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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)

In Escherichia coli the genes encoding ribosomal protein S21 (rpsU), DNA primase (dnaG), and the 70-kDal sigma subunit of RNA polymerase (rpoD) are contained in a single operon. These gene products are involved in the initiation of translation, DNA replication, and transcription, respectively. We have examined the homologous region in the closely related bacterium Salmonella typhimurium and have found that the same three genes are similarly organized. We have sequenced the DNA for this operon in S. typhimurium and have compared the (nt) nucleotide and amino acid (aa) sequences with E. coli. In the coding regions, the sequence conservation varies from extremely high for rpsU to moderate for dnaG with respect to both nt and aa sequence. In the noncoding regions, sequences thought to be important for the regulation of transcription are conserved, while other sequences are not conserved. aa differences in DNA primase and sigma are not randomly distributed and suggest regions that may be important for protein structure or function.
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PMID:Nucleotide sequence of the rpsU-dnaG-rpoD operon from Salmonella typhimurium and a comparison of this sequence with the homologous operon of Escherichia coli. 300 29

A simplified DNA-directed in vitro system which measures synthesis of the NH2-terminal dipeptides of gene products has been used to study the expression of rpoD, the gene coding for the sigma subunit of Escherichia coli RNA polymerase. The rpoD gene is part of a complex operon which also includes the genes for ribosomal protein S21 (rpsU) and primase (dnaG). Primary promoters have been identified upstream of the structural genes, but there are secondary (internal) promoters within the dnaG gene that are involved in the expression of rpoD. Significant expression of the rpsU and rpoD genes was observed in the in vitro dipeptide system using plasmid pBS105, which contains both external and internal promoters. With plasmid pMRG-1, which contains only the internal promoters, only rpoD expression was observed. From either template, synthesis of the NH2-terminal dipeptide of sigma, fMet-Glu, is stimulated about threefold by the E. coli nusA gene product. In addition, NusA protein stimulates synthesis of the entire sigma protein in a defined in vitro system. NusA protein has no effect on the expression of the upstream gene rpsU, and the stimulation of rpoD expression by NusA protein is at the level of transcription. The results are consistent with the known role of NusA protein in modulating transcription at pause or attenuation sites.
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PMID:In vitro stimulation of Escherichia coli RNA polymerase sigma subunit synthesis by NusA protein. 388 85

The rpoD gene (encoding the 70,000 Mr sigma subunit of Escherichia coli RNA polymerase) is the most distal gene in an operon that contains three genes. The promoter-proximal gene is rpsU (encoding ribosomal protein S21) and the middle gene is dnaG (encoding DNA primase). During the stringent response, caused by a deficiency in an aminoacyl-tRNA, expression of rpsU is decreased, while expression of rpoD is not. This disco-ordinate regulation is due to increased transcription from a minor promoter upstream from rpoD, in the dnaG gene. Transcription from this promoter is also increased during the heat shock response. Expression of other heat shock proteins was found to increase during the stringent response. Thus, the stringent response in E. coli induces expression of heat shock proteins. The requirements for this stringent induction of the heat shock proteins differ from those for temperature induction during the heat shock response.
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PMID:Stringent response in Escherichia coli induces expression of heat shock proteins. 391 Aug 41

The sigma subunit of E. coli RNA polymerase is encoded by the rpoD gene. Within the sequence upstream from rpoD, we have identified the structural genes rpsU and dnaG, which encode the 30S ribosomal protein S21 and DNA primase, respectively. The three genes are in the order rpsU, dnaG rpoD, and are all encoded by the same DNA strand. Analysis of in vivo transcripts from this region shows that these genes are all within the same operon. By correlating the 5' and 3' ends of in vivo transcripts with our DNA sequence, we have identified several regulatory features of the operon. These features include tandem promoters upstream from rpsU, a terminator between rpsU and dnaG, an RNA processing site separating dnaG and rpoD, and the operon terminator just downstream from rpoD. Immediately upstream of the operon promoters is an active promoter for an unidentified gene. We discuss the regulatory significance of the operon features and the biological significance of an operon encoding proteins essential for translation, replication and transcription.
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PMID:The operon that encodes the sigma subunit of RNA polymerase also encodes ribosomal protein S21 and DNA primase in E. coli K12. 618 93

The rpoD gene encoding the sigma subunit of E. coli RNA polymerase is cotranscribed with rpsU and dnaG, encoding ribosomal protein S21 and DNA primase, respectively. After temperature upshift, a heat shock promoter (Phs) located within dnaG is transiently induced, causing increased transcription of rpoD. The extent of induction is sufficient to account for the heat shock response of sigma synthesis. The initiation site of this promoter was located about 360 bp upstream of rpoD by promoter cloning and S1 nuclease mapping. Plasmid deletions generated with Bal 31 nuclease show that the DNA sequence CTGCCACCC in the -44 to -36 region of this promoter is necessary for its heat shock activity. Heat induction of transcription from Phs is under the control of HtpR, a positive regulator of the heat shock response.
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PMID:Transcription from a heat-inducible promoter causes heat shock regulation of the sigma subunit of E. coli RNA polymerase. 638 Jul 64