scholarly journals Deoxyribonucleic acid-dependent ribonucleic acid polymerases from murine spleen cells. Increased amounts of the nucleolar species in leukaemic tissue

1973 ◽  
Vol 133 (4) ◽  
pp. 797-804 ◽  
Author(s):  
Donner F. Babcock ◽  
Marvin A. Rich
Keyword(s):  
Rna Synthesis ◽  
Rna Polymerases ◽  
Infected Tissue ◽  
Leukaemia Virus ◽  
Bivalent Cations ◽  
Murine Spleen ◽  
Insoluble Product ◽  
Polymerase I ◽  
Dna Template ◽  
Nucleolar Rna

1. In the spleens of infected mice, the Friend leukaemia virus induces a sharp increase in the ability of subsequently isolated nuclei to incorporate exogenous UTP into an acid-insoluble product. Inhibitor studies indicate that the incremental RNA synthesis proceeds from a DNA template and that both nucleolar and nucleoplasmic activities are involved. 2. The partially purified DNA-dependent RNA polymerases from control and virus-infected tissue are indistinguishable with respect to chromatographic mobility, dependence on bivalent cations, ionic strength, pH and their susceptibility to α-amanitin. The RNA polymerases of the murine spleen resemble the enzymes of other mammalian tissue in these properties. 3. A comparison of the amount of polymerase solubilized from normal and infected tissue correlates with the activity observed in assays of the respective nuclei. These experiments indicated that the increase in nucleolar RNA synthesis after infection is mediated by increased extractable polymerase I activity whereas the change in nucleoplasmic RNA synthesis results from an alteration of chromatin or a chromatin-associated factor.

scholarly journals High concentration of RNA polymerase I is responsible for the high rate of nucleolar transcription

1980 ◽  
Vol 188 (2) ◽  
pp. 381-385 ◽  
Author(s):  
F L Yu
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Rna Polymerases ◽  
Rna Polymerase I ◽  
High Rate ◽  
Unit Weight ◽  
High Concentration ◽  
Steady State Condition ◽  
Polymerase I ◽  
Nucleolar Rna

When isolated rat liver nuclei and nucleoli are compared for RNA synthesis in vitro, the rate of nucleolar RNA synthesis is found to be more than 10 times higher. In order to understand this high rate of nucleolar transcription, DNA from both nuclear and nucleolar fractions was isolated and compared for the ability to direct RNA synthesis with homologous RNA polymerases. No difference between these two templates is evident. On the other hand, when the total nuclear and nucleolar RNA polymerases are isolated and compared on a per-unit-weight-of-DNA basis, it becomes clear that the nucleolus has a 10-fold higher RNA polymerase concentration than the nucleus. This result suggests that RNA polymerase I concentration rather than the nucleolar DNA template efficiency is responsible for the observed high rate of nucleolar transcription under the normal steady-state condition.

Phosphorylation of RNA polymerases: specific association of protein kinase NIl with RNA polymerase I

1983 ◽  
Vol 302 (1108) ◽  
pp. 135-142 ◽  
Keyword(s):  
Protein Kinase ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
Rna Polymerase Iii ◽  
Rna Polymerases ◽  
Rna Polymerase I ◽  
Liver Protein ◽  
Protein Kinase N ◽  
Polymerase I

The activities of the three DNA-dependent RNA polymerases from a rapidly growing rat tumour, Morris hepatoma 3924 A, and from rat liver were examined. The activity of RNA polymerase I was higher in the tumour than in the liver. The enhanced capacity for RNA synthesis was a result of a higher concentration of polymerase I in the tumour as well as of an activation of this enzyme vivo. The possibility that the high specific activity of the hepatoma polymerase I resulted from phosphorylation was investigated. Two major cyclic-AMP-independent nuclear casein kinases (NI and N il) were identified; the activity of protein kinase N il in the tumour was ten times that in liver. Protein kinase N il was capable of activating and phosphorylating RNA polymerase I in vitro . This kinase could also stimulate RNA polymerase II activity, although to a lesser extent than RNA polymerase I. RNA polymerase III was not affected by protein kinase NIL Protein kinase N il was tightly associated with polymerase I and was found even in purified preparations of the polymerase. Antibodies against both RNA polymerase I and protein kinase N il were present in sera of patients with certain rheumatic autoimmune diseases. These results imply that RNA polymerase I and protein kinase NIl are in close association in vivo as well as in vitro and that polymerase phosphorylation may regulate the rate of ribosomal RNA synthesis in the cell.

The Effect of a New Antibiotic, Cryptosporiopsin, on RNA Synthesis in L-Cells

1975 ◽  
Vol 53 (2) ◽  
pp. 149-154 ◽  
Author(s):  
J. Dessureault ◽  
M. O. Krause
Keyword(s):  
Rna Synthesis ◽  
Double Labelling ◽  
Cell Nuclei ◽  
Intact Cells ◽  
Uptake Inhibition ◽  
L Cells ◽  
Polymerase I ◽  
Nucleolar Rna

The effect of cryptosporiopsin on RNA synthesis in L-cells was studied as part of an investigation on the mechanism of action and potential toxicity of the antibiotic in mammalian cells.RNA synthesis in vitro was tested in intact isolated L-cell nuclei, in conjunction with selective inhibitors of nucleolar and nucleoplasmic RNA synthetic activities. It was found that only the nucleoplasmic activity (polymerase II), was inhibited by cryptosporiopsin and that the drug showed no effect on the activity of the nucleolar enzyme (polymerase I).RNA synthesis in vivo was tested using double labelling with [14C]guanine and [3H]-uridine in an attempt at discriminating between G + C nucleolar RNA and high A + U nucleoplasmic RNA synthesis. Results revealed that the uptake of these precursors into both types of RNA was inhibited by cryptosporiopsin in intact cells. Measurements of the nucleotide pools in these cells indicated that the antibiotic affects uptake and phosphorylation of nucleosides and nucleotides, especially the production of ATP. These results suggest that the uptake inhibition observed in vivo could be due, at least in part, to energy and/or precursor shortage.

scholarly journals The mechanism of inhibition of ribonucleic acid synthesis by 8-hydroxyquinoline and the antibiotic lomofungin.

1975 ◽  
Vol 147 (3) ◽  
pp. 401-410 ◽  
Author(s):  
R S Fraser ◽  
J Creanor
Keyword(s):  
Rna Polymerase ◽  
Direct Contact ◽  
Rna Synthesis ◽  
Chelating Agent ◽  
Acid Synthesis ◽  
Polymerase Activity ◽  
5S Rna ◽  
Bivalent Cations ◽  
Mechanism Of Inhibition ◽  
Dna Template

RNA synthesis in yeast is rapidly inhibited by 8-hydroxyquinoline and the phenazine antibiotic lomofungin (5-formyl-1-methoxycarbonyl-4,6,8-trihydroxyphenazine). It is shown that lomofungin, like 8-hydroxyquinoline, is a chelating agent for bivalent cations. The mechanism of inhibition of RNA synthesis by lomofungin and 8-hydroxyquinoline was investigated in experiments with isolated Escherichia coli RNA polymerase. The results show that both inhibitors are capable of inhibiting polymerase activity solely by chelating the dissociable cations Mn2+ and Mg2+. Evidence is presented which shows that inhibition may occur in the absence of any direct contact between the RNA polymerase or DNA template and the inhibitor. The possibility that inhibition might also occur by chelation of the Zn2+, which is tightly bound to the polymerase, is discussed: it is concluded that lomofungin or 8-hydroxyquinoline is likely to inhibit the enzyme by removal of Mn2+ and Mg2+ before chelating the Zn2+. On the basis of inhibition by chelation of Mn2+ and Mg2+, explanations are proposed for why lomofungin and 8-hydroxyquinoline inhibit synthesis of ribosomal and polydisperse RNA more than that of 5S RNA and tRNA, and for why protein synthesis is not immediately inhibited in the intact yeast cell.

scholarly journals INHIBITING EFFECT OF THE NEW CYTOTOXIC ANTIBIOTIC DAUNOMYCIN ON NUCLEIC ACIDS AND MITOTIC ACTIVITY OF HELA CELLS

1965 ◽  
Vol 27 (3) ◽  
pp. 545-550 ◽  
Author(s):  
A. Di Marco ◽  
R. Silvestrini ◽  
S. Di Marco ◽  
T. Dasdia
Keyword(s):  
Mitotic Activity ◽  
Rna Synthesis ◽  
Thymidine Incorporation ◽  
Acid Synthesis ◽  
Acetyl Derivative ◽  
Total Inhibition ◽  
Nuclear Rna ◽  
Nucleolar Rna ◽  
Higher Doses

The effect has been studied of Actinomycin D, Daunomycin (Da.), and Da. N acetyl derivative on mitotic activity and on the nucleic acid synthesis of in vitro HeLa cell cultures. The experiments were carried out by means of the radioautographic technique using stripping films. The relative uptake of thymidine-H3 and uridine-H3 was determined by means of the reduced silver grain count present in the nuclei of controls and treated cells. The mitotic activity and thymidine incorporation were noticeably reduced by Daunomycin and Actinomycin, whereas both processes appeared less affected by Da. N acetyl derivative. As regards nuclear RNA synthesis, all three antibiotics at low doses chiefly inhibit nucleolar RNA synthesis. On the other hand, whilst Actinomycin at higher doses causes an almost total inhibition of the synthesis of the whole nuclear RNA, in Daunomycin- and Da. N acetyl derivative-treated cells extranucleolar RNA synthesis is less susceptible to inhibition.

scholarly journals Selective inhibition by zinc of RNA synthesis initiation in the RNA polymerase I reaction

FEBS Letters ◽  
1979 ◽  
Vol 99 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Yoshikuni Nagamine ◽  
Den'ichi Mizuno ◽  
Shunji Natori
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Selective Inhibition ◽  
Rna Polymerase I ◽  
Polymerase I

scholarly journals VPg-Primed RNA Synthesis of Norovirus RNA-Dependent RNA Polymerases by Using a Novel Cell-Based Assay

2011 ◽  
Vol 85 (24) ◽  
pp. 13027-13037 ◽  
Author(s):  
C. V. Subba-Reddy ◽  
I. Goodfellow ◽  
C. C. Kao
Keyword(s):  
Rna Synthesis ◽  
Rna Polymerases
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