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)

We have developed general methods for joining together, via cleavable disulfide bonds, either two unprotected polynucleotides or a polynucleotide and a peptide or protein. To join two oligonucleotides, each is first converted to an adduct in which cystamine is joined to the 5'-terminal phosphate of the oligonucleotide by a phosphoramidate bond. The adducts are mixed and reduced with dithiothreitol. The dithiothreitol is then removed by dialysis. Oxidation by atmospheric oxygen occurs to yield the required dimer. To join an oligonucleotide to a cysteine-containing peptide or protein, the 5'-cystamine oligomer is first converted to a 2'-pyridyldisulfide adduct and then reacted with an excess of the peptide or protein. If the peptide does not contain a free cysteine residue, it is first treated with iminothiolane to introduce one or more sulfhydryl groups. We have used these procedures to join a 16 mer deoxynucleotide probe and MDV-1 RNA, a substrate of Q beta RNA polymerase. This adduct hybridizes with a complementary target DNA. We have also joined a 16mer probe to peroxidase and MDV-1 RNA to human IgG. The probe-peroxidase adduct maintains enzymatic activity and the MDV-1 RNA-IgG adduct binds to a complementary anti-IgG.
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PMID:Ligation of oligonucleotides to nucleic acids or proteins via disulfide bonds. 337 70

We have used a microinjection technique to examine whether injected phosvitin, in its capacity as substrate for casein kinase NII, could compete out the endogenous phosphorylation of some nuclear phosphoproteins with regulatory potential and thereby interfere with the activity of RNA polymerase II. Phosphorylation, which utilizes ATP as phosphate donor, was separated from phosphorylation which uses GTP. Phosvitin introduced into nuclei of salivary gland cells becomes phosphorylated by the endogenous nuclear protein kinase(s) and incorporates phosphates from ATP as well as from GTP. The phosphorylation of nuclear proteins and phosvitin is heparin-sensitive, indicating that they are phosphorylated by casein kinase NII. Microinjected phosvitin does not seem to affect the incorporation of phosphate groups from ATP into nuclear proteins, but protein phosphorylation by GTP is influenced. Apart from a minor overall reduction of 32P-incorporation, the phosphorylation of a 42 kDa nuclear protein, a putative transcription stimulatory factor, and of a 115 kDa nuclear protein was competed out by 70%-80% compared with the control value obtained in the absence of phosvitin. Parallel analyses of DNA transcription in phosvitin-injected nuclei showed that the RNA polymerase II-mediated synthesis of hnRNA and Balbiani ring RNA was diminished by 80% and 90%, respectively. In contrast, the transcription of nucleolar pre-ribosomal 38 S RNA by RNA polymerase I remained unaffected. The inhibitory effect of injected phosvitin could be reversed by in vitro phosphorylation of phosvitin prior to injection, using isolated nuclei as source of protein kinase(s). Taken together, the results suggest a causal relationship between the modification of the GTP-dependent phosphorylation of specific non-histone proteins and the activity of RNA polymerase II.
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PMID:Selective repression of RNA polymerase II by microinjected phosvitin. 347 Jan 71

Purified RNA polymerase II from chicken leukemia cells was found to be an effective substrate for protein kinase C but not cAMP-dependent protein kinase. Protein kinase C catalyzed the incorporation of 1-2 mol of phosphate per mol of polymerase II and the reaction was totally calcium and lipid dependent. Electrophoresis studies revealed a time-dependent increase of phosphate incorporation into RNA polymerase II subunits of 220 KDa, 180 KDa and 150 KDa, with a preferential phosphorylation of the 180 KDa polypeptide. The phosphorylated enzyme has a preference for using single-stranded DNA as the template for transcription, including transcription of the single-stranded myb oncogene sequence. Phosphoamino acid analysis indicated that both serine and threonine residues were phosphorylated at equal amounts. Phosphorylation by protein kinase C increased the affinity of substrate-polymerase binding and the initial rate of RNA synthesis, suggesting a mechanism by which gene expression can be activated by protein kinase C.
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PMID:Protein kinase C phosphorylates leukemia RNA polymerase II. 347 67

RNA polymerase was treated in the presence of promoter-containing templates with 16 affinity reagents, derivatives on NMPs, NDPs and NTPs with reactive substituents at the terminal phosphate. This treatment was followed by addition of a pyrimidine [alpha-32P]NTP. Due to 'catalytic competence' of some of the residues of the affinity reagents bound covalently near the active center at the first stage, active-center-catalyzed synthesis of a phosphodiester bond occurred, and radioactive residues with the general formula -pNpN (where p = radioactive phosphate) appeared covalently attached to the enzyme. Such affinity labelling was super-selective because affinity reagent residues bound outside the active center were not elongated and thus remained non-radioactive. Labelling took place only when the combination of the reagent and [alpha-32P]NTP corresponded to the sequence of nucleotides of the promoter. With reagents having short 'arms', only the beta subunit was labelled; the targets were His and/or Lys residues. With reagents having longer 'arms', the sigma subunit was also labelled.
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PMID:Studies on the functional topography of Escherichia coli RNA polymerase. Highly selective affinity labelling by analogues of initiating substrates. 354 23

Nucleotide binding sites on DNA-dependent RNA polymerase from E. coli have been studied by photoaffinity labeling with a GTP analog [gamma-32P]-8-AzidoGTP and a guanosine-3'-diphosphate-5'-diphosphate analog, 8-Azidoguanosine-3'-phosphate-5'-85'-32P]phosphate. The guanosine diphosphate photoprobe labeled the beta, beta', and sigma subunits with the sigma subunit being most heavily labeled. The GTP photoprobe also labeled the beta, beta', sigma subunits but the beta' subunit was most heavily labeled. In competition experiments guanosine-3'-diphosphate-5'-diphosphate decreased photolabeling by 8-Azidoguanosine-3'-phosphate-5'-[5'-32P]phosphate better than GTP, while the opposite was true for photolabeling with [gamma-32P]8- AzidoGTP. The guanosine diphosphate photoprobe inhibited transcription on E. coli DNA with Ki of ca. 150 microM. Present studies suggest a unique ppGpp binding site distinct from substrate binding site(s) and this photoprobe may be used to localize this binding site(s).
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PMID:Characterization of the guanosine-3'-diphosphate-5'-diphosphate binding site on E. coli RNA polymerase using a photoprobe, 8-azidoguanosine-3'-5'-bisphosphate. 354 21

Mammalian cells contain two subspecies of RNA polymerase II, designated IIO and IIA. The objectives of these studies were to determine the structural relationship between these subspecies and to determine the functional significance of these differences. Subunits IIo and IIa were purified from calf thymus, and the effect of alkaline phosphatase treatment on electrophoretic mobility and immunochemical reactivity was examined. The removal of phosphate converts subunit IIo to a form indistinguishable from that of subunit IIa. These results indicate that subunit IIo is produced by multisite phosphorylation of subunit IIa. The distribution of phosphate within subunit IIo was determined by CNBr cleavage of in vivo labeled HeLa cell RNA polymerase II. 32P-Labeled subunit IIo was purified by immunoprecipitation and cleaved with CNBr, and the resultant peptides were analyzed. The quantitative recovery of 32P in the C-terminal peptide establishes that this domain is the primary site of phosphorylation. In an effort to assess the level of phosphorylation of the transcriptionally active form of RNA polymerase II in HeLa nuclei, transcription was carried out in the presence of 4-thiouracil triphosphate and the nascent labeled transcript cross-linked to RNA polymerase. Specific photoaffinity labeling of subunit IIo was observed. Alkaline phosphatase treatment results in an increase in the mobility of photoaffinity labeled subunit IIo to approach that of subunit IIa. These results indicate that subunit IIo is a component of transcriptionally active RNA polymerase II.
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PMID:Messenger RNA synthesis in mammalian cells is catalyzed by the phosphorylated form of RNA polymerase II. 362 68

RNA polymerase II-specific transcription requires, in addition to auxiliary protein factors, the hydrolysis of the beta-gamma phosphate bond of ATP. The nonhydrolyzable analog of ATP, imidoadenosine triphosphate does not suffice for specific in vitro transcription (Bunick, D., Zandomeni, R., Ackerman, S., and Weinmann, R. (1982) Cell 29, 877-886), although it can be incorporated into RNA. The experiments presented here suggest two energy-dependent steps in RNA polymerase II transcription. One of these steps is required at, or close to, the point of initiation, as determined by 5' end primer extension analysis. In vitro transcription occurs efficiently in vitro when imidoadenosine triphosphate is supplemented with dATP to fulfill the energy requirement. In the presence both of imidoadenosine triphosphate and imidoguanosine triphosphate, the concentration of dATP required for transcription initiation is dramatically increased. This suggests that ATP and GTP are co-substrates in transcription initiation, supporting the role of protein kinase II in this process (Zandomeni, R., Zandomeni, M. C., Shugar, D., and Weinmann, R. (1986) J. Biol. Chem. 261, 3414-3419). The concentration of dATP required for maximal initiation is inadequate for the production of full-length transcripts, suggesting a second energy-dependent step in the RNA elongation process. Since the elongation step is unaffected by the presence of imidoguanosine triphosphate, GTP beta-gamma phosphate bond hydrolysis appears to be required only for initiation.
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PMID:Purine triphosphate beta-gamma bond hydrolysis requirements for RNA polymerase II transcription initiation and elongation. 369 65

CI-920 is a structurally novel, phosphate-containing polyene lactone antitumor agent isolated from a previously undescribed subspecies of Streptomyces pulveraceus cultured from a Brazilian soil sample. CI-920 was active against murine leukemia P388, and highly active and curative against L1210 leukemia in vivo. CI-920 was less active or inactive against the murine solid tumors tested. Daily administration for five to nine days was more effective against L1210 leukemia than a single dose or doses every four days. Given three times daily for five days, CI-920 was more toxic and less active. CI-920 had similar activity intravenously and intraperitoneally. Oral administration was inactive and nontoxic. Subcutaneous treatment was less effective and more toxic. Structure-activity relationship studies showed that the phosphate group was essential for antitumor activity in vivo and in vitro. Hydrolyzing the lactone ring also resulted in loss of antitumor activity, as did acetylation of the 6-hydroxyl group. Hydroxylation at the 5-position of the lactone ring resulted in partial retention of antitumor activity, but in greater toxicity to mice. Removal of the 13-hydroxyl group resulted in retention of high antitumor activity with approximately three-fold improvement in dose-potency. CI-920 is not cytotoxic to prokaryotic cells. CI-920 causes inhibition of biosynthesis of RNA and DNA in intact L1210 cells. Protein synthesis is also inhibited at higher drug concentrations. The inhibition of nucleic acid synthesis is not an antimetabolite effect, since pools of ribonucleoside triphosphates and deoxyribonucleoside triphosphates are not depleted. CI-920 does not cause DNA strand breakage, as measured by alkaline elution, and is not mutagenic in the Ames test at concentrations up to 200 micrograms/ml. CI-920 does not cause direct inhibition of RNA polymerase or DNA polymerase in permeabilized cells. It is possible that CI-920 must be metabolically activated within the target cells; alternatively it may interact with a component of chromatin other than DNA or the polymerases. Flow cytometry studies showed that growth-inhibitory levels of CI-920 caused accumulation of cells in the G2+M region. Higher drug concentrations caused an S-phase block. CI-920 is an inhibitor and irreversible inactivator of reduced folate membrane transport, and appears to enter cells by this receptor. L1210 cells selected for resistance to CI-920 are cross-resistant to methotrexate, and deficient in reduced folate transport.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The biochemical pharmacology of CI-920, a structurally novel antibiotic with antileukemic activity. 384 Sep 49

Southern transfer analysis of Bacillus licheniformis MC14 DNA, using as probe a DNA fragment from within the coding region of a previously cloned alkaline phosphatase (APase) gene, revealed a second area of hybridization adjacent to the cloned APase gene. A second APase gene (APase II) was subcloned from the same plasmid clone, pMH8, from which the first APase gene (APase I) had been subcloned. The two genes are arranged in tandem with several hundred base pairs separating them. Immunoblot analysis showed that both code for Mr 60,000 proteins that crossreact with anti-APase. Both proteins enzymatically cleave 5-bromo-4-chloro-3-indolyl phosphate. In vitro transcription showed that APase I and APase II are transcribed in the same direction but that the two genes require different forms of Bacillus RNA polymerase: sigma 55- and sigma 37-containing RNA polymerase holoenzymes, respectively.
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PMID:Two alkaline phosphatase genes positioned in tandem in Bacillus licheniformis MC14 require different RNA polymerase holoenzymes for transcription. 385 44

We have used affinity chromatography on columns containing immobilized calf thymus RNA polymerase II to isolate three phosphoproteins (RAP72, RAP38, and RAP30) that bind directly to RNA polymerase II. All could be isolated from cell nuclei, and all three could be detected in mouse and human tissue culture cell lines, but only RAP38 and RAP30 have so far been isolated from calf thymus. RAP38 stimulates nonspecific transcription of native DNA templates by RNA polymerase II in the presence of Mn2+; it appears to be similar or identical to SII, a previously identified RNA polymerase II stimulatory factor (Nakanishi, Y., Mitsuhashi, Y., Sekimizu, K., Yokoi, H., Tanaka, Y., Horikoshi, M., and Natori, S. (1981) FEBS Lett. 130, 69-72). Unlike RAP38, RAP72 and RAP30 do not affect nonspecific transcription by RNA polymerase II. However, RAP30 may have a role in regulating some alterations of transcription that accompany cellular differentiation; RAP30 is partially dephosphorylated when murine erythroleukemia cells are induced with dimethyl sulfoxide to undergo terminal erythroid differentiation. We suggest that phosphate groups in RNA polymerase II-binding proteins may regulate transcription by modulating the interaction of RNA polymerase II with other regulatory proteins that possess sequence recognition specificity.
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PMID:Isolation of three proteins that bind to mammalian RNA polymerase II. 386 May 4


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