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)

In the presence of RNA polymerase, RNase H, discriminatory factors alpha and beta, Escherichia coli binding protein, DNA elongation factor I, DNA elongation factor II preparation, DNA polymerase III, and ATP, UTP, GTP, CTP, dATP, dTTP, dGTP, and dCTP, fd viral DNA can be quantitatively converted to RFII containing a unique gap in the linear minus strand. This gap, mapped with the aid of restriction endonucleases HinII and HpaII, is located within Fragment Hpa-H of the fd genome. The discrimination reaction has been resolved into two steps: Step A, fd viral DNA, E. coli binding protein, and discriminatory factors alpha and beta form a protein DNA complex; Step B, the complex isolated by agarose gel filtration selectively forms fd RFII when supplemented with RNase H, RNA polymerase, and the DNA elongation proteins. The omission of any of the proteins described above during the first reaction resulted in either no discrimination or a decrease in discrimination when the missing protein was added during the second step. Results are presented which indicate that E. coli binding protein, discriminatory factors alpha and beta, and RNase H must be present during the time RNA synthesis occurs in order to selectively form RFII from fd DNA and not phiX RFII. The amount of fd and phiX174 RNA-DNA hybrid formed in vitro is directly related to the DNA synthesis observed. Thus, under discriminatory conditions, only fd viral DNA leads to fd RNA-DNA complexes and no phiX RNA-DNA hybrid is formed. Under nondiscriminatory conditions, both DNAs yield RNA-DNA hybrids and DNA synthesis. In the absence of discriminatory factor alpha, no RNA-DNA hybrid is formed with either DNA, and in turn, no DNA synthesis is detected with either DNA template.
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PMID:Selective inhibition of phiX RFII compared with fd RFII DNA synthesis in vitro. II. Resolution of discrimination reaction into multiple steps. 32 48

Restriction endonuclease Bgl II cleaves T7 DNA at a unique site (28.76% on the standard T7 map), yielding two fragments of molecular weights 18.9 x 10(6) (A) and 7.6 x 10(6) (B). Fragment B, representing the leftmost portion of the genome, has been purified by zone sedimentation. Transcription of fragment B by T7-specific RNA polymerase gives only r-strand-specific RNA. Analysis of the products by polyacrylamide gel electrophoresis reveals four major RNA species which have apparent molecular weights of 2.1 x 10(6), 1.36 x 10(6), 0.85 x 10(6) and 0.125 x 10(6), respectively. Each of these RNAs is reduced in size when transcription is carried out with fragment B, which has been shortened by treatment with Escherichia coli exonuclease III. Therefore, each of the transcripts must be terminated at the right end of fragment B. Analysis of the molecular weights of the four transcripts produced from whole and from exonucleolytically shortened fragment B suggests that these transcripts are read from promoters located at 13.5, 18.9, 22.6, and 27.9%, respectively, on the standard T7 map. Hence, there are at least four promoters governing the transcription of the class II region. Transcripts initiated at these promoters on intact T7 DNA appear to read through the class II and part of the class III genetic region and terminate at the strong terminator for T7-specific RNA polymerase near 61%. Transcription of fragment B which has been cleaved with the restriction endonuclease Hpa I seems to activate a fifth promoter for T7-specific RNA polymerase. This promoter appears to be identical to the promoter previously described by Oakley and Coleman (Proc. Natl. Acad. Sci. U.S.A. 74:4266-4270, 1977) that maps near 15% on the standard T7 map. Little or no RNA is read from T7 Bgl II fragment B, which has a mobility expected for a transcript read from this promoter. However, upon cleavage with Hpa I, this promoter is utilized approximately 10-fold more efficiently than the other class II promoters. The mechanism of this activation is not yet known.
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PMID:Mapping of class II promoter sites utilized in vitro by T7-specific RNA polymerase on bacteriophage T7 DNA. 43 May 92

The differentiation of the vaccine or wild origin of Poliovirus at the laboratory is an important step towards the process of the poliomyelitis eradication. We report herein the results obtained from Poliovirus types 3 and 2, isolated in Madagascar in 1997 and 2002 from healthy children and cases of acute flaccid paralysis, respectively. The technique used is based on the amplification of genome (RT-PCR), followed by Restriction Fragment Length Polymorphism assay (RFLP), performed in 3 different regions of the genome. In the capsid region (VP3-VP1 and VP1-2A), RFLP analysis allowed us to differentiate without ambiguity the wild or vaccine origin of the Poliovirus type 3, and to identify Vaccine-Derived Poliovirus (VDPV) type 2. In the noncapsid region, including the RNA polymerase and 3' non coding region (3Dpol-3' NTR), the VDPV were found to be recombinant with other Enteroviruses. These results confirm that RFLP assay is a reliable tool for intratypic differentiation and to study the genetic drift and recombination of Poliovirus.
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PMID:[Genetic variability of Poliovirus: typing of strains isolated in Madagascar by restriction fragment length polymorphism (RFLP) assay]. 1567 12

RNA transcripts after transcription elongation with T7 RNA polymerase in vitro were visualized by using atomic force microscopy (AFM). Fragment of pGEMEX linear DNA with the length of 1414 nucleotide pairs carrying promoter and terminator of bacteriophage T7 was used as DNA template for transcription. Immobilized on the mica (AFM substrate) RNA transcripts formed rod-like condensed structures with the length of 122 +/- 10 nm and characteristic aspect ratio ca. 4.5-5. Problems of RNA immobilization onto mica for subsequent visualization by AFM are discussed.
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PMID:[Visualization of RNA transcripts with atomic force microscopy]. 1749 38

Complexes of bacteriophage T7 RNA polymerase (RNAP) with a DNA template for transcription elongation were visualized by atomic force microscopy (AFM). Fragment of pGEMEX linear DNA with length of 1414 bp carrying promot- er and terminator of bacteriophage T7 was DNA template for transcription. Promoter and terminator are located unsymmetrically on the ends of DNA template. Images of stable complexes of T7 RNAP with terminal fragments of DNA template were obtained for single molecules. Complexes of a single DNA template molecule with 2-3 T7 RNAP molecules corresponding to stages of initiation, elongation and termination of transcription were visualized under the elimination of non-specific DNA-protein binding. Also complexes of DNA, RNAP and RNA transcripts were imaged. Our results suggest that the initial stage is the formation of complex between T7 RNAP and terminal fragment of DNA template. Because promoter is localized near DNA terminus, it makes impossible an ommision of the promoter site.
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PMID:[Visualization of elongation complexes for t7 Rna polymerase by atomic force microscopy]. 1870 13

Fragment-based approaches have now become firmly established in the drug discovery armoury. After notable early successes against protein kinases, the versatility and power of fragment-based approaches are increasingly being demonstrated on more diverse and difficult protein targets. This review highlights seven examples including targeting protein-protein interactions, a RNA polymerase and a DNA-binding protein. It shows how fragment-based approaches using small libraries have been successful when large HTS screens have failed. It also highlights the range of biophysical approaches being used and the interplay between experimental and in silico screens. The examples all show the iterative way in which potency is built up by synthetic elaboration of the initial fragment hits.
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PMID:Drugging challenging targets using fragment-based approaches. 2022 99

During persistent infection, optimal expression of bacterial factors is required to match the ever-changing host environment. The gastric pathogen Helicobacter pylori has a large set of simple sequence repeats (SSR), which constitute contingency loci. Through a slipped strand mispairing mechanism, the SSRs generate heterogeneous populations that facilitate adaptation. Here, we present a model that explains, in molecular terms, how an intergenically located T-tract, via slipped strand mispairing, operates with a rheostat-like function, to fine-tune activity of the promoter that drives expression of the sialic acid binding adhesin, SabA. Using T-tract variants, in an isogenic strain background, we show that the length of the T-tract generates multiphasic output from the sabA promoter. Consequently, this alters the H. pylori binding to sialyl-Lewis x receptors on gastric mucosa. Fragment length analysis of post-infection isolated clones shows that the T-tract length is a highly variable feature in H. pylori. This mirrors the host-pathogen interplay, where the bacterium generates a set of clones from which the best-fit phenotypes are selected in the host. In silico and functional in vitro analyzes revealed that the length of the T-tract affects the local DNA structure and thereby binding of the RNA polymerase, through shifting of the axial alignment between the core promoter and UP-like elements. We identified additional genes in H. pylori, with T- or A-tracts positioned similar to that of sabA, and show that variations in the tract length likewise acted as rheostats to modulate cognate promoter output. Thus, we propose that this generally applicable mechanism, mediated by promoter-proximal SSRs, provides an alternative mechanism for transcriptional regulation in bacteria, such as H. pylori, which possesses a limited repertoire of classical trans-acting regulatory factors.
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PMID:A repetitive DNA element regulates expression of the Helicobacter pylori sialic acid binding adhesin by a rheostat-like mechanism. 2499 12

Marine Bacteroidetes constitute a very abundant bacterioplankton group in the oceans that plays a key role in recycling particulate organic matter and includes several photoheterotrophic members containing proteorhodopsin. Relatively few marine Bacteroidetes species have been described and, moreover, they correspond to cultured isolates, which in most cases do not represent the actual abundant or ecologically relevant microorganisms in the natural environment. In this study, we explored the microdiversity of 98 Single Amplified Genomes (SAGs) retrieved from the surface waters of the underexplored North Indian Ocean, whose most closely related isolate is Kordia algicida OT-1. Using Multi Locus Sequencing Analysis (MLSA) we found no microdiversity in the tested conserved phylogenetic markers (16S rRNA and 23S rRNA genes), the fast-evolving Internal Transcribed Spacer and the functional markers proteorhodopsin and the beta-subunit of RNA polymerase. Furthermore, we carried out a Fragment Recruitment Analysis (FRA) with marine metagenomes to learn about the distribution and dynamics of this microorganism in different locations, depths and size fractions. This analysis indicated that this taxon belongs to the rare biosphere, showing its highest abundance after upwelling-induced phytoplankton blooms and sinking to the deep ocean with large organic matter particles. This uncultured Kordia lineage likely represents a novel Kordia species (Kordia sp. CFSAG39SUR) that contains the proteorhodopsin gene and has a widespread spatial and vertical distribution. The combination of SAGs and MLSA makes a valuable approach to infer putative ecological roles of uncultured abundant microorganisms.
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PMID:Exploring Microdiversity in Novel Kordia sp. (Bacteroidetes) with Proteorhodopsin from the Tropical Indian Ocean via Single Amplified Genomes. 2879 Sep 80

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