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

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Promoter sequences recognized by Escherichia coli RNA polymerase were isolated from Brevibacterium sp. R312, a coryneform strain producing nitrile hydratase and amidase. Ten Escherichia coli clones containing promoter sequences were selected for their ability to grow with chloramphenicol concentrations of up to 1500 micrograms/ml. The strength of these promoter sequences was determined. We carried out a preliminary study of the strongest promoter having a chloramphenicol acetyl-transferase/beta-lactamase activities ratio of 18.4.
...
PMID:Isolation of promoter sequences from Brevibacterium sp. R312. 147 39

The region preceding the beta-lactamase promoter of Escherichia coli plasmid pUC19 has a curved DNA (bent DNA) structure. The center of the curvature was revealed to exist around nucleotide position 2580 of the plasmid, which is just beside RNA polymerase binding region. It was indicated that the identified region is curved even at 60 degrees C. The gross geometry of the curvature was altered by inserting synthetic double-stranded oligonucleotides between positions 2585 and 2586. Effect of the alteration on strength of the promoter was not detected in vitro. However, in vivo analyses showed that the promoter strength is apparently dependent, in part, on the gross geometry of the curvature. Insertions of 4 and 16 bp, both of which altered the gross geometry of the curvature greatly, caused considerable reductions of in vivo level of beta-lactamase mRNA. In vivo, overall three-dimensional structure of the region covering the promoter and the curvature seems to play some significant role in transcription of the gene.
...
PMID:Alteration of the curved helical structure located in the upstream region of the beta-lactamase promoter of plasmid pUC19 and its effect on transcription. 157 52

Oligonucleotides are being developed to selectively inhibit gene expression at the translational level (antisense oligonucleotides) and at the transcriptional level (anti-gene oligonucleotides). This review deals with the anti-gene strategy whereby an oligonucleotide binds to the major groove of double helical DNA where it forms a local triple helix. The molecular mechanisms for DNA recognition by triple helix formation are discussed together with some of the rules presently available to design the sequence and orientation of the triple helix forming oligonucleotide. Triplex stability can be enhanced by covalent attachment of an intercalating agent to the terminal nucleotide of the oligonucleotide. The intercalating agent can be used to induce irreversible reactions in the target sequence: double strand cleavage by a phenanthroline-Cu chelate in the presence of a reducing agent, photo-induced cleavage by ellipticine derivatives, photo-induced cross-linking of the two DNA strands by psoralen... Triple helix-forming oligonucleotides can be used to control gene expression at the transcriptional level. Inhibition of binding of transcription activating factors by triplex formation modulates the level of transcription of the target gene. Binding of a triplex-forming oligonucleotide immediately downstream of the RNA polymerase binding site can inhibit transcription initiation as shown with the E. coli beta-lactamase gene. Studies with cells in culture show that triple helix formation may occur in the intracellular environment and consequently leads to transcription inhibition. This inhibitory effect can be made irreversible by using, e.g., psoralen-substituted oligonucleotides. Oligonucleotides synthesized with the alpha-anomers of nucleotide units are resistant to nucleases and still form triple helices with double-stranded DNA. Oligo-[alpha]-deoxynucleotides can be derived by stabilizing (intercalating) agents or reactive groups (cleaving reagents, cross-linkers ...). The results presently available provide a rational basis for the development of new tools for cellular biology and of new therapeutical approaches to selectively control gene expression at the transcriptional level.
...
PMID:The anti-gene strategy: control of gene expression by triplex-forming-oligonucleotides. 177 70

BlaI repressor for the beta-lactamase gene (blaP) of Bacillus licheniformis 749, was shown to repress expression of blaP and of the repressor gene (blaI), using the purified protein in a DNA-directed in vitro translation assay. Binding of BlaI to the promoter regions of blaP and blaI was examined by equilibrium and competitive binding assays. BlaI binds to the blaP promoter with an equal or only slightly higher affinity than to the blaI promoter. DNase I footprinting shows that BlaI binds directly to the blaP and blaI promoters, such that RNA polymerase binding and/or transcript elongation would be blocked.
...
PMID:Interaction of BlaI, the repressor for the beta-lactamase gene of Bacillus licheniformis, with the blaP and blaI promoters. 265 Nov 54

A promoter with the potential to adopt a 50 basepair (bp) cruciform spanning from -19 to -69 has been constructed in the plasmid pBR322 tetracycline resistance gene (tet) by forming an inverted repeat from '-35' sequences. Compared to a control promoter, the sequence of this cruciform promoter differs only by a 22 bp insertion between -48 and -69, upstream from the usual location of promoter sequences. The cruciform is extruded in a supercoil-dependent manner, and transcription from this promoter in vitro by RNA polymerase decreases as the negative supercoil density of the plasmid DNA increases. In contrast, transcription from the control promoter increases with negative supercoiling. Thus, DNA secondary structure in the '-35' region can affect promoter-polymerase interaction. The tet promoter cruciform also influences expression of the pBR322 beta-lactamase gene (bla). This apparently results when extrusion of the cruciform reduces the superhelicity of the plasmid molecule to a level that is below the optimum for expression from the bla promoter, illustrating one mechanism for how DNA secondary structure may effect action-at-a-distance. Transcription from both promoters in vivo does not differ from controls, suggesting that this cruciform is not generated to a significant extent intracellularly, most probably as a result of the slow kinetics of extrusion.
...
PMID:Transcription regulation in vitro by an E. coli promoter containing a DNA cruciform in the '-35' region. 266 90

Citrobacter freundii encodes an inducible chromosomal beta-lactamase. Induction requires the product of the ampR gene, which is transcribed in the opposite orientation from the ampC beta-lactamase gene. We show here that the AmpR protein acts as a transcriptional activator by binding to a DNA region immediately upstream of the ampC promoter. The DNase I footprint pattern was not affected by growth in the presence of beta-lactam inducer or by the use of extracts prepared from cells carrying the ampD2 allele leading to semiconstitutive production of beta-lactamase. It is suggested that activation of AmpR facilitates binding or open complex formation for RNA polymerase at the ampC promoter. The AmpR-binding site overlaps the ampR promoter, and beta-galactosidase activity was decreased from an ampR-lacZ transcriptional fusion when AmpR was expressed from a coresident plasmid, suggesting that ampR is autogenously controlled. The AmpR protein belongs to a family of highly homologous transcriptional activators that includes LysR, which regulates the E. coli lysine synthetase gene, and the NodD protein, which regulates expression of a number of genes involved in nodulation in Rhizobium. The lack of sequence homology to any known beta-lactam-binding protein suggests that AmpR does not bind directly to the beta-lactam inducer but interacts with a second messenger of unknown nature.
...
PMID:Binding of the Citrobacter freundii AmpR regulator to a single DNA site provides both autoregulation and activation of the inducible ampC beta-lactamase gene. 278 68

The synthesis of the inducible enzyme penicillinase of Bacillus licheniformis is negatively controlled by a repressor (D.A. Dubnau and M.R. Pollock, J. Gen. Microbiol. 41:7-21, 1965; D. J. Sherratt and J. F. Collins, J. Gen. Microbiol. 76:217-230,1973). The molecular organization of the genes coding for penicillinase (penP) and its repressor (penI) has recently been determined (T. Himeno, T. Imanaka, and S. Aiba, J. Bacteriol. 168:1128-1132, 1986). These two genes are transcribed divergently from within a 364-nucleotide region separating the coding sequences. We cloned and sequenced the repressor gene (penIc) from strain 749/C that constitutively produces penicillinase. The penIc and penI+ (wild-type) genes were expressed in Escherichia coli. Complementation analysis indicated that the repressor is the only trans-acting protein required to regulate the expression of the penI and penP genes. We purified the wild-type repressor protein, used it in gel retardation and DNase I protection experiments, and identified three operators positioned in the region between the penP and penI coding sequences. The spatial arrangement of the operators and the hierarchy in repressor binding seen in the protection experiments indicate that (i) the penI gene product represses the expression of the penP gene by physically blocking the RNA polymerase-binding site and (ii) the penI gene is autoregulated.
...
PMID:Regulation of the penicillinase genes of Bacillus licheniformis: interaction of the pen repressor with its operators. 326 Feb 34

Concrete evidence is presented for conformational changes elicited in RNA polymerase upon binding ppGpp by circular dichroism measurements. In the presence of 100 microM ppGpp, the molar ellipticity of RNA polymerase at 220 nm is reduced by 14% from the initial value of - 11,100 deg X cm2 X dmol-1 at 25 degrees C. In vitro transcription on templates containing the beta-lactamase promoter and colicin E1 promoter on poly[d(A-T)] is inhibited by ppGpp. None of these templates had GC-rich nucleotide sequence near the transcription initiation site, and yet they were influenced by ppGpp. Comparison of the effect on the synthesis of mRNAs for beta-lactamase and colicin E1 and the synthesis of the proteins themselves indicates that the effect of ppGpp is at the level of transcription for the former case and involves coupled transcription-translation for the latter case. Difference absorption, polyacrylamide gel electrophoresis, and nitrocellulose filter-binding studies show that the binding of ppGpp to RNA polymerase does not impair the extent of the interaction between enzyme and DNA. Kinetic studies suggest that ppGpp affects transcription initiation on beta-lactamase promoter. On poly[d(A-T)], ppGpp affects the rate of open complex formation and is a mixed inhibitor with respect to the incorporation of nucleotides. Our results are consistent with the idea that ppGpp acts as a regulator by binding at a site different from the active site and changes the RNA polymerase conformation, causing altered transcriptional behavior on different DNA templates.
...
PMID:Effects of ppGpp on transcription by DNA-dependent RNA polymerase from Escherichia coli: circular dichroism, absorption and specific transcription studies. 329 57

A promoter-probe system, based on the ampC beta-lactamase gene of Escherichia coli, has been developed for the isolation and characterization of transcriptional signals in the gram-positive bacterium Streptomyces lividans. The promoter-probe vector, denoted pJAS14, has the SLP1.2 replicon with a copy number of four-five plasmids per cell. It contains a unique BamHI site just in front of the ampC ribosome-binding site, and upstream of this BamHI site a transcriptional terminator signal that prevents readthrough transcription from plasmid-borne promoters has been inserted. Using pJAS14, we have shot-gun cloned chromosomal DNA from S. lividans and S. lavendulae into the BamHI site, and isolated a number of promoter containing DNA fragments by the use of the chromogenic cephalosporin nitrocefin. On plates, we identified promoters of varying strengths and also with differences in nutritional and temporal expression. Using liquid cultures of S. lividans, it has been demonstrated that one promoter, denoted P1 (SEP8), as well as the ampC gene of E. coli, show activity corresponding to the vegetative growth of the cells. The P1 (SEP8) promoter was shown to be expressed also in E. coli, and it initiates RNA synthesis at exactly the same nucleotides in both S. lividans and E. coli. The promoter shows good homology to the E. coli promoter consensus sequence in both the -35 and -10 regions. Thus, this promoter is a representative of the SEP (Streptomyces E. coli-type promoter) class of promoters recently described (Jaurin and Cohen 1985). This indicates that an S. lividans RNA polymerase recognizes the same sequence determinants and chooses the point of initiation of RNA synthesis in the same way as the corresponding E. coli enzyme.
...
PMID:Chromogenic identification of promoters in Streptomyces lividans by using an ampC beta-lactamase promoter-probe vector. 332 38

The location of the repressor gene, blaI, for the beta-lactamase gene blaP of Bacillus licheniformis 749, on the 5' side of blaP, was confirmed by sequencing the bla region of the constitutive mutant 749/C. An amber stop codon, likely to result in a nonfunctional truncated repressor, was found at codon 32 of the 128 codon blaI open reading frame (ORF) located 5' to blaP. In order to study the DNA binding activity of the repressor, the structural gene for blaI, from strain 749, with its ribosome binding site was expressed using a two plasmid T7 RNA polymerase/promotor system (S. Tabor and C. C. Richardson. Proc. Natl. Acad. Sci. 82, 1074-1078 (1985). Heat induction of this system in Escherichia coli K38 resulted in the production of BlaI as 5-10% of the soluble cell protein. Repressor protein was then purified by ammonium sulfate fractionation and cation exchange chromatography. The sequence of the N-terminal 28 amino acid residues was determined and was as predicted from the DNA. Binding of BlaI to DNA was detected by the slower migration of protein DNA complexes during polyacrylamide gel electrophoresis. BlaI was shown to selectively bind DNA fragments carrying the promoter regions of blaI and blaP.
...
PMID:Purification and DNA binding properties of the blaI gene product, repressor for the beta-lactamase gene, blaP, of Bacillus licheniformis. 349 48


1 2 3 4 Next >>

---