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)

Taking advantage of sequence conservation of portions of the alpha, beta, and beta' subunits of RNA polymerase of bacteria and plant chloroplasts, we have designed degenerate oligonucleotides corresponding to these domains and used these synthetic DNA sequences as primers in a polymerase chain reaction to amplify DNA sequences from the chlamydial genome. The polymerase chain reaction products were used as a probe to recover the genomic fragments encoding the beta subunit and the 5' portion of the beta' subunit from a library of cloned murine Chlamydia trachomatis DNA. Similar attempts to recover the alpha subunit were unsuccessful. Sequence analysis demonstrated that the beta subunit of RNA polymerase was located between genes encoding the L7/L12 ribosomal protein and the beta' subunit of RNA polymerase; this organization is reminiscent of the rpoBC operon of Escherichia coli. The C. trachomatis beta subunit overproduced in E. coli was used as an antigen in rabbits to make a polyclonal antibody to this subunit. Although this polyclonal antibody specifically immunoprecipitated the beta subunit from Chlamydia-infected cells, it did not immunoprecipitate core or holoenzyme. Immunoblots with this antibody demonstrated that the beta subunit appeared early in infection.
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PMID:Cloning and characterization of RNA polymerase core subunits of Chlamydia trachomatis by using the polymerase chain reaction. 221 7

The E. coli genes rplKAJL specifying ribosomal proteins L11, L1, L10, L7/L12 are co-transcribed with the genes rpoBC encoding the beta- and beta'-subunits of RNA polymerase, but are separated by the site of attenuation. The efficiency of attenuation within rplKAJL-rpoBC operon was determined as a ratio of rplKAJL transcription frequency to the same of rpoBC genes. The efficiency of attenuation was found to be a growth-rate dependent parameter of E. coli cells. At growth rate 1.2 doublings per hour the attenuation is rare and simultaneously increases with the increase in the growth rate (at mu = 1.2 doublings per hour the efficiency of attenuation is 4). Rifampicin (10-30 micrograms/ml) inhibits the transcription of both rplKAJL and rpoBC genes in fast growing cells but paradoxically stimulates their transcription in slowly growing cells. The stimulatory effect of rifampicin on rplKAJL genes transcription is supposed to be based on its ability to repress the ppGpp synthesis. The possible role of ppGpp in the regulation of transcription attenuation in rplKAJL-rpoBC operon is discussed.
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PMID:[Transcription of ribosomal protein genes rplKAJL and RNA-polymerase genes rpoBC in Escherichia coli cells: metabolic regulation of attenuation and the effect of rifampicin]. 243 Jan 72

Transcripts from the rplKAJL-rpoBC ribosomal protein-RNA polymerase gene cluster have been quantified and their ends mapped using RNA-DNA hybridization, sucrose density-gradient sedimentation, Northern hybridization and S1 nuclease protection. The results indicate that the most abundant transcript is the 2600 nucleotide tetracistronic L11-L1-L10-L12 mRNA initiated at the upstream major PL11 promoter and terminated at the transcription attenuator in the L12-beta intergenic space. Somewhat less abundant 1300 nucleotide L11-L1 and L10-L12 bicistronic transcripts were observed. The 3' ends of the L11-L1 transcripts were heterogeneous; most of the ends were localized to three sites within a 110 base-pair region in the L1-L10 intergenic space. This intergenic space encodes also the major PL10 promoter and the mRNA binding site for the L10 translational control protein. Two 5' ends were observed for L10-L12 bicistronic mRNA, one at the PL10 promoter and the other 150 nucleotides further downstream in a region in which promoter activity has not been detected. It is suggested that this second downstream 5' end is generated by processing of the transcripts initiated at the major PL10 promoter. No transcript initiation in the L10-L12 intergenic space was detected. About 80% of the transcripts reading through the L12 gene were terminated in the vicinity of the transcription attenuator that is responsible for the reduction in the expression of the downstream RNA polymerase genes. Transcripts reading through the attenuator were partially processed by RNase III within a potential hairpin structure in the RNA transcript. Processing appears to produce 3' and 5' transcript end sites separated by about ten nucleotides. No other major 5' ends were observed in the L12-beta intergenic space. These results indicate that the two major promoters, PL11 and PL10, are both utilized to drive the interrelated transcriptional expression of this ribosomal protein-RNA polymerase gene cluster.
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PMID:Transcription products from the rplKAJL-rpoBC gene cluster. 244 6

cDNA clones encoding three antigenically related human ribosomal phosphoproteins (P-proteins) P0, P1, and P2 were isolated and sequenced. P1 and P2 are analogous to Escherichia coli ribosomal protein L7/L12, and P0 is likely to be an analog of L10. The three proteins have a nearly identical carboxy-terminal 17-amino-acid sequence (KEESEESD(D/E)DMGFGLFD-COOH) that is the basis of their immunological cross-reactivity. The identities of the P1 and P2 cDNAs were confirmed by the strong similarities of their encoded amino acid sequences to published primary structures of the homologous rat, brine shrimp, and Saccharomyces cerevisiae proteins. The P0 cDNA was initially identified by translation of hybrid-selected mRNA and immunoprecipitation of the products. To demonstrate that the coding sequences are full length, the P0, P1, and P2 cDNAs were transcribed in vitro by bacteriophage T7 RNA polymerase and the resulting mRNAs were translated in vitro. The synthetic P0, P1, and P2 proteins were serologically and electrophoretically identical to P-proteins extracted from HeLa cells. These synthetic P-proteins were incorporated into 60S but not 40S ribosomes and also assembled into a complex similar to that described for E. coli L7/L12 and L10.
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PMID:Human acidic ribosomal phosphoproteins P0, P1, and P2: analysis of cDNA clones, in vitro synthesis, and assembly. 332 86

E. coli DNA fragment containing the rpoB gene with an rpoB3 rifampicin resistance dominant mutation (coding for the beta-subunit of RNA polymerase), genes rpI J and rpI L coding for the ribosomal proteins L7/L12 and L10, and promoters determining transcription of all these genes were cloned in M13mp8 and WB2348 filamentous phages. E. coli cells containing recombinant phages acquired resistance to rifampicin up to its 600 micrograms/ml concentration. When cloned into M13mp8 and WB2348 phages, the given fragment is oriented in such a way that the direction of the transcription initiated from its own promoter coincides with that initiated from the lac UV5 promoter. In both cases the recombinant phages have no stable rifampicin resistance which is coded by the fragment.
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PMID:[Unidirectional orientation of the rpo B gene of E. coli cloned into filamentous M13mp8 and M13WB2348 phages]. 609 81

We provide evidence that, in terms of transcriptional organisation, the rpoBC operon carried by lambdarifd 18 accurately represents the corresponding region of the E. coli K12 chromosome. A restriction fragment of E. coli K12 chromosomal DNA carrying the genes rpoBC (encoding the beta and beta' subunits of RNA polymerase) and rplL (coding for ribosomal proteins L7/L12) was cloned in a lambda vector, and the resulting phage tested for gene expression. In common with the corresponding fragment of lambdarifd 18 DNA, the chromosomal fragment has no strong promoter for rplL or rpoBC transcription. Another new phage was constructed by adding, to the restriction fragment carrying the rplL rpoBC structural genes from lambdarifd 18, a sequence from the E. coli K12 chromosome which includes a promoter for these genes. As in lambdarifd 18 itself, this promoter is shared with rplJ but not with rplKA. The properties of the latter phage also show that the dominant rifampicin-resistance characteristic of lambdarifd 18 results from more than one mutation.
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PMID:Cloning of DNA of the rpoBC operon from the chromosome of Escherichia coli K12. 624 4

The 319 nucleotide long intergenic region between the rplL (L12) and the rpoB (beta) genes of the L10 operon contains a transcription attenuation sequence and a RNase III mRNA processing sequence. Four site specific deletions located within this intergenic space which remove either the transcription attenuation sequence or the RNase III mRNA processing sequence or both sequences have been isolated on recombinant DNA plasmids carrying this operon. Deletions of sequences surrounding the RNase III processing site result in a uniform 80-90% reduction in the translational efficiency of beta subunit mRNA. This reduction in translation efficiency appears not to be related to processing per se; transcription of the rpoB and rpoC genes and the translation efficiency of the respective mRNA sequences were indistinguishable in an RNase III processing defective mutant (rnc) and its isogenic parent (rnc+). Deletions of the attenuator sequence result in a substantial increase in the downstream transcription of the beta subunit gene. The translational efficiency of RNase III processed beta subunit mRNA was found to be related in an inverse manner to the level of beta subunit synthesis. These result suggest that sequences on the mRNA in the vicinity of the RNase III processing site (i) are essential for efficient translation of beta subunit mRNA and (ii) are utilized for reducing the translational efficiency of the beta subunit mRNA when the beta subunit protein is produced in excess of that required for RNA polymerase assembly.
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PMID:Site specific deletions of regulatory sequences in a ribosomal protein-RNA polymerase operon in Escherichia coli. Effects on beta and beta' gene expression. 632 99

Amber mutations in the rpoB gene specifying the beta subunit of RNA polymerase coupled with conditional amber suppressors were used to restrict the synthesis of core RNA polymerase in strains of Escherichia coli. Such a restriction stimulated transcription of genetic units containing RNA polymerase subunit genes. Within the L10 transcription unit (genetic structure: promotor (PL10), rplJ (L10), rplL (L7/L12), attenuator, rpoB (beta), rpoC (beta'), terminator), the initiation of transcription at the promotor was enhanced and termination at the transcription attenuator was relaxed. Transcription of the genetic unit containing the rpoA gene (alpha) was also enhanced. In the strain containing a non-polar amber mutation, the synthesis rate of the beta' subunit protein during the restriction correlated with the level of transcription of the beta and beta' genes. In contrast, synthesis of L7/L12 ribosomal protein remained essentially unaltered in spite of the elevated levels of L10-L7/L12 mRNA.
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PMID:Regulation of RNA polymerase synthesis. Conditional lethal amber mutations in the beta subunit gene. 698 28

A partial restriction of ribonucleic acid (RNA) polymerase activity has been used to dissociate the coordinate synthesis of ribosomal proteins and subunits of RNA polymerase and to identify transcriptional and post-transcriptional control signals which regulate the expression of these component genes. Within the beta operon [which has the genetic organization: promoter (p beta), rplJ (L10), r;lL (L7/L12), attenuator, rpoB (beta), rpoC (beta'), terminator], the restriction caused a disproportionate increase between proximal and distal gene transcriptions; the transcriptional intensities of the proximal ribosomal protein genes and the distal RNA polymerase genes were elevated about two- and fourfold, respectively. Transcription within the operon containing four ribosomal protein genes and the RNA polymerase alpha gene was also enhanced, whereas transcription within operons containing only ribosomal protein genes was virtually unaffected by the restriction. It was thus concluded that the mechanisms controlling transcription initiation or attenuation or both in operons containing RNA polymerase subunit genes are coupled to the global rate of RNA synthesis. By introducing the composite ColE1 plasmid pJC701 carrying the proximal portion of the L10 operon, including the beta subunit gene, it was possible to achieve a 10- and a 30-fold range in the transcriptional intensities of the genes specifying L10 and L7/L12 and beta, respectively. Under these conditions, the relative synthesis rates of L7/L12 and beta protein varied by less than 2-fold and by about 15-fold, respectively. These observations corroborate the existence of a post-transcriptional mechanism which severely restricts translation of excess L7/L12 and L10 ribosomal protein messenger RNA; this mechanism is probably important in maintaining the balanced synthesis of ribosome components under conditions in which their messenger RNA levels are dissociated. Furthermore, the observed reduction in the translation efficiency of beta subunit messenger RNA may be related to an inhibitory effect caused by accumulation of RNA polymerase assembly intermediates.
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PMID:Transcriptional and post-transcriptional control of ribosomal protein and ribonucleic acid polymerase genes. 701 43

E. coli ribosomal protein L12, because of its unique features, has been studied in more detail than perhaps any of the other ribosomal proteins. Unlike the other ribosomal proteins that are generally present in stoichiometric amounts, there are four copies of L12 per ribosome, some of which are acetylated on the N-terminal serine. The acetylated species, referred to as L7, has not been shown, as yet, to possess any different biological activity than L12. A specific enzyme that acetylates L12 to form L7, using acetyl-CoA as the acetyl donor, has been purified from E. coli extracts. L12 is also unique in that it does not contain cysteine, tryptophan, histidine, or tyrosine, is very acidic (pI: 4.85) and has a high content of ordered secondary structure (approximately 50%). The protein is normally found in solution as a dimer and also forms a tight complex with ribosomal protein L10. There are three methionine residues in L12, located in the N-terminal region of the protein, one or more of which are essential for biological activity. Oxidation of the methionines to methionine sulfoxide prevents dimer formation and inactivates the protein. The four copies of L12 are located in the crest region(s) of the 50S ribosomal subunit. There is good evidence that the soluble factors, such as IF-2, EF-Tu, EF-G and RF, interact with L12 on the ribosome during the process of protein synthesis. This interaction is essential for the proper functioning of each of the factors and for GTP hydrolysis associated with the individual partial reactions of protein synthesis. The L12 gene is located on an operon that contains the genes for L10 and beta beta' subunits of RNA polymerase at about 88 min on the bacterial chromosome. DNA-directed in vitro systems have been used to study the unique regulation of the expression of these genes. Autogenous regulation, translational control, and transcription attenuation are regulatory mechanisms that function to control the synthesis of these proteins.
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PMID:Chemistry and biology of E. coli ribosomal protein L12. 701 80


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