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)

A protein from bacteriophage T4 responsible for the alteration of host DNA-dependent RNA polymerase and absent in T4 alt- phage was purified from T4 phage and enriched from T4-infected cells. It is injected during infection together with the known internal proteins. It has a molecular weight of about 70000 and catalyses the release of nicotinamide and the transfer of the ADP-ribosyl moiety from NAD+ to arginyl residues of various proteins including itself. RNA polymerase from Escherichia coli accepts ADP-ribosyl residues in all four subunits; the alpha subunit reacts with very high specificity. Only half of the alpha subunits are labelled, 45% with one, 5% with two residues. The main product shows the same electrophoretic mobility as alpha subunits altered or modified in vivo. The alpha subunit in modified RNA polymerase is no acceptor.
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PMID:ADP-ribosylation of DNA-dependent RNA polymerase of Escherichia coli by an NAD+: protein ADP-ribosyltransferase from bacteriophage T4. 17 40

Progesterone causes in goblet cells of oviducts of estrogen hormone-stimulated immature quails selectively gene activation without affecting DNA synthesis. This biological model has been used to study the influence of poly ADP-ribosylation during the processes of DNA transcription. Administration of progesterone in vivo causes an increase of the activity of RNA polymerase I and II in isolated nuclei. This increase is accompanied by a marked decrease of the specific activity of poly (ADP-Rib) polymerase. After in vitro ADP-ribosylation of nuclear proteins the template capacity of chromatin for ""exogenous'' RNA synthesis (with E. coli DNA-dependent RNA polymerases) as well as for ""endogenous'' RNA synthesis with DNA dependent RNA polymerases II is not affected, whereas the data presented seem to indicate that the capacity for RNA synthesis mediated by ""endogenous'' DNA-dependent RNA polymerase I might be inhibited after ADP-ribosylation. Evidence is presented to show that a considerable amount of poly (ADP-Rib), synthesized by poly (ADP-Rib) polymerase in isolated nuclei, is linked with RNA polymerase I. The rate of synthesis of poly (ADP-Rib) is dependent on the incubation temperature (optimum at 25 degrees C) and it can be inhibited by the specific inhibitors of poly (ADP-Rib) polymerase nicotineamide, thymidine and formycin B. Poly (ADP-Rib) is probably associated with RNA polymerase I through a covalent linkage. ADP-ribosylated RNA polymerase I has been purified 550 fold with respect to the nuclear extract corresponding to a 4,000 fold purification from the whole cell homogenate. The ratio between poly (ADP-Rib), formed during preincubation of nuclei with NAD, and RNA polymerase I remains almost constant during the purification procedures. The extent of ADP-ribosylation of RNA polymerase I decreases during gene expression. Thus we conclude that poly ADP-ribosylation of this enzyme is one of the regulatory mechanisms by which specificity of DNA transcription is achieved.
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PMID:Poly ADP-ribosylation of DNA-dependent RNA polymerase I from quail oviduct. Dependence on progesterone stimulation. 18 9

Purified cores of vesicular stomatitis virus contain an enzymatic activity that converts GDP, UDP, and CDP into their corresponding triphosphates using ATP as the phosphate donor. Thus, the virion-associated RNA polymerase can synthesize mRNA normally in vitro even when one of the ribonucleoside triphosphates is replaced by its corresponding diphosphate. RNA synthesis does not proceed if ATP is replaced by ADP. Similarly RNA synthesis is impaired if CDP and UDP are present in the same reaction. The role of the nucleoside diphosphate kinase (NDP kinase, EC 2.7.4.6) in vesicular stomatitis virus mRNA synthesis in vitro is discussed.
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PMID:Nucleoside diphosphate kinase activity in purified cores of vesicular stomatitis virus. 22 22

We have cloned a gene from a Salmonella typhimurium with the ability to complement the rfaC mutation (heptose-deficient lipopolysaccharide, sensitivity to rough-specific bacteriophages, and susceptibility to hydrophobic antibiotics). A 1018-base pair EcoRV-Tth111I fragment, subcloned into the pBluescriptKS+ vector to yield pKZ103, retains complementing activity. Nucleotide sequencing revealed an open reading frame corresponding to a protein of 317 amino acids (M(r) approximately 35,100). The plasmid pKZ103, which has a properly aligned T7 promoter, can overexpress a protein of M(r) = 31,000 when T7 RNA polymerase is supplied. An in vitro system was established for analysis of heptose addition to the precursor [4'-32P](KDO)2-IVA (Brozek, K. A., Hosaka, K., Robertson, A. D., and Raetz, C. R. H. (1989) J. Biol. Chem, 264, 6956-6966). Soluble fractions from wild-type or heptose-deficient rfa mutants were tested for their ability to convert [4'-32P](KDO)2-IVA to more polar substances. In wild-type extracts, these conversions required addition of ATP or ADP-heptose. In extracts of rfaC-, rfaD-, or rfaE-deficient strains, no polar products were observed with ATP. ADP-heptose restored synthesis in rfaD and rfaE but not rfaC extracts, indicating that rfaD and rfaE are involved in ADP-heptose formation. When the cloned rfaC gene was introduced into an rfaC-deficient mutant, extracts from such cells regained the ability to metabolize [4'-32P](KDO)2-IVA, showing that rfaC encodes the enzyme that attaches the proximal heptose to lipopolysaccharide.
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PMID:The rfaC gene of Salmonella typhimurium. Cloning, sequencing, and enzymatic function in heptose transfer to lipopolysaccharide. 152 14

A complete cell cycle of mature, concanavalin A (Con A) stimulated rat thymocytes was documented by analyzing the cell number as well as the content and synthesis of DNA and RNA. Cell cycle progression is accompanied by an elevation of class I, II and III RNA polymerase activities (about 10-fold) in the S phase maximum, 48 h after stimulation. Moreover, maximal cellular contents of DNA, ATP, ADP and AMP were observed at this culture period, whereas the RNA level peaked at 60 h. The synthesis of purine and pyrimidine nucleotides de novo was detected by use of [14C]HCO3-. Maximal incorporation rates of [14C]HCO3- into nucleotides (de novo synthesis) and of [3H]adenine into adenylates ('salvage pathway') occur during the S phase. However, the de novo synthesis rates were markedly lower than those of the 'salvage pathway'. The highest cellular level of the nucleotide precursor 5-phosphoribosyl-1-pyrophosphate (8.4-fold increase) also coincided with the S phase.
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PMID:Nucleotide and nucleic acid metabolism in rat thymocytes during cell cycle progression. 171 37

Vaccinia virus RNA polymerase requires the vaccinia early transcription factor, VETF, for the in vitro initiation of transcription at early gene promoters in a reaction requiring ATP hydrolysis. VETF binds specifically to early gene promoters and has an associated DNA-dependent ATPase activity. The effect of ATP on the interaction of VETF with the promoter for the vaccinia growth factor gene promoter has been examined. ATP had no marked effect on the steady-state level of promoter binding but dramatically affected the kinetics of dissociation of VETF from the promoter. The half-life of the VETF-promoter complex was greatly reduced in the presence of ATP. The destabilization of the complex was specific for ATP and dATP, consistent with the substrate specificity of the VETF-associated ATPase. ADP or the non-hydrolyzable ATP analog adenylyl-imidodiphosphate did not destabilize the complex suggesting that ATP hydrolysis is obligatory for dissociation. These findings provide a link between the promoter binding and ATPase activities associated with VETF and suggest that the ATP-dependent dissociation of the VETF-promoter complex is an important event in the transcription of vaccinia virus early genes.
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PMID:A role for ATP hydrolysis in vaccinia virus early gene transcription. Dissociation of the early transcription factor-promoter complex. 186 72

The initiation of Escherichia coli DNA replication is a highly regulated event with many parameters exerting positive and negative effects. The activity of the dnaA protein (the initiator protein) is profoundly influenced by the tight binding of the adenine nucleotides ATP and ADP. Further regulation of dnaA protein activity may occur through dnaA protein-cell membrane associations. A replicatively inactive form of dnaA protein is found aggregated with phospholipids; enzymatic treatment of the aggregates with phospholipase A2 or dnaK protein liberates dnaA protein with restored replication activity. Proper DNA structure is essential for replication. The energy stored in the DNA's supercoiling is crucial for dnaA protein's ability to initiate replication. Under conditions where strand-opening by dnaA protein is inhibited, such as low free superhelicity, an R-loop formed by RNA polymerase activates the origin at a distance by aiding strand-opening. A novel protein has been identified as a specific inhibitor of the initiation of DNA replication. This 33-kDa protein binds to the AT rich region of oriC and inhibits strand-opening by dnaA protein.
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PMID:E. coli minichromosome replication: regulation of initiation at oriC. 192 9

Diverse biological activities of hot-water and alkali extracts of lignified materials were reviewed and the molecular species involved are discussed. Materials tested included pine cone of Pinus parviflora SIEB. et Zucc., wood chips of slash pine, Douglas fir, and tallow wood, and two basidiocarps, in addition to their partially degraded preparations and commercial lignins. As a tentative conclusion, the lignin structure of these extracts might be responsible for the potent stimulation of granulocytic cell iodination, inhibition of viral infection and/or proliferation in vitro, and inactivation of viral ribonucleic acid (RNA)-dependent RNA polymerase and (adenosine diphosphate-ribose)n glycohydrolase. Other activities displayed by some of these extracts, such as antibacterial and antitumor activities, induction of hemolytic plaque-forming-cells in mice, and stimulation of deoxyribonucleic acid synthesis of isolated splenocytes, remain to be investigated.
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PMID:Lignified materials as potential medicinal resources. III. Diversity of biological activity and possible molecular species involved. 208 83

The gene for exoenzyme S, an ADP-ribosyl transferase, was cloned from Pseudomonas aeruginosa strain DG1 using an oligonucleotide probe based on the partial N-terminal amino acid sequence to screen a library of DG1 SstI fragments inserted into pKT230 in Escherichia coli DH1. A positive clone, designated pPD3, hybridized with the oligonucleotide probe and contained a 15 kb SstI insert. In E. coli minicells pPD3 expressed a single protein of Mr 68,000. This protein was localized primarily in the periplasm in E. coli. A 3.6 kb HindIII-BamHI fragment was subcloned into the vector pT7-4 which contains the promoter from bacteriophage T7 to construct pT7-4HB. In E. coli strains expressing the T7 RNA polymerase on a second plasmid, the Mr 68,000 protein was expressed and shown to react with antibodies to exoenzyme S. No enzymatic activity was detected in cell sonicates or culture supernatants of E. coli (pPD3). Cell sonicates of E. coli (pT7-4HB) however were cytotoxic to HeLa cells and this cytotoxicity was neutralizable with anti-exoenzyme S antiserm. Thus, exoenzyme S expressed in E. coli is toxic but not enzymatically active. When plasmids carrying the exoenzyme S gene were introduced into P. aeruginosa, there was a significant increase in ADP-ribosyl transferase activity, indicating that the plasmid encoded protein is enzymatically active in P. aeruginosa.
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PMID:Cloning and expression of the Pseudomonas aeruginosa exoenzyme S toxin gene. 211 26

RNA polymerase II from human placenta was affinity labelled in crude preparation using two-step technique, which includes treatment of the enzyme with an aldehyde-containing reactive analogue of ATP, ADP or AMP in the presence of poly[d(A-T)] followed (after borohydride reduction) by the elongation of the attached label with [alpha-32P]UTP. A polypeptide of the molecular mass ca. 140 kDa proved to be the labelling target. No labelling was observed in the absence of poly[d(A-T)] or the reagent or in the presence of alpha-amanitin. All the results suggest the attachment of the affinity reagents to the second-largest subunit of the human RNA polymerase II, which therefore takes part in the initiation substrate's binding.
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PMID:[Highly selective affinity labeling of DNA-dependent RNA-polymerase II from human placenta]. 228 30


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