Evidence against transcription termination within the E. coli lac operon

One of the major ways of acquiring multidrug resistance in bacteria is via drug influx and efflux pathways. Here, we show that E. coli with compromised Rho-dependent transcription termination function has enhanced broad-spectrum antibiotic susceptibility, which arises from the inefficient TolC-efflux process and increased permeability of the membrane. The Rho mutants have altered morphology, distinct cell surface, and increased levels of lipopolysaccharide in their outer membrane, which might have rendered the TolC efflux pumps inefficient. These alterations are due to the upregulations of poly-N-acetyl-glucosamine and lipopolysaccharide synthesis operons because of inefficient Rho functions. The Rho mutants are capable of growing on various dipeptides and carbohydrate sources, unlike their WT counterpart. Dipeptides uptake arises from the upregulations of the di-peptide permease operon in these mutants. The metabolomics of the Rho mutants revealed the presence of a high level of novel metabolites. Accumulation of these metabolites in these Rho mutants might titrate out the TolC-efflux pumps, which could further reduce their efficiency. We conclude that the transcription termination factor, Rho, regulates the broad-spectrum antibiotic susceptibility of E. coli through multipartite pathways in a TolC-dependent manner. The involvement of Rho-dependent termination in multiple pathways and its association with antibiotic susceptibility should make Rho-inhibitors useful in the anti-bacterial treatment regimen.

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Fast Translation within the First 45 Codons Decreases mRNA Stability and Increases Premature Transcription Termination in E. coli

Journal of Molecular Biology ◽

10.1016/j.jmb.2019.01.026 ◽

2019 ◽

Vol 431 (6) ◽

pp. 1088-1097 ◽

Cited By ~ 1

Author(s):

Steen Pedersen ◽

Thilde Bagger Terkelsen ◽

Mette Eriksen ◽

Magnus Krarup Hauge ◽

Casper Carstens Lund ◽

...

Keyword(s):

Mrna Stability ◽

Transcription Termination ◽

E Coli

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Cloning and Heterologous Expression of Plantaricin ZJ5, a Novel Bacteriocin from Lactobacillus plantarum ZJ5, in Escherichia coli

Natural Product Communications ◽

10.1177/1934578x1801301231 ◽

2018 ◽

Vol 13 (12) ◽

pp. 1934578X1801301

Author(s):

Dafeng Song ◽

Ping Li ◽

Qing Gu

Keyword(s):

Escherichia Coli ◽

Fusion Protein ◽

Lactobacillus Plantarum ◽

Micrococcus Luteus ◽

Biologically Active ◽

Biological Method ◽

Lac Operon ◽

E Coli ◽

First Time ◽

Soluble Material

A novel bacteriocin, plantaricin ZJ5 (PZJ5) was yielded from Lactobacillus plantarum ZJ5, cloned, and produced in Escherichia coli BL21 (DE3) pLys. The PZJ5 structural gene was fused with a Trx tag, and cloned into the pET32a plasmid under the control of the inducible lac operon. Induction was performed with isopropyl-β-D-thiogalactopyranoside (IPTG), with subsequent overexpression of the fusion protein, followed by purification to homogeneity via His affinity chromatography. Recombinant E. coli produced greater quantities of PZJ5 than L. plantarum ZJ5, and PZJ5 in E. coli was expressed in the form of soluble material. Biologically active PZJ5 was recovered by cleaving the purified fusion protein using enterokinase. The released PZJ5 demonstrated antibacterial activity against Micrococcus luteus. In this study, an inexpensive biological method using a Trx fusion system was presented, and for the first time, bacteriocin PZJ5 was expressed and purified in E. coli.

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Robust Invariant Set Analysis of Boolean Networks

Complexity ◽

10.1155/2019/2731395 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 15

Author(s):

Bowen Li ◽

Jungang Lou ◽

Yang Liu ◽

Zhen Wang

Keyword(s):

Fixed Point ◽

Output Feedback ◽

Invariant Set ◽

Boolean Networks ◽

Sufficient Condition ◽

Lac Operon ◽

Feedback Controllers ◽

Control Networks ◽

E Coli ◽

Necessary And Sufficient

In this paper, the robust invariant set (RIS) of Boolean (control) networks with disturbances is investigated. First, for a given fixed point, consider a special set called immediate neighborhoods of the fixed point; then a discrete derivative of Boolean functions at the fixed point is used to analyze the robust invariance, based on which a sufficient condition is obtained. Second, for more general sets, the robust output control invariant set (ROCIS) of Boolean control networks (BCNs) is investigated by semitensor product (STP) of matrices. Then, under a given output feedback controller, we obtain a necessary and sufficient condition to check whether a given set is robust control invariant set (RCIS). Furthermore, output feedback controllers are designed to make a set to be a RCIS. Finally, the proposed methods are illustrated by a reduced model of the lac operon in E. coli.

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Expression of Different-Size Transcripts from theclpP-clpX Operon of Escherichia coli during Carbon Deprivation

Journal of Bacteriology ◽

10.1128/jb.182.23.6630-6637.2000 ◽

2000 ◽

Vol 182 (23) ◽

pp. 6630-6637 ◽

Cited By ~ 13

Author(s):

Chin Li ◽

Yi Ping Tao ◽

Lee D. Simon

Keyword(s):

Escherichia Coli ◽

Rna Polymerase ◽

Type Strain ◽

Wild Type Strain ◽

Transcription Termination ◽

Carbon Starvation ◽

Lower Percentage ◽

Wild Type ◽

Lower Efficiency ◽

E Coli

ABSTRACT Transcription of the clpP-clpX operon ofEscherichia coli leads to the production of two different sizes of transcripts. In log phase, the level of the longer transcript is higher than the level of the shorter transcript. Soon after the onset of carbon starvation, the level of the shorter transcript increases significantly, and the level of the longer transcript decreases. The longer transcript consists of the entireclpP-clpX operon, whereas the shorter transcript contains the entire clpP gene but none of the clpXcoding sequence. The RpoH protein is required for the increase in the level of the shorter transcript during carbon starvation. Primer extension experiments suggest that there is increased usage of the ς32-dependent promoter of the clpP-clpXoperon within 15 min after the start of carbon starvation. Expression of the clpP-clpX operon from the promoters upstream of theclpP gene decreases to a very low level by 20 min after the onset of carbon starvation. Various pieces of evidence suggest, though they do not conclusively prove, that production of the shorter transcript may involve premature termination of the longer transcript. The half-life of the shorter transcript is much less than that of the longer transcript during carbon starvation. E. coli rpoBmutations that affect transcription termination efficiency alter the ratio of the shorter clpP-clpX transcript to the longer transcript. The E. coli rpoB3595 mutant, with an RNA polymerase that terminates transcription with lower efficiency than the wild type, accumulates a lower percentage of the shorter transcript during carbon starvation than does the isogenic wild-type strain. In contrast, the rpoB8 mutant, with an RNA polymerase that terminates transcription with higher efficiency than the wild type, produces a higher percentage of the shorter clpP-clpXtranscript when E. coli is in log phase. These and other data are consistent with the hypothesis that the shorter transcript results from premature transcription termination during production of the longer transcript.

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