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)

Vaccinia virus-dependent CAT expression was observed in virus-infected cells cotransfected with a promoterless CAT gene. Restriction endonuclease resection of the CAT plasmid indicated that expression was due to recognition by vaccinia virus RNA polymerase of sequences within the CAT gene itself, probably located within the 5' untranslated region of the gene. This observation is relevant to the design of reverse-genetic systems which use CAT as a reporter gene to detect replication of negative-strand RNA virus pseudogenomes.
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PMID:Tn9 CAT gene contains a promoter for vaccinia virus transcription: implications for reverse-genetic techniques. 131 41

We examined the effects of okadaic acid (OA), a potent and specific inhibitor of serine phosphatases 2A and 1, on the transient expression of an hsp 70 promoter-reporter gene construct in IMR-90 human diploid lung fibroblasts. We showed that OA markedly potentiated the heat-induced but not the basal expression of pHBCAT, a full-length human hsp-70-promoter-driven CAT gene construct. This effect of OA was dose and time dependent and promoter specific. Importantly, the potentiating effects of OA appeared to be independent of the binding of the activated heat shock transcription factor (HSTF) to its consensus DNA sequence, the heat shock element (HSE). Thus, OA had no effect on the HSTF DNA-binding activity as measured by mobility shift assay, and mutation of the HSE sequence did not obliterate the stimulatory effects of OA on reporter gene expression under a heat shock condition, although heat shock by itself was without effect. Analysis of the status of phosphorylation of the largest subunit of RNA polymerase II provided evidence that this effect of OA is attributable, at least in part, to the increased phosphorylation of RNA polymerase II. These results provided evidence that the heat-induced hsp 70 promoter activity is negatively regulated by serine phosphatases. We propose that the heat-induced transcriptional activation of hsps is associated with phosphorylation of component(s) of the transcription complex; one of the likely candidates being the transcriptionally engaged RNA polymerase II. OA, by inhibiting phosphatase 2A and 1 activity, enhanced this phosphorylation and potentiated the transcriptional activation of hsps.
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PMID:The heat-induced hsp 70 promoter activity is negatively regulated by serine phosphatases: evidence from the effects of okadaic acid. 133 79

The variant-specific surface glycoprotein (VSG) gene 221 of Trypanosoma brucei is transcribed as part of a 60 kb expression site (ES). We have identified the promoter controlling this multigene transcription unit by the use of 221 chromosome-enriched DNA libraries and VSG gene 221 expression site specific transcripts. The start of transcription was determined by hybridization and RNase protection analysis of nascent RNA. The 5' ends of the major transcripts coming from the initiation region map at nucleotide sequences that do not strongly resemble rRNA transcriptional starts even though the transcripts are synthesized by an RNA polymerase highly resistant to alpha-amanitin. The cloned VSG gene 221 ES transcription initiation region promotes high CAT gene expression, when reintroduced by electroporation into T. brucei. We show that the activity of this expression site is controlled at or near transcription initiation in bloodstream trypanosomes. The 221 ES is inactivated without any sequence alteration within 1.4 kb of the transcription start site. This excludes mechanisms of promoter inactivation involving DNA rearrangements in the vicinity of the transcription start site, e.g. promoter inversion or conversion.
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PMID:The promoter for a variant surface glycoprotein gene expression site in Trypanosoma brucei. 169 65

Strains of a new type of slowly growing scotochromogenic mycobacterium were isolated repeatedly from sphagnum vegetation and surface water of moors in New Zealand. These strains grew at 31 and 22 degrees C but not at 37 degrees C and possessed catalase, acid phosphatase, and arylsulfatase activities. They did not split amides, and most of them were susceptible to antituberculotic drugs. Furthermore, they did not tolerate 0.1% NaOH2 and 0.2% picric acid and did not grow on compounds used as single carbon sources and single nitrogen and carbon sources. The internal similarity of the strains as determined by numerical taxonomy methods was 96.6% +/- 3.09%. The whole-mycolate pattern is unique in that it has not been found previously in 23 species of slowly growing mycobacteria. Evaluation of long-reverse-transcriptase-generated stretches of the primary structure of the 16S rRNA confirmed that these organisms belong to the genus Mycobacterium. The phylogenetic position of these bacteria is unique; they are situated between slowly growing pathogenic and rapidly growing saprophytic species. The strains are not pathogenic for mice, guinea pigs, and rabbits, but they provoke a nonspecific hypersensitivity reaction to bovine tuberculin. Hence, they are considered members of a new species of nonpathogenic, slowly growing mycobacteria, for which the name Mycobacterium cookii is proposed. Strain NZ2 is the type strain; a culture of this strain has been deposited in the American Type Culture Collection as strain ATCC 49103.
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PMID:Mycobacterium cookii sp. nov. 169 63

During carbon-starvation-induced entry into stationary phase, Escherichia coli cells exhibit a variety of physiological and morphological changes that ensure survival during periods of prolonged starvation. Induction of 30-50 proteins of mostly unknown function has been shown under these conditions. In an attempt to identify C-starvation-regulated genes we isolated and characterized chromosomal C-starvation-induced csi::lacZ fusions using the lambda placMu system. One operon fusion (csi2::lacZ) has been studied in detail. csi2::lacZ was induced during transition from exponential to stationary phase and was negatively regulated by cAMP. It was mapped at 59 min on the E. coli chromosome and conferred a pleiotropic phenotype. As demonstrated by two-dimensional gel electrophoresis, cells carrying csi2::lacZ did not synthesize at least 16 proteins present in an isogenic csi2+ strain. Cells containing csi2::lacZ or csi2::Tn10 did not produce glycogen, did not develop thermotolerance and H2O2 resistance, and did not induce a stationary-phase-specific acidic phosphatase (AppA) as well as another csi fusion (csi5::lacZ). Moreover, they died off much more rapidly than wild-type cells during prolonged starvation. We conclude that csi2::lacZ defines a regulatory gene of central importanc e for stationary phase E. coli cells. These results and the cloning of the wild-type gene corresponding to csi2 demonstrated that the csi2 locus is allelic with the previously identified regulatory genes katF and appR. The katF sequence indicated that its gene product is a novel sigma factor supposed to regulate expression of catalase HPII and exonuclease III (Mulvey and Loewen, 1989). We suggest that this novel sigma subunit of RNA polymerase defined by csi2/katF/appR is a central early regulator of a large starvation/stationary phase regulon in E. coli and propose 'rpoS' ('sigma S') as appropriate designations.
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PMID:Identification of a central regulator of stationary-phase gene expression in Escherichia coli. 184 9

We show that the ribosomal RNA (rRNA) promoter can efficiently direct expression of protein-coding genes in the parasitic protozoan Trypanosoma brucei. The rRNA promoter was characterized by: (i) point mutations at the rRNA transcription initiation site which completely abolished its promoter function in transient CAT transformation assays; (ii) the alpha-amanitin resistance of transcription of rRNA promoter-neomycin phosphotransferase (neo) genes in stably transformed trypanosomes; and (iii) the nucleolar location of neo RNA, synthesized under the control of the rRNA promoter. The rRNA promoter-derived CAT mRNA required a 3' splice acceptor site and the neo mRNA was trans-spliced and polyadenylated. In situ hybridization revealed neo RNA at the nucleolus in stably transformed trypanosomes in which rRNA promoter-neo constructs were integrated either at a rRNA locus or at a locus for the procyclic acidic repetitive protein (PARP) coding genes. We postulate that trans-splicing, by uncoupling the requirement for transcription of protein-coding genes by RNA polymerase II, allows RNA polymerase I mediated protein-coding gene transcription, presumably because a 5' cap can be transferred to the pre-mRNA by trans-splicing.
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PMID:RNA polymerase I can mediate expression of CAT and neo protein-coding genes in Trypanosoma brucei. 191 99

The sequences preceding the albumin mRNA start site are able to direct efficient transcription only upon introduction into cells expressing the endogenous albumin gene. In transient expression assays, the activity of a reporter gene (CAT) linked to this promoter is 100-fold higher in H4II differentiated hepatoma cells than in H5 dedifferentiated cells which no longer express their albumin gene. This tissue specificity depends on the very proximal promoter region, composed of a CCAAT box, the proximal element and a TATA box. Deletion of the CCAAT box leads to a two- to threefold decrease in activity, deletion of the proximal element (PE) results in loss of activity. The PE is a high-affinity binding site for HNF1/APF, a strictly liver specific trans-acting factor. When the affinity of this factor for PE is decreased by bacterial methylation (PE includes a dam methylase site), by mutation, or by its replacement with the homologous element from the alpha-fetoprotein gene (AFP), the activity of the short promoter (PE plus the TATA box) is abolished. This activity can be rescued in the presence of the more upstream elements: DEII, DEI and the CCAAT box (recognized, respectively, by the NF1/CTF, C/EBP and NFY/ACF factors) which are then absolutely required. Our results suggest that the upstream elements contribute to promoter activity by stabilizing the HNF1-PE complex and not by direct interaction with TFIID or the RNA polymerase. It is probable that these elements, essentially dispensable in already differentiated hepatoma cells, play a crucial role during development or differentiation to activate the promoter in cells that contain a low concentration of HNF1 and/or an HNF1 unable to open inactive chromatin alone.
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PMID:Anatomy of the rat albumin promoter. 218 62

Treatment of Salmonella typhimurium and Escherichia coli cells with low doses of hydrogen peroxide results in the induction of thirty proteins and resistance to killing by higher doses of hydrogen peroxide. The expression of nine of the hydrogen peroxide-inducible proteins, including catalase, glutathione reductase and a novel alkyl hydroperoxide reductase is controlled by the positive regulator oxyR. OxyR is homologous to the LysR-NodD family of bacterial regulatory proteins and binds to the promoters of oxyR-regulated genes. The oxidized but not reduced form of the OxyR protein activates transcription of oxyR-regulated genes in vitro suggesting that oxidation of the OxyR protein brings about a conformational change by which OxyR both senses and transduces an oxidative stress signal to RNA polymerase.
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PMID:The OxyR regulon. 225 75

Using purified sigma 55 RNA polymerase from Bacillus subtilis in an in vitro transcription system, we have shown that both promoters and terminators of Gram negative origin are recognized by this enzyme. Furthermore, when B. subtilis is transformed with a shuttle vector containing certain of these promoters, synthesis of the Staphylococcus aureus CAT protein is achieved, and levels up to 25% of the total cellular protein can be obtained. These findings indicate a closer evolutionary relationship of the expression machinery of these two bacterial species than has been assumed so far. On the basis of these results, the construction of new expression vectors for B. subtilis is likely to be facilitated, since a variety of well-characterized signal elements from Escherichia coli are available.
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PMID:Efficient utilization of Escherichia coli transcriptional signals in Bacillus subtilis. 241 70

A mutation is described that alters the promoter specificity of sigma 70, the primary sigma factor of Escherichia coli RNA polymerase. In strains carrying both the mutant and wild-type sigma gene (rpoD), the mutant sigma causes a large increase in the activity of mutant P22 ant promoters with A.T or C.G instead of the wild-type, consensus G.C base-pair at position -33, the third position of the consensus -35 hexamer 5'-TTGACA-3'. There is little or no effect on the activities of the wild-type and 23 other mutant ant promoters, including one with T.A at -33. The mutant sigma also activates E. coli lac promoters with A.T or C.G, but not T.A, at the corresponding position. The rpoD mutation (rpoD-RH588) changes a CGT codon to CAT. The corresponding change in sigma 70 is Arg588----His. This residue is in a region that is conserved among most sigma factors, a region that is also homologous with the helix-turn-helix motif of DNA-binding proteins. These results suggest that this region of sigma 70 is directly involved in recognition of the -35 hexamer.
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PMID:A mutant Escherichia coli sigma 70 subunit of RNA polymerase with altered promoter specificity. 266 27


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