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.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

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 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.

A SitABCD homologue from an avian pathogenic Escherichia coli strain mediates transport of iron and manganese and resistance to hydrogen peroxide

Microbiology ◽  
2006 ◽  
Vol 152 (3) ◽  
pp. 745-758 ◽  
Author(s):  
Mourad Sabri ◽  
Simon Léveillé ◽  
Charles M. Dozois
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Growth Promotion ◽  
Coli Strain ◽  
Transport Systems ◽  
Virulence Plasmid ◽  
E Coli ◽  
K 12 ◽  
Iron And Manganese

An operon encoding a member of the family of ATP-binding cassette (ABC) divalent metal ion transporters, homologous to Salmonella enterica SitABCD, has been identified in the avian pathogenic Escherichia coli (APEC) strain χ7122. The sitABCD genes were located on the virulence plasmid pAPEC-1, and were highly similar at the nucleotide level to the chromosomally encoded sitABCD genes present in Shigella spp. A cloned copy of sitABCD conferred increased growth upon a siderophore-deficient E. coli strain grown in nutrient broth supplemented with the chelator 2,2′-dipyridyl. Ion rescue demonstrated that Sit-mediated growth promotion of this strain was due to the transport of iron. SitABCD mediated increased transport of both iron and manganese as demonstrated by uptake of 55Fe, 59Fe or 54Mn in E. coli K-12 strains deficient for the transport of iron (aroB feoB) and manganese (mntH) respectively. Isotope uptake and transport inhibition studies showed that in the iron transport deficient strain, SitABCD demonstrated a greater affinity for iron than for manganese, and SitABCD-mediated transport was higher for ferrous iron, whereas in the manganese transport deficient strain, SitABCD demonstrated greater affinity for manganese than for iron. Introduction of the APEC sitABCD genes into an E. coli K-12 mntH mutant also conferred increased resistance to the bactericidal effects of hydrogen peroxide. APEC strain χ7122 derivatives lacking either a functional SitABCD or a functional MntH transport system were as resistant to hydrogen peroxide as the wild-type strain, whereas a Δsit ΔmntH double mutant was more sensitive to hydrogen peroxide. Overall, the results demonstrate that in E. coli SitABCD represents a manganese and iron transporter that, in combination with other ion transport systems, may contribute to acquisition of iron and manganese, and resistance to oxidative stress.

scholarly journals mcr-9, an Inducible Gene Encoding an Acquired Phosphoethanolamine Transferase in Escherichia coli, and Its Origin

2019 ◽  
Vol 63 (9) ◽  
Author(s):  
Nicolas Kieffer ◽  
Guilhem Royer ◽  
Jean-Winoc Decousser ◽  
Anne-Sophie Bourrel ◽  
Mattia Palmieri ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lipid A ◽  
Acquired Resistance ◽  
Regulatory System ◽  
Amino Acid Identity ◽  
Gene Encoding ◽  
Content Type ◽  
E Coli ◽  
K 12 ◽  
A Minor

ABSTRACT The plasmid-located mcr-9 gene, encoding a putative phosphoethanolamine transferase, was identified in a colistin-resistant human fecal Escherichia coli strain belonging to a very rare phylogroup, the D-ST69-O15:H6 clone. This MCR-9 protein shares 33% to 65% identity with the other plasmid-encoded MCR-type enzymes identified (MCR-1 to -8) that have been found as sources of acquired resistance to polymyxins in Enterobacteriaceae. Analysis of the lipopolysaccharide of the MCR-9-producing isolate revealed a function similar to that of MCR-1 by adding a phosphoethanolamine group to lipid A and subsequently modifying the structure of the lipopolysaccharide. However, a minor impact on susceptibility to polymyxins was noticed once the mcr-9 gene was cloned and produced in an E. coli K-12-derived strain. Nevertheless, we showed here that subinhibitory concentrations of colistin induced the expression of the mcr-9 gene, leading to increased MIC levels. This inducible expression was mediated by a two-component regulatory system encoded by the qseC and qseB genes located downstream of mcr-9. Genetic analysis showed that the mcr-9 gene was carried by an IncHI2 plasmid. In silico analysis revealed that the plasmid-encoded MCR-9 shared significant amino acid identity (ca. 80%) with the chromosomally encoded MCR-like proteins from Buttiauxella spp. In particular, Buttiauxella gaviniae was found to harbor a gene encoding MCR-BG, sharing 84% identity with MCR-9. That gene was neither expressed nor inducible in its original host, which was fully susceptible to polymyxins. This work showed that mcr genes may circulate silently and remain undetected unless induced by colistin.

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.

Transcriptome analysis of all two-component regulatory system mutants of Escherichia coli K-12

2002 ◽  
Vol 46 (1) ◽  
pp. 281-291 ◽  
Author(s):  
Taku Oshima ◽  
Hirofumi Aiba ◽  
Yasushi Masuda ◽  
Shigehiko Kanaya ◽  
Masahito Sugiura ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Transcriptome Analysis ◽  
Regulatory System ◽  
Two Component ◽  
K 12
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