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)

Nucleoside triphosphate phosphohydrolase [EC 3.6.1.15] activity was found to be included in silkworm cytoplasmic polyhedrosis (CP) virus, which synthesizes mRNA carrying the 5'-terminal modification. This enzyme releases orthophosphate from the gamma-position in a nucleoside triphosphate, leaving nucleoside diphosphate. The rate of hydrolysis of ATP is faster than that of any other ribonucleoside triphosphate. Deoxy ATP is hydrolyzed rather faster than ATP. However, polynucleotides carrying triphosphate at the 5'-terminus, that is, 4S RNA which was synthesized by E. coli RNA polymerase [EC 2.7.7.6] using calf thymus DNA as a template, and the phage Q beta RNA (30S), are not effective substrates for this enzyme. Although the CP virion loses the viral genome and one kind of protein component on proteolytic treatment with pronase, the partially degraded virion still retains phosphohydrolase activity. The phosphohydrolase must therefore be associated firmly with the virion. This enzyme does not require the presence of nucleic acid for its function. Phosphohydrolysis of ATP by this enzyme activity represents a first step in the synthesis of the 5'-terminal modified mRNA of CP virus.
...
PMID:Nucleoside triphosphate phosphohydrolase associated with cytoplasmic polyhedrosis virus. 1 44

Washed mature spermatozoa from bulls incorporate ribonucleoside triphosphates into RNA using an endogenous template. Maximum incorporation was observed at 31 degrees C in the presence of MgCl2, all four ribonucleoside triphosphates, beta-mercaptoethanol, and glycine sodium hydroxide buffer at pH 9.0. The amount of synthesis was linearly dependent upon the concentration of spermatozoa and continued for at least 4 h. Digestion studies revealed the RNA to be present in a protected (intracellular?) location in the spermatozoa. The RNA synthesis was inhibited by ethidium bromide, rifampicin, acriflavine, actinomycin D, and caffeine, but not by alpha-amanitine or rifamycin SV. Fractionation of the spermatozoa by sonication and separation of the heads and tails by centrifugation through a discontinuous gradient revealed that more than half of the total RNA polymerase activity was associated with the tail fraction.
...
PMID:RNA polymerase activity in bovine spermatozoa. 2 Apr 46

DNA synthesis in vitro using intact duplex T7 DNA as template is dependent on a novel group of three phage T7-induced proteins: DNA-priming protein (activity which complements a cell extract lacking the T7 gene 4-protein), T7 DNA polymerase (gene 5-protein plus host factor), and T7 DNA-binding protein. The reaction requires, in addition to the four deoxyribonucleoside triphosphates, all four ribonucleoside triphosphates and is inhibited by low concentrations of actinomycin D. Evidence is presented that the priming protein serves as a novel RNA polymerase to form a priming segment which is subsequently extended by T7 DNA polymerase. T7 RNA polymerase (gene 1-protein) can only partially substitute for the DNA-priming protein. At 30 degrees C, deoxyribonucleotide incorporation proceeds for more than 2 hours and the amount of newly synthesized DNA can exceed the amount of template DNA by 10-fold. The products of synthesis are not covalently attached to the template and sediment as short (12S) DNA chains in alkaline sucrose gradients. Sealing of these fragments into DNA of higher molecular weight requires the presence of E.coli DNA polymerase I and T7 ligase. Examination of the products in the electron microscope reveals many large, forked molecules and a few "eye"-shaped structures resembling the early replicative intermediates normally observed in vivo.
...
PMID:Studies on bacteriophage T7 DNA synthesis in vitro. II. Reconstitution of the T7 replication system using purified proteins. 5 68

The synthesis of RNA by chromatin-bound RNA polymerase (E.C. 2.7.7.6.) from white potato tubers proceeds at a low rate, which is enhanced after slicing the tissue, however. Concomitantly DNA template availability as measured with saturating amounts of Escherichia coli polymerase is diminished drastically. Nearest neighbor frequency analysis proved that the RNA synthesized on chromatin of intact tubers is different from that synthesized on chromatin of sliced tissue. The RNA polymerase of white potato tubers is dependent on all four ribonucleoside triphosphates and a divalent metal ion such as Mg2+ or Mn2+ and totally inhibited by the presence of pyrophosphate. Actinomycin D blocks the formation of the RNA product, which could be shown to be a heteropolymer by nearest neighbour frequency technique. The Km of the chromatin-bound enzyme with regard to ATP, GTP, CTP and UTP was 5.1 X 10(-5) M, 1.6X10(-5) M, 0.9X10(-5) M and 0.45X10(-5) M/l respectively. alpha-amanitin inhibits the overall activity to about 50%, which indicates the presence of equal amounts of polymerase I and polymerase II.
...
PMID:Activation of chromatin-bound DNA-dependent RNA polymerase (E.C. 2.7.7.6.) in plant storage tissue slices. 14 5

A new class of Escherichia coli mutants, referred to as grn, has been isolated by localized mutagenesis. These mutations affect the sigma subunit of DNA-dependent RNA polymerase (ribonucleoside 5'-triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) by abolishing the expression of the lambda N gene, and they are closely lniked to dnaG in the order dnaG-grn-uxaA. Detailed study of one such mutant, grn1, yielded the following results: (i) grn1 is a single mutation and the mutant cell shows cold-sensitivity in growth; (ii) the Grn phenotype of the mutant can easily be suppressed by secondary mutations in the beta subunit gene of RNA polymerase; (iii) purified holoenzyme of RNA polymerase isolated from the mutant showed an altered salt-dependency in vitro, and the mixed reconstitution of the mutant with the wild-type subunits showed that the sigma subunit of the grn1 mutant is altered; (iv) lambda phage mutants (lambda grg), which overcome the grn mutation, can be classified into two groups, the "nin-deletion" and the "N-mutant" groups (both of these are also able to grow on the previously described groN mutant of Georgopoulos and nusAB of Friedman); (iv) the mutant polymerase transcribed 12S as well as 7S RNA from lambda DNA in the presence of the rho factor in vitro. These results indicate that the grn mutation alters the sigma subunit of RNA polymerase and that the sigma subunit participates in activating the N-mediated antitermination mode of lambda phage transcription.
...
PMID:Sigma subunit of Escherichia coli RNA polymerase affects the function of lambda N gene. 15 60

Simian virus 40 (SV40) DNA I was transcribed with Escherichia coli RNA polymerase in the presence of gamma-32P-labeled ribonucleoside triphosphates in order to investigate the specificity of initiation of in vitro transcription. ATP and GTP served as predominant initiating nucleotides, the former being incorporated about twice as much as the latter. Cleavage of [gamma-32P]ATP-labeled SV40 complementary RNA (cRNA) with T1 RNase followed by homochromatographic analysis of the resultant 5' initiation fragments revealed the presence of four specific initiation fragments 6 to 9 nucleotides in length, designated AI, AII, AIIIa, and AIIIb. By means of hybridization of [gamma-32P]ATP-labeled SV40 cRNA to DNA from specific adenovirus 2-SV40 hybrids and specific restriction endonuclease fragments of SV40 DNA before chromatographic analysis, it was possible to identify and determine approximate localizations of five [gamma-32P]ATP initiation sites on the SV40 genome: one in Hin-G close to the Hin-G-B junction, giving rise to the AII fragment, two in the overalpping fragment Hin-A-Hae-A,giving rise to AI and AIII fragments, and two in the fragment Hin-A-Hae-E, also giving rise to AI and AIII fragments. All five sites either fall within or lie near regions of the genome that are cleaved by S1 nuclease and subject to partial alkaline denaturation. These five sites lie on the minus strand of SV40 DNA and initiate RNAs that are copied in a leftward direction. Cleavage of [gamma-32P]GTP-labeled cRNA with pancreatic RNase liberated three major 5' initiation fragments of short length, GI, GII, and GIII, suggesting the presence of three principal GTP initiation sites.
...
PMID:Specificity of initiation of transcription of simian virus 40 DNA I by Escherichia coli RNA polymerase: identification and localization of five sites for initiation with [gamma-32P]ATP. 19 61

A nucleoprotein complex that is an intermediate in viral transcription has been isolated from simian virus 40 (SV40)-infected BSC-1 cells after lysing infected nuclei with Sarkosyl. It contain DNA, DNA-dependent RNA polymerase II, and nascent RNA chains. RNA chain elongation continues for several hours in vitro and is dependent on exogenous ribonucleoside triphosphates. The complex sediments in neutral sucrose gradients with a main peak at about 24 to 26S. When the nascent RNA on the complex is treated with RNase A, a fraction of the RNA remains resistant to RNase and is hydrogen bonded to the DNA template. The pulse-labeled RNase-resistant RNA can be chased into RNase-sensitive RNA, indicating that it is located at the 3' terminus of the RNA chain. The rate of RNA displacement from the DNA template is consistent with an average rate of RNA chain elongation of 15 to 30 nucleotides per min. At least 70% of the RNA synthesized in this in vitro system is SV40 specific. Hybridization with the separated strands of SV40 DNA and with fragments of SV40 DNA generated with endonucleases HindII + III indicates that this RNA is complementary to all regions of the "late" SV40 DNA strand. Studies of SV40 RNA synthesis in this partially purified preparation at early and late times after infection should provide a way of locating promoter sites for transcription and identifying the form of SV40 DNA that serves as a template for late transcription.
...
PMID:Properties of simian virus 40 transcriptional intermediates isolated from nuclei of permissive cells. 19 3

Synthesis of ribonucleic acid (RNA) by the deoxyribonucleic acid-dependent RNA polymerase of Coxiella burnetii required adenosine, uridine, guanosine, and cytidine 5'-triphosphates. Cell-free preparations of this obligate intracellular procaryotic parasite had competence to phosphorylate ribonucleoside mono- and diphosphates in the presence of exogenous adenosine and guanosine 5'-triphosphates to the corresponding di- and triphosphates. C. burnetii contained about 2 nmol of adenosine 5'-triphosphate per mg of protein, which could serve as a approximately P donor for in vivo synthesis of nucleoside triphosphates. The latter were then used as substrates in the synthesis of RNA in a coordinated metabolic system with C. burnetii RNA polymerase. It is suggested that during infection the rickettsiae might obtain the nucleotides necessary for RNA synthesis from the vacuoles in which C. burnetii proliferates.
...
PMID:Synthesis of ribonucleotides and their participation in ribonucleic acid synthesis by Coxiella burnetii. 20 Jun 3

Nucleoside triphosphate phosphohydrolase (NTPase) activity was found in a preparation of E. Coli RNA polymerase. This enzymatic activity is capable of hydrolysing all four ribonucleoside triphosphates to the nucleoside diphosphates. However, during in vitro RNA synthesis directed by poly(dC) or poly(dT), only the non-complementary nucleoside triphosphate of the same heterocyclic class was hydrolysed. No incorporation of the non-complementary precursor into RNA could be detected in these experiments. When another RNA polymerase preparation, devoid of NTPase activity, was employed, there was no hydrolysis of any nucleoside triphosphate and significant incorporation of non-complemtary precursor into RNA was observed. These observations lead us to the conclusion that NTPase, acting in conjunction with RNA polymerase, has the function of correcting errors in transcription.
...
PMID:A possible mechanism responsible for the correction of transcription errors. 22 87

Purified cores of vesicular stomatitis virus contain an enzymatic activity that converts GDP, UDP, and CDP into their corresponding triphosphates using ATP as the phosphate donor. Thus, the virion-associated RNA polymerase can synthesize mRNA normally in vitro even when one of the ribonucleoside triphosphates is replaced by its corresponding diphosphate. RNA synthesis does not proceed if ATP is replaced by ADP. Similarly RNA synthesis is impaired if CDP and UDP are present in the same reaction. The role of the nucleoside diphosphate kinase (NDP kinase, EC 2.7.4.6) in vesicular stomatitis virus mRNA synthesis in vitro is discussed.
...
PMID:Nucleoside diphosphate kinase activity in purified cores of vesicular stomatitis virus. 22 22


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

---