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)

RNA polymerase transcribed the hutUH operon of Klebsiella aerogenes if the catabolite gene activator protein (CAP) and cyclic AMP (cAMP) were present or if the DNA template was derived from a promoter mutant in which hutUH expression was independent of the need for positive effectors. In the absence of CAP or cAMP, not only was hutUH transcription absent, but transcription in the opposite direction (toward hutC) was initiated at a site (pC) ca. 70 base pairs from the site (pUH) of hutUH mRNA initiation. When the pC promoter was cloned in front of a promoterless galK gene, active expression of galK was observed. Thus, the pC promoter is active in vivo as well as in vitro. Transcription from pUH and pC may be mutually exclusive, with the major effect of CAP and cAMP being to prevent transcription from pC, thus relieving the antagonistic effect on transcription from pUH. This "double-negative" control by CAP-cAMP is supported by two observations: (i) CAP-cAMP was unable to activate transcription from pUH if RNA polymerase had been previously bound to pC and (ii) a mutation that allowed transcription from pUH in the absence of positive effectors simultaneously eliminated the activity of pC. An alternative model, in which CAP-cAMP is required for pUH expression and RNA polymerase binding at pC serves to modulate this control in some unknown way, is also considered. The physiological role of the transcript from pC other than regulation of pUH is unknown.
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PMID:Regulation of hutUH operon expression by the catabolite gene activator protein-cyclic AMP complex in Klebsiella aerogenes. 609 Mar 99

The activities of the three DNA-dependent RNA polymerases from a rapidly growing rat tumour, Morris hepatoma 3924A, and from rat liver were examined. The activity of RNA polymerase I was higher in the tumour than in the liver. The enhanced capacity for RNA synthesis was a result of a higher concentration of polymerase I in the tumour as well as of an activation of this enzyme in vivo. The possibility that the high specific activity of the hepatoma polymerase I resulted from phosphorylation was investigated. Two major cyclic-AMP-independent nuclear casein kinases (NI and NII) were identified; the activity of protein kinase NII in the tumour was ten times that in liver. Protein kinase NII was capable of activating and phosphorylating RNA polymerase I in vitro. This kinase could also stimulate RNA polymerase II activity, although to a lesser extent than RNA polymerase I. RNA polymerase III was not affected by protein kinase NII. Protein kinase NII was tightly associated with polymerase I and was found even in purified preparations of the polymerase. Antibodies against both RNA polymerase I and protein kinase NII were present in sera of patients with certain rheumatic autoimmune diseases. These results imply that RNA polymerase I and protein kinase NII are in close association in vivo as well as in vitro and that polymerase phosphorylation may regulate the rate of ribosomal RNA synthesis in the cell.
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PMID:Phosphorylation of RNA polymerases: specific association of protein kinase NII with RNA polymerase I. 613 1

The abortive initiation reaction of RNA polymerase has been used to prepare adenylyl-(3'--5')-uridine 5'-phosphate (pApU) in 74% yield from AMP and UTP. The reactive intermediate p-azidophenyl phosphorimidazolidate has been prepared by starting from p-nitrophenyl phosphate. Reaction of this compound with the terminal phosphates of adenosine 5'-phosphate and adenylyl-(3'--5')-uridine 5'-phosphate gives the corresponding beta-substituted 5'-diphosphates. These products are incorporated into the 5' (leading) end of RNA by RNA polymerase (Escherichia coli) and can be photoactivated at a specific stage of RNA elongation. The dinucleotide photoaffinity label beta-(4-azidophenyl) adenylyl-(3'--5')-uridine 5'-diphosphate stimulates RNA synthesis more strongly than adenylyl-(3'--5')-uridine.
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PMID:Synthesis of mono- and dinucleotide photoaffinity probes of ribonucleic acid polymerase. 616 87

The regulatory mechanism of transcription involved in the phosphorylation of a 13 kDa non-histone chromatin protein from calf thymus, which is the most effective phosphate acceptor for cyclic AMP-independent protein kinase purified from the nuclei of mouse spleen cells, by the kinase has been studied in vitro. An analytical study of the circular dichroism (CD) spectra of the 13 kDa protein under different conditions showed that it underwent a major conformational change when incubated with DNA. The presented data suggest that the DNA-induced conformational change may result in a great increase of the 13 kDa protein phosphorylation by the kinase in vitro. Mg2+ (8-10 mM) enhanced the binding of the protein to DNA. Furthermore, the phosphorylated 13 kDa protein stimulated elongation of RNA synthesis by RNA polymerase II from calf thymus. However, neither the 13 kDa protein nor the phosphorylated 13 kDa protein had any affect on DNA synthesis. The available evidence suggests that the 13 kDa protein may play a role in the regulation of transcription through its phosphorylation by the kinase in vitro.
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PMID:Biochemical characterization of a specific phosphate acceptor of nuclear cyclic AMP-independent protein kinase. 618 76

The qualitative and quantitative characteristics of the synthesis of the short oligonucleotides by Escherichia coli RNA polymerase on A1 promoter of the bacteriophage T7 deletion mutant delta D111 DNA in the presence of the incomplete set of nucleoside triphosphates were studied. It was shown, that in conformity with the structure of A1 promoter the oligonucleotides pppApU, pppApUpC were synthesized in the presence of ATP, UTP, CTP; the oligonucleotides pApU, pApUpC-in the presence of AMP, UTP, CTP and oligonucleotides pApU, pApUpC, pApUpCpG-in the presence of AMP, UTP, CTP, GTP. The curves of di- and trinucleotide syntheses as the functions of the substrate concentrations were obtained. The analytical formulas for the rates of the coupled synthesis were derived from these curves. A kinetic scheme that is in conformity with the experimental data was proposed. This scheme includes the stage of the reversible, random and release of di- and trinucleotides from the enzyme-template complex.
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PMID:[Kinetics of DNA-dependent RNA synthesis: coupled synthesis of di- and trinucleotides in the presence of a minimum complement of substrate]. 620 18

Kinetics of RNA chain elongation catalyzed by wheat germ RNA polymerase II have been studied using various synthetic DNA templates in the presence of excess dinucleotide monophosphate primers. With single- or double-stranded homopolymer templates, the double reciprocal plots 1/(velocity) as a function of 1/(nucleotide substrate) exhibit positive, negative or no curvature. With poly(dAT) as template, the mechanism of nucleoside monophosphate incorporation into RNA is not the ping-pong kinetic mechanism which was derived for E. coli RNA polymerase (6). Noncomplementary nucleoside triphosphates inhibit RNA transcription allosterically. Cordycepin triphosphate behaves as ATP, and not only inhibits AMP incorporation but also that of UMP and GMP on appropriate templates. The reason for this complex kinetic behavior is not yet understood. Possibilities are raised that there are several nucleoside triphosphate binding sites on wheat germ RNA polymerase II, that additional nucleoside triphosphate dependent enzymatic activities are required for reaction to occur or that the Km value for incorporation of a given nucleoside monophosphate into RNA is dependent on the length of the RNA chain and/or the nucleotide sequence surrounding the complementary base on the DNA template.
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PMID:Complex RNA chain elongation kinetics by wheat germ RNA polymerase II. 620 28

The reaction product of the ribosomal poly(A) polymerase [ATP(UTP):RNA nucleotidyltransferase] is analyzed. Two systems are used in vitro: (a) isolated polyribosomes with endogenous enzyme and RNA primer and (b) purified enzyme with total polyribosomal RNA as primer. In the polyribosome system about 50% of the [3H]AMP label is in poly(A)-containing mRNA. This RNA displays a heterogeneous size ditribution in the range of 8--30 S with a maximum at about 14 S. Upon denaturation the maximum is shifted towards the 10-S zone. The poly(A) polymerase catalyzes the addition of 12--18 adenylate residues to pre-existing mRNA poly(A) sequences of 40--160 residues. The [3H]AMP incorporated into poly(A)-lacking RNA is mainly in a fraction with an electrophoretic mobility corresponding to 4-S RNA. In the purified enzyme system, specificity towards poly(A)-containing mRNA is lost to a considerable extent. Only 10% of the [3H]AMP label is retained by oligo(dT)-cellulose. The bulk of the product is in 18-S rRNA and heterogeneous small molecular weight RNA. We conclude that the ribosome-associated poly(A) polymerase is most likely the enzyme responsible for the cytoplasmic polyadenylation of poly(A)-containing mRNA in vivo.
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PMID:Primer specificity of ribosome-associated poly(A) polymerase from Ehrlich ascites tumour cells. 624 52

The locations of DNA binding by the proteins involved with positive and negative regulation of transcription initiation of the L-arabinose operon in Escherichia coli have been determined by the DNase I protection method. Two cyclic AMP receptor protein sites were found, at positions -78 to -107 and -121 to -146, an araC protein--arabinose binding site was found at position -40 to -78, and an araC protein-fucose binding site was found at position -106 to -144. These locations, combined with in vivo data on induction of the two divergently oriented arabinose promoters, suggest the following regulatory mechanism: induction of the araBAD operon occurs when cyclic AMP receptor protein, araC protein, and RNA polymerase are all present and able to bind to DNA. Negative regulation is accomplished by the repressing form of araC protein binding to a site in the regulatory region such that it stimultaneously blocks access of cyclic AMP receptor protein to two sites on the DNA, one site of which serves each of the two promoters. Thus, from a single operator site, the negative regulator represses the two outwardly oriented ara promoters. This regulatory mechanism explains the known positive and negative regulatory properties of the ara promoters.
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PMID:The Escherichia coli L-arabinose operon: binding sites of the regulatory proteins and a mechanism of positive and negative regulation. 625 57

The cyclic AMP receptor protein (CRP) stimulates transcription of the lactose operon by binding to the lac promoter. I have identified those 5-positions of thymines in the promoter that lie close to bound CRP. Although ultraviolet irradiation of DNA with 5-bromouracil substituted in place of thymine normally cleaves the DNA at the bromouracils, a protein bound to the DNA can perturb these cleavages at those locations at which the protein lies close to the bromine. The contacts inferred from this photochemical probe and the results of nucleolytic attack of this complex by exonuclease III support a model where the cyclic AMP receptor protein binds to the promoter making symmetrical contacts with one face of the double helix and then stimulates transcription through contacts with RNA polymerase.
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PMID:Interaction of the cAMP receptor protein with the lac promoter. 625 23

The 2.9 A resolution crystal structure of Escherichia coli catabolite gene activator protein (CAP) complexed with cyclic AMP reveals two distinct structural domains separated by a cleft. The smaller carboxy-terminal domain is presumed to bind DNA while the amino-terminal domain is seen to bind cyclic AMP. Model building studies suggest that CAP binds to left-handed B-type DNA, contracting its major groove via two alpha-helices. It is possible that the CAP conversion of right- to left-handed DNA in a closed supercoil, is what activates transcription by RNA polymerase.
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PMID:Structure of catabolite gene activator protein at 2.9 A resolution suggests binding to left-handed B-DNA. 626 Nov 52


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