scholarly journals Global Analysis of Genes Regulated by EvgA of the Two-Component Regulatory System in Escherichia coli

2003 ◽  
Vol 185 (8) ◽  
pp. 2667-2672 ◽  
Author(s):  
Kunihiko Nishino ◽  
Yoshihiko Inazumi ◽  
Akihito Yamaguchi

ABSTRACT The response regulator EvgA controls expression of multiple genes conferring antibiotic resistance in Escherichia coli (K. Nishino and A. Yamaguchi, J. Bacteriol. 184:2319-2323, 2002). To understand the whole picture of EvgA regulation, DNA macroarray analysis of the effect of EvgA overproduction was performed. EvgA activated genes related to acid resistance, osmotic adaptation, and drug resistance.

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 635
Author(s):  
Hidetada Hirakawa ◽  
Jun Kurushima ◽  
Yusuke Hashimoto ◽  
Haruyoshi Tomita

Bacteria adapt to changes in their environment using a mechanism known as the two-component regulatory system (TCS) (also called “two-component signal transduction system” or “two-component system”). It comprises a pair of at least two proteins, namely the sensor kinase and the response regulator. The former senses external stimuli while the latter alters the expression profile of bacterial genes for survival and adaptation. Although the first TCS was discovered and characterized in a non-pathogenic laboratory strain of Escherichia coli, it has been recognized that all bacteria, including pathogens, use this mechanism. Some TCSs are essential for cell growth and fitness, while others are associated with the induction of virulence and drug resistance/tolerance. Therefore, the TCS is proposed as a potential target for antimicrobial chemotherapy. This concept is based on the inhibition of bacterial growth with the substances acting like conventional antibiotics in some cases. Alternatively, TCS targeting may reduce the burden of bacterial virulence and drug resistance/tolerance, without causing cell death. Therefore, this approach may aid in the development of antimicrobial therapeutic strategies for refractory infections caused by multi-drug resistant (MDR) pathogens. Herein, we review the progress of TCS inhibitors based on natural and synthetic compounds.


1998 ◽  
Vol 180 (20) ◽  
pp. 5421-5425 ◽  
Author(s):  
Evelyn Zientz ◽  
Johannes Bongaerts ◽  
Gottfried Unden

ABSTRACT In Escherichia coli the genes encoding the anaerobic fumarate respiratory system are transcriptionally regulated by C4-dicarboxylates. The regulation is effected by a two-component regulatory system, DcuSR, consisting of a sensory histidine kinase (DcuS) and a response regulator (DcuR). DcuS and DcuR are encoded by the dcuSR genes (previouslyyjdHG) at 93.7 min on the calculated E. coli map. Inactivation of the dcuR anddcuS genes caused the loss of C4-dicarboxylate-stimulated synthesis of fumarate reductase (frdABCD genes) and of the anaerobic fumarate-succinate antiporter DcuB (dcuB gene). DcuS is predicted to contain a large periplasmic domain as the supposed site for C4-dicarboxylate sensing. Regulation by DcuR and DcuS responded to the presence of the C4-dicarboxylates fumarate, succinate, malate, aspartate, tartrate, and maleate. Since maleate is not taken up by the bacteria under these conditions, the carboxylates presumably act from without. Genes of the aerobic C4-dicarboxylate pathway encoding succinate dehydrogenase (sdhCDAB) and the aerobic succinate carrier (dctA) are only marginally or negatively regulated by the DcuSR system. The CitAB two-component regulatory system, which is highly similar to DcuSR, had no effect on C4-dicarboxylate regulation of any of the genes.


1999 ◽  
Vol 181 (17) ◽  
pp. 5263-5272 ◽  
Author(s):  
Tracy L. Raivio ◽  
Daniel L. Popkin ◽  
Thomas J. Silhavy

ABSTRACT In Escherichia coli, the Cpx two-component regulatory system activates expression of protein folding and degrading factors in response to misfolded proteins in the bacterial envelope (inner membrane, periplasm, and outer membrane). It is comprised of the histidine kinase CpxA and the response regulator CpxR. This response plays a role in protection from stresses, such as elevated pH, as well as in the biogenesis of virulence factors. Here, we show that the Cpx periplasmic stress response is subject to amplification and repression through positive and negative autofeedback mechanisms. Western blot and operon fusion analyses demonstrated that the cpxRA operon is autoactivated. Conditions that lead to elevated levels of phosphorylated CpxR cause a concomitant increase in transcription ofcpxRA. Conversely, overproduction of CpxP, a small, Cpx-regulated protein of previously unknown function, represses the regulon and can block activation of the pathway. This repression is dependent on an intact CpxA sensing domain. The ability to autoactivate and then subsequently repress allows for a temporary amplification of the Cpx response that may be important in rescuing cells from transitory stresses and cueing the appropriately timed elaboration of virulence factors.


2002 ◽  
Vol 184 (15) ◽  
pp. 4168-4176 ◽  
Author(s):  
Natalya Baranova ◽  
Hiroshi Nikaido

ABSTRACT Screening of random fragments of Escherichia coli genomic DNA for their ability to increase the novobiocin resistance of a hypersusceptible ΔacrAB mutant resulted in the isolation of a plasmid containing baeR, which codes for the response regulator of the two-component regulatory system BaeSR. When induced for expression, baeR cloned in multicopy plasmid pTrc99A significantly increased the resistance of the ΔacrAB host strain to novobiocin (16-fold) and to deoxycholate (8-fold). Incubation of cells with novobiocin followed by a chromatographic assay for intracellular drug showed that overproduced BaeR decreased drastically the drug accumulation, presumably via increased active efflux. The genes baeSR are part of a putative operon, yegMNOB baeSR. Direct binding of BaeR to the yegM promoter was demonstrated in vitro by gel retardation assay. The gene yegB, which codes for a major facilitator superfamily transporter, was not necessary for increased resistance, but deletion of yegO or an in-frame deletion of yegN, both of which code for resistance-nodulation-cell division-type multidrug transporters, abolished the BaeR-induced increase in resistance. It is likely that both YegN and YegO produce a complex(es) with the membrane fusion protein family member YegM and pump out novobiocin and deoxycholate. We accordingly propose to rename yegMNOB as mdtABCD (mdt for multidrug transporter). Finally, the expression of two other genes, yicO and ygcL, was shown to be regulated by BaeR, but it is not known if they play any roles in resistance.


2005 ◽  
Vol 187 (5) ◽  
pp. 1763-1772 ◽  
Author(s):  
Kunihiko Nishino ◽  
Takeshi Honda ◽  
Akihito Yamaguchi

ABSTRACT The BaeSR two-component regulatory system controls expression of exporter genes conferring drug resistance in Escherichia coli (S. Nagakubo, K. Nishino, T. Hirata, and A. Yamaguchi, J. Bacteriol. 184:4161-4167, 2002; N. Baranova and H. Nikaido, J. Bacteriol. 184:4168-4176, 2002). To understand the whole picture of BaeSR regulation, a DNA microarray analysis of the effect of BaeR overproduction was performed. BaeR overproduction activated 59 genes related to two-component signal transduction, chemotactic responses, flagellar biosynthesis, maltose transport, and multidrug transport, and BaeR overproduction also repressed the expression of the ibpA and ibpB genes. All of the changes in the expression levels were also observed by quantitative real-time reverse transcription-PCR analysis. The expression levels of 15 of the 59 BaeR-activated genes were decreased by deletion of baeSR. Of 11 genes induced by indole (a putative inducer of the BaeSR system), 10 required the BaeSR system for induction. Combination of the expression data sets revealed a BaeR-binding site sequence motif, 5′-TTTTTCTCCATDATTGGC-3′ (where D is G, A, or T). Several genes up-regulated by BaeR overproduction, including genes for maltose transport, chemotactic responses, and flagellar biosynthesis, required an intact PhoBR or CreBC two-component regulatory system for up-regulation. These data indicate that there is cross-regulation among the BaeSR, PhoBR, and CreBC two-component regulatory systems. Such a global analysis should reveal the regulatory network of the BaeSR system.


2021 ◽  
Vol 12 ◽  
Author(s):  
Joan Marunga ◽  
Eunhye Goo ◽  
Yongsung Kang ◽  
Ingyu Hwang

Bacteria have specific signaling systems to overcome selective pressure, such as exposure to antibiotics. The two-component system (TCS) plays an important role in the development of antibiotic resistance. Using the rice pathogen Burkholderia glumae BGR1 as a model organism, we showed that the GluS (BGLU_1G13350) – GluR (BGLU_1G13360) TCS, consisting of a sensor kinase and response regulator, respectively, contributes to β-lactam resistance through a distinct mechanism. Inactivation of gluS or gluR conferred resistance to β-lactam antibiotics in B. glumae, whereas wild-type (WT) B. glumae was susceptible to these antibiotics. In gluS and gluR mutants, the expression of genes encoding metallo-β-lactamases (MBLs) and penicillin-binding proteins (PBPs) was significantly higher than in the WT. GluR-His bound to the putative promoter regions of annotated genes encoding MBL (BGLU_1G21360) and PBPs (BGLU_1G13280 and BGLU_1G04560), functioning as a repressor. These results demonstrate that the potential to attain β-lactam resistance may be genetically concealed in the TCS, in contrast to the widely accepted view of the role of TCS in antibiotic resistance. Our findings provide a new perspective on antibiotic resistance mechanisms, and suggest a different therapeutic approach for successful control of bacterial pathogens.


2003 ◽  
Vol 185 (6) ◽  
pp. 1851-1856 ◽  
Author(s):  
Hidetada Hirakawa ◽  
Kunihiko Nishino ◽  
Takahiro Hirata ◽  
Akihito Yamaguchi

ABSTRACT In Escherichia coli, there are 32 open reading frames (ORFs) that are assumed to be response regulator genes of two-component signal transduction systems on the basis of sequence similarities. We cloned all of these 32 ORFs into a multicopy expression vector and investigated whether or not they confer drug resistance via control of drug resistance determinants. Fifteen of these ORFs, i.e., baeR, citB, cpxR, evgA, fimZ, kdpE, narL, narP, ompR, rcsB, rstA, torR, yedW, yehT, and dcuR, conferred increased single- or multidrug resistance. Two-thirds of them conferred deoxycholate resistance. Five of them, i.e., evgA, baeR, ompR, cpxR, and rcsB, modulated the expression of several drug exporter genes. The drug resistance mediated by evgA, baeR, and cpxR could be assigned to drug exporters by using drug exporter gene knockout strains.


Microbiology ◽  
2004 ◽  
Vol 150 (6) ◽  
pp. 1851-1857 ◽  
Author(s):  
Nicole Gliese ◽  
Viola Khodaverdi ◽  
Max Schobert ◽  
Helmut Görisch

The response regulator AgmR was identified to be involved in the regulation of the quinoprotein ethanol oxidation system of Pseudomonas aeruginosa ATCC 17933. Interruption of the agmR gene by insertion of a kanamycin-resistance cassette resulted in mutant NG3, unable to grow on ethanol. After complementation with the intact agmR gene, growth on ethanol was restored. Transcriptional lacZ fusions were used to identify four operons which are regulated by the AgmR protein: the exaA operon encodes the pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase, the exaBC operon encodes a soluble cytochrome c 550 and an aldehyde dehydrogenase, the pqqABCDE operon carries the PQQ biosynthetic genes, and operon exaDE encodes a two-component regulatory system which controls transcription of the exaA operon. Transcription of exaA was restored by transformation of NG3 with a pUCP20T derivative carrying the exaDE genes under lac-promoter control. These data indicate that the AgmR response regulator and the exaDE two-component regulatory system are organized in a hierarchical manner. Gene PA1977, which appears to form an operon with the agmR gene, was found to be non-essential for growth on ethanol.


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