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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)

An amber fragment of the beta subunit of Escherichia coli RNA polymerase has been recovered from strains carrying the rpoB12 amber mutation, indicating that the B12 mutation resides in the structural gene for the beta subunit. The fragment is readily assayed and can be used to determine the degree of expression of a single rpoB cistron in strains haploid or diploid for this region. These studies confirm that the bacterial mechanism, which can compensate for reduced translation of the beta message, operates by the co-ordinate induction of rpoB and rpoC. Furthermore, I show that rpo control depends upon cistron(s) located on the F' factor, KLF10, whose product(s) can act negatively in trans on rpoBC expression.
Mol Gen Genet 1977 Feb 28
PMID:Identification of an amber fragment of the beta subunit of Escherichia coli RNA polymerase: a yardstick for measuring controls on RNA polymerase subunit synthesis. 32 70

Bacterial ribosomal RNA synthesis was studied in an in vitro system in which the presence of heparin prevented reinitiation of transcription. The number of heparin-resistant binary complexes of RNA-polymerase and E. coli DNA depended strongly on the quality of the template. High-molecular weight DNA was a much superior template than DNA prepared by conventional techniques. Using this high-molecular weight DNA as template the amount of ribosomal RNA synthetized in one round of transcription was found to be 4-5 fold higher than the amount of rDNA present. Controls have shown that the transcription probably started at the proper initiation sites and no significant read-through form distant promoters contributed to this effect. If the binary polymerase-DNA complexes were dissociated in the presence of 0.5 M KC1 prior to transcription all RNA synthesis was strongly reduced but the proportion of rRNA increased in the transcript. However, in this case the amount of rRNA did not exceed the amount of rDNA. We propose that the promoters of the rRNA genes are complex structures, able to store 4-5 molecules of RNA polymerase and of these several polymerase only one is bound in an extremely salt-resistant form.
Mol Gen Genet 1977 Mar 16
PMID:In vitro transcription of the ribosomal RNA genes of E. coli DNA. 32 75

Ribosomal RNA synthesis from three different rRNA cistrons of E. coli, located on different phage DNAs was compared and found to have the same characteristics as regards chain length, salt and temperature dependence and the effect of ppGpp. However, some clear and reproducible quantitative differences between rRNA synthesis from the different templates both in presence and absence of ppGGpp were found. Rifampicin and heparin experiments showed that these differences were located at the initiation sites. We propose that heterogeneity exists in the RNA polymerase binding regions of the rRNA prmoters in E. coli.
Mol Gen Genet 1977 Mar 28
PMID:In vitro transcription of three different ribosomal RNA cistrons of E. coli; heterogeneity of control regions. 32 80

The product of phage P22 gene c1 has two functions: (1) it promotes synthesis of repressor and (2) during the first minutes of infection it retards expression of some lytic genes. We call the second, negative function "c1 retardation". We investigated c1 retardation in a mutant host of Salmonella typhimurium that is resistant to rifampicin and carries an altered RNA polymerase. No c1 retardation of DNA synthesis was detectable in this host after infection with wild-type phages. This elimination of the normally detectable c1 function leads to the conclusion that the mutant RNA polymerase interferes with the expression of c1 gene activity. Wild-type genes form clear plaques on the mutant host. Mutants of P22 called cly were isolated by others. These mutants form turbid plaques on the altered RNA polymerase host. Infections with P22 cly in the mutant host resulted in detectable c1 retardation. The cly mutation therefore restores c1 activity in a host which wild-type c1 is not expressed. Two spontaneous mutants were isolated from the mutant host. These two strains allowed partial expression of c1 retardation, although they remained rifampicin resistant. We interpret our data to indicate that expression of the normal functions of the gene c1 product requires an interaction of that product with the host RNA polymerase.
Mol Gen Genet 1977 Jun 08
PMID:Effect of mutant host RNA polymerase on the bifunctional activities of P22 gene c1. 32 18

The firA200 mutation of E. coli not only renders RNA synthesis thermosensitive but also eliminates the high-level resistance to rifampicin associated with certain mutations in the beta subunit of the RNA polymerase. A priori, the firA gene is likely to code for an essential component of the transcription apparatus. The isolation is reported of transducing phages for the firA gene, constructed in vitro by fusing fragments of the E. coli chromosomes into a lambdoid bacteriophage. Such phages carry at least two essential genes and are able to suppress both the thermosensitivity and abnormal rifampicin sensitivity associated with the firA200 allele. The finding that some, but not all, of the lambdafirA phages have a temperature dependent growth defect is discussed.
Mol Gen Genet 1977 Jul 07
PMID:The firA gene, a locus involved in the expression of rifampicin resistance in Escherichia coli. I. Characterisation of lambdafirA transducing phages constructed in vitro. 33 Oct 78

The cell-free transcription of the argF and argI genes of the arginine biosynthetic regions is described using an S-30 system capable of coupled in vitro transcription-translation. Template DNA isolated from two independently isolated arginine transducing phages was used in this work. Steady state mRNA synthesis was observed which was attributed to RNAase degradation. Regulation of argF mRNA synthesis, directed by the argF gene carried on the specialized transducing phage phi80dargF is effected to the extent of at least 95% by the arginine holorepressor at the transcriptional stage and at least 80% of the regulation of the expression of the argI gene is mediated at the transcriptional stage. Evidence is presented which indicates that the arginine holorepressor prevents RNA polymerase from binding to the arginine promoter and suggests that the operator and promoter sites may overlap.
Mol Gen Genet 1977 Sep 21
PMID:Transcription of the argF and argI genes of the arginine biosynthetic regulon of Escherichia coli K12, performed in vitro. 33 19

S. tyrphimurium strain BY324 is temperature sensitive due to a mutation (rpo C32) in the gene for the RNA polymerase beta' subunit. Transcription of T7 DNA by RNA polymerase purified from this strain is temperature sensitive in vitro. The enzyme is slightly defective in template binding and RNA chain initiation, but the major defect is in RNA chain elongation. The rate of RNA chain elongation is reduced 4-5 fold relative to wild-type. RNA chain termination does not appear to be affected by the beta' mutation. While the elongation defect is suppressed by glycerol or dimethylsulfoxide, the initiation defect is not. Possible roles for the beta' subunit in enzyme function are discussed in light of these results.
Mol Gen Genet 1977 Oct 20
PMID:Multiple effects of an RNA polymerase beta' mutation on in vitro transcription. 33 27

Specific transformation of a rifampicin sensitive strain of Escherichia coli to rifampicin resistance has been performed by a single, defined DNA restriction fragment carrying the genetic information for the beta subunit of E. coli RNA polymerase. In this transformation the transforming genetic character has been substituted for the corresponding recipient gene locus by recombination. The value of the described transformation system for locating genetic markers on DNA restriction fragments is discussed in comparison to previously reported in vitro systems.
Mol Gen Genet 1977 Oct 20
PMID:Transformation of Escherichia coli by a specific DNA restriction fragment. 33 30

The genome of virulent coliphage T5 contains about 30 sites which form stable complexes with E. coli RNA polymerase. Some of these sites bind RNA polymerase with high rates, others form extremely stable complexes as compared with promotors of other E. coli systems. The transcriptional activity of these promotors in vivo and in vitro reflects the rate of complex formation with RNA polymerase rather than the stability of the enzyme/promotor complex. The fastest, i.e. the most active promotors are found in the "early" region of gene expression followed by promotors of the "preearly" class. The few binding sites for the E. coli holoenzyme within the "late" region react more slowly with the enzyme.
Mol Gen Genet 1977 Dec 09
PMID:Interaction of E. coli RNA polymerase with promotors of coliphage T5: the rates of complex formation and decay and their correlation with in vitro and in vivo transcriptional activity. 34 Sep 27

RNA polymerase from T2 infected E. coli has greatly reduced activity as compared to the enzyme from uninfected bacteria. Nevertheless both RNA polymerases synthesize heterogenous RNA species with the same maximum corresponding to chain length of 5600 nucleotides on T2 DNA. Rifampicin-challenge experiments suggest that these enzymes have identical kinetics of RNA chain initiation and elongation but their ability to form rapidly starting (RS) and delay starting (I) binary complexes with phage DNA are different. The temperature of I leads to RS transition on T2 DNA is 15 degrees for E. coli holoenzyme, but is 35 degrees for the RNA polymerase from infected cells. The transition temperature depends both on the core and on sigma fraction. Shift temperature technique was developed to investigate the kinetics of I in equilibrium RS complexes rearrangements and their temperature dependence. The rate of these rearrangements is strongly temperature dependent for E. coli holoenzyme, while for RNA polymerase from infected cells it is much lower and is practically temperature independent. From the kinetic data and from the temperature dependence of equilibrium RS-complexes concentration, the rate constants of RS-complexes formation and decay are calculated. The kinetic data obtained in rifampicin challenge experiments are in agreement with the data on the dissociation of DNA-enzyme complexes performed by the filter assay.
Mol Biol (Mosk)
PMID:[Interaction of DNA with RNA-polymerase from Escherichia coli cells infected and uninfected with T2 phage]. 34 5


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