Inactivation of the Escherichia coli B41 (0101:K99/F41) rfb gene encoding an 80-kDa polypeptide results in the synthesis of an antigenically altered lipopolysaccharide in E. coli K-12

Gene ◽  
1993 ◽  
Vol 123 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Keat-Chye Cheah ◽  
Paul A. Manning
Keyword(s):  
Escherichia Coli ◽  
Gene Encoding ◽  
E Coli ◽  
K 12

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 Opening a Novel Biosynthetic Pathway to Dihydroxyacetone and Glycerol in Escherichia coli Mutants through Expression of a Gene Variant (fsaAA129S) for Fructose 6-Phosphate Aldolase

2020 ◽  
Vol 21 (24) ◽  
pp. 9625
Author(s):  
Emma Guitart Font ◽  
Georg A. Sprenger
Keyword(s):  
Escherichia Coli ◽  
Mutant Strain ◽  
Catalytic Efficiency ◽  
Glycerol Dehydrogenase ◽  
Gene Encoding ◽  
E Coli ◽  
Glycerol Formation ◽  
Type Gene ◽  
K 12 ◽  
Glucose 6 Phosphate Dehydrogenase

Phosphofructokinase (PFK) plays a pivotal role in glycolysis. By deletion of the genes pfkA, pfkB (encoding the two PFK isoenzymes), and zwf (glucose 6-phosphate dehydrogenase) in Escherichia coli K-12, a mutant strain (GL3) with a complete block in glucose catabolism was created. Introduction of plasmid-borne copies of the fsaA wild type gene (encoding E. coli fructose 6-phosphate aldolase, FSAA) did not allow a bypass by splitting fructose 6-phosphate (F6P) into dihydroxyacetone (DHA) and glyceraldehyde 3-phosphate (G3P). Although FSAA enzyme activity was detected, growth on glucose was not reestablished. A mutant allele encoding for FSAA with an amino acid exchange (Ala129Ser) which showed increased catalytic efficiency for F6P, allowed growth on glucose with a µ of about 0.12 h−1. A GL3 derivative with a chromosomally integrated copy of fsaAA129S (GL4) grew with 0.05 h−1 on glucose. A mutant strain from GL4 where dhaKLM genes were deleted (GL5) excreted DHA. By deletion of the gene glpK (glycerol kinase) and overexpression of gldA (of glycerol dehydrogenase), a strain (GL7) was created which showed glycerol formation (21.8 mM; yield approximately 70% of the theoretically maximal value) as main end product when grown on glucose. A new-to-nature pathway from glucose to glycerol was created.

scholarly journals Apramycin resistance plasmids inEscherichia coli: possible transfer toSalmonella typhimuriumin calves

1992 ◽  
Vol 108 (2) ◽  
pp. 271-278 ◽  
Author(s):  
J. E. B. Hunter ◽  
J. C. Shelley ◽  
J. R. Walton ◽  
C. A. Hart ◽  
M. Bennett
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
High Frequency ◽  
Inescherichia Coli ◽  
Gene Encoding ◽  
E Coli ◽  
Resistance Plasmids ◽  
Effect Of Treatment ◽  
K 12

SUMMARYAn outbreak of salmonellosis in calves was monitored for persistence ofSalmonella typhimuriumexcretion in faeces and the effect of treatment with apramycin. Prior to treatment apramycin-resistantEscherichia coliwere present but allS. typhimuriumisolates were sensitive. Following the treatment of six calves with apramycin, apramycin-resistantS. typhimuriumwere isolated from two treated calves and one untreated calf. Plasmid profiles ofE. coliandS. typhimuriumwere compared and plasmids conferring resistance to apramycin and several other antibiotics were transferred by conjugationin vitrofrom calfE. coliandS. typhimuriumisolates toE. coliK-12 and fromE. colitoS. typhimurium. The plasmids conjugated with high frequencyin vitrofromE. colitoS. typhimurium, and hybridized to a DNA probe specific for the gene encoding aminoglycoside acetyltransferase 3-IV (AAC(3)-IV) which confers resistance to apramycin, gentamicin, netilmicin and tobramycin.

scholarly journals The Global Regulatory hns Gene Negatively Affects Adhesion to Solid Surfaces by Anaerobically Grown Escherichia coli by Modulating Expression of Flagellar Genes and Lipopolysaccharide Production

2002 ◽  
Vol 184 (6) ◽  
pp. 1522-1529 ◽  
Author(s):  
Paolo Landini ◽  
Alexander J. B. Zehnder
Keyword(s):  
Escherichia Coli ◽  
Sharp Decrease ◽  
Luria Broth ◽  
Bacterial Cells ◽  
Gene Encoding ◽  
Aerobic Conditions ◽  
E Coli ◽  
Hydrophilic Surfaces ◽  
K 12 ◽  
Initial Binding

ABSTRACT The initial binding of bacterial cells to a solid surface is a critical and essential step in biofilm formation. In this report we show that stationary-phase cultures of Escherichia coli W3100 (a K-12 strain) can efficiently attach to sand columns when they are grown in Luria broth medium at 28°C in fully aerobic conditions. In contrast, growth in oxygen-limited conditions results in a sharp decrease in adhesion to hydrophilic substrates. We show that the production of lipopolysaccharide (LPS) and of flagella, as well as the transcription of the fliC gene, encoding the major flagellar subunit, increases under oxygen-limited conditions. Inactivation of the global regulatory hns gene counteracts increased production of LPS and flagella in response to anoxia and allows E. coli W3100 to attach to sand columns even when it is grown under oxygen-limited conditions. We propose that increased production of the FliC protein and of LPS in response to oxygen limitation results in the loss of the ability of E. coli W3100 to adhere to hydrophilic surfaces. Indeed, overexpression of the fliC gene results in a decreased adhesion to sand even when W3100 is grown in fully aerobic conditions. Our observations strongly suggest that anoxia is a negative environmental signal for adhesion in E. coli.

scholarly journals Active Genetic Elements Present in the Locus of Enterocyte Effacement in Escherichia coli O26 and Their Role in Mobility

2006 ◽  
Vol 74 (7) ◽  
pp. 4190-4199 ◽  
Author(s):  
Maite Muniesa ◽  
Mark A. Schembri ◽  
Nadja Hauf ◽  
Trinad Chakraborty
Keyword(s):  
Escherichia Coli ◽  
Direct Repeat ◽  
Gene Encoding ◽  
Integrase Gene ◽  
E Coli ◽  
Recombination Processes ◽  
Strong Homology ◽  
Enterocyte Effacement ◽  
K 12 ◽  
Trna Locus

ABSTRACT The locus of enterocyte effacement (LEE) is a large multigene chromosomal segment encoding gene products responsible for the generation of attaching and effacing lesions in many diarrheagenic Escherichia coli strains. A recently sequenced LEE harboring a pathogenicity island (PAI) from a Shiga toxin E. coli serotype O26 strain revealed a LEE PAI (designated LEE O26) almost identical to that obtained from a rabbit-specific enteropathogenic O15:H− strain. LEE O26 comprises 59,540 bp and is inserted at 94 min within the mature pheU tRNA locus. The LEE O26 PAI is flanked by two direct repeats of 137 and 136 bp (DR1 and DR2), as well as a gene encoding an integrase belonging to the P4 integrase family. We examined LEE O26 for horizontal gene transfer. By generating mini-LEE plasmids harboring only DR1 or DR2 with or without the integrase-like gene, we devised a simple assay to examine recombination processes between these sequences. Recombination was shown to be integrase dependent in a ΔrecA E. coli K-12 strain background. Recombinant plasmids harboring a single direct repeat cloned either with or without the LEE O26 integrase gene were found to insert within the chromosomal pheU locus of E. coli K-12 strains with equal efficiency, suggesting that an endogenous P4-like integrase can substitute for this activity. An integrase with strong homology to the LEE O26 integrase was detected on the K-12 chromosome associated with the leuX tRNA locus at 97 min. Strains deleted for this integrase demonstrated a reduction in the insertion frequency of plasmids harboring only the DR into the pheU locus. These results provide strong evidence that LEE-harboring elements are indeed mobile and suggest that closely related integrases present on the chromosome of E. coli strains contribute to the dynamics of PAI mobility.

scholarly journals Sequence Analysis of the GntII (Subsidiary) System for Gluconate Metabolism Reveals a Novel Pathway for l-Idonic Acid Catabolism in Escherichia coli

1998 ◽  
Vol 180 (14) ◽  
pp. 3704-3710 ◽  
Author(s):  
Christoph Bausch ◽  
Norbert Peekhaus ◽  
Cristina Utz ◽  
Tessa Blais ◽  
Elizabeth Murray ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sequence Analysis ◽  
Genomic Sequence ◽  
Regulatory Protein ◽  
Gene Encoding ◽  
E Coli ◽  
Cell Extracts ◽  
Genomic Sequence Analysis ◽  
Metabolic Sequence ◽  
K 12

ABSTRACT The presence of two systems in Escherichia coli for gluconate transport and phosphorylation is puzzling. The main system, GntI, is well characterized, while the subsidiary system, GntII, is poorly understood. Genomic sequence analysis of the region known to contain genes of the GntII system led to a hypothesis which was tested biochemically and confirmed: the GntII system encodes a pathway for catabolism of l-idonic acid in whichd-gluconate is an intermediate. The genes have been named accordingly: the idnK gene, encoding a thermosensitive gluconate kinase, is monocistronic and transcribed divergently from the idnD-idnO-idnT-idnRoperon, which encodes l-idonate 5-dehydrogenase, 5-keto-d-gluconate 5-reductase, an l-idonate transporter, and an l-idonate regulatory protein, respectively. The metabolic sequence is as follows: IdnT allows uptake of l-idonate; IdnD catalyzes a reversible oxidation ofl-idonate to form 5-ketogluconate; IdnO catalyzes a reversible reduction of 5-ketogluconate to formd-gluconate; IdnK catalyzes an ATP-dependent phosphorylation of d-gluconate to form 6-phosphogluconate, which is metabolized further via the Entner-Doudoroff pathway; and IdnR appears to act as a positive regulator of the IdnR regulon, withl-idonate or 5-ketogluconate serving as the true inducer of the pathway. The l-idonate 5-dehydrogenase and 5-keto-d-gluconate 5-reductase reactions were characterized both chemically and biochemically by using crude cell extracts, and it was firmly established that these two enzymes allow for the redox-coupled interconversion of l-idonate andd-gluconate via the intermediate 5-ketogluconate. E. coli K-12 strains are able to utilize l-idonate as the sole carbon and energy source, and as predicted, the ability ofidnD, idnK, idnR, andedd mutants to grow on l-idonate is altered.

scholarly journals Bacteriophage 2851 Is a Prototype Phage for Dissemination of the Shiga Toxin Variant Gene 2c in Escherichia coli O157:H7

2008 ◽  
Vol 76 (12) ◽  
pp. 5466-5477 ◽  
Author(s):  
Eckhard Strauch ◽  
Jens Andre Hammerl ◽  
Antje Konietzny ◽  
Susanne Schneiker-Bekel ◽  
Walter Arnold ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Nucleotide Sequence Analysis ◽  
Escherichia Coli O157 ◽  
Gene Encoding ◽  
Reading Frame ◽  
Shiga Toxins ◽  
E Coli ◽  
K 12 ◽  
Specific Sequences

ABSTRACT The production of Shiga toxin (Stx) (verocytotoxin) is a major virulence factor of Escherichia coli O157:H7 strains (Shiga toxin-producing E. coli [STEC] O157). Two types of Shiga toxins, designated Stx1 and Stx2, are produced in STEC O157. Variants of the Stx2 type (Stx2, Stx2c) are associated with high virulences of these strains for humans. A bacteriophage designated 2851 from a human STEC O157 encoding the Stx2c variant was described previously. Nucleotide sequence analysis of the phage 2851 genome revealed 75 predicted coding sequences and indicated a mosaic structure typical for lambdoid phages. Analyses of free phages and K-12 phage 2851 lysogens revealed that upon excision from the bacterial chromosome, the loss of a phage-encoded IS629 element leads to fusion of phage antA and antB genes, with the generation of a recombined antAB gene encoding a strong antirepressor. In wild-type E. coli O157 as well as in K-12 strains, phage 2851 was found to be integrated in the sbcB locus. Additionally, phage 2851 carries an open reading frame which encodes an OspB-like type III effector similar to that found in Shigella spp. Investigation of 39 stx 2c E. coli O157 strains revealed that all except 1 were positive for most phage 2851-specific genes and possessed a prophage with the same border sequences integrated into the sbcB locus. Phage 2851-specific sequences were absent from most stx 2c-negative E. coli O157 strains, and we suggest that phage 2851-like phages contributed significantly to the dissemination of the Stx2c variant toxin within this group of E. coli.

scholarly journals Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 691-702 ◽  
Author(s):  
B L Berg ◽  
V Stewart
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Formate Dehydrogenase ◽  
Recombinant Dna ◽  
Structural Genes ◽  
Respiratory Pathway ◽  
E Coli ◽  
Formate Oxidation ◽  
Operon Expression ◽  
K 12

Abstract Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

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.

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