Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rate of RNA chain elongation has been measured with DNA and chromatin as template. RNA propagation on chromatin is about 50% of the rate found with DNA. Kinetic experiments demonstrate that the inhibition is not due to interference with the addition of the nucleoside triphosphates. Analysis of the dependence of propagation on the Tm of DNA shows that the chromatin proteins interfere with the translocation of the RNA polymerase along the DNA template.
Nucleic Acids Res 1976 Sep
PMID:RNA chain elongation on a chromatin template. 78 33

The phosphodiester bond formation by DNA-dependent RNA-polymerase (RNA nucleotidyltransferase, nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) can in principle result in retention, inversion, or racemization of configuration at the alpha-phosphorus of the nucleoside 5'-triphosphate being polymerized. As a first step in elucidating the stereochemistry of this reaction, one diastereomer (A) of adenosine 5'-O-(1-thiotriphosphate) (ATPalphaS) was polymerized with UTP in the presence of poly(dA-dT)-poly(dA-dT). The resulting polymer was enzymatically cleaved to uridine 2',3'-cyclic phosphorothioate which was determined to be the endo-isomer by comparison with an authentic sample. This shows that no reacemization had occurred and that isomer A of ATPalphaS gives a phosphorothioate diester bond with the R-configuration. Whether this represents inversion of retention of configuration awaits elucidation of the absolute configuration of isomer A for ATPalphaS.
Proc Natl Acad Sci U S A 1976 Sep
PMID:Stereochemistry of polymerization by DNA-dependent RNA-polymerase from Escherichia coli: an investigation with a diastereomeric ATP-analogue. 78 80

E. coli fMet-tRNAfMEet and E. coli RNA plymerase (RNA nucleotidyltransferase; EC 2.7.7.6; nucleoside-triphosphate:RNA nucleotidyltransferase) form a 1:1 complex with an apparent association constant of 9.0 X 10(6)M-1 at 37 degrees. The affinity of polymerase to tRNA depends on the tRNA as well as the formyl methionine moiety. Core polymerase has a greatly reduced affinity for initiator tRNA. Optimal binding conditions are similar to those that are also optimal for binding initiator tRNA to ribosomes. Binding of initiator tRNA to polymerase stimulates the transcription of lambda plac DNA, as determined in a crude cell-free system for beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase) synthesis as well as in a highly purified transcription system.
Proc Natl Acad Sci U S A 1976 Sep
PMID:Specific binding of formylated initiator-tRNA to Escherichia coli RNA polymerase. 78 83

RNA obtained through the transcription of wheat DNA by E. coli RNA polymerase was examined. This RNA contains double chain sequences which, after thermal denaturation, show instantaneous reassociation. A "hair-pin" like structure is proposed for this type of sequence.
C R Acad Hebd Seances Acad Sci D 1975 Sep 29
PMID:[Double-stranded sequences in RNA transcribed in vitro by E. coli RNA polymerase on wheat nuclear DNA]. 81 1

alpha-Amanitin-resistant clones were selected in the mouse lymphoblastoid cell line L5178Y. One resistant clone, named A169b, was recloned and the properties of its DNA-dependent RNA polymerases were examined. The RNA polymerase II activity from A169b differs from the parental cell line in that approximately half the activity is resistant to 0.5 microgram/mL alpha-amanitin, while the parental enzyme is 50% inhibited at 0.005 microgram/mL. The enzymes from A169b and the parental line were purified free of polymerase III and their properties compared. The two preparations were identical in their apparent affinities for the four nucleoside triphosphates, in their salt and divalent cation preferences, and in their preference for denatured over native DNA. They differed in their response to alpha-amanitin. The apparent K1 for the parental enzyme was 3.5 X 10(-9) M; plots of 1/V vs. alpha-amanitin concentration gave a biphasic curve with A169b enzyme. The two apparent K1 values were 4.1 X 10(-9) and 2.1 X 10(-6) M. In addition, the enzyme from A169b showed a twofold higher activity on poly [d(AT)] as template, compared to native DNA, than that of the parental enzyme. Other template preferences may be affected, but differences were marginal. These results indicate that mutation to alpha-amanitin resistance may alter other enzymatic parameters; such mutations may be helpful in elucidating structure-function relationships in these complex enzymes.
Biochemistry 1977 Sep 20
PMID:Properties of an altered RNA polymerase II activity from an alpha-amanitin-resistant mouse cell line. 90 71

4 S RNA isolated from the dimorphic fungus Histoplasma capsulatum inhibited the DNA-dependent RNA polymerase activity of the yeast phase of this fungus. Inhibition was specific for initiation, and resulted from binding of the RNA to the enzyme. Among a variety of synthetic polynucleotides tested, only poly(G) and oligo(dG) were effective inhibitors, suggesting a role for guanines or guanine-rich sequences of RNA in the inhibition reaction.
Biochim Biophys Acta 1977 Sep 20
PMID:Mechanism of the inhibition by RNA of the RNA polymerases of Histoplasma capsulatum. 90 93

Two previously undescribed stable polypeptides (referred to as nsp 90 and nsp 63) appear in mammalian and avian cells infected with Semliki Forest virus. They are distinguishable from the virus structural proteins and their known precursors by their molecular weights and tryptic peptide maps, and are identical in size to two polypeptides found in purified preparations of virus-specific RNA polymerase. Data from pulse-chase experiments and from the use of inhibitors of proteolytic cleavage indicate that nsp 90 and nsp 63 are synthesized via a series of post-translational cleavages from three larger polypeptides, p200, p184 and p150. The labelling kinetics after synchronous initiation of protein synthesis are also consistent with the synthesis of nsp 90 and nsp 63 from a common initiation site, and show that nsp 63 is located close to this site. It is concluded that nsp 90 and nsp 63 are components of the virus-specific RNA polymerase, and are synthesized via a post-translational cleavage scheme entirely separate from that leading to the synthesis of the virus structural proteins.
J Gen Virol 1976 Sep
PMID:RNA polymerase components in Semliki Forest virus-infected cells: synthesis from large precursors. 96 48

The nonhistone proteins of Ehrlich ascites tumor chromatin have been separated into a loosely bound and two tightly bound protein fractions by sequential extraction of chromatin with 0.35 M NaCl and 2 M NaCl:5 M urea. The nonhistone proteins thus obtained were examined for their chemical composition and distribution of DNA polymerase, RNA polymerase, and protein kinase activities. In addition, the effect of these nonhistone proteins on transcription of DNA in vitro has been determined. The results indicate that these nonhistone proteins, fractionated on the basis of their extractability, exhibit varied compositional characteristics and play different functional roles in the synthesis of DNA and RNA and in the possible control of gene activity.
Cancer Res 1976 Sep
PMID:A comparison of the loosely bound and tightly bound nonhistone proteins from Ehrlich ascites tumor chromatin. 97 79

Previous investigators have reported binding of the drug 5,5'-diphenylhydantoin (DPH) to RNA and DNA and an effect of this compound on protein synthesis. We have studied the effect of DPH on in vitro protein synthesis by investigating the possible role of this drug on poly-Uracil-directed polyphenylalanine synthesis and natural mRNA-directed amino acid incorporation into polypeptides. There was no demonstrable effect of DPH on either of these reactions. It was also found the DPH did not alter the rate of aminoacylation of purified rat liver tRNAs. The in vivo daily administration of DPH to animals for a period of 2 weeks did not appear to affect the in vitro poly-Uracil-directed polyphenylalanine synthesis (chain elongation aspects of protein synthesis) in adult rat brain. It was also found that DPH did not inhibit DNA-dependent RNA synthesis as catalyzed by RNA polymerase. These studies do not support the hypothesis that DPH plays a role in protein synthesis in adult brain cells.
J Pharmacol Exp Ther 1976 Sep
PMID:Studies on the effect of 5,5'-diphenylhydantoin on in vitro protein synthesis in rat brain. 97 65

DNA alpha-polymerase has been partially purified from nuclei of cultured chic, fibroblasts and separated on phosphocellulose columns into two distinct activities designated DNA polymerases alpha(a) and alpha(b), respectively. The enzyme preparations were devoid of activities of DNA beta,gamma-polymerases terminal deoxyribonucleoside transferase, DNase, DNA-dependent RNA polymerase, and phosphatase. DNA polymerases alpha(a) and alpha(b) both having molecular weights of 160 000, constitute 35-50 and 65-50%, respectively, of the activity of alpha-polymerase in the nucleus. These enzymes differ in their requirements for maximal activity, their relative ability to copy oligo(dG)-poly(dC), their response to ribonucleoside triphosphates, and their kinetics of heat inactivation. When the properties of alpha polymerases derived from early or late passage cultures have been compared, no difference could be detected as a function of cell age in the specific activities of the polymerases in crude cell extracts, their chromatographic behavior on diethylaminoethylcellulose and phosphocellulose columns, and their relative abilities to utilize single deoxyribonucleoside triphosphates with activated DNA template. On the other hand, both enzymes become partially heat labile in aging cells. Also, the activity of DNA polymerase alpha(a) from young cells was stimulated by 2--10 mM adenosine or cytidine triphosphates, whereas the same enzyme from old cultures was inhibited by these agents. Conversely, these ribonucleoside triphosphates inhibited the activity of polymerase alpha(b) in young cells but slightly stimulated this enzyme derived from senescent fibroblasts. In addition, the relative ability of DNA polymerase alpha(a) to copy oligo(dG)-poly(dC) decreased in aged cells, whereas that of DNA polymerase alpha(b) increased. We have also observed significant differences in the effects of potassium chloride and N-ethylmaleimide on the activity of DNA polymerase alpha(a) from old cells as compared to young cells. These age-related alterations in the properties of the two avian DNA polymerases may reflect structural or conformational changes in these enzymes.
Biochemistry 1976 Sep 21
PMID:Altered nuclear deoxyribonucleic acid alpha-polymerases in senescent cultured chick embryo fibroblasts. 98 31


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