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

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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 Escherichia coli dapB gene encodes dihydrodipicolinate reductase. This enzyme is part of the diaminopimelate-lysine pathway, and its synthesis is repressed by lysine. The dapB gene was cloned into pBR322 from a transducing lambda bacteriophage, its complete nucleotide sequence established, and the transcriptional start localized. The DNA sequence predicts that the dapB gene codes for a 273-amino acid polypeptide, Mr 28,798. No attenuation-type sequence can be found between the mRNA start and the coding sequence. The dapB promoter signals appear to be weak as compared to RNA polymerase consensus sequences. Nevertheless an efficient in vivo synthesis of beta-galactosidase was obtained when the lac operon was inserted in vitro in the dapB gene, downstream of the dapB regulatory signals. Further studies were performed on an in-frame gene fusion constructed in vitro between the dapB and the lacZ genes. They indicated that repression by lysine is exerted on a DNA region restricted to a 153-base pair fragment with only 102 nontranscribed nucleotides. Finally, dapB gene expression showed a gene dosage effect which suggests that it is not controlled by an element present in limiting amounts in the cell.
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PMID:Nucleotide sequence and expression of the Escherichia coli dapB gene. 609 78

Reverse transcriptase from avian myeloblastosis virus can react with periodate-treated primer tRNATrp (beef) to form a Schiff's base between an epsilon-NH2 lysine group within the active center of the enzyme and the dialdehyde derivative of the 3' terminal ribose of tRNA. In the presence of cyanoborohydride the reversible imminium moiety of the Schiff's base is reduced to a more stable adduct. Non-primer tRNAs were not able to reduce the extent of primer fixation to the enzyme. Complete inactivation of the enzyme was attained when the ratio enzyme:tRNA in the complex was 1:1. When the 1:1 adduct was analyzed by polyacrylamide gel electrophoresis, radioactivity from the terminal adenosine of tRNA was found exclusively associated with the alpha subunit. At longer times of labeling the beta subunit was also found linked to the oxidized primer tRNA.
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PMID:Study of the interactions between avian myeloblastosis virus reverse transcriptase and primer tRNA. Affinity labeling and inactivation of the enzyme by periodate-treated tRNATrp. 616 Apr 74

Nuclear protein kinases include enzymes that transfer the gamma-phosphate of ATP to serine, threonine, lysine or histidine in proteins. Nuclear kinases with a preference for basic proteins are known as histone kinases; those preferring acidic protein substrates are casein kinases. Histone kinases include both cyclic AMP-independent protein kinases and cyclic AMP-dependent protein kinases. The best-characterized cyclic AMP-independent nuclear protein kinase is associated with cell proliferation and is activated (or transported to the nucleus) in G2 phase of the cell cycle. It phosphorylates specific serine and threonine residues in the non globular domains of histone H1 and appears to promote chromosome condensation. The cyclic AMP-dependent protein kinase has unknown nuclear function(s), although it may be translocated from cytoplasm to nucleus in response to specific hormonal stimuli which are also associated with changes in transcriptional activity. There is a massive peak of nuclear cyclic AMP-dependent protein kinase activity in G2 phase of the cell cycle. Nuclear casein kinases are apparently very heterogeneous. Two of these enzymes have been purified to homogeneity. They phosphorylate non-histone chromosomal proteins, including RNA polymerase and ornithine decarboxylase. Phosphorylated ornithine decarboxylase is inactive enzymatically but, in Physarum, it binds to the rDNA minichromosome and stimulates rRNA transcription. Kinases forming phosphoramidate bonds occur in a variety of rat tissues and form phosphohistide in histone H4 and phospholysine in histone H1.
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PMID:Nuclear protein kinases. 632 62

The reversible effect of dietary lysine deficiency was studied in young adult rats. During 6 days on a lysine diet the rats maintained the same body weight. During 2 days of recovery body weight gain was that of the controls. Liver nuclei were isolated, incubated with micrococcus nuclease and chromatin fractionated in to a 2 000 X g pellet, 102 000 X g pellet and supernatant fraction. Chromatin-bound RNA polymerase 1 plus III activity decreased by 15% per mg of fractional and nuclear DNA and by 30% per total liver. The corresponding decrease of RNA polymerase II activity was 30% and 40%. Recovery from lysine deficiency was complete after 2 days of refeeding the amino acid. Chromatin proteins of the 102 000 X g pellet were characterized by polyacrylamide gel electrophoresis in sodium dodecylsulfate and by 2-dimensional gel electrophoresis. Quantitative but no qualitative differences between the proteins of the dietary groups were observed. Relative to DNA the non-histone proteins decreased in the lysine deficient group by 43% and histones by 10%. It is concluded that RNA synthesis is restored to its original level within 2 days of refeeding lysine after 6 days of lysine deficiency.
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PMID:Lysine deficiency reduces transcription activity and concentration of chromatin proteins reversibly in rat liver. 641 Jun 87

The 9-(3'-azido-3'-deoxy-beta-D-xylofuranosyl) nucleoside 5'-triphosphate derivatives of adenine (3'-azido, x-dATP) and guanine (3'-azido, x-dGTP) were prepared by chemical phosphorylation of the corresponding nucleosides. The compounds were characterized by 31P and 1H NMR, high performance liquid chromatography, IR, and TLC. The compounds were examined kinetically and observed to be linear mixed inhibitors for the DNA-dependent RNA polymerase of Escherichia coli (EC 2.7.7.6); Ki values for the 3'-azido, x-dATP and 3'-azido, x-dGTP compounds are 33 and 0.95 microM, respectively. Neither compound functions as an alternate substrate or as a chain terminator during the normal kinetic time course. The 3'-azido, x-dGTP does exhibit a slow time-dependent irreversible inhibition and may therefore function as an alternate substrate and chain terminator with prolonged incubation. Both compounds (3'-azido, x-dATP and 3'-azido, x-dGTP) are photolabile and will derivatize lysine in a coupled photolytic reaction.
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PMID:RNA polymerase. Synthesis and kinetic inhibition by 9-(3'-azido-3'-deoxy-beta-D-xylofuranosyl) derivatives of 5'-ATP and 5'-GTP. 654 40

Phospholipid liposomes affect the histone pattern of isolated rat liver nuclei. Multilamellar vesicles (MLV) obtained with phosphatidylserine (PS) release a large amount of the lysine rich histones, while those obtained with phosphatidylcholine (PC) do not induce significant changes with respect to controls. This different response has been compared to the effects obtained with Heparin, which slightly modifies the relative ratio of the histone fractions. These data might account for the mode by which phospholipids induce transitions of the chromatin structure and changes of the endogenous RNA polymerase activity.
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PMID:Response of isolated nuclei to phospholipid vesicles: analysis of the nuclear proteins after treatment with phosphatidylserine and phosphatidylcholine and comparison with heparin. 673 88

The imido ester, methyl acetimidate, which specifically amidinates lysine residues, modifies RNA polymerase core enzyme, leading to rapid loss of activity. Calf thymus DNA partially protects the enzyme against this inactivation, an effect which disappears at high salt concentration. DNA protects 17 +/- 6 lysines from amidination at low salt concentration. The dependence of amidination on methyl acetimidate concentration is examined in the presence of DNA at high and low salt concentration. Analysis of the data suggests a class of approximately 12 lysines which are protected by DNA, consistent with the above estimate. These lysines are approximately 5--10-fold more reactive than most other available lysine residues.
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PMID:Identification of a class of lysines within the non-specific DNA-binding site of RNA polymerase core enzyme from Escherichia coli. 680 29

The catalytic center of wheat germ DNA-dependent RNA polymerase II (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) as a model eukaryotic enzyme system was probed with two purine nucleoside dialdehydes, 6-methylthioinosinedicarboxaldehyde (MMPR-OP) and a derivative 6-[(acetylaminoethyl)-1-naphthylamine-5-sulfonyl]thioinosinedicarboxaldehyde (AMPR-OP). Both drugs gave noncompetitive inhibition with respect to [3H]UMP incorporations into RNA, and inhibitor bindings were reversed with initiation substrates. The Ki values for MMPR-OP and AMPR-OP were determined to be 0.64 mM and 1.0 muM respectively. The drugs were covalently bound to the catalytic center by NaBH4 reduction. Both were found bound to the largest enzyme subunit, IIa. It is tentatively concluded that MMPR-OP and AMPR-OP inhibit RNA polymerase II by binding to an essential lysine in the initiation subsite of the catalytic center located on the IIa subunit.
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PMID:Probes of eukaryotic DNA-dependent RNA polymerase II-II. Covalent binding of two purine nucleoside dialdehydes to the initiation subsite. 713 56

Using immunofluorescent labeling and laser-scanning confocal microscopy, we show that isoforms of histone H4 acetylated on lysine 5, 8 and/or 12 (H4.Ac5-12), as well as RNA polymerase II, become enriched at the nuclear periphery around the time of zygotic gene activation, i.e., the 2-cell stage, in the preimplantation mouse embryo. In contrast, DNA and H4 acetylated on lysine 16 are uniformly distributed throughout the cytoplasm. Culture of embryos with inhibitors of histone deacetylase trichostatin A and trapoxin results in an increase in the (1) amount of acetylated histone H4 detected by immunoblotting, (2) intensity and sharpness of the peripheral staining for H4.Ac5-12, and (3) relative rate of synthesis of proteins that are markers for zygotic gene activation. The enhanced staining for H4.Ac5-12 at the nuclear periphery seems to require DNA replication, but appears independent of cytokinesis or transcription, since its development is inhibited by aphidicolin but not by either cytochalasin D or alpha-amanitin. Lastly, the restricted localization of H4.Ac 5-12 is not observed in the 4-cell embryo or at later stages of preimplantation development. These results suggest that changes in chromatin structure underlie, at least in part, zygotic gene activation in the mouse.
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PMID:Temporally restricted spatial localization of acetylated isoforms of histone H4 and RNA polymerase II in the 2-cell mouse embryo. 755 21

Direct chemical acetylation of an oligonucleosomal template for bacteriophage T7 RNA polymerase is accompanied by a substantial increase in its capability to support RNA synthesis. The template was assembled from a plasmid, containing a promoter and a terminator for T7 RNA polymerase, plus one (H3-H4)2 tetramer and two H2A.H2B dimers for each 200 base pairs of DNA. Under the employed conditions, acetylation modifies in a preferential way the lysine residues located in the amino-terminal domains of core histones. When the template is assembled with acetylated tetramers and untreated dimers, its efficiency in promoting RNA synthesis is also largely increased. Since a previous work reported transcriptional stimulation upon acetylation of H2A.H2B dimers [Puerta et al. (1995) Biochem. Biophys. Res. Commun. 210, 409], the transcriptional repression brought about by core histone octamers seems to require that the amino-terminal domains of both (H3.H4)2 tetramers and H2A.H2B dimers are not acetylated.
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PMID:Transcriptional properties of oligonucleosomal templates containing acetylated (H3-H4)2 tetramers. 763 40


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