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 multicopy plasmid pLMN1 expressing a wild type rpoB gene encoding Escherichia coli RNA polymerase beta subunit gene was constructed. Introduction of this plasmid into rifampicin-resistant RpoB mutants makes them rifampicin-sensitive. Rifampicin-resistant clones appear in such strains with frequencies up to 10(-3), due to recombinational (recA-dependent) transfer of rif-r mutations from chromosome to pLMN1. This provides a simple selection procedure for transfer of any rpoB mutation, together with a rif-r mutation from a chromosome to pLMN1. In this way, we transferred rpoB22 amber mutation to pLMN1 for localization of the mutant codon by DNA sequencing.
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PMID:[Mutations in the Escherichia coli RNA-polymerase beta-subunit gene cloned in a multicopy plasmid]. 306 79

The interaction of bovine seminalplasmin and rifampicin with E. coli RNA polymerase was studied using fluorescence spectroscopy. Both seminalplasmin and rifampicin are known to be the inhibitors for the initiation of RNA synthesis in E. coli. Rifampicin quenced the intrinsic fluorescence of RNA polymerase and seminalplasmin when excited at 280 nm. However, excess of seminalplasmin reversed the quenching of RNA polymerase fluorescence by rifampicin. Upon addition of rifampicin to the seminalplasmin-RNA polymerase complex, no change in fluorescence spectrum was observed. It appeared that although rifampicin could form complexes with RNA polymerase and seminalplasmin alone, no binding domain was available for rifampicin in the RNA polymerase-seminalplasmin complex. These observations are discussed in the light of the 'initiation site' of E. coli RNA polymerase.
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PMID:Interaction of bovine seminalplasmin with Escherichia coli RNA polymerase in the presence of rifampicin. 388 59

The shoulder of the UV fluence-survival curve of exponentially growing Escherichia coli B/r WP2 trpE65 was expanded by chloramphenicol pretreatment and an exponential segment with intermediate slope appeared between the shoulder and the final exponential segment. These changes were dependent on DNA replication. The transitions with UV exposure to increased slopes were ascribed to UV inactivation of qualitatively different repair systems, each dependent upon the accumulation in each bacterium of multiple DNA-containing redundant repair components, which must be inactivated before the respective transitions to decreased resistance occur. Rifampin, which blocks DNA-dependent RNA polymerase function, limited drastically expansion of the shoulder and development of the intermediate exponential slope. Bacteria defective in DNA polymerase I (polA) showed only a slight expansion of the shoulder with pretreatment with chloramphenicol. Since certain bacterial plasmids require RNA primer formation for initiation of replication and are not maintained in a polA strain, it is proposed that the chloramphenicol-promoted increase in resistance depends on the formation of multiple numbers of specific resistance episomes (called repairons in view of their role in DNA repair).
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PMID:Modification of survival after ultraviolet light exposure in a wild-type and a polA strain of Escherichia coli B/r by preirradiation treatment with chloramphenicol or rifampin. 390 85

Transcription of the ribosomal protein genes rplKAJL and of the RNA polymerase genes proBC in the E. coli cells depends on the level of regulatory nucleotide ppGpp. The ppGpp acts as a negative regulator of transcription of the rpoBC genes in conditions of moderate deficiency of amino acids (after the cells were shifted down from amino acid rich to minimal media) or after incomplete deacylation of tRNA exerted by addition of serine-hydroxamate, or by partial inactivation of valyl-tRNA synthetase. Rifampicin of low concentrations, which inhibit total transcription not more than to 50%, stimulates transcription of the genes rpoBC and rplKAJL. It was estimated that stimulatory effect of rifampicin results from the ability of this antibiotic to decrease synthesis of ppGpp--the negative regulator of transcription of genes rplKAJL and rpoBC.
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PMID:[The role of ppGpp in the coordination of transcription of the ribosomal protein genes rplKAJL and RNA-polymerase rpoBC genes in Escherichia coli cells]. 390 13

The release of the ribonucleic acid (RNA)-containing phage MS2 from Escherichia coli is accompanied by cellular lysis at 37 C, whereas at 30 C phage are released from intact cells. Chloramphenicol or rifampin prevents the release of progeny phage particles at both temperatures. Neither drug causes an immediate cessation of phage release and after inhibition of protein synthesis by chloramphenicol phage release proceeds for about 17 min at 37 C and about 35 min at 30 C. Rifampin does not inhibit phage release from mutant cells possessing a rifampin-resistant deoxyribonucleic acid-dependent RNA polymerase. The results indicate that a short-lived host-controlled protein(s) is essential for the release of RNA phage particles at both temperatures.
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PMID:Ribonucleic acid bacteriophage release: requirement for host-controlled protein synthesis. 410 40

Rifampin reversibly inhibits the intracellular replication of a VSV mutant, whereas a revertant variant selected from this viral population, as well as the wild strain, are not affected by this drug. Rifampin inhibits transcriptase activity of the sensitive mutant only and, consequently, total viral RNA synthesis decreases significantly in the cells.
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PMID:Inhibition of a vesicular stomatitis virus mutant by rifampin. 436 21

Soluble enzyme fractions from uninfected Escherichia coli convert M13 and varphiX174 viral single strands to their double-stranded replicative forms. Rifampicin, an inhibitor of RNA polymerase, blocks conversion of M13 single strands to the replicative forms in vivo and in vitro. However, rifampicin does not block synthesis of the replicative forms of varphiX174 either in vivo or in soluble extracts. The replicative form of M13 synthesized in vitro consists of a full-length, linear, complementary strand annealed to a viral strand. The conversion of single strands of M13 to the replicative form proceeds in two separate stages. The first stage requires enzymes, ribonucleoside triphosphates, and single-stranded DNA; the reaction is inhibited by rifampicin. The macromolecular product separated at this stage supports DNA synthesis with deoxyribonucleoside triphosphates and a fresh addition of enzymes; ribonucleoside triphosphates are not required in this second stage nor does rifampicin inhibit the reaction. We presume that in the first stage there is synthesis of a short RNA chain, which then primes the synthesis of a replicative form by a DNA polymerase.
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PMID:RNA synthesis initiates in vitro conversion of M13 DNA to its replicative form. 455 37

Deoxyribonucleic acid (DNA) of Escherichia coli was found to be attached to the cell membrane at about 20 points. This was determined by fractionation of X-irradiated cells with the M band (magnesium-Sarkosyl crystals) technique. The number of attachment points was computed from the relationship between the amount of DNA in M bands and the number of double-strand breaks introduced by the X-ray treatment. The number of attachment points was decreased fourfold by treatment of cells with rifampin. This effect was apparently due to the action of the drug on ribonucleic acid (RNA) polymerase since the drug did not affect a mutant whose RNA polymerase is resistant to rifampin. This suggests that there may be two classes of attachment points of DNA on the membrane, some of which are removed by rifampin treatment and some which are not. Rifampin treatment also resulted in the uncondensing of isolated nucleoids and in an axial appearance of the nucleoids in ultrathin sections. The results suggest that RNA polymerase plays a role, direct or indirect, in maintaining the structure of the bacterial nucleoid and in some of its attachment to the membrane.
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PMID:Effect of rifampin on the structure and membrane attachment of the nucleoid of Escherichia coli. 458 13

A new form of RNA polymerase, termed RNA polymerase III, has been recognized as a large fraction of the rifampicin-sensitive enzyme in E. coli. It is physically separable from RNA polymerase (holoenzyme, RNA polymerase I) by gel filtration and is distinguished by its capacity to discriminate between M13 and varphiX174 viral DNA templates in priming DNA synthesis. This template specificity is manifested only with saturating levels of DNA unwinding protein and characterizes the priming of DNA synthesis on viral single strands in cell-free extracts and in vivo. RNA polymerase III has less than 5% of the specific activity of RNA polymerase I in transcribing duplex DNA of phages lambda and T4, salmon sperm DNA, and the copolymer poly[d(A-T)]. Rifampicin inactivation of RNA polymerase III releases a factor, presumably a small subunit, which can be isolated and used to confer on RNA polymerase I the properties of III, namely, discrimination between M13 and varphiX174 templates in priming DNA synthesis, and a relative inability to transcribe duplex DNA.
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PMID:A novel form of RNA polymerase from Escherichia coli. 461 17

RNA synthesis in an in vitro RNA polymerase system at low ionic strength soon ceases, due to inhibition by accumulated RNA. Measurement of RNA chain initiation by the incorporation of gamma-(32)P-ATP and GTP with native T2 or T4 DNA as template shows that only one RNA chain is formed per molecule of enzyme added. In contrast, when the polymerase reaction is carried out in 10 mM Mg(++) and 0.2 M KCl, RNA synthesis proceeds nearly linearly for hours, resulting in a marked increase in accumulated RNA. Incorporation of gamma-(32)P-ATP also proceeds throughout the course of the reaction and the number of chains initiated per molecule of enzyme is increased severalfold. Most RNA chains formed are released from the DNA template as free RNA. Polymerase is released also in this process and acting catalytically reinitiates new chains. Rifampicin inhibits initiation of RNA synthesis and also blocks reinitiation of RNA chains without affecting growth of RNA chains already initiated.
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PMID:DNA-dependent synthesis of RNA by Escherichia coli RNA polymerase: release and reinitiation of RNA chains from DNA templates. 490 8


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