scholarly journals Employment of a Promoter-Swapping Technique Shows that PhoU Modulates the Activity of the PstSCAB2 ABC Transporter in Escherichia coli

2008 ◽  
Vol 75 (3) ◽  
pp. 573-582 ◽  
Author(s):  
Christopher D. Rice ◽  
Jacob E. Pollard ◽  
Zachery T. Lewis ◽  
William R. McCleary
Keyword(s):  
Escherichia Coli ◽  
Regulatory System ◽  
Negative Regulator ◽  
Growth Defect ◽  
Pho Regulon ◽  
E Coli ◽  
Regulatory Module ◽  
Two Component ◽  
Severe Growth Defect ◽  
Promoter Swapping

ABSTRACT Expression of the Pho regulon in Escherichia coli is induced in response to low levels of environmental phosphate (Pi). Under these conditions, the high-affinity PstSCAB2 protein (i.e., with two PstB proteins) is the primary Pi transporter. Expression from the pstSCAB-phoU operon is regulated by the PhoB/PhoR two-component regulatory system. PhoU is a negative regulator of the Pho regulon; however, the mechanism by which PhoU accomplishes this is currently unknown. Genetic studies of phoU have proven to be difficult because deletion of the phoU gene leads to a severe growth defect and creates strong selection for compensatory mutations resulting in confounding data. To overcome the instability of phoU deletions, we employed a promoter-swapping technique that places expression of the phoBR two-component system under control of the Ptac promoter and the lacO ID regulatory module. This technique may be generally applicable for controlling expression of other chromosomal genes in E. coli. Here we utilized PphoB ::Ptac and PpstS ::Ptac strains to characterize phenotypes resulting from various ΔphoU mutations. Our results indicate that PhoU controls the activity of the PstSCAB2 transporter, as well as its abundance within the cell. In addition, we used the PphoB ::Ptac ΔphoU strain as a platform to begin characterizing new phoU mutations in plasmids.

scholarly journals Identification of a Streptococcus pneumoniae Gene Locus Encoding Proteins of an ABC Phosphate Transporter and a Two-Component Regulatory System

1999 ◽  
Vol 181 (4) ◽  
pp. 1126-1133 ◽  
Author(s):  
Rodger Novak ◽  
Anje Cauwels ◽  
Emmanuelle Charpentier ◽  
Elaine Tuomanen
Keyword(s):  
Response Regulator ◽  
Regulatory System ◽  
Phosphate Limitation ◽  
Pho Regulon ◽  
Loss Of Function ◽  
Gene Encoding ◽  
E Coli ◽  
Two Component ◽  
Pst System

ABSTRACT The Escherichia coli Pst system belongs to the family of ABC transporters. It is part of a phosphate (PHO) regulon which is regulated by extracellular phosphate. Under conditions of phosphate limitation, the response regulator PhoB is phosphorylated by the histidine kinase PhoR and binds to promoters that share a consensus PHO box. Under conditions of phosphate excess, PhoR, Pst, and PhoU downregulate the PHO regulon. Screening of a library of pneumococcal mutants with defects in exported proteins revealed a putative two-component regulatory system, PnpR-PnpS, and a downstream ABC transporter, similar to the Pst system in E. coli including a gene encoding a PhoU protein. Similar to E. coli, mutagenesis of the ATP-binding cassette gene, pstB, resulted in decreased uptake of phosphate. The effects of the loss of the pneumococcal Pst system extended to decreased transformation and lysis. Withdrawal of phosphate led to transformation deficiency in the parent strain R6x but not to penicillin tolerance, suggesting that reduced bacterial death was independent of phosphate. None of these phenotypes was observed in the pneumococcal loss-of-function mutantphoU. By using a lacZ reporter construct, it was demonstrated that expression of the two-component regulatory system PnpR-PnpS was not influenced by different concentrations of phosphate. These results suggest a more complex role of the Pst system in pneumococcal physiology than in that of E. coli.

scholarly journals Fumarate Regulation of Gene Expression in Escherichia coli by the DcuSR (dcuSR Genes) Two-Component Regulatory System

1998 ◽  
Vol 180 (20) ◽  
pp. 5421-5425 ◽  
Author(s):  
Evelyn Zientz ◽  
Johannes Bongaerts ◽  
Gottfried Unden
Keyword(s):  
Escherichia Coli ◽  
Histidine Kinase ◽  
Response Regulator ◽  
Regulation Of Gene Expression ◽  
Regulatory System ◽  
E Coli ◽  
Expression In Escherichia Coli ◽  
Two Component ◽  
Genes Encoding ◽  
Periplasmic Domain

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.

scholarly journals Identification of a Copper-Responsive Two-Component System on the Chromosome of Escherichia coli K-12

2000 ◽  
Vol 182 (20) ◽  
pp. 5864-5871 ◽  
Author(s):  
George P. Munson ◽  
Deborah L. Lam ◽  
F. Wayne Outten ◽  
Thomas V. O'Halloran
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Syringae ◽  
Metal Ion ◽  
Copper Ions ◽  
Copper Ion ◽  
Regulatory System ◽  
Copper Resistance ◽  
E Coli ◽  
Two Component ◽  
K 12

ABSTRACT Using a genetic screen we have identified two chromosomal genes,cusRS (ylcA ybcZ), from Escherichia coli K-12 that encode a two-component, signal transduction system that is responsive to copper ions. This regulatory system is required for copper-induced expression of pcoE, a plasmid-borne gene from the E. coli copper resistance operon pco. The closest homologs of CusR and CusS are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: PcoR and PcoS from the pcooperon of E. coli; CopR and CopS from thecop operon, which provides copper resistance toPseudomonas syringae; and SilR and SilS from thesil locus, which provides silver ion resistance toSalmonella enterica serovar Typhimurium. The genescusRS are also required for the copper-dependent expression of at least one chromosomal gene, designated cusC(ylcB), which is allelic to the recently identified virulence gene ibeB in E. coli K1. Thecus locus may comprise a copper ion efflux system, because the expression of cusC is induced by high concentrations of copper ions. Furthermore, the translation products of cusCand additional downstream genes are homologous to known metal ion antiporters.

scholarly journals The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool

2009 ◽  
Vol 192 (3) ◽  
pp. 746-754 ◽  
Author(s):  
Martijn Bekker ◽  
Svetlana Alexeeva ◽  
Wouter Laan ◽  
Gary Sawers ◽  
Joost Teixeira de Mattos ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Redox State ◽  
Enzyme Regulation ◽  
Regulatory System ◽  
Anaerobic Growth ◽  
E Coli ◽  
Two Component ◽  
Microaerobic Conditions

ABSTRACT ArcBA is a two-component regulatory system of Escherichia coli involved in sensing oxygen availability and the concomitant transcriptional regulation of oxidative and fermentative catabolism. Based on in vitro data, it has been postulated that the redox state of the ubiquinone pool is the determinant for ArcB kinase activity. Here we report on the in vivo regulation of ArcB activation, as determined using a lacZ reporter specifically responsive to phosphorylated ArcA. Our results indicate that upon deletion of a ubiquinone biosynthetic enzyme, regulation of ArcB in the anaerobic-aerobic transition is not affected. In contrast, interference with menaquinone biosynthesis leads to inactivation of ArcB during anaerobic growth; this phenotype is fully rescued by addition of a menaquinone precursor. This clearly demonstrates that the menaquinones play a major role in ArcB activation. ArcB shows a complex pattern of regulation when E. coli is titrated through the entire aerobiosis range; ArcB is activated under anaerobic and subaerobic conditions and is much less active under fully aerobic and microaerobic conditions. Furthermore, there is no correlation between ArcB activation and the redox state of the ubiquinone pool, but there is a restricted correlation between the total cellular ubiquinone content and ArcB activity due to the considerable increase in the size of the ubiquinone pool with increasing degrees of aerobiosis. These results lead to the working hypothesis that the in vivo activity of ArcB in E. coli is modulated by the redox state of the menaquinone pool and that the ubiquinone/ubiquinol ratio in vivo surely is not the only determinant of ArcB activity.

scholarly journals Identification and Characterization of a Two-Component Sensor-Kinase and Response-Regulator System (DcuS-DcuR) Controlling Gene Expression in Response to C4-Dicarboxylates in Escherichia coli

1999 ◽  
Vol 181 (4) ◽  
pp. 1238-1248 ◽  
Author(s):  
Paul Golby ◽  
Suzanne Davies ◽  
David J. Kelly ◽  
John R. Guest ◽  
Simon C. Andrews
Keyword(s):  
Escherichia Coli ◽  
Rhodobacter Capsulatus ◽  
Carbon Sources ◽  
Receptor Protein ◽  
Growth Defect ◽  
Sensor Kinase ◽  
Triple Mutant ◽  
E Coli ◽  
Dicarboxylate Transport ◽  
Two Component

ABSTRACT The dcuB gene of Escherichia coli encodes an anaerobic C4-dicarboxylate transporter that is induced anaerobically by FNR, activated by the cyclic AMP receptor protein, and repressed in the presence of nitrate by NarL. In addition,dcuB expression is strongly induced by C4-dicarboxylates, suggesting the presence of a novel C4-dicarboxylate-responsive regulator in E. coli. This paper describes the isolation of a Tn10mutant in which the 160-fold induction of dcuB expression by C4-dicarboxylates is absent. The corresponding Tn10 mutation resides in the yjdH gene, which is adjacent to the yjdG gene and close to thedcuB gene at ∼93.5 min in the E. colichromosome. The yjdHG genes (redesignateddcuSR) appear to constitute an operon encoding a two-component sensor-regulator system (DcuS-DcuR). A plasmid carrying the dcuSR operon restored the C4-dicarboxylate inducibility of dcuB expression in the dcuSmutant to levels exceeding those of the dcuS +strain by approximately 1.8-fold. The dcuS mutation affected the expression of other genes with roles in C4-dicarboxylate transport or metabolism. Expression of the fumarate reductase (frdABCD) operon and the aerobic C4-dicarboxylate transporter (dctA) gene were induced 22- and 4-fold, respectively, by the DcuS-DcuR system in the presence of C4-dicarboxylates. Surprisingly, anaerobic fumarate respiratory growth of the dcuS mutant was normal. However, under aerobic conditions with C4-dicarboxylates as sole carbon sources, the mutant exhibited a growth defect resembling that of a dctA mutant. Studies employing a dcuA dcuB dcuC triple mutant unable to transport C4-dicarboxylates anaerobically revealed that C4-dicarboxylate transport is not required for C4-dicarboxylate-responsive gene regulation. This suggests that the DcuS-DcuR system responds to external substrates. Accordingly, topology studies using 14 DcuS-BlaM fusions showed that DcuS contains two putative transmembrane helices flanking a ∼140-residue N-terminal domain apparently located in the periplasm. This topology strongly suggests that the periplasmic loop of DcuS serves as a C4-dicarboxylate sensor. The cytosolic region of DcuS (residues 203 to 543) contains two domains: a central PAS domain possibly acting as a second sensory domain and a C-terminal transmitter domain. Database searches showed that DcuS and DcuR are closely related to a subgroup of two-component sensor-regulators that includes the citrate-responsive CitA-CitB system of Klebsiella pneumoniae. DcuS is not closely related to the C4-dicarboxylate-sensing DctS or DctB protein ofRhodobacter capsulatus or rhizobial species, respectively. Although all three proteins have similar topologies and functions, and all are members of the two-component sensor-kinase family, their periplasmic domains appear to have evolved independently.

The curli biosynthesis regulator CsgD co-ordinates the expression of both positive and negative determinants for biofilm formation in Escherichia coli

Microbiology ◽  
2003 ◽  
Vol 149 (10) ◽  
pp. 2847-2857 ◽  
Author(s):  
Eva Brombacher ◽  
Corinne Dorel ◽  
Alexander J. B. Zehnder ◽  
Paolo Landini
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Regulatory System ◽  
Multicopy Plasmid ◽  
Transcription Activator ◽  
Transcription Start ◽  
Promoter Regions ◽  
E Coli ◽  
Two Component ◽  
Extracellular Structures

Production of curli, extracellular structures important for biofilm formation, is positively regulated by OmpR, which constitutes with the EnvZ protein an osmolarity-sensing two-component regulatory system. The expression of curli is cryptic in most Escherichia coli laboratory strains such as MG1655, due to the lack of csgD expression. The csgD gene encodes a transcription activator of the curli-subunit-encoding csgBA operon. The ompR234 up-mutation can restore csgD expression, resulting in curli production and increased biofilm formation. In this report, it is shown that ompR234-dependent csgD expression, in addition to csgBA activation during stationary phase of growth, stimulates expression of the yaiC gene and negatively regulates at least two other genes, pepD and yagS. The promoter regions of these four genes share a conserved 11 bp sequence (CGGGKGAKNKA), necessary for csgBA and yaiC regulation by CsgD. While at both the csgBA and yaiC promoters the sequence is located upstream of the promoter elements, in both yagS and pepD it overlaps either the putative −10 sequence or the transcription start point, suggesting that CsgD can function as both an activator and a repressor. Adhesion experiments show that csgD-independent expression of both yagS and pepD from a multicopy plasmid negatively affects biofilm formation, which, in contrast, is stimulated by yaiC expression. Thus it is proposed that CsgD stimulates biofilm formation in E. coli by contemporary activation of adhesion positive determinants (the curli-encoding csg operons and the product of the yaiC gene) and repression of negative effectors such as yagS and pepD.

scholarly journals HypVW is an HOCl-Sensing Two Component System in Escherichia coli

2021 ◽  
Author(s):  
Sara El Hajj ◽  
Camille Henry ◽  
Alexandra Vergnes ◽  
Laurent Loiseau ◽  
Brasseur Gael ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hypochlorous Acid ◽  
Methionine Sulfoxide ◽  
Methionine Sulfoxide Reductase ◽  
Bacterial Cells ◽  
E Coli ◽  
Two Component ◽  
Redox Switch ◽  
Two Component Systems ◽  
Methionine Residues

Two component systems (TCS) are signalling pathways that allow bacterial cells to sense, respond and adapt to fluctuating environments. Among the classical TCS of Escherichia coli, YedVW has been recently showed to be involved in the regulation of msrPQ, encoding for the periplasmic methionine sulfoxide reductase system. In this study, we demonstrate that hypochlorous acid (HOCl) induces the expression of msrPQ in a YedVW dependant manner, whereas H2O2, NO and paraquat (a superoxide generator) do not. Therefore, YedV appears to be an HOCl-sensing histidine kinase. Based on this finding, we proposed to rename this system HypVW.  Moreover, using a directed mutagenesis approach, we show that Met residues located in the periplasmic loop of HypV (formerly YedV) are important for its activity. Given that HOCl oxidizes preferentially Met residues, we bring evidences that HypV could be activated via the reversible oxidation of its methionine residues, thus conferring to MsrPQ a role in switching HypVW off. Based on these results, we propose that the activation of HypV by HOCl could occur through a Met redox switch. HypVW appears to be the first characterized TCS able to detect HOCl in E. coli. This study represents an important step in understanding the mechanisms of reactive chlorine species resistance in prokaryotes.

scholarly journals Elucidation of Regulatory Modes for Five Two-Component Systems in Escherichia coli Reveals Novel Relationships

mSystems ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Kumari Sonal Choudhary ◽  
Julia A. Kleinmanns ◽  
Katherine Decker ◽  
Anand V. Sastry ◽  
Ye Gao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Target Gene ◽  
Target Genes ◽  
Rna Seq ◽  
Content Type ◽  
E Coli ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

ABSTRACT Escherichia coli uses two-component systems (TCSs) to respond to environmental signals. TCSs affect gene expression and are parts of E. coli’s global transcriptional regulatory network (TRN). Here, we identified the regulons of five TCSs in E. coli MG1655: BaeSR and CpxAR, which were stimulated by ethanol stress; KdpDE and PhoRB, induced by limiting potassium and phosphate, respectively; and ZraSR, stimulated by zinc. We analyzed RNA-seq data using independent component analysis (ICA). ChIP-exo data were used to validate condition-specific target gene binding sites. Based on these data, we do the following: (i) identify the target genes for each TCS; (ii) show how the target genes are transcribed in response to stimulus; and (iii) reveal novel relationships between TCSs, which indicate noncognate inducers for various response regulators, such as BaeR to iron starvation, CpxR to phosphate limitation, and PhoB and ZraR to cell envelope stress. Our understanding of the TRN in E. coli is thus notably expanded. IMPORTANCE E. coli is a common commensal microbe found in the human gut microenvironment; however, some strains cause diseases like diarrhea, urinary tract infections, and meningitis. E. coli’s two-component systems (TCSs) modulate target gene expression, especially related to virulence, pathogenesis, and antimicrobial peptides, in response to environmental stimuli. Thus, it is of utmost importance to understand the transcriptional regulation of TCSs to infer bacterial environmental adaptation and disease pathogenicity. Utilizing a combinatorial approach integrating RNA sequencing (RNA-seq), independent component analysis, chromatin immunoprecipitation coupled with exonuclease treatment (ChIP-exo), and data mining, we suggest five different modes of TCS transcriptional regulation. Our data further highlight noncognate inducers of TCSs, which emphasizes the cross-regulatory nature of TCSs in E. coli and suggests that TCSs may have a role beyond their cognate functionalities. In summary, these results can lead to an understanding of the metabolic capabilities of bacteria and correctly predict complex phenotype under diverse conditions, especially when further incorporated with genome-scale metabolic models.

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