Evidence that rifampicin can stimulate readthrough of transcriptional terminators in<i>Escherichia coli,</i>including the attenuator of the<i>rpoBC</i>operon

Newman, Andrew; Ma, Jian-Chuan; Howe, Kathy; Garner, Ian; Hayward, Richard S.

doi:10.1093/nar/10.22.7409

Cited by 35 publications

(22 citation statements)

References 47 publications

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“…Fusions to galK have also suggested that both these and three other terminators are rendered less efficient in the presence of the drug. We have reported those results elsewhere, have argued that all are very likely to reflect transcriptional effects (although this remains to be proved by mRNA analysis), and have concluded that low concentrations of rifampicin increase readthrough of transcriptional terminators generally (5). The results of both studies favour the view that rifampicin stimulates rpoBC transcription mainly by increasing readthrough of rpotl.…”

Section: Discussionsupporting

confidence: 51%

“…The present work has also shown that streptolydigin does not have this effect, consistent with our previous observation (16) that it does not stimulate chromosomal rpoBC gene expression in E.coli. The question, whether or not rifampicin has a special effect at rpotl additional to that observed for other terminators, is discussed elsewhere (5).…”

Section: Discussionmentioning

confidence: 99%

“…It is noticeable that the drug effects on the lacZ fusions of pHR4 (and pHR5) are weaker than for the corresponding galK fusions (5). Perhaps this is due to the different promoters operating in the two cases, or to translational differences (cf.…”

Section: B53mentioning

confidence: 99%

“…1, is such that the rpo genes which encode the a and a' subunits of RNA polymerase lie downstream of, and are obligatorily co-transcribed with several ribosomal protein (rpl) genes: see reviews by Yura and Ishihama (3) and Matzura (4), briefly updated in (5). However, certain growth constraints can partially uncouple the transcription of the rpo and rpl genes (reviewed in 3, 4, 6, 7).…”

Section: Introductionmentioning

confidence: 99%

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Effect of rifampicin on expression oflacZfused to promoters or terminators of theE.coli rpoBCoperon

et al. 1982

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The genes encoding the f and a' subunits of RNA polymerase in E.coli lie downstream of at least two ribosomal protein genes in a single unit of transcription. Treatment of E.coli with rifampicin, under conditions producing partial inhibition of general RNA synthesis, can strongly stimulate transcription of the polymerase genes, while activating the neighbouring ribosomal genes only slightly. We have investigated the mechanism of this effect by fusing strong promoters, a weak internal promoter, and an attenuator of the polymerase operon to the lacZ gene, in derivatives of plasmid pMC81. Studies of these fusions confirm our conclusion, based on similar fusions to galK, that rifampicin can foster readthrough of transcriptional terminators. They also suggest the existence of extra terminatois and anti-termination elements in the above transcription unit.

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Section: Discussionsupporting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

Section: B53mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of rifampicin on expression oflacZfused to promoters or terminators of theE.coli rpoBCoperon

et al. 1982

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“…pPM2029 and pPM2030 were constructed by ligating BamHI-cut pPM2000 into promoter probe plasmid pKO4 (26) and selecting Ampr Gal' progeny of C600 galK. pIR2010, pIR2011, pIR2020, pIR2030, and pIR2031 were constructed by cloning the BamHI fragments into the tet gene of pBR322.…”

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confidence: 99%

Proteins encoded by the Escherichia coli replication terminus region

et al. 1992

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The replication terminus region (31 to 35 min) of the Escherichia coli chromosome contains very few mapped genes (two per min) compared with the remainder of the chromosome, and much of the DNA appears dispensable. In order to determine whether, despite this, the terminus region consists of protein-coding sequences, we cloned 44 kb (1 min) of terminus region DNA (that surrounding trg at 31.4 min) and examined its ability to catalyze protein synthesis in vitro or in minicells. We were able to account for more than half the coding capacity of the cloned DNA with proteins synthesized in these systems, indicating that the sparsity of mapped genes in the terminus region does not result from a lack of identifiable coding sequences. We can therefore conclude that the terminus region is composed mainly of expressable, albeit inessential, proteinencoding genes. (6) which spans the 9-min region from 27 to 36 min enabled us to limit our cloning and screening to restriction fragments of known size.We report here our isolation and study of overlapping fragments of DNA representing nearly 1% of the chromosome (about 44 kb in total). This DNA and subclones prepared from it were either introduced on a plasmid vector into a minicell-producing strain and used to direct the synthesis of labelled polypeptides in purified minicells (32) or used as DNA in an in vitro protein-synthesizing system. Individually identified polypeptides were assigned to subsegments of the region, allowing us to account for close to 60% of total coding capacity. Our results show that a 1-min segment within the terminus region codes for a substantial number of polypeptides, indicating that the region as a whole, although dispensable by deletion and lacking genetic markers, nevertheless encodes a substantial number of polypeptides and thus cannot be said to be gene sparse. The functions of these genes remain to be discovered, but the terminus region remains distinctly different from the rest of the chromosome in that it encodes so large a number of apparently inessential proteins and no essential ones.

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Transcriptional termination at a fully rho-independent site in Escherichia coli is prevented by uninterrupted translation of the nascent RNA.

Wright¹,

Hayward²

1987

The EMBO Journal

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We have examined the possibility that translation reading through a fully rho‐independent transcriptional terminator in Escherichia coli might prevent termination, as already established for rho‐dependent terminators. Plasmids were constructed with and without interposition of the rho‐independent coliphage T7 ‘early’ terminator between a promoter and galK. Our constructions ensured either that there was no upstream translation, or that translation (initiated at the galE ribosome binding site) stopped upstream of, or at the normal position (the T7 gene 1.3 stop codon) with respect to, the transcriptional terminator; or else downstream of both this stop codon and the terminator. Our galactokinase enzyme and mRNA measurements on strains harbouring these plasmids indicate that ‘readthrough translation’ eliminates transcriptional termination at the T7 site. This effect is suppressed if the rate of ribosome movement is reduced with fusidic acid.

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Evidence that rifampicin can stimulate readthrough of transcriptional terminators inEscherichia coli,including the attenuator of therpoBCoperon

Cited by 35 publications

References 47 publications

Effect of rifampicin on expression oflacZfused to promoters or terminators of theE.coli rpoBCoperon

Effect of rifampicin on expression oflacZfused to promoters or terminators of theE.coli rpoBCoperon

Proteins encoded by the Escherichia coli replication terminus region

Transcriptional termination at a fully rho-independent site in Escherichia coli is prevented by uninterrupted translation of the nascent RNA.

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