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 catabolite-sensitive promoter was found to be involved in transcription of the heat shock regulatory gene rpoH encoding the sigma 32 protein. Expression of lacZ from the operon fusion, rpoHp-lacZ, was partially inhibited by glucose added to the broth medium. Dissection of the rpoH promoter region allowed us to localize the glucose-sensitive promoter to the 110-base-pair (bp) segment directly upstream of the rpoH coding region. Experiments on lacZ expression from the set of fusions in cya (adenylate cyclase) and crp (cyclic AMP [cAMP] receptor protein) mutants also supported the involvement of a catabolite-sensitive promoter. Analysis of rpoH mRNAs by S1 nuclease protection experiments led us to identify a novel promoter, designated P5, that is regulated by cAMP and the cAMP receptor protein. Studies of rpoH transcription in vitro demonstrated that RNA polymerase-sigma 70 can transcribe from the P5 promoter only in the presence of cAMP and its receptor protein. The 5' ends of P5 transcripts obtained in vivo and in vitro were found to be at 61 to 62 bp upstream of the initiation codon, and a putative binding sequence for the cAMP receptor protein was found at 38 to 39 bp further upstream. Transcription from the P5 promoter is increased by the addition of ethanol to the growth medium; however, the increase is greater in the presence of glucose than in its absence. These results add a new dimension to the transcriptional control of rpoH and to the regulation of the heat shock response in Escherichia coli.
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PMID:Transcriptional regulation of the heat shock regulatory gene rpoH in Escherichia coli: involvement of a novel catabolite-sensitive promoter. 213 50

The synthesis of ribosomal proteins (r proteins) under the conditions of greatly reduced RNA synthesis were studied by using a strain of the yeast Saccharomyces cerevisiae in which the production of the largest subunit (RPA190) of RNA polymerase I was controlled by the galactose promoter. Although growth on galactose medium was normal, the strain was unable to sustain growth when shifted to glucose medium. This growth defect was shown to be due to a preferential decrease in RNA synthesis caused by deprivation of RNA polymerase I. Under these conditions, the accumulation of r proteins decreased to match the rRNA synthesis rate. When proteins were pulse-labeled for short periods, no or only a weak decrease was observed in the differential synthesis rate of several r proteins (L5, L39, L29 and/or L28, L27 and/or S21) relative to those of control cells synthesizing RPA190 from the normal promoter. Degradation of these r proteins synthesized in excess was observed during subsequent chase periods. Analysis of the amounts of mRNAs for L3 and L29 and their locations in polysomes also suggested that the synthesis of these proteins relative to other cellular proteins were comparable to those observed in control cells. However, Northern analysis of several r-protein mRNAs revealed that the unspliced precursor mRNA for r-protein L32 accumulated when rRNA synthesis rates were decreased. This result supports the feedback regulation model in which excess L32 protein inhibits the splicing of its own precursor mRNA, as proposed by previous workers (M. D. Dabeva, M. A. Post-Beittenmiller, and J. R. Warner, Proc. Natl. Acad. Sci. USA 83:5854-5857, 1986).
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PMID:Conditional expression of RPA190, the gene encoding the largest subunit of yeast RNA polymerase I: effects of decreased rRNA synthesis on ribosomal protein synthesis. 218 18

The effect of infusion of a methionine-free total parenteral nutrition solution for 7 d on ribonucleic acids in liver of rats were investigated. The control solution contained leucine, valine, isoleucine, lysine, phenylalanine, threonine, tryptophan, arginine, histidine, glycine, methionine, glucose and vitamins and minerals. Deprivation of a methionine is known to increase the activity of RNA polymerase I. Infusing the methionine-free solution resulted in the accumulation of RNA molecules larger than 28S in the liver nuclei and resulted in a higher rate of rRNA synthesis than in rats infused with the control solution. A methionine deficiency did not impede either the processing of 45S pre-rRNA or transport of 28S and 18S rRNA into cytoplasm. When rats were infused with the methionine-free solution for 7 d followed by the control solution for 2 d, the level of RNA in the nucleus as well as the rate of RNA polymerase I were similar to the levels in rats receiving the control solution for 9 d. There were no significant changes in the rate of DNA synthesis due to nutritional manipulations.
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PMID:Alteration in the ribonucleic acids in rat liver induced by a methionine-free total parenteral nutrition solution. 243 90

We have identified stable transcripts from the so-called nontranscribed spacer region (NTS) of the nuclear ribosomal DNA repeat in certain respiration-deficient strains of Saccharomyces cerevisiae. These RNAs, which are transcribed from the same strand as is the 37S rRNA precursor, are 500 to 800 nucleotides long and extend from the 5' end of the 5S rRNA gene to three major termination sites about 1,780, 1,830, and 1,870 nucleotides from the 3' end of the 26S rRNA gene. A survey of various wild-type and respiration-deficient strains showed that NTS transcript abundance depended on the mitochondrial genotype and a single codominant nuclear locus. In strains with that nuclear determinant, NTS transcripts were barely detected in [rho+] cells, were slightly more abundant in various mit- derivatives, and were most abundant in petites. However, in one petite that was hypersuppressive and contained a putative origin of replication (ori5) within its 757-base-pair mitochondrial genome, NTS transcripts were no more abundant than in [rho+] cells. The property of low NTS transcript abundance in the hypersuppressive petite was unstable, and spontaneous segregants that contained NTS transcripts as abundant as in the other petites examined could be obtained. Thus, respiration deficiency per se is not the major factor contributing to the accumulation of these unusual RNAs. Unlike RNA polymerase I transcripts, the abundant NTS RNAs were glucose repressible, fractionated as poly(A)+ RNAs, and were sensitive to inhibition by 10 micrograms of alpha-amanitin per ml, a concentration that had no effect on rRNA synthesis. Abundant NTS RNAs are therefore most likely derived by polymerase II transcription.
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PMID:Interaction between the yeast mitochondrial and nuclear genomes influences the abundance of novel transcripts derived from the spacer region of the nuclear ribosomal DNA repeat. 247 90

We have cloned and expressed in Escherichia coli the gene encoding the trimeric fiber protein of human adenovirus type 2. A gene expression system based on bacteriophage T7 RNA polymerase was used. Optimal gene expression was obtained with 1-h induction, at a temperature of 30 degrees C. The synthesized protein constituted about 1% of total host-cell protein. During induction, the growth of bacteria carrying the plasmid containing the fiber gene, was retarded compared with that of bacteria carrying the plasmid without the fiber gene. This toxic effect of fiber protein on bacterial hosts could be diminished by addition of glucose to the medium and by maintaining the pH above 7, thus improving the yield of recombinant fiber protein. The fiber protein produced in E. coli is stable during the course of induction. It is insoluble in buffers at physiological pH, in various salt solutions, and in the presence of nonionic detergents. It can be solubilized in 1% sodium dodecyl sulfate or in urea solutions above 2 M. There are indications that recombinant fiber trimerizes spontaneously, since after the removal of urea by dialysis at pH 8, recombinant fibers runs similarly to native trimeric fiber, on nondenaturing polyacrylamide gels. This trimer has, however, a less compact structure than native Ad2 fiber, since during gel filtration recombinant protein is excluded before native protein. It is also more sensitive to chymotrypsin digestion than native fiber.
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PMID:Synthesis of human adenovirus type 2 fiber protein in Escherichia coli cells. 268 Jul 70

A cDNA encoding the rat brain glucose transporter was inserted between the 5' and 3' untranslated regions from the Xenopus globin gene and downstream of an SP6 RNA polymerase start site. RNA synthesized from this vector was microinjected into oocytes from Xenopus laevis; this resulted in expression of the glucose transporter, as determined by both immunoblotting and the appearance of transport activity. The properties of the transporter were those expected from previous studies: it was glycosylated, and its activity, measured by 3-O-methylglucose transport, was inhibited by D-glucose and cytochalasin B, but not by L-glucose. The low level of endogenous glucose transport activity found in water-injected oocytes makes this a useful system in which to determine the kinetic parameters of transport. The Km for 3-O-methylglucose was found to be 20 mM under equilibrium exchange conditions. Despite the fact that oocytes exhibit insulin-dependent responses, insulin did not stimulate 3-O-methylglucose transport by injected oocytes.
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PMID:Expression of a functional glucose transporter in Xenopus oocytes. 269 9

S1 nuclease mapping of RNA prepared from Pseudomonas amyloderamosa SB-15 suggested that the iam gene coding for isoamylase (glycogen 6-glucanohydrolase [EC 3.2.1.68]) is transcribed from two promoters. The transcription start site for the upstream promoter (termed P1) was located -182 base pairs from the first nucleotide of the initiation codon of iam, whereas the start site for the downstream promoter (termed P2) was 99 base pairs downstream of the P1 start site. Transcriptions from these promoters were induced by maltose and were not repressed by glucose. The promoter regions contained sequences homologous to the consensus sequence recognized by sigma 54 RNA polymerase of enteric bacteria and found in promoters of other Pseudomonas species. Northern (RNA) hybridization provided evidence that the iam gene is transcribed as monocistronic mRNAs with an approximate size of 2.6 kilobases.
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PMID:Transcription of the isoamylase gene (iam) in Pseudomonas amyloderamosa SB-15. 275 57

We have mapped the chromosomal locus of rpoD, which encodes the major sigma factor of Bacillus subtilis RNA polymerase. The rpoD locus lay between aroD and lys, tightly linked to dnaE and inseparable from crsA. Marker order in this region was acf-aroD-dnaE-rpoD(crsA)-spoOG-lys. By transformation using cloned donor DNA from the rpoD region, we identified the gene immediately upstream of rpoD as dnaE, which coded for a 62,000 dalton protein essential for DNA replication. Both dnaE and rpoD were transcribed in the same direction, counterclockwise on the chromosome. The gene functions and organization in the rpoD region are thus similar to those of the E. coli sigma operon. We also used transformation to identify crsA47 as a mutation within the sigma coding region itself. The crsA alteration of sigma renders the sporulation process insensitive to glucose catabolite repression, and also restores sporulation ability to strains carrying early-blocked spoOE, spoOF, and spoOK mutations. Thus the major sigma factor and these spoO gene products directly or indirectly affect the same cellular function.
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PMID:Genetic mapping of rpoD implicates the major sigma factor of Bacillus subtilis RNA polymerase in sporulation initiation. 299 85

We have identified two chromatographically separable forms of mitochondrial RNA polymerase from Saccharomyces cerevisiae which utilize different DNA templates. One form is only active in a nonselective assay utilizing a poly[d(A-T)] template. The other form selectively initiates from a mitochondrial promoter consensus sequence. Both enzymes can be extracted from yeast mitochondria and all components are encoded by nuclear genes. The possibility that these two activities represent core and holoenzyme forms of the multicomponent mitochondrial RNA polymerase is supported by our observation that both enzymes are absent from a strain bearing a disrupted copy of the RPO41 gene (Greenleaf, A. L., Kelly, J. L., and Lehman, I. R. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 3391-3399). The two enzyme activities are differentially regulated by carbon source; the nonselective enzyme is repressed during growth on glucose relative to the selective enzyme. The 5-fold increase in RNA polymerase activity on a nonrepressing carbon source correlates with the increased level of transcript production from mitochondrial DNA. These results suggest that the mitochondrial RNA polymerase and, in consequence, mitochondrial transcription are regulated by carbon catabolite control.
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PMID:Two forms of RPO41-dependent RNA polymerase. Regulation of the RNA polymerase by glucose repression may control yeast mitochondrial gene expression. 304 16

We have constructed a yeast strain (UKY403) in which the sole histone H4 gene is under control of the GAL1 promoter. This allows the activation of H4 mRNA synthesis on galactose and its repression on glucose. UKY403 cells, pre-synchronized in G1 with alpha-mating factor, have been used to show that glucose treatment results in the loss of approximately half the chromosomal nucleosomes. This depletion is only partially reversible when the H4 gene is reactivated on galactose. It was found that the resultant lethality manifests itself first in S phase, the period of nucleosome assembly, but leads to highly synchronous arrest in G2 and a virtually complete block in chromosomal segregation. Histone H4-depleted chromatin was analyzed for its efficiency as a template for all three RNA polymerases. Using pulse-labeling, we find no evidence for altered transcription by RNA polymerase I (25S, 18S and 5.8S rRNAs) or RNA polymerase III (5S rRNA, tRNAs). Northern blot analysis was used to measure levels of RNA polymerase II transcripts. There was little effect on the activation or repression of the CUP1 chelatin gene. While there may be some decrease in the level of certain mRNAs (e.g. HIS4, ARG4) other message levels (HIS3, TRP1) show little change upon glucose repression. Therefore, nucleosome loss certainly does not have a general effect on transcription.
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PMID:Effects of histone H4 depletion on the cell cycle and transcription of Saccharomyces cerevisiae. 304 33


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