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 bacteriophage lambda clone containing a 20-kb human DNA segment was isolated and found to harbor a cluster of four tRNA genes. An 8.2-kb HindIII subfragment encompassing the genes was cloned into pBR322 for restriction mapping and DNA sequence analysis. The genes were found to be arranged as two tandem pairs, separated by 3 kb. A proline tRNAAGG gene is separated from a leucine tRNAAAG gene by a 724-bp intergenic region in the first pair, and a second proline tRNAAGG gene is 316 bp from a threonine tRNAUGU gene in the second pair, with the leucine tRNA gene being of opposite polarity to the other three genes. A putative Alu-like element was found to occur within a 2.0-kb DNA fragment, at least 0.7 kb from the tRNA gene cluster. The coding sequences of the two proline tRNAAGG genes are identical. The coding regions of all four tRNA genes contain consensus internal split promoter sequences and do not have intervening sequences nor the CCA trinucleotide found in mature tRNAs. The 3'-flanking regions of these four tRNA genes have normal RNA polymerase III termination sites of at least four consecutive T nucleotides. No apparent homologies occur between the 5'-flanking regions of these genes. All four tRNA genes are accurately transcribed in an in vitro HeLa cell-free system, and the RNase T1 fingerprints of the mature-sized tRNA transcripts were found to be consistent with the DNA sequences of the genes.
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PMID:Nucleotide sequence and transcription of a human tRNA gene cluster with four genes. 355 25

In glutaraldehyde-prefixed exponential-phase cells of Streptococcus faecalis the nucleoid is "frozen" in a dispersed configuration. Exposure of exponential-phase cells to threonine starvation or to antibiotics inhibiting protein synthesis resulted in progressive condensation of nucleoid fibrils producing an expanding central nucleoid zone or pool. The condensation of the nucleoid was observed to occur at a rate directly proportional to the rate of inhibition of protein synthesis. However, the extent of nucleoid condensation depended on continuing deoxyribonucleic acid synthesis. Significantly less nucleoid condensation occurred when cells were inhibited in deoxyribonucleic acid and protein synthesis than when cells were inhibited in protein synthesis alone. These results suggest a model in which, during nucleoid replication, the chromosome fibrils are normally maintained in a dispersed state by the active agents of transcription-translation, such as ribonucleic acid polymerase molecules and ribosomes.
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PMID:Morphokinetic reaction of Streptococcus faecalis (ATCC 9790) cells to the specific inhibition of macromolecular synthesis: nucleoid condensation on the inhibition of protein synthesis. 411 Sep 25

Ornithine decarboxylase may undergo posttranslational modifications which alter its function. Both transamidation of glutamine residues in the enzyme catalyzed by TGase and phosphorylation of serine and threonine residues catalyzed by a polyamine-stimulated protein kinase have been demonstrated. Data are presented which suggest that these modifications result in translocation of the modified protein to the nucleolus where it regulates the activity of RNA polymerase I to transcribe rDNA, the only active nucleolar genes. Transamidation of specific proteins with primary amines catalyzed by intracellular TGase may be an important posttranslational modification, capable of altering genetic transcription. The rapid half-life of ODC (10-15 min) may be related to rapid posttranslational modification with loss of enzymatic activity rather than to protein degradation.
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PMID:Ornithine decarboxylase may be a multifunctional protein. 608 23

The RNA polymerase binding with two hybrid plasmids carrying threonine operon genes was studied. RNA polymerase binding sites were localized using nitrocellulose binding assay and electron microscopy visualization of the RNA polymerase--DNA complexes. To confirm that observed RNA polymerase binding sites are real promoters we analyzed RNA transcripts synthesized in vitro by hybridization with DNA fragments. The promoters of following genes were localized on the plasmid maps: ampicilline, threonine and RNA-primer of DNA replication. Two latter promoters bound RNA polymerase only being in the supercoiled DNA molecule. Several additional binding sites were found. The positions of some of these sites corresponded with known sites of rho-independent transcription termination.
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PMID:[Interaction of RNA polymerase with hybrid plasmids carrying Escherichia coli threonine operon]. 627 58

The 6 S leader RNA transcript from the Escherichia coli threonine operon controlling region was synthesized in vitro using purified RNA polymerase and restriction fragment DNA templates. The terminated leader transcript was analyzed by RNase T1 digestion followed by electrophoresis on 20% polyacrylamide, 8 M urea gels. Oligonucleotides of 7, 8, 13, 15, and 35 bases in length were detected and correlated with the known DNA sequence. The kinetics of RNase T1 digestion indicated that the RNA forms extensive secondary structure, especially at the 3'-terminus of the transcript. The sites of transcription initiation were determined by labeling the 5'-end of the transcript with [gamma-32P]ATP or -GTP followed by direct RNA sequencing. The DNA sequence preceding the initiation site shows homology with the equivalent regions of other bacterial and bacteriophage promoters. The transcription termination sites were determined by mapping of the RNase T1 oligonucleotides arising from the 3'-terminus of the transcript. Comparison of the mobilities of the 3'-oligonucleotides with the mobilities of standards on 20% polyacrylamide, 8 M urea gels indicated that the RNA contains a heterogeneous 3'-terminus. The two predominant oligonucleotides were CU7 and CU8. The 3'-terminus of the transcript also contains a region of dyad symmetry immediately preceding a stretch of uridine residues, characteristic of other rho-independent transcripts. In addition, kinetic studies indicated that RNA polymerase pauses approximately 50 base pairs upstream from the site of termination. The pause site appears to be immediately distal to another region of dyad symmetry.
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PMID:Initiation, pausing, and termination of transcription in the threonine operon regulatory region of Escherichia coli. 627 52

Nuclear protein kinases include enzymes that transfer the gamma-phosphate of ATP to serine, threonine, lysine or histidine in proteins. Nuclear kinases with a preference for basic proteins are known as histone kinases; those preferring acidic protein substrates are casein kinases. Histone kinases include both cyclic AMP-independent protein kinases and cyclic AMP-dependent protein kinases. The best-characterized cyclic AMP-independent nuclear protein kinase is associated with cell proliferation and is activated (or transported to the nucleus) in G2 phase of the cell cycle. It phosphorylates specific serine and threonine residues in the non globular domains of histone H1 and appears to promote chromosome condensation. The cyclic AMP-dependent protein kinase has unknown nuclear function(s), although it may be translocated from cytoplasm to nucleus in response to specific hormonal stimuli which are also associated with changes in transcriptional activity. There is a massive peak of nuclear cyclic AMP-dependent protein kinase activity in G2 phase of the cell cycle. Nuclear casein kinases are apparently very heterogeneous. Two of these enzymes have been purified to homogeneity. They phosphorylate non-histone chromosomal proteins, including RNA polymerase and ornithine decarboxylase. Phosphorylated ornithine decarboxylase is inactive enzymatically but, in Physarum, it binds to the rDNA minichromosome and stimulates rRNA transcription. Kinases forming phosphoramidate bonds occur in a variety of rat tissues and form phosphohistide in histone H4 and phospholysine in histone H1.
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PMID:Nuclear protein kinases. 632 62

More than 40 protein species including RNA polymerase were found to be phosphorylated in Escherichia coli on analyses of 32P-labeled cell lysates by single and two-dimensional gel electrophoresis and autoradiography. The protein species and the level of phosphorylation varied depending on the cell growth phase. With [gamma-32P]ATP as a substrate, cell lysates phosphorylated endogenous proteins in vitro which were predominantly phosphorylated in vivo. Both serine and threonine were the major phosphate acceptors in whole cell lysates. Starting from a partially purified RNA polymerase preparation with the protein phosphorylation activity and using an E. coli protein with an apparent Mr = 90K (K represents X 1000) as the substrate, we purified a protein kinase with a native Mr approximately 120K to apparent homogeneity. The protein kinase is either a heterodimer of 61K and 66K polypeptides or a homodimer of one of these polypeptides. We also isolated a 100K protein with self-phosphorylation activity.
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PMID:Protein phosphorylation in Escherichia coli and purification of a protein kinase. 636 41

A number of proteins of the sulphur-dependent archaebacterium Sulfolobus acidocaldarius are phosphorylated in vivo. The extent of phosphorylation depends on the state of growth and is most intense in the late exponential phase. Some of the phosphorylated proteins are strongly associated with the bacterial membrane. Ribosomal proteins and DNA-dependent RNA polymerase are not phosphorylated. Studies in vitro show a high target selectivity. The activity is not increased by cyclic nucleotides. The reaction in vitro is optimal in the presence of Mg2+, Mn2+ or Ca2+. Both serine and threonine residues are modified. Acetate ions do not induce additional phosphorylation.
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PMID:Protein phosphorylation in the archaebacterium Sulfolobus acidocaldarius. 643 62

The (1)H n.m.r. study of the DNA-dependent RNA polymerase from Escherichia coli has revealed that the holoenzyme (betabeta'alpha(2)sigma) displays two mobile regions: one, observable also in the core enzyme (betabeta'alpha(2)), is characterized by basic amino acids and its appearance and form depend on ionic strength; the other, specific to the holoenzyme, is characterized by threonine residues and its appearance does not depend on ionic strength.
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PMID:1H n.m.r. of the DNA-dependent RNA polymerase from Escherichia coli. 675 66

We have recently purified a cyclic nucleotide-independent, heparin-sensitive nuclear protein kinase (NII) from Morris hepatoma 3924A and demonstrated an apparent relationship of this kinase to the two subunits (Mr = 42,000 and 24,600) of RNA polymerase I. When homogeneous protein kinase NII was recombined with purified homologous RNA polymerase I containing limiting quantities of endogenous kinase, RNA synthesis was stimulated as much as 5-fold during a 90-min incubation. The enhanced RNA synthesis was due to an increase in the average RNA chain length; protein kinase did not alter the number of RNA molecules synthesized by the polymerase. Phosphorylation of RNA polymerase occurred at serine and threonine moieties. Unlike the NII kinase, purified homologous NI kinase did not phosphorylate RNA polymerase I and, as a result, did not alter transcription. These data indicate that 1) RNA polymerase I is activated by protein kinase NII, 2) endogenous protein kinase NII remaining with highly purified RNA polymerase I does not fully phosphorylate RNA polymerase I in vitro, and 3) protein kinase NII is capable of regulating RNA polymerase I activity by preventing premature termination of RNA chains.
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PMID:Activation of purified hepatoma RNA polymerase I by homologous protein kinase NII. 728 32


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