Convolution analysis of transcription by yeast DNA-dependent ribonucleic acid polymerase A A mathematical method for studying ribonucleic acid chain elongation

1979 ◽  
Vol 179 (3) ◽  
pp. 449.b1-449.b1
Keyword(s):  
Mathematical Method ◽  
Ribonucleic Acid ◽  
Chain Elongation

scholarly journals Convolution analysis of transcription by yeast DNA-dependent ribonucleic acid polymerase A. A mathematical method for studying ribonucleic acid chain elongation

1979 ◽  
Vol 177 (3) ◽  
pp. 825-831
Author(s):  
C S Cooper ◽  
R V Quincey
Keyword(s):  
Mathematical Method ◽  
Rna Polymerase ◽  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Integral Solution ◽  
Chain Elongation ◽  
Enzyme Molecule ◽  
Convolution Integral ◽  
Calf Thymus ◽  
Biphasic Profile

The rate of initiation of RNA synthesis catalysed by yeast RNA polymerase A on native calf thymus DNA decayed exponentially with a half-life of about 4.3 min. The rate constant for initiation was unaffected by preincubating the enzyme with DNA, or by decreasing the concentration of GTP 4-fold. The rate of RNA synthesis was constant for 15–20 min and then decreased. Each enzyme molecule made no more than one RNA molecule. In this situation, initiation, elongation and total RNA synthesis are related by a convolution integral. Solution of the convolution integral revealed that the rate of elongation was apparently biphasic. Analysis of the size of the RNA product showed that this biphasic profile arose because most but not all of the enzyme stopped RNA synthesis soon after initiation.

scholarly journals Rate of synthesis and half-life of globin messenger ribonucleic acid. Rate of synthesis of globin messenger ribonucleic acid calculated from data of cell haemoglobin content

1974 ◽  
Vol 138 (3) ◽  
pp. 499-510 ◽  
Author(s):  
John A. Hunt
Keyword(s):  
Ribonucleic Acid ◽  
Half Life ◽  
Chain Elongation ◽  
Erythroid Cell ◽  
Synthesis Rate ◽  
Mrna Synthesis ◽  
Base Pairs ◽  
Messenger Ribonucleic Acid ◽  
Nucleotide Base ◽  
Mrna Half Life

By the use of the favoured models defining mRNA synthesis and half-life from the preceding paper (Hunt, 1974) and the known content of globin in a reticulocyte it is possible to estimate the absolute rate of mRNA and globin synthesis and the mRNA and globin content in each type of erythroid cell. The best model requires an mRNA-synthetic rate of 3000 molecules per h/cell. This rate compares favourably with the estimated chain-extension rate of 43 nucleotides/s in Escherichia coli (Manor et al., 1969) provided that the four α- and β-chain cistrons per cell are transcribed by polymerases spaced 50 nucleotide base pairs apart. Similar calculations can be made for erythropoiesis in the chick embryo, where cell times and relative globin content at each mitosis have been measured (Campbell et al., 1971), but where no reliable estimates of mRNA half-life have been made. In this case it was estimated that a constant rate of mRNA synthesis at 10000 molecules per h/cell through six cell divisions is necessary if the mRNA half-life is 15h; after the sixth mitosis the mRNA synthesis would stop and its half-life would increase to approx. 20h. If an mRNA half-life of 4.5h is used, the synthesis rate through the six mitoses would be 21000 molecules per h/cell, ceasing at the sixth mitosis, when the half-life would need to increase to 25h. The chain-elongation rate for the four α- and β-globin cistrons per cell would be 1–2 times higher than in E. coli and would either require a greater rate, polymerases spaced between 25 and 50 nucleotide base pairs apart on the DNA, or limited gene replication. These possibilities are discussed in the light of the low values found for globin cistron multiplicity in ducks and mice.

scholarly journals The control of ribonucleic acid synthesis in bacteria. The synthesis and stability of ribonucleic acid in chloramphenicol-inhibited cultures of Escherichia coli

1971 ◽  
Vol 122 (2) ◽  
pp. 149-159 ◽  
Author(s):  
J. E. M. Midgley ◽  
W. J. H. Gray
Keyword(s):  
Escherichia Coli ◽  
Ribonucleic Acid ◽  
Acid Synthesis ◽  
Chain Elongation ◽  
23S Rrna ◽  
Initiation Rate ◽  
Rate Of Polymerization ◽  
Antibiotic Inhibition ◽  
Kinetics Of ◽  
Small Acceleration

The rate of polymerization of ribosomal ribonucleic acid chains was estimated for steadily growing cultures of Escherichia coli M.R.E.600, from the kinetics of incorporation of exogenous [5-3H]uracil into completed 23S rRNA molecules. The analytical method of Avery & Midgley (1971) was used. Measurements were made at 37°C, in the presence or the absence of chloramphenicol, in each of three media; enriched broth, glucose–salts or sodium lactate–salts. The rate of chain elongation of 23S rRNA was virtually constant in all media at 37°C, as 24±4 nucleotides added/s. Accelerations in the rate of biosynthesis of rRNA by chloramphenicol in growth-limiting media are due primarily to an increase in the rate of initiation of new RNA chains, up to the rates existing in cultures growing rapidly in broth. Thus, in poorer media, only a small fraction of the available DNA-dependent RNA polymerase molecules are active at any given instant, since the chain-initiation rate is limiting in these conditions. In cultures growing rapidly in enriched broth, antibiotic inhibition caused a rise of some 12% in the rate of incorporation of exogenous uracil into total RNA. This small acceleration was due entirely to the partial stabilization of the mRNA fraction, which accumulated as 14′ of the RNA formed after the addition of chloramphenicol. In cultures growing more slowly in glucose–salts or lactate–salts media, chloramphenicol caused an immediate acceleration of two- to three-fold in the overall rate of RNA synthesis. Studies by DNA–RNA hybridization showed that the synthesis of mRNA was accelerated in harmony with the other affected species. However, just over half the mRNA formed after the addition of chloramphenicol quickly decayed to acid-soluble products, whereas the remainder was more stable and accumulated in the cells. The mRNA fraction constituted about 6% of the total cellular RNA after 3h inhibition. A model was suggested to explain the partial stabilization and accumulation of the mRNA fraction and the acceleration in the rate of synthesis of mRNA when chloramphenicol was added to cultures in growth-limiting media.

scholarly journals Ribonucleic acid synthesis in the myocardium of spontaneously hypertensive rats. Quantification of transcribing ribonucleic acid polymerases

1980 ◽  
Vol 188 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Constantinos J. Limas
Keyword(s):  
Cardiac Hypertrophy ◽  
Ribonucleic Acid ◽  
Spontaneously Hypertensive Rats ◽  
Acid Synthesis ◽  
Rna Polymerases ◽  
Chain Elongation ◽  
Hypertensive Rats ◽  
Appreciable Change ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

Cardiac hypertrophy accompanies the progressive rise in blood pressure in spontaneously hypertensive rats. The role of endogenous RNA polymerases in this process was examined in nuclei from isolated cardiac myocytes of 20-week-old spontaneously hypertensive rats and normotensive Wistar–Kyoto controls. Both template-engaged (involved in transcription) and free (loosely attached to endogenous template, transcribing only with exogenous templates) RNA polymerases were increased in spontaneously hypertensive rats. In addition, the ratio of RNA polymerases I/II was lower in the spontaneously hypertensive rats for both functional pools of the enzyme. Endogenous transcribing RNA polymerases were quantified by t.l.c. of RNA-hydrolysis products. Increased numbers of enzyme molecules were present in nuclei from spontaneously hypertensive rats, without appreciable change in the rate of polyribonucleotide-chain elongation. These results could not be explained by differences in the activities of contaminating phosphatases or ribonucleases, nor by changes in endogenous nucleoside pools or recoveries of labelled nucleosides. Enhanced myocardial RNA synthesis in the spontaneously hypertensive rats at the stage of established cardiac hypertrophy is associated with increased numbers of RNA polymerase molecules. This increase may, in turn, reflect altered chromatin structure, resulting in increased polymerase binding and/or chain initiation.

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