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 RNA polymerase of bacteriophage T7 is sensitive to cleavage by a protease associated with the membrane fraction of many strains of Escherichia coli. A major degradation product is a T7 RNA polymerase that is proteolytically cleaved between amino acids 172 (lysine) and 173 (arginine) (Tabor, S., and Richardson, C.C. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 1074-1078). The cleavage splits the enzyme into a large fragment (Mr approximately 75,000) and a small fragment (Mr approximately 23,000) which remain tightly associated during the purification of nicked RNA polymerase. The protein retains RNA polymerase activity, but specific activity is reduced 3.5-fold. The proteolytic cleavage also reduces the Mg2+ requirements, increases the apparent Michaelis-Menten constants for the utilization of the ribonucleoside 5'-triphosphates, increases the temperature sensitivity, increases the sensitivity to inhibition by heparin, and increases the probability that a transcript will not be removed from the template. The reduced activity of nicked T7 RNA polymerase is apparently a consequence of inefficient initiation and premature termination. Nicked T7 RNA polymerase successfully initiates at the phi 10 promoter at half the efficiency of native T7 RNA polymerase. Transcripts synthesized by the nicked enzyme are also significantly shorter than transcripts synthesized by the native enzyme. In contrast, nicked T7 RNA polymerase and T7 RNA polymerase exhibit equivalent poly(dI).poly(dC)-dependent activity and equivalent polymerization velocities (60 bases/s at 25 degrees C).
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PMID:Enzymatic properties of a proteolytically nicked RNA polymerase of bacteriophage T7. 354 19

The effect of histones on accessibility of DNA to DNase in chromatin of thymus nuclei has been studied by selective extraction of either lysine-rich or arginine-rich histones. It was found that all histones block accessibility but that, weight for weight, lysine-rich histones block much more effectively than do arginine-rich histones. We point to the contrast between accessibility of DNA to DNase and of DNA to RNA polymerase, and to what may be the similarity between accessibility to DNase and DNA polymerase.
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PMID:Blocking by histones of accessibility to DNA in chromatin. 450 81

Exogenous DNA and RNA polymerases were used to measure the template activity of DNA in chromatin in isolated thymus nuclei from which lysinerich or arginine-rich histones were selectively extracted. Measurements were on nuclei containing 20-1200 mug of DNA per ml, the distinctions becoming clear at the higher concentrations. Experiments with RNA polymerase showed only moderate increases in template activity upon extraction of histone, although the removal of lysinerich histone had a greater effect than that of arginine-rich histone. DNA polymerase action on nuclei minus lysinerich histone achieved high results, exceeding even those on DNA itself.
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PMID:Effects of selective extraction of histones on template activities of chromatin by use of exogenous DNA and RNA polymerases. 457 8

The ability of histones to block the accessibility of DNA in chromatin to DNA and RNA polymerases was measured by addition of lysine-rich or arginine-rich histones to nuclei selectively depleted of these histones. By this procedure nuclei were obtained in which all of the original lysine-rich histone in the chromatin was replaced by arginine-rich histone. Conversely in other nuclei, additional lysine-rich histone replaced some of the endogenous arginine-rich histone. Lysine-rich histone was much more effective than arginine-rich histone in blocking accessibility to DNA polymerase. Both classes of histone inhibited template activity toward RNA polymerase to a similar extent. In addition to lysine-rich histone and total arginine-rich histone, phosphorylated lysine-rich histone, two fragments of lysine-rich histone produced by cleavage with N-bromosuccinamide, and fractions IIB and IV of arginine-rich histone were added to histone-depleted nuclei. With both DNA and RNA polymerases as probes, no differences in inhibition of template activity were found when native lysine-rich histone was compared to phosphorylated lysine-rich histone. Similarly, fractions IIB and IV were indistinguishable from total arginine-rich histone. On a molar basis, the carboxyl fragment of lysine-rich histone was as effective as intact lysine-rich histone only when the amino fragment was added to it. By itself, the amino portion of lysine-rich histone was without inhibitory effect in the RNA polymerase assay and resulted in only slight inhibition of template activity toward DNA polymerase.
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PMID:Addition of histones to histone-depleted nuclei: effect on template activity toward DNA and RNA polymerases. 458 93

Arginine-rich histones (F3) interact with both the bacterial and mammalian RNA polymerase and inhibit the in vitro RNA synthesis to a much greater extent than when associated with the DNA template. The lysine-rich histones (F1) inhibit the RNA synthesis mainly through template inhibition. Neither histone fraction displayed such an interaction with DNA polymerase. The RNA polymerase-F3 histone interaction takes place at ionic strength equal to or greater than those occurring in living cells, suggesting a possible role of arginine-rich histones in the regulation of RNA synthesis.
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PMID:The interaction of RNA polymerase with histones. 525 18

Nonhistone acidic proteins were isolated, by equilibrium density centrifugation in 4 M cesium chloride, from the chromatin isolated and purified from the uterus of the ovariectomized rat or from calf endometrium. Evidence is presented to show (1) that arginine-rich histones are more effective inhibitors of chromatin-directed RNA synthesis in vitor than lysine-rich histones, (2) that the nonhistone acidic proteins of chromatin do not inhibit the synthesis of RNA directed by chromatin in vitro, (3) that added nonhistone acidic chromatin proteins effect a restoration of histone-inhibited RNA synthesis directed by chromatin in vitro, and (4) that the synthesis of nonhistone acidic chromatin proteins is under estrogen control in the uterus, but not in the liver. It is concluded that a major feature of the early action of estrogen in the uterus of the ovariectomized rat is the stimulation of synthesis and the accumulation in the interphase chromosomes of nonhistone acidic proteins which counter the inhibitory effect of histone on transcription by RNA polymerase. Presumably this would permit more and perhaps a new synthesis of RNA programmed for transport to the cytoplasm.
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PMID:Role of chromatin in estrogen action in the uterus. II. Hormone-induced synthesis of nonhistone acidic proteins which restore histone-inhibited DNA-dependent RNA synthesis. 525 38

The synthesis of cell-specific ribonucleic acid (RNA) appeared to be stimulated in human embryonic kidney (HEK) cultures infected with adenovirus 2 or 12. Deoxyribonucleic acid (DNA)-RNA hybridization experiments revealed that by 44 to 70 hr after infection with either virus, the relative amount of pulse-labeled RNA capable of hybridizing with HEK cell DNA increased considerably; such RNA was detected in both nuclear and cytoplasmic fractions. The main increase in apparent host RNA synthesis was preceded by (i) a relatively early transient stimulation of the DNA-dependent RNA polymerase activity in isolated nuclei, and (ii) a small but consistently observed increase in the rate of acetylation of lysine-rich and arginine-rich histone fractions. The Mn(2+)-(NH(4))(2)SO(4) and Mg(2+)-activated RNA polymerase reactions measured in nuclei isolated from cells infected with adenovirus 2 or 12 were stimulated at about the same time; a rapid loss of polymerase activity followed. The augmentation of the two RNA polymerase reactions found in adenovirus 12-infected cells was independent of protein synthesis. After the initial increase, the acetylation rate of histones of cells infected with adenovirus 2 or 12 declined, until late in infection it was approximately 40 to 70% of the control cell rate.
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PMID:Transient stimulation of deoxyribonucleic acid-dependent ribonucleic acid polymerase and histone acetylation in human embryonic kidney cultures infected with adenovirus 2 or 12: apparent induction of host ribonucleic acid synthesis. 547 77

The uptake of nucleosides and the synthesis of RNA in Tetrahymena thermophila were examined following amino acid starvation. Omission of leucine, phenylalanine, or arginine from the medium resulted in a rapid decrease in the incorporation of [3H]uridine into the acid-soluble pool and acid-insoluble material (RNA). Amino acid starvation inhibited the uptake of all ribo- and deoxyribonucleosides tested but did not affect the uptake of amino acids or glucose. In addition, under the conditions used, the omission of an amino acid did not result in a large decrease in amino acid incorporation into total protein. Treatment of cells with cycloheximide or emetine gave results similar to the effects of amino acid starvation, but in these experiments the inhibition of protein synthesis was essentially complete. Nucleotide pool sizes were also measured following amino acid starvation. ATP and UTP levels were essentially unchanged, but the dTTP pool size was decreased by 40%. The decrease in RNA synthesis in vivo in the absence of an essential amino acid was reflected in the endogenous RNA synthetic activity of isolated nuclei. However, when solubilized RNA polymerase activity was measured with calf thymus DNA as template, no significant difference was observed between control and amino acid-starved cells.
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PMID:The effect of amino acid starvation on nucleoside uptake and RNA synthesis in Tetrahymena. 615 97

The nucleotide sequence for human argininosuccinate synthetase cDNA was determined by analysis of six clones isolated from a single experiment. The sequence covered 1623 nucleotides including 76 bases of poly(A) and contained a 1236 nucleotide open reading frame encoding a protein of 46,434 daltons. In one cDNA isolate, a cloning artifact or perhaps RNA polymerase error involving addition of an A in a region of six A's within the coding sequence was documented. Single base variations in the 3' untranslated region were examined in detail since detection of DNA polymorphisms in the cDNAs could imply over-expression of both alleles at the active locus in canavanine-resistant cells, i.e. a trans-acting mechanism for enzyme overproduction. However, the sequence from five cDNAs suggested some single base artifacts, and DNA polymorphism remains uncertain. The occurrence of three tandem arginine codons in the 5' untranslated region of the cDNA suggested the possibility of an interaction of arginyl-tRNA with mRNA to regulate RNA processing or half-life as a mechanism for arginine-mediated repression.
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PMID:Sequence for human argininosuccinate synthetase cDNA. 619 10

The DNA sequences which encode the Mr = 28,500 flagellin polypeptide of Caulobacter crescentus CB15 have been determined. The size of the protein, deduced from its DNA sequence (276 amino acids), is in agreement with its apparent molecular weight as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The distribution of arginine residues within the protein sequence encoded by the gene correlates with their relative location as predicted by peptide alignment analysis (Gill, P.R., and Agabian, N. (1982) J. Bacteriol. 150, 925-933). DNA sequences 5' and 3' to the coding sequence were also determined. In the 5' region, DNA sequences homologous to consensus sequences associated with RNA polymerase recognition and transcription initiation sites in Escherichia coli (Pribnow box) are found. These are centered around 60, 90, and 120 base pairs upstream from the ATG codon at the beginning of the structural gene. Sequences 3' to the coding region were identified which might signal transcription termination. A typical E. coli 16 S ribosomal binding site (Shine-Dalgarno sequence) is located just 5' to the coding sequence, and for most of the amino acids there is a strong codon usage preference. Although this protein is exported from the cell (Gill, P.R., and Agabian, N. (1982) J. Bacteriol. 150, 925-933), the encoded NH2-terminal amino acid sequence is not different from the mature product.
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PMID:The nucleotide sequence of the Mr = 28,500 flagellin gene of Caulobacter crescentus. 630 39


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