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)

Upon release of rifampicin inhibition of Escherichia coli cells, the initiation of transcription will resume. The sequential resumption of the synthesis of proteins after release of rifampicin inhibition reflects the genetic order and size of the corresponding transcriptional units. We have used this approach to analyze whether the genes for alpha and sigma are on the same transcriptional unit as the genes for beta and beta', employing a method, which allowed us to measure the amounts of RNA polymerase subunits, alpha, beta, beta' and sigma in crude extracts. We have found that the alpha and sigma subunits are synthesized concurrently with the beta subunit in the rifampicin restart experiment, which suggests that the genes for alpha and sigma belongs to different transcriptional units.
Mol Gen Genet 1976 Feb 02
PMID:Biosynthesis of Escherichia coli RNA polymerase subunits upon release of rifampicin inhibition. 76 61

The paper deals with the comparative investigation of initiation and in vitro RNA synthesis on DNA template by E. coli RNA polymerase and B-form of calf thymus RNA polymerase. It was shown in hybridization experiments that in the range of Cot values between 10(2) and 10(4) RNA synthesized by calf thymus RNA polymerase was hybridized with homologous DNA more effectively than RNA synthesized by E. coli RNA polymerase. No differences were observed in the case of low Cot values. RNA chains synthesized by calf thymus RNA polymerase contained in average about 300-600 nucleotides per chain as determined in the kinetic experiments with ATP-gamma-32P and GTP-gamma-32P. These values are in average 5-10 times lower than in the case of bacterial enzyme. The data presented show that calf thymus and E. coli RNA polymerases initiate the RNA synthesis at apparently different sites of calf thymus DNA. The results obtained make the possibility of specific transcription of eucaryotic DNA by bacterial RNA polymerase to be doubtful.
Mol Biol (Mosk)
PMID:[Transcription of DNA by RNA polymerases of E. coli and calf thymus]. 76 44

An E. coli mutant rpoA109 unable to support the growth of phage P2 produces DNA-dependent RNA polymerase with an altered alpha subunit. Histidine is substituted for leucine in one tryptic peptide from the mutant alpha subunit. The existence of only one rpoA gene within the E. coli chromosome is indicated.
Mol Gen Genet 1976 Apr 23
PMID:Identification of a mutation within the structural gene for the a subunit of DNA-dependent RNA polymerase of E. coli. 77 6

We describe a bacterial RNA polymerase mutation, rif 501, which confers rifampicin resistance and thermosensitivity to E. coli K 12. The purified RNA polymerase enzyme from rif 501 bacteria shows increased heatsensitivity in vitro at 51 degrees C. However, in vivo, at 42 degrees C the non-permissive temperature, mutant bacteria continue to grow and to synthesize RNA for 90 min. On a lawn of the mutant bacteria, at 40-41 degrees C, phage lambda forms clear plaques (LycA phenotype); this is probably due to an enhancement of cro function; we surmise that at 42 degrees C the transcription originating from the pR (but not from the pL) promoter on the lamdba genome becomes N-independent and less sensitive to the absence of the cro product. We discuss the possibility that both the N and cro proteins of phage lambda interact directly with the bacterial RNA polymerase. These observations indicate that the loss of viability of the rif 501 mutant at the restrictive temperature is not a consequence of an immediate inactivation of RNA polymerase; rather we feel it is due to a modification of the activity of RNA polymerase, leading to a disruption of the cellular regulation.
Mol Gen Genet 1976 Apr 23
PMID:A bacterial RNA polymerase mutant that renders lambda growth independent of the N and cro functions at 42 degrees C. 77 9

Four mutants of Escherichia coli KL16 resistant to the antibiotic Thiolutin have been isolated. This drug was earlier reported to be an inhibitor of RNA chain elongation. The first mutant, TLrI, is resistant only in rich or partially rich media: it can, however, grow in minimal medium containing the drug with a very long doubling time. The other mutants TLrII, TLrIIIa and TLrIIIb are resistant in rich as well as minimal media. beta-galactosidase could not be induced in TLrI and TLrII in the presence of thiolutin whereas the enzyme is constitutively synthesised in TLrIIIa and TLrIIIb irrespective of the drug. The mutants do not support the development of phage T4 in presence of the drug, if the drug is added along with the phage, but "escape" the inhibition if phage development is allowed to proceed for some time before the addition of the drug. The time of this escape is characteristic of the mutant. Even in a sensitive strain, T7 growth escapes inhibition very soon after infection, around the time the phage-specific RNA polymerase is synthesized. In the parent strain the kinetics of inhibition of beta-galactosidase induction resembles more the inhibition caused by rifampicin than by streptolydigin. It is proposed that thiolutin could be an inhibitor of RNA chain initiation and resistance might be due to mutation in the subunit(s)/factor(s) involved in initiation.
Mol Gen Genet 1976 Apr 23
PMID:Thiolutin resistant mutants of Escherichia coli are they RNA chain initiation mutants? 77 14

By using rifampicin to increase the rate of beta and beta' synthesis in a heterodiploid strain of E. coli carrying the mutation rifpr (Km7), which codes for a rifampicin sensitive RNA polymerase to which the drug binds weakly, and the dominant mutation rifRD, which codes for a rifampicin resistant RNA polymerase, the concentration of these subunits in the cell was increased 1.6 fold. Measurements made after removal of rifampicin from the cells showed that the excess beta and beta' subunits did not reduce the rate of their own synthesis below normal.
Mol Gen Genet 1976 May 07
PMID:Evidence against autorepression of the betabeta' operon in Escherichia coli. 77 88

During the course of kinetic studies on the synthesis of RNA polymerase subunits in Escherichia coli K12, strain Km7 (CP372), certain anomalies were found that seemed to be associated with the system of reversible inhibition of RNA and protein synthesis by rifampicin. To find a possible explanation for these anomalies, effects of rifampicin on RNA chain elongation and on residual synthesis of polymerase subunits were investigated with several strains including Km7. Examination of mRNA synthesis for the tryptophan operon suggested that RNA chain growth as well as RNA chain initiation is inhibited at high drug concentration (500 mug/ml), wheras RNA chain initiation is inhibited specifically at low concentration (20 mug/ml). Analysis of effect of rifampicin concentration on total RNA synthesis gave results that are also consistent with this conclusion. These results emphasize the need for selecting a proper drug concentration whenever rifampicin or other related antibiotic is used as a specific inhibitor of transcription initiation. When rifampicin was added to a culture of these strains absolute rates of synthesis of all subunits of RNA polymerase increased for several minutes and then decreased. The extent of this transient stimulation varied depending on the strain, drug concentration and other conditions, but was most striking for the beta and sigma subunits with strain Km7 at high drug concentration (500 mug/ml). With a rifampicin-sensitive wild-type strain tested, the maximum stimulation was found at about 50 mug/ml of the drug, with a particularly marked effect for sigma subunit. Streptolydigin, on the other hand, inhibited the synthesis of core subunits much faster than the bulk of protein, but inhibited synthesis of sigma subunit only after a lag. Hence a specific effect of rifampicin but not the inactivation of beta subunit per se appears to be involved in transient stimulation of polymerase synthesis observed. Implications of these findings on the control of RNA polymerase synthesis are discussed.
Mol Gen Genet 1976 Jun 15
PMID:Effects of rifampicin on synthesis and functional activity of DNA-dependent RNA polymerase in Escherichia coli. 78 14

The analysis of tryptic peptides was performed on the unassembled as well as assembled form f alpha subunit of the DNA-dependent RNA polymerase from Escherichia coli. The peptide profiles obtained by Dowex 50 column chromatography of the unassembled alpha subunit prepared from cells, either pulse-labeled or continuously labeled with radioactive lysine or arginine, were essentially identical with those of the alpha subunit from intact RNA polymerase. The results suggest that newly synthesized free alpha subunit is assembled into the polymerase structure without any remarkable modifications. The number of lysine- and arginine-containing peaks were close to the values expected from the amino acid composition of alpha subunit assuming that the two alpha subunits in RNA polymerase core enzyme have identical primary structure.
Mol Gen Genet 1976 Jun 15
PMID:Peptide analysis of RNA polymerase alpha subunit from Escherichia coli: comparison of free with assembled form. 78 18

The influence of mutations in structural genes of beta and beta subunits of RNA polymerase upon the synthesis of these subunits in E. coli cells have been investigated. An amber-mutation ts22 in the beta subunit gene decreases the intracellular concentration of this subunit and the rate of its synthesis. At the same time the concentration and the rate of beta subunit synthesis is increased. These suggest the compensatory activation of the RNA polymerase operon that takes place under the conditions of shortage of one of the subunits. Reversions as well as more effective suppression of ts22 amber mutation, achieved by streptomycin addition, substitution of su2 by sul, or by specific mutations, result in a rise of beta and drop of beta subunit concentration and synthesis in ts22 mutant. TsX missense-mutation in the beta subunit gene alters the properties of the enzyme increasing, at the same time, the concentration and the rate of synthesis of both beta and beta subunits, particularly at a nonpermissive temperature. This points to an inversely proportional relationship between the rate of synthesis of RNA polymerase subunits and the total intracellular activity of the enzyme. Extra subunits are rapidly degraded in ts22 and tsX mutants. The whole complex of our data and those of others suggest that the regulation of the synthesis of RNA polymerase subunits is accomplished by interaction of a negative and a positive mechanisms of regulation which include not only activators and repressors but the enzyme itself as well.
Mol Gen Genet 1976 Jun 15
PMID:The influence of mutations upon the synthesis of RNA polymerase subunits in Escherichia coli cells. 78 19

RNA polymerase of E. coli (EC 2.7.7.6) is able to bind certain oligoribonucleotides with the length greater than or equal to 5 from the corresponding isoplith mixtures (Knorre V.L., Vasilenko S.V., Salganik R.I., FEBS Letters 30, 229, 1973). It has been shown in this study that all pentaribonucleotides able to be bound by RNA polymerase can be extracted from the random mixture by the enzyme saturation procedure. Loosely and tightly bound pentaribonucleotides subfractions were isolated and each was separated by chromatography into 3-4 isopliths. Blocking of the enzyme SH groups by p-chloromercurium benzoate (10(-3) M) and denaturation by urea (6.3 M) prevent formation of the enzyme-pentaribonucleotides complexes. Complexes are destroyed by heat denaturation. Removal of sigma-subunit does not influence the enzyme capacity for pentaribonucleotides binding.
Mol Biol (Mosk)
PMID:[Conditions for specific oligoribonucleotide binding with E. coli RNA-polymerase]. 78 22


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