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)

The expression of the genes specifying the beta and beta' subunits of RNA polymerase (nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) was examined in an Escherichia coli strain bearing a temperature-sensitive mutation in the beta' subunit gene. A shift to 42 degrees results in a restriction of RNA chain initiation and a cessation of RNA synthesis. A shift to 39 degrees results in only partial restriction, allowing RNA and protein synthesis to continue. The partial restriction produces a 5- to 6-fold increase in the relative transcription rate of the beta and beta' genes and a concomitant increase in the relative synthesis rate of the beta and beta' proteins. The transcription rate of ribosomal protein genes was also increased somewhat. These results indicate that the genes specifying the beta and beta' subunits of RNA polymerase are regulated at the level of transcription and that this regulation is related to the transcription of ribosomal protein genes. Furthermore, the results indicate that this regulation of the beta and beta' RNA polymerase subunit genes is somehow triggered by a reduction in the ability of RNA polymerase to initiate transcription on the bacterial chromosome.
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PMID:Regulation of synthesis and activity of a mutant RNA polymerase in Escherichia coli. 34 Nov 56

Analysis of the synthetic rate of individual protein species at various times after complete inhibition of transcription with either streptolygidin or rifampicin was carried out by two-dimensional polyacrylamide electrophoresis of total Escherichia coli cell extracts. The decay rate of the potential to synthesize different proteins was assumed to be equal to the functional decay rate of the corresponding mRNA. We conclude the following: (a) The tufA and tufB messengers have different half lives (3.0 and 2.4 min, respectively). (b) Different genes within the same transcriptional unit can have different half lies (S7, EGF and EFTuA--2.5, 3.8 and 3.0 min, respectively). (c) There is at least a twenty-fold variation in individual mRNA half lives in E. coli; ribosomal protein S1 mRNA was observed to have the shortest half life in the cell (40 sec), while the longest observed half life was approximately 20 min (all values at 30 degrees C). (d) Addition of rifampicin increases the absolute rate of RNA polymerase subunit alpha and beta synthesis two-fold. (e) The induction of the synthesis of alpha subunit of RNA polymerase takes place without a concomitant induction of ribosomal protein S4 and L17, which are reported to be on either side of alpha in the same transcriptional unit.
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PMID:Functional mRNA half lives in E. coli. 36 81

The 3072-nucleotide-long sequence of a segment from the 88-min region of the Escherichia coli chromosome has been determined. The sequence covers the genes for ribosomal proteins L11 (rplK), LI (rplA), L10 (rplJ), and L7/L12 ((rplL), and the 5' end of the gene for the beta subunit of RNA polymerase (rpoB), along with the presumed regulatory regions for these genes. The probable locations of the promoter for the first two genes (the L11 operon) and the promoter for the latter three genes (the proximal part of the beta operon) have been identified. We have also found that the four ribosomal protein genes preferentially use codons that are recognized efficiently by the most abundant tRNA species. These and other features of the sequence results are discussed in relation to available information obtained from both in vitro and in vivo experiments on the expression of these ribosomal and RNA polymerase subunit genes.
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PMID:Nucleotide sequence of the ribosomal protein gene cluster adjacent to the gene for RNA polymerase subunit beta in Escherichia coli. 37 81

We have previously shown that the synthesis of ribosomal proteins (r proteins) in E. coli cells is under stringent control (Dennis and Nomura, 1974). Since guanosine tetraphosphate (ppGpp) has been implicated in stringent control, we examined the effects of ppGpp on the in vitro synthesis of r proteins directed by DNA from transducing phage lambdafus3 and lambdarifd18. lambdafus3 carries genes for protein elongation factors EF-Tu and EF-G, and RNA polymerase subunit alpha, in addition to genes for approximately 27 r proteins. lambdarifd18 carries genes for EF-Tu, RNA polymerase subunits beta and beta1, and a set of rRNAs, in addition to genes for approximately five r proteins. We have shown that low concentrations of ppGpp (0.2-0.3 mM) specifically inhibit DNA-dependent r protein synthesis in this system, and that this inhibition takes place directly, rather than as a consequence of the inhibition of rRNA synthesis by ppGpp. In addition, we have also shown that ppGpp inhibits the synthesis of EF-G, EF-Tu, and RNA polymerase subunit alpha, as well as rRNAs.
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PMID:DNA-dependent in vitro synthesis of fibosomal proteins, protein elongation factors, and RNA polymerase subunit alpha: inhibition by ppGpp. 99 Dec 74

The genes for the beta (rpoB) and beta' (rpoC) subunits of Escherichia coli RNA polymerase are the distal members of a complex transcriptional unit that contains four upstream ribosomal protein genes. The RNA polymerase subunit genes are transcribed at a lower frequency than the ribosomal protein genes as a result of termination at an attenuator preceding rpoB. A purified in vitro transcription system was developed using linear DNA templates that carry the attenuator. The ability of known termination and antitermination proteins to modulate termination at the attenuator was tested. Both NusA and NusG increase the frequency of transcriptional readthrough at the attenuator whereas NusB, S10, and Rho had no significant effect in this system.
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PMID:The NusA and NusG proteins of Escherichia coli increase the in vitro readthrough frequency of a transcriptional attenuator preceding the gene for the beta subunit of RNA polymerase. 137 Apr 74

The RPC34 gene of Saccharomyces cerevisiae was cloned by immunological screening, using antibodies raised against the C34 polypeptide of the RNA polymerase III (C). This single copy gene was located near the centromere of chromosome XIV. It included a coding sequence of 317 amino acids that strictly matched two internal oligopeptides of C34. This polypeptide is a specific component of RNA polymerase III, with no significant homology to any other RNA polymerase subunit known so far. It is an essential subunit, since inactivation by deletion or nonsense mutations led to a recessive lethal phenotype. Moreover, a partially blocked mutant, rpc34-F297, had a reduced tRNA synthesis in vivo but no detectable effect on 5 S RNA synthesis. The latter phenotype was observed for all conditionally defective RNA polymerase III mutants isolated so far.
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PMID:An essential and specific subunit of RNA polymerase III (C) is encoded by gene RPC34 in Saccharomyces cerevisiae. 140 Apr 51

An affinity-purified antibody raised against the fifth largest subunit of cauliflower (Brassica oleracea) RNA polymerase II was used to screen an expression library and isolate an Arabidopsis thaliana cDNA clone. This cDNA clone was used to isolate a soybean (Glycine max) cDNA clone, and both clones were sequenced. The open reading frames contain 176 amino acids and predict polypeptides of 19.5 and 19.6 kDa for Arabidopsis and soybean, respectively. The amino acid sequences of the Arabidopsis and soybean polypeptides are 91.5% identical. The fifth largest subunit in plant RNA polymerase II is present at unit stoichiometry in purified enzyme and does not dissociate from the holoenzyme during nondenaturing polyacrylamide gel electrophoresis. The gene encoding the 19.5-kDa subunit has been isolated and sequenced from Arabidopsis. The gene is single copy and contains five introns. The size of the mRNA encoding this RNA polymerase II subunit in Arabidopsis and soybean is approximately 1 kilobase. None of the published yeast or animal RNA polymerase subunit sequences show similarity to the fifth largest subunit in plants.
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PMID:Sequence of the fifth largest subunit of RNA polymerase II from plants. 142 63

Incubation of the E. coli RNA polymerase with a polypeptide factor from the protozoan Tetrahymena reduces the affinity of the holoenzyme for DNA. SDS-polyacrylamide gel electrophoresis of the peptide-treated RNA polymerase showed that the band pattern of the polymerase subunits was strongly altered. The three large subunits, beta', beta and sigma, disappear and a high number of rapidly migrating bands appeared. However, a brief heat treatment of the samples almost restored the original RNA polymerase subunit composition, and in addition a high molecular weight protein band approximately 240 kDa appeared. It is suggested that the Tetrahymena peptide specifically binds to the RNA polymerase and changes the structures of the large subunits.
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PMID:A peptide from Tetrahymena disrupts subunit organization of E. coli RNA polymerase. 147 89

A previously unrecognized 7-kDa polypeptide copurified with the DNA-dependent RNA polymerase of vaccinia virus virions. Internal amino acid sequences of the small protein matched a viral genomic open reading frame of 63 codons. Antipeptide antiserum was used to confirm the specific and complete association of the 7-kDa protein with RNA polymerase. The amino acid sequence predicted from the viral gene, named rpo7, was 23% identical to that of the smallest subunit of Saccharomyces cerevisiae RNA polymerase II, and a metal-binding motif, Cys-X-X-Cys-Gly, was located at precisely the same location near the N terminus in the two proteins. RNA analyses demonstrated early transcriptional initiation and termination signals in the rpo7 gene sequence. The viral RNA polymerase subunit was synthesized during the early phase of infection and continued to accumulate during the late phase.
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PMID:Characterization of a 7-kilodalton subunit of vaccinia virus DNA-dependent RNA polymerase with structural similarities to the smallest subunit of eukaryotic RNA polymerase II. 156 May 34

Nucleotide sequence analysis of a 17043 base-pair (bp) region of the Chlamydomonas reinhardtii plastome indicates the presence of three open reading frames (ORFs) similar to RNA polymerase subunit genes. Two, termed rpoB1 and rpoB2, are homologous to the 5'- and 3'-halves of the Escherichia coli beta subunit gene, respectively. A third, termed rpoC2, is similar to the 3'-half of the bacterial beta' subunit gene. These genes exhibit several unusual features: (1) all three represent chimeric structures in which RNA polymerase gene sequences are juxtaposed in-frame with long sequences of unknown identity; (2) unlike their counterparts in plants and eubacteria, rpoB1 and rpoB2 are separated from rpoC2 by a long (7 kilobase-pair, kbp) region containing genes unrelated to RNA polymerase; (3) DNA homologous to the 5' half of rpoC (termed rpoC1 in other species) is not present at the 5' end of rpoC2 and could not be detected in C. reinhardtii chloroplast DNA. RNA expression could not be detected for any of the RNA polymerase genes, suggesting that they are pseudogenes or genes expressed at stages of the C. reinhardtii life-cycle not investigated. The three genes are flanked by GC-rich repeat elements. We suggest that repeat DNA-mediated chloroplast recombination events may have contributed to their unusual arrangement.
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PMID:Chloroplast RNA polymerase genes of Chlamydomonas reinhardtii exhibit an unusual structure and arrangement. 161 38


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