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 alkoxybenzophenanthridine alkaloids (coralyne acetosulfate, fagaronine chloride, and nitidine chloride) have been reported to possess antileukemic activity in mice. These compounds were tested for inhibition of reverse transcriptase activity of an RNA tumor virus and DNA polymerase, RNA polymerase, and polyadenylic acid polymerase activities of NIH-Swiss mouse embryos. Reverse transcriptase and DNA polymerase activities were strongly inhibited by these antileukemic alkaloids, whereas RNA polymerase and polyadenylic acid polymerase activities were only moderately affected. Viral and cellular DNA polymerase activities were potently diminished by the alkaloids when poly[d(A-T)], poly(dA)-oligo(dT), and poly(rA)-oligo(dT) template primers were used in the reaction mixture; however, no inhibition of enzyme activity was obtained with poly(rC)-oligo(dG) as template primer. These results suggest that alkoxybenzophenanthridine alkaloids inhibit DNA polymerase activity by interaction with A:T base pairs of the template primer.
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PMID:Inhibition of mammalian and oncornavirus nucleic acid polymerase activities by alkoxybenzophenanthridine alkaloids. 5 19

The coat protein of Bacillus subtilis spores comprises about 10% of the total dry weight of spores and 25% of the total spore protein. One protein with a molecular weight of 13,000 to 15,000 comprises a major portion of the spore coat. This mature spore coat protein has histidine at its NH2 terminus and is relatively rich in hydrophobic amino acids. Netropsin, and antibiotic which binds to A-T-rich regions of DNA and inhibits sporulation, but not growth, decreased the synthesis of this spore coat protein by 75%. A precursor spore coat protein with a molecular weight of 25,000 is made initially at t1 of sporulation and is converted to the mature spore coat protein with a molecular weight of 13,500 at t2 - t3. These data indicate that the spore coat protein gene is expressed very early in sporulation prior to the modifications of RNA polymerase which have been noted.
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PMID:Spore coat protein of Bacillus subtilis. Structure and precursor synthesis. 9 46

By using a modification of the BAC spreading method for mounting the DNA for electron microscopy, partial denaturation maps of protein-free phi 29 DNA and of phi 29 DNA containing protein p3 were obtained. In phi 29 p3-DNA1 the protein does not seem to influence the melting of the ends of the molecules. The comparison of the partial denaturation map and the B. subtilis RNA polymerase binding sites indicates that five of the seven early promoters (A1, A2, A3, B2 and C2) are located in A-T rich DNA regions whereas the other two early promoters (B1 and C1) are located in less A-T rich sites.
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PMID:Comparison of the A-T rich regions and the Bacillus subtilis RNA polymerase binding sites in phage phi 29 DNA. 11 82

We report the nucleotide sequences of two promoters for bacteriophage SP01 "middle" genes. These promoters are recognized by a modified form of Bacillus subtilis RNA polymerase that contains a phage-coded "sigma-like" regulatory protein (gp28) in place of the bacterial sigma factor. Both promoters shared the identical hexanucleotide 5'A-G-G-A-G-A at about 35 base pairs preceding the start point of transcription and the identical heptanucleotide 5'-T-T-T-A-T-T-T (T is the thymine analog 5-hydroxymethyluracil in SP01 DNA) located about 10 base pairs preceding the transcriptional start point. The significance of these sequences in comparison with nucleotide sequences of promoters recognized by sigma-containing RNA polymerases is discussed.
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PMID:Distinctive nucleotide sequences of promoters recognized by RNA polymerase containing a phage-coded "sigma-like" protein. 11 47

Two types of RNA polymerases [EC 2.7.7.6], polymerases A and B, exist in thermophilic bacteria, Thermus thermophilus HB8. Polymerase B is apparently like the core enzyme of polymerase A but is active only when an alternating copolymer of deoxyadenylic and deoxythymidylic acids (poly d(A-T)) or a mixture of homopolymers of deoxyadenylic acid and deoxythymidylic acid (poly dAdT) is used as a template. Polymerase B was further characterized to elucidate its relation to polymerase A and to determine why it is inactive on natural DNA's. 1. Polymerase B did not show pyrophosphate exchange activity. Dinucleoside monophosphates did not activate the RNA-synthesizing activity. The results suggested that polymerase B had no initiation and presumably no elongation activities. 2. Polymerase B had about 6 times greater affinity to DNA than polymerase A. The binding of polymerase B to DNA was, however, reversible. The complex of DNA with polymerase A was stable and the polymerase was not removed from the initial complex even when a large amount of DNA was added. 3. E. coli sigma subunit could not stimulate the activity of polymerase B toward DNA's. 4. Polymerase B could utilize poly d(A-T) and poly dAdT as templates, but could not use Bacillus cereus DNA though the structure is reported to be similar to that of poly d(A-T).
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PMID:Studies on a thermophilic RNA polymerase which is active only on poly d(A-T) and poly dAdT. 17 54

The interaction of Mn2+, substrates and initiators with RNA polymerase have been studied by kinetic and magnetic resonance methods. As determined by electron paramagnetic resonance, Mn2+ binds to RNA polymerase at one tight binding site with a dissociation constant less than 10 muM and at 6 +/- 1 weak binding sites with dissociation constants 100-fold greater. The binding of Mn2+ to RNA polymerase at both types of sites causes an order of magnitude enhancement of the paramagnetic effect of Mn2+ on the longitudinal relaxation rate of water protons, indicating the presence of residual water ligands on the enzyme-bound Mn2+. A kinetic analysis of the Mn2+-activated enzyme with poly(dT) as template indicates the substrate to be MnATP under steady-state conditions in the presence or absence of the initiator ApA. ATP and UTP interact with the tightly bound Mn2+ to form ternary complexes with approximately 50% greater enhancement factors. The dissociation constant of MnATP from the tight Mn2+ site as determined by longitudinal proton relaxation rate (PRR) titration (4.7 muM) is similar to the KM of MnATP in the ApA-initiated RNA polymerase reaction (10 +/- 3 muM) but not in the ATP-initiated reaction (160 +/- 30 muM). Similarly, the dissociation constant of the substrate MnUTP from the tight Mn2+ site (90 muM) is in agreement with the KM of MnUTP (101 +/- 13 muM) when poly[d(A-T)]-poly[d(A-T)] is used as template, indicating the tight Mn2+ site to be the catalytic site for RNA chain elongation. Manganese adenylyl imidodiphosphate (MnAMP-PNP) has been found to be a substrate for RNA polymerase. It has the same affinity as MnATP for the tight site but, unlike the results obtained with MnATP, the enhancement is decreased by 43% in the enzyme Mn-AMP-PNP complex. These results suggest that the enzyme-bound Mn2+ interacts with the leaving pyrophosphate group. The initiators ApA and ApU and the inhibitor rifamycin interact with the enzyme-Mn2+ complex producing small (15-20%) decreases in the enhancement. The dissociation constant of ApA estimated from PRR data (less than or equal to 1.5 muM) agrees with that determined kinetically (1.0 +/- 0.5 muM) as the concentration of ApA required to produce half-maximal change in the KM of MnATP. In the presence of the initiation specific reagents ApA, ApU, or rifamycin, the affinity of the enzyme-Mn complex for ATP or UTP shows little change. However, ATP and UTP no longer increase the enhancement factor of the tightly bound Mn2+ but decrease it by 30-55%, indicating a change in the environment of the Mn2+-substrate complex on the enzyme when the initiation site is either occupied or blocked. Although the role of the six weak Mn2+ binding sites is not clear, the presence of a single tightly bound Mn2+ at the catalytic site for chain elongation which interacts with the substrate reinforces the number of active sites as one per molecule of holoenzyme and provides a paramagnetic reference point for further structural studies.
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PMID:Magnetic resonance and kinetic studies of the role of the divalent cation activator of RNA polymerase from Escherichia coli. 18 95

The in vitro binding of the Escherichia coli RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) to fragments of lambdaplac5 DNA generated by restriction endonucleases HindII and HindIII has been studied by a filter binding technique. The results are consistent with RNA polymerase binding at p(R)', the INT promoter (p(I)), several sites in the b2 region, the mis promoter, the oop promoter (or p(O)), and p(rm). Binding was also observed on some fragments that are not known to contain active promoters, including the fragment from the cIII-t(L) region. Some of these binding reactions might also be explained by interaction of RNA polymerase with termination sites. Additional polymerase binding sites have been detected by examining which HindII and HindIII sites were not cleaved when digestion was performed after RNA polymerase had been bound to the DNA. This technique revealed polymerase binding at p(L), at p(R), at a site between R and cos, and at a site at the junction of the gamma and cIII-t(L) fragments. A comparison of the location of polymerase binding fragments with the partial denaturation map of the lambda genome indicates that RNA polymerase binding sites are located within A-T rich regions. It is suggested that RNA polymerase binding is a function both of specific sequences (where recognition occurs) and of the base composition of the surrounding regions (which affects the stability of the helix at the specific site).
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PMID:RNA polymerase binding sites in lambdaplac5 DNA. 27 Jul 25

We describe a new method for quantitatively assaying the omega subunit of Escherichia coli RNA polymerase. The assay is based on the ability of RNA polymerase holoenzyme to catalyze the continuous synthesis of the dinucleotide pApU on a poly[d(A-T)] . poly[d(A-T)] template when supplied with AMP and UTP as substrates. Core enzyme, lacking omega subunit, catalyzed this reaction at a rate less than 1% that of holoenzyme. The omega subunit was not released from the enzyme/DNA complex during dinucleotide synthesis. Using this assay, a titration of a fixed concentration of core enzyme was observed with increasing concentrations of added omega subunit. Below a 1:1 omega:core ratio the measured activity increased linearly with omega concentration, whereas above a 1:1 ratio the activity remained constant. An immediate application of the assay is in determining the concentration of active omega, or equivalently of active holoenzyme, in any RNA polymerase preparation.
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PMID:A noncycling activity assay for the omega subunit of Escherichia coli RNA polymerase. 37 16

Termination of RNA synthesis with 3'-O-Methylnucleoside 5'-triphosphates have been studied using E. coli RNA polymerase holoenzyme and poly [d(A-T)] as well as unfractionated T7 D delta III DNA as templates. It was shown that the termination can be used for DNA sequencing. A sequence of a part of RNA synthesized from AI promoter of the DNA have been determined. Syntheses of four 3'-O-Methylnucleoside 5'-triphosphates are described.
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PMID:Specific termination of RNA polymerase synthesis as a method of RNA and DNA sequencing. 72 95

We describe a method for the rapid, one-step determination of the specific radioactivity and pool size of ATP, UTP, CTP or GTP. Escherichia coli RNA polymerase and poly[d(A-T)] or poly[d(G-C)] are used to synthesize an alternating copolymer from a [3H]nucleoside triphosphate of unknown specific activity and a [14C]nucleoside triphosphate of known specific activity. The fact that [3H]nucleotide and [14C]nucleotide are incorporated into poly[r(A-U)] or poly[r(G-C)] in equimolar amounts, coupled with a knowledge of the [14C]nucleotide specific activity, permits calculation of the [3H]nucleotide specific activity. The requirement for direct knowledge of the [14C]nucleotide specific activity may be bypassed by an isotope dilution procedure. The pool size of a nucleoside triphosphate can be estimated either from isotope dilution data or by determining the fraction of [3H]nucleotide polymerized, dividing the number of counts 3H/min in the polymer by this fraction and by the [3H]nucleotide specific activity. The method was successfully applied to acid extracts made from sea urchin embryos labeled with a [3H]RNA precursor.
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PMID:A simple method for measuring specific radioactivities of ribonucleoside triphosphates using RNA polymerase. 77 Jan 64


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