Synthesis of the β and β′ subunits of Escherichia coli RNA polymerase is autogenously regulated in vivo by both transcriptional and translational mechanisms

Derek M Dykxhoorn, Rebecca St. Pierre, Thomas Linn

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Numerous experiments have indicated that the synthesis of RNA polymerase (ββ′α2σ70) in Escherichia coli is autogenously regulated. In the present study, we have examined expression of the rpoB and rpoC genes which encode the β and β′ subunits of RNA polymerase. These genes are the distal cistrons of the rplKAJLrpoBC ribosomal protein-RNA polymerase transcription unit. Both transcriptional (operon) and translational (gene) fusions of either rpoB or rpoC to the lacZ reporter were used to monitor their in vivo expression by inserting single copies of these fusions into the bacterial chromosome on integration-proficient lambda vectors. In order to examine the expression of the rpoBC genes in response to varied intracellular concentrations of the RNA polymerase subunits, a series of expression plasmids carrying the rpoB, rpoC, rpoA (α) and rpoD (σ70) genes in different combinations were then introduced into these cells. Elevated concentrations of either β or β′ were found to repress the expression of both rpoB and rpoC at the translational level. However, the simultaneous increase in the concentration of all the subunits that comprise holoenzyme repressed the transcription of rpoBC. To determine the site of this repression, additional operon fusions were utilized which placed lacZ downstream of each of the transcriptional regulatory sites of this gene cluster, including two promoters, rplKp and rplJp, and a transcriptional attenuator in the rplL-rpoB intercistronic region. Expression from these fusions showed that transcriptional repression is achieved primarily by reducing initiation at both upstream promoters, coupled with a small increase in termination at the attenuator.

Original languageEnglish
Pages (from-to)483-493
Number of pages11
JournalMolecular Microbiology
Volume19
Issue number3
StatePublished - Dec 1 1996
Externally publishedYes

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DNA-Directed RNA Polymerases
Escherichia coli
Operon
Genes
Bacterial Chromosomes
Holoenzymes
Intergenic DNA
Ribosomal RNA
Ribosomal Proteins
Gene Fusion
Regulator Genes
Multigene Family
Plasmids
Gene Expression

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

Cite this

Synthesis of the β and β′ subunits of Escherichia coli RNA polymerase is autogenously regulated in vivo by both transcriptional and translational mechanisms. / Dykxhoorn, Derek M; St. Pierre, Rebecca; Linn, Thomas.

In: Molecular Microbiology, Vol. 19, No. 3, 01.12.1996, p. 483-493.

Research output: Contribution to journalArticle

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