 7, 8, 13, 15, and 35 bases in length were detected and correlated with the known DNA sequence. The kinetics of RNase T1 digestion indicated that the RNA forms extensive secondary structure, especially at the 3'-terminus of the transcript. The sites of transcription initiation were determined by labeling the 5'-end of the transcript with [gamma-32P]ATP or -GTP followed by direct RNA sequencing. The DNA sequence preceding the initiation site shows homology with the equivalent regions of other bacterial and bacteriophage promoters. The transcription termination sites were determined by mapping of the RNase T1 oligonucleotides arising from the 3'-terminus of the transcript. Comparison of the mobilities of the 3'-oligonucleotides with the mobilities of standards on 20% polyacrylamide, 8 M urea gels indicated that the RNA contains a heterogeneous 3'-terminus. The two predominant oligonucleotides were CU7 and CU8. The 3'-terminus of the transcript also contains a region of dyad symmetry immediately preceding a stretch of uridine residues, characteristic of other rho-independent transcripts. In addition, kinetic studies indicated that RNA polymerase pauses approximately 50 base pairs upstream from the site of termination. The pause site appears to be immediately distal to another region of dyad symmetry.
...
PMID:Initiation, pausing, and termination of transcription in the threonine operon regulatory region of Escherichia coli. 627 52

We have studied transcriptional initiation in the mitochondria of the yeast Saccharomyces cerevisiae by analyzing mitochondrial transcripts from grande and petite yeast after labeling in vitro with vaccinia virus guanylyltransferase and [alpha-32P]GTP. This procedure labels triphosphate-terminated RNA which arises from transcriptional initiation. Exploiting the extremely low GC content (18%) of yeast mitochondrial DNA, we digested the in vitro capped transcripts with the G-specific ribonuclease T1; this resulted in 27 oligonucleotides varying in size from 2 to 51 nucleotides. RNA from 14 overlapping petites was analyzed and 20 transcripts were localized by deletion mapping. Nineteen oligonucleotides were sequences and 13 were identified and precisely localized by comparison with known DNA sequences. In all cases, transcription is initiated at a consensus nonanucleotide sequence which can be considered part of the yeast mitochondrial promoter. We identified initiation sites for the 21 S and 14 S rRNAs; the phenylalanine, f-methionine, and glutamic tRNAs; two sites for the OLI-1 gene; and three for the ori (rep) regions. Most promoters appear to give rise to very long multigene primary transcripts. Examples are multigene transcripts for the glutamic tRNA and COB genes and for the OLI-1, serine tRNA, and Var genes. Since the consensus nonanucleotide sequences at the ori regions are similar to those at other transcriptional initiation sites, it is likely that the same RNA polymerase primes DNA replication and gene transcription.
...
PMID:Identification of multiple transcriptional initiation sites on the yeast mitochondrial genome by in vitro capping with guanylyltransferase. 631 17

We have mapped a major initiation site of purified calf thymus RNA polymerase II in the cloned adenovirus 2 major late promoter. The specificity of this initiation site has been determined by "run-off" transcriptional analysis and by RNase T1 analysis which employs single-stranded M13 phage DNA containing the Adenovirus 2 major late promoter as probe. The TATAAA region which is used as the start site by the purified RNA polymerase II for in vitro transcription is 30 base pairs upstream from the adenovirus major late in vivo start site. The exact sequence also exists at two sites within the pBR322 plasmid but initiation does not occur at either of these sites. This indicates that the purified enzyme is not just recognizing AT-rich regions but that it is recognizing both the TATA box and its surrounding sequences. The purified RNA polymerase II transcriptional initiation site is used when transcription was carried out on either a superhelical (FI) or linear (FIII) DNA template. Selective initiation of transcription on FI DNA required (NH4)2SO4 concentrations which ranged from 90 to 150 mM. In contrast, selective initiation of transcription on FIII DNA was observed at (NH4)2SO4 concentrations that ranged from 30 to 120 mM.
...
PMID:In vitro transcription initiation by purified RNA polymerase II within the adenovirus 2 major late promoter region. 632 64

Bacteriophage lambda transcripts were synthesized in vitro using lambda b2 DNA and Escherichia coli RNA polymerase. RNA molecules initiating with ATP were labeled exclusively at the 5'-end by transcribing in the presence of [gamma-32P]ATP. They were analyzed by electrophoresis in 3.5% polyacrylamide, 7.5 M urea gels followed by autoradiography. The previously known 6 S rho-independent transcript and rho-dependent 9 S and 8 S transcripts were observed. A new rho-dependent 5 S transcript was also detected. The 5 S RNA was not the result of cleavage of larger RNAs by ribonuclease III. Analysis of partial ribonuclease T1 digestion products of isolated 5'-end-labeled transcripts showed that the 5 S RNA is synthesized from promoter pR, the promoter for the 9 S and 8 S RNA species. A similar analysis of transcripts labeled with 32P exclusively at the 3'-terminus by the post-transcriptional addition of a [32P]pCp moiety with T4 RNA ligase revealed the positions of guanosine nucleotides proximal to the 3'-hydroxyl end. This information, and inspection of the known DNA nucleotide sequence downstream from pr, allowed us to conclude that the 5 S RNA is a mixture of molecules 112 and 113 nucleotides long terminating in the middle of gene cro. The nucleotide sequence at the 3'-end of the 5 S RNA is similar to that of other rho-dependent transcripts and lacks the oligo(U) found at the terminus of rho-independent transcripts.
...
PMID:Characterization of a rho-dependent termination site within the cro gene of bacteriophage lambda. 644 59

Mammalian RNA polymerase II was shown to utilize dinucleoside monophosphates for priming of promoter specific RNAs. In a reconstituted system containing purified polymerase and HeLa cell fractions, dinucleotides were incorporated by complementarity with template sequences at the in vivo cap sites of the adenovirus major late and adenovirus early region IV promoters. Incorporation was shown by label transfer experiments and by determining the size of 5'-terminal RNase T1-resistant oligonucleotides. All 16 dinucleotides were tested for priming of RNA chains at the major late promoter. RNA polymerase II initiated with various primers over a contiguous region of 9 bases, centered around the in vivo initiation site. We suggest that the polymerase drifts or oscillates over this region. Using a dinucleotide challenge protocol, the rate of initiation at the major late promoter was measured following preincubation of the template DNA with RNA polymerase II and factors. Initiation with ATP was 90% complete within the 1st min after addition of nucleotide triphosphates. Stimulation of transcription by dinucleotides was not observed, due to this rapid initiation. The 5'-hydroxyl terminus of dinucleotide-primed RNAs remained unmodified. Although transcripts initiated with ATP were rapidly capped in whole cell extracts, ATP-primed RNA synthesized in the reconstituted system retained free 5'-terminal phosphates. Thus, capping was not essential for synthesis of long runoff RNAs.
...
PMID:Dinucleotide priming of transcription mediated by RNA polymerase II. 658 1

Variant double-stranded RNAs are often associated with the genome of transmission-defective isolates of wound tumor virus. These RNAs are replicated and packaged into virus particles in systemically infected plants and are transcribed in vitro by the virion-associated transcriptase. Direct physical evidence that the variant RNAs are remnants of particular WTV genome segments was provided by molecular hybridization studies. Subsequently, ribonuclease T1 digestion products of 3'-end-labeled genome and remnant RNAs were analyzed by one- and two-dimensional electrophoretic techniques. One-dimensional partial and complete digestion patterns were indistinguishable, indicating that the guanosine positions relative to the 3' terminus of the corresponding strands of a particular genome segment and its remnant RNA are the same for at least 40 nucleotides from each end. Fingerprints of the 3' terminal ribonuclease T1-resistant fragments were identical, showing that the nucleotide composition of the 3' terminal ends of the corresponding strands of a particular genome segment and its remnant RNA are also identical. These results indicate that variant RNAs associated with transmission-defective WTV isolates are formed by deletion of an internal portion (as much as 85%) of genomic RNA segments yielding terminally conserved genomic remnants that are functional with respect to transcription, replication, and packaging.
...
PMID:Variant dsRNAs associated with transmission-defective isolates of wound tumor virus represent terminally conserved remnants of genome segments. 671 Aug 65


<< Previous 1 2 3 4 5 Next >>

---