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:2.7.7.8 (polynucleotide phosphorylase)
723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interaction of pyridoxal, pyridoxal-5'-mono-, di- and triphosphate with certain enzymes of polynucleotide synthesis (DNA-dependent RNA polymerase, DNA-dependent DNA polymerase I and polynucleotide phosphorylase from Escherichia coli and terminal deoxyribonucleotide transferase from calf thymus) was studied. All compounds tested was found to be reversible and competitive inhibitors of these enzymes. The reduction of the enzyme-inhibitor complex with NaBH4 gives rise to the complete irreversible inhibition of the enzymes under study. The comparison of the inhibition constants for pyridoxal and its phosphorylated derivatives with those for mono-, di- and triphosphates of nucleosides was carried out for the enzymes. The results obtained suggest that the modified epsilon-amino-group of lysine residue should be localized at the catalytic site in the vicinity of the pyrophosphate binding area of an enzyme.
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PMID:[Interaction of oligophosphates of pyridoxal with certain enzymes of polynucleotide synthesis]. 38 98

Benzimidazoles are weak mutagens acting through base substitutions; they are incorporated into nucleic acids. Experiments with deoxyribohomopolymers as templates demonstrated that benzimidazole nucleoside triphosphate is polymerized by RNA polymerase only in the presence of poly dC, i.e., instead of guanine. In plasmolyzed Escherichia coli cells, benzimidazole ribonucleoside diphosphate is polymerized by polynucleotide phosphorylase and can, after blocking of the normal mRNA synthesis with actinomycin D, be used as a messenger for polypeptide formation. The addition of radioactive amino acids to this system showed that benzimidazole is not read preferentially as guanine, as would have been expected from the RNA polymerase results. Instead, the reading was position dependent and brnzimidazole is recognized (1) in the first codon position as adenine, (2) in the second as purine, and (3) in the third possibly only as base. Benzimidazole mutagenicity is thus explained as a G in equilibrium A transition.
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PMID:The molecular mechanism of benzimidazole mutagenicity: in vitro studies on transcription and translation. 110 1

As a first step to approach the structural and functional analysis of DNA-dependent RNA polymerase II (EC 2.7.7.8), we have isolated genomic sequences for the large subunit of the human enzyme. The sequences homologous to Drosophila RNA polymerase II large subunit sequences are present in the genome as single copy genes, when assayed at high stringency. The polypeptide information is encoded in a mRNA of 7.35 kilobases, as determined by Northern blot analysis. In vitro translation reveals a polypeptide of 220 kDa, similar in electrophoretic mobility to the largest subunit of the enzyme. A fusion-polypeptide synthesized in bacteria contains a region that cross-reacts with anti-RNA polymerase II antiserum. Antiserum directed against the purified fusion protein reacts with the large subunit of RNA polymerase II, whether in the intact IIA (220 kDa) or in the degraded IIB (180 kDa) forms. Moreover, the antifusion protein antibody inhibits not only the purified calf thymus RNA polymerase II activity but also specific RNA polymerase II transcription in a HeLa cell extract. Thus, the DNA fragment isolated contains structural and functional domains of the human RNA polymerase II large subunit.
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PMID:The gene encoding the large subunit of human RNA polymerase II. 299 7

The transcripts covering pnp, the gene encoding polynucleotide phosphorylase, are processed by ribonuclease III. In this study, it is shown that the steady state level of the pnp mRNA increased 11-fold in a ribonuclease III-deficient strain. The synthesis rate of this messenger is only slightly affected in the mutant strain whereas the half-life, which is 1.5 min in the wild type, is considerably increased to more than 40 min. Moreover, polynucleotide phosphorylase is 10-fold over-expressed in the mutant strain, which shows that unprocessed pnp mRNA is functional. The position of the ribonuclease III-sensitive site suggests that the sequence involved in the stabilization of the pnp mRNA is located at the 5' end of the message and that the RNase III processing triggers the decay of the transcripts downstream. A similar function for ribonuclease III in the processing of the messenger for the beta beta' subunits of RNA polymerase is proposed.
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PMID:The first step in the functional inactivation of the Escherichia coli polynucleotide phosphorylase messenger is a ribonuclease III processing at the 5' end. 330 54

Distribution of the DNA polymerase I large fragment (Klenow fragment) was studied during fractionation of the E. coli MRE-600 cell-free extract with polyethylenimine. On the basis of the results obtained a simple procedure is proposed that enables the Klenow fragment to be obtained as a coproduct of DNA polymerase I, RNA polymerase, polynucleotide phosphorylase, nucleotide kinases with acetokinase and nucleoside deoxy-ribosyltransferase in the framework of a combined technological scheme.
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PMID:[Behavior of the large fragment of DNA polymerase I (the Klenow fragment) during fractionation of a cell-free extract of E. coli MRE-600]. 330 31

1. Conditions have been established for the estimation of molecular weights of proteins by analytical gel filtration and sucrose-density-gradient centrifugation in 2.5m-potassium chloride-1m-sodium chloride; Halobacterium cutirubrum polynucleotide phosphorylase, DNA-dependent RNA polymerase and RNA-dependent RNA polymerase have been studied by these methods. 2. The RNA-dependent polymerase has also been studied by density-gradient centrifugation in the absence of salt. 3. All three proteins are of unusually low molecular weight compared with similar enzymes from non-halophilic bacteria.
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PMID:Nucleic acid enzymology of extremely halophilic bacteria. Gel-filtration and density-gradient-centrifugation studies of the molecular weights of Halobacterium cutirubrum polynucleotide phosphorylase and deoxyribonucleic acid- and ribonucleic acid-dependent ribonucleic acid polymerases. 511 75

Novel RNA polymerase activities (termed type II reaction) can be found in toluene-treated Escherichia coli with Ca2+, Fe2+, or endogenously bound cations, probably Mg2+. These activities are distinguishable from the well characterized DNA-dependent RNA polymerase (type I reaction) by: (i) their divalent cation requirements, i.e., the classical enzyme is activated by exogenously added Mn2+, Mg2+, or CO2+ ions; (ii) their relative resistance to inhibition by actinomycin D, rifampicin, and streptolydigin; (iii) their selective synthesis of low molecular weight RNA; (iv) their sensitivity to inhibition by arabinonucleoside 5'-triphosphates or deoxyribonucleoside 5'-triphosphates; and (v) the strict requirement for ATP in Ca2+ and bound cation-activated reactions. The Ca2+-activated and endogenous RNA polymerase activities are inhibited by orthophosphate. The properties of the type II RNA polymerase(s) are compared with those of polynucleotide phosphorylase, and dnaG gene product, and the RNA polymerase described by Ohasa and Tsugita.
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PMID:Divalent cation-activated RNA synthesis in toluene-treated Escherichia coli. 617 Apr 2

As a starting point for the study of the biosynthesis of polyadenylated RNA in bacteria, the characteristics of RNA synthesis by cells of Escherichia coli B made permeable to small molecules by treatment with toluene were examined. Such cells mediated the incorporation of radiolabeled ribonucleoside triphosphates into RNA in a reaction that was sensitive to inhibitors of RNA polymerase and required the simultaneous presence of the four ribonucleoside triphosphates. Between 10 to 15% of the RNA synthesized under these conditions was polyadenylated as shown by affinity chromatography on oligo(dT)-cellulose. The presence of orthophosphate or dADP, inhibitors of polynucleotide phosphorylase, had no effect on the reaction and the rate of RNA synthesis was indistinguishable in the polynucleotide phosphorylase-deficient strain PR-7 and in its otherwise isogenic parent strain PR-100. The poly(A) tracts associated with the newly synthesized RNA could be isolated after exhaustive digestion with pancreatic and T1 ribonucleases and accounted for 14% of the poly(A)-RNA. At least 74% of the poly(A) sequences were located at the 3' ends of RNA molecules and their weight-average length was 48 nucleotide residues. The size distribution of total RNA and poly(A)-RNA synthesized in the toluenized cell system was similar to that of the corresponding pulse-labeled fractions derived from growing cultures. The sequence complexity of poly(A)-RNA and unadenylated RNA synthesized in toluenized cells with [alpha-32P]CTP as the labeled substrate was analyzed by hybridization to fragments of Escherichia coli B DNA generated by digestion with EcoRI restriction endonuclease and immobilized on nitrocellulose sheets. Both RNA fractions hybridized with many DNA fractions, the hybridization patterns being similar with poly(A)-RNA and unadenylated RNA. This indicated that many different types of RNA transcripts synthesized in toluenized cells were subject to polyadenylation, but that polyadenylation was incomplete so that each transcript was present in both an adenylated and an unadenylated state.
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PMID:Synthesis of polyadenylate-containing RNA in vitro in permeable cells of Escherichia coli B. 619 64

RNA was extracted from purified Bluegill virus (BGV) and fractionated onto a poly (U)-Sepharose-4 B column. More than 70 per cent of this RNA became bound and could be subsequently eluted from the column. By polynucleotide phosphorylase digestion, the poly (A) sequences were located at the 3'-terminus of the RNA. This RNA and purified BGV RNA were infectious as shown by plaque assay titration of the virus produced. Furthermore, we were unable to detect RNA polymerase activity in preparations of BGV. These results indicate that the genome in the BGV particle is a positive-strand RNA.
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PMID:Bluegill virus is a ribovirus of positive-strand polarity. 619 98

Polynucleotides containing adenosine and 8-azidoadenosine or inosine and 8-azidoinosine residues have been prepared from mixtures of nucleoside diphosphates using polynucleotide phosphorylase from Escherichia coli. These copolymers can form complexes with polyuridylic or polycytidylic acids respectively. Single stranded poly(adenylic, 8-azidoadenylic acid) [poly(A,z8A)] has been used as a photoaffinity reagent to explore the subunit topography of RNA polymerase from E. coli.
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PMID:Azidopolynucleotides as photoaffinity reagents. 700 70


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