scholarly journals Curli Fibers Are Highly Conserved between Salmonella typhimurium and Escherichia coli with Respect to Operon Structure and Regulation

1998 ◽  
Vol 180 (3) ◽  
pp. 722-731 ◽  
Author(s):  
Ute Römling ◽  
Zhao Bian ◽  
Mårten Hammar ◽  
Walter D. Sierralta ◽  
Staffan Normark
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Transcriptional Activation ◽  
Protein Level ◽  
Amino Acid Homology ◽  
E Coli ◽  
Low Copy Number ◽  
High Level ◽  
High Degree

ABSTRACT Mouse-virulent Salmonella typhimurium strains SR-11 and ATCC 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by Western blot analysis and electron microscopy. Concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye Congo red (called the rdar morphotype). Cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgBA(C)and csgDEFG, from S. typhimurium SR-11 revealed the same gene order and flanking genes as in Escherichia coli. The divergence of the curli region between S. typhimurium and E. coli at the nucleotide level is above average (22.4%). However, a high level of conservation at the protein level, which ranged from 86% amino acid homology for the fiber subunit CsgA to 99% homology for the lipoprotein CsgG, implies functional constraints on the gene products. Consequently, S. typhimurium genes on low-copy-number plasmids were able to complement respective E. coli mutants, although not always to wild-type levels. rpoS and ompR are required for transcriptional activation of (at least) the csgDpromoter. The high degree of conservation at the protein level and the identical regulation patterns in E. coli and S. typhimurium suggest similar roles of curli fibers in the same ecological niche in the two species.

scholarly journals A qnr-plasmid allows aminoglycosides to induce SOS in Escherichia coli

2021 ◽  
Author(s):  
Anamaria Babosan ◽  
David Skurnik ◽  
Anaëlle Muggeo ◽  
Gerald Pier ◽  
Thomas Jové ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Resistance ◽  
Sos Response ◽  
E Coli ◽  
Fluoroquinolone Antibiotics ◽  
Plasmid Genes ◽  
High Level ◽  
Emergence Of Resistance ◽  
Fad Binding

The plasmid-mediated quinolone resistance (PMQR) genes have been shown to promote high level bacterial resistance to fluoroquinolone antibiotics, potentially leading to clinical treatment failures. In Escherichia coli, sub-inhibitory concentrations (sub-MIC) of the widely used fluoroquinolones are known to induce the SOS response. Interestingly, the expression of several PMQR qnr genes is controlled by the SOS master regulator. During the characterization of a small qnrD-plasmid carried in E. coli, we observed that the aminoglycosides become able to induce the SOS response in this species, thus leading to the transcription of qnrD. We found that induction of the SOS response is due to nitric oxide (NO) accumulation in presence of sub-MIC of aminoglycosides. We demonstrated that the NO accumulation is driven by two plasmid genes, ORF3 and ORF4, whose products act at two levels. ORF3 encode a FAD-binding oxidoreductase which helps NO synthesis, while ORF4 code for an FNR-type transcription factor, related to an O2-responsive regulator of hmp expression, able to repress the Hmp-mediated NO detoxification pathway of E. coli. Thus, this discovery, that other major classes of antibiotics may induce the SOS response could have worthwhile implications for antibiotic stewardship efforts in preventing the emergence of resistance.

Genomic characterization of 16S rRNA methyltransferase-producing Escherichia coli isolates from the Parisian area, France

2020 ◽  
Vol 75 (7) ◽  
pp. 1726-1735 ◽  
Author(s):  
François Caméléna ◽  
Florence Morel ◽  
Manel Merimèche ◽  
Jean-Winoc Decousser ◽  
Hervé Jacquier ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
16S Rrna ◽  
Genomic Diversity ◽  
Health Concern ◽  
M Gene ◽  
Genetic Environment ◽  
E Coli ◽  
Genomic Characterization ◽  
High Level

Abstract Background The resistance to all aminoglycosides (AGs) conferred by 16S rRNA methyltransferase enzymes (16S-RMTases) is a major public health concern. Objectives To characterize the resistance genotype, its genetic environment and plasmid support, and the phylogenetic relatedness of 16S-RMTase-producing Escherichia coli from France. Methods We screened 137 E. coli isolates resistant to all clinically relevant AGs from nine Parisian hospitals for 16S-RMTases. WGS was performed on clinical isolates with high-level AG resistance (MIC ≥256 mg/L) and their transformants. Results Thirty of the 137 AG-resistant E. coli produced 16S-RMTases: 11 ArmA, 18 RmtB and 1 RmtC. The 16S-RMTase producers were also resistant to third-generation cephalosporins (90% due to a blaCTX-M gene), co-trimoxazole, fluoroquinolones and carbapenems (blaNDM and blaVIM genes) in 97%, 83%, 70% and 10% of cases, respectively. Phylogenomic diversity was high in ArmA producers, with 10 different STs, but a similar genetic environment, with the Tn1548 transposon carried by a plasmid closely related to pCTX-M-3 in 6/11 isolates. Conversely, RmtB producers belonged to 12 STs, the most frequent being ST405 and ST complex (STc) 10 (four and four isolates, respectively). The rmtB gene was carried by IncF plasmids in 10 isolates and was found in different genetic environments. The rmtC gene was carried by the pNDM-US plasmid. Conclusions ArmA and RmtB are the predominant 16S-RMTases in France, but their spread follows two different patterns: (i) dissemination of a conserved genetic support carrying armA in E. coli with high levels of genomic diversity; and (ii) various genetic environments surrounding rmtB in clonally related E. coli.

scholarly journals Evaluation of Virulence Factor Profiling in the Characterization of Veterinary Escherichia coli Isolates

2010 ◽  
Vol 76 (22) ◽  
pp. 7509-7513 ◽  
Author(s):  
Donna E. David ◽  
Aaron M. Lynne ◽  
Jing Han ◽  
Steven L. Foley
Keyword(s):  
Escherichia Coli ◽  
Virulence Factor ◽  
Pcr Analysis ◽  
Animal Host ◽  
Fourth Group ◽  
E Coli ◽  
Animal Source ◽  
Components Analysis ◽  
High Degree

ABSTRACT Escherichia coli has been used as an indicator organism for fecal contamination of water and other environments and is often a commensal organism in healthy animals, yet a number of strains can cause disease in young or immunocompromised animals. In this study, 281 E. coli isolates from bovine, porcine, chicken, canine, equine, feline, and other veterinary sources were analyzed by BOXA1R PCR and by virulence factor profiling of 35 factors to determine whether they had utility in identifying the animal source of the isolates. The results of BOXA1R PCR analysis demonstrated a high degree of diversity; less than half of the isolates fell into one of 27 clusters with at least three isolates (based on 90% similarity). Nearly 60% of these clusters contained isolates from more than one animal source. Conversely, the results of virulence factor profiling demonstrated clustering by animal source. Three clusters, named Bovine, Chicken, and Porcine, based on discriminant components analysis, were represented by 90% or more of the respective isolates. A fourth group, termed Companion, was the most diverse, containing at least 84% of isolates from canine, feline, equine, and other animal sources. Based on these results, it appears that virulence factor profiling may have utility, helping identify the likely animal host species sources of certain E. coli isolates.

scholarly journals Characterization of the fomA andfomB Gene Products from Streptomyces wedmorensis, Which Confer Fosfomycin Resistance on Escherichia coli

2000 ◽  
Vol 44 (3) ◽  
pp. 647-650 ◽  
Author(s):  
Seiji Kobayashi ◽  
Tomohisa Kuzuyama ◽  
Haruo Seto
Keyword(s):  
Escherichia Coli ◽  
Resistance Mechanism ◽  
Biosynthetic Gene Cluster ◽  
Magnesium Ion ◽  
Gene Products ◽  
Biosynthetic Gene ◽  
E Coli ◽  
Fosfomycin Resistance ◽  
High Level

ABSTRACT Together, the fomA and fomB genes in the fosfomycin biosynthetic gene cluster of Streptomyces wedmorensis confer high-level fosfomycin resistance onEscherichia coli. To elucidate their functions, thefomA and fomB genes were overexpressed inE. coli and the gene products were characterized. The recombinant FomA protein converted fosfomycin to fosfomycin monophosphate, which was inactive on E. coli, in the presence of a magnesium ion and ATP. On the other hand, the recombinant FomB protein did not inactivate fosfomycin. However, a reaction mixture containing FomA and FomB proteins converted fosfomycin to fosfomycin monophosphate and fosfomycin diphosphate in the presence of ATP and a magnesium ion, indicating that FomA and FomB catalyzed phosphorylations of fosfomycin and fosfomycin monophosphate, respectively. These results suggest that the self-resistance mechanism of the fosfomycin-producing organism S. wedmorensis is mono- and diphosphorylation of the phosphonate function of fosfomycin catalyzed by FomA and FomB.

scholarly journals Preparation and characterization of human interleukin-5 expressed in recombinant Escherichia coli

1990 ◽  
Vol 270 (2) ◽  
pp. 357-361 ◽  
Author(s):  
A E I Proudfoot ◽  
D Fattah ◽  
E H Kawashima ◽  
A Bernard ◽  
P T Wingfield
Keyword(s):  
Escherichia Coli ◽  
Inducible Promoter ◽  
Cellular Protein ◽  
Biological Assays ◽  
Interleukin 5 ◽  
E Coli ◽  
Gene Coding ◽  
High Level

The gene coding for human interleukin-5 was synthesized and expressed in Escherichia coli under control of a heat-inducible promoter. High-level expression, 10-15% of total cellular protein, was achieved in E. coli. The protein was produced in an insoluble state. A simple extraction, renaturation and purification scheme is described. The recombinant protein was found to be a homodimer, similar to the natural murine-derived protein. Despite the lack of glycosylation, high specific activities were obtained in three ‘in vitro’ biological assays. Physical characterization of the protein showed it to be mostly alpha-helical, supporting the hypothesis that a conformational similarity exists among certain cytokines.

scholarly journals Distribution of espM and espT among enteropathogenic and enterohaemorrhagic Escherichia coli

2009 ◽  
Vol 58 (8) ◽  
pp. 988-995 ◽  
Author(s):  
Ana Arbeloa ◽  
Miguel Blanco ◽  
Fabiana C. Moreira ◽  
Richard Bulgin ◽  
Cecilia López ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rho Gtpases ◽  
Virulence Gene ◽  
Gene Repertoire ◽  
E Coli ◽  
Enterohaemorrhagic Escherichia Coli ◽  
Household Members ◽  
High Level ◽  
Human Infections

Enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) translocate dozens of type III secretion system effectors, including the WxxxE effectors Map, EspM and EspT that activate Rho GTPases. While map, which is carried on the LEE pathogenicity island, is absolutely conserved among EPEC and EHEC strains, the prevalence of espM and espT is not known. Here we report the results of a large screen aimed at determining the prevalence of espM and espT among clinical EPEC and EHEC isolates. The results suggest that espM, detected in 51 % of the tested strains, is more commonly found in EPEC and EHEC serogroups that are linked to severe human infections. In contrast, espT was absent from all the EHEC isolates and was found in only 1.8 % of the tested EPEC strains. Further characterization of the virulence gene repertoire of the espT-positive strains led to the identification of a new ζ2 intimin variant. All the espT-positive strains but two contained the tccP gene. espT was first found in Citrobacter rodentium and later in silico in EPEC E110019, which is of particular interest as this strain was responsible for a particularly severe diarrhoeal outbreak in Finland in 1987 that affected 650 individuals in a school complex and an additional 137 associated household members. Comparing the protein sequences of EspT to that of E110019 showed a high level of conservation, with only three strains encoding EspT that differed in 6 amino acids. At present, it is not clear why espT is so rare, and what impact EspM and EspT have on EPEC and EHEC infection.

scholarly journals Escherichia coli Malic Enzymes: Two Isoforms with Substantial Differences in Kinetic Properties, Metabolic Regulation, and Structure

2007 ◽  
Vol 189 (16) ◽  
pp. 5937-5946 ◽  
Author(s):  
Federico P. Bologna ◽  
Carlos S. Andreo ◽  
María F. Drincovich
Keyword(s):  
Escherichia Coli ◽  
Metal Ion ◽  
Metabolic Regulation ◽  
Oxidative Decarboxylation ◽  
Kinetic Properties ◽  
Oligomeric State ◽  
E Coli ◽  
Divalent Metal Ion ◽  
High Degree

ABSTRACT Malic enzymes (MEs) catalyze the oxidative decarboxylation of malate in the presence of a divalent metal ion. In eukaryotes, well-conserved cytoplasmic, mitochondrial, and plastidic MEs have been characterized. On the other hand, distinct groups can be detected among prokaryotic MEs, which are more diverse in structure and less well characterized than their eukaryotic counterparts. In Escherichia coli, two genes with a high degree of homology to ME can be detected: sfcA and maeB. MaeB possesses a multimodular structure: the N-terminal extension shows homology to ME, while the C-terminal extension shows homology to phosphotransacetylases (PTAs). In the present work, a detailed characterization of the products of E. coli sfcA and maeB was performed. The results indicate that the two MEs exhibit relevant kinetic, regulatory, and structural differences. SfcA is a NAD(P) ME, while MaeB is a NADP-specific ME highly regulated by key metabolites. Characterization of truncated versions of MaeB indicated that the PTA domain is not essential for the ME reaction. Nevertheless, truncated MaeB without the PTA domain loses most of its metabolic ME modulation and its native oligomeric state. Thus, the association of the two structural domains in MaeB seems to facilitate metabolic control of the enzyme. Although the PTA domain in MaeB is highly similar to the domains of proteins with PTA activity, MaeB and its PTA domain do not exhibit PTA activity. Determination of the distinct properties of recombinant products of sfcA and maeB performed in the present work will help to clarify the roles of MEs in prokaryotic metabolism.

scholarly journals Characterization of a Group of Anaerobically Induced, fnr-Dependent Genes of Salmonella typhimurium

1999 ◽  
Vol 181 (19) ◽  
pp. 6092-6097 ◽  
Author(s):  
Yan Wei ◽  
Charles G. Miller
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Dna Sequence ◽  
Abc Transporter ◽  
E Coli

ABSTRACT We have previously reported the isolation of a group of anaerobically regulated, fnr-dependent lacfusions in Salmonella typhimurium and have grouped theseoxd genes into classes based on map position. In order to identify these genes, we have replaced the original Mud-lacfusion in a member of each oxd class with the much smaller Mud-cam element, cloned the fusion, and determined DNA sequence sufficient to define the oxd gene. Several of the fusions correspond to previously known genes from S. typhimurium or Escherichia coli: oxd-4 = cbiA and oxd-11 = cbiK, oxd-5 = hybB, oxd-7 = dcuB, oxd-8 = moaB, oxd-12 = dmsA, and oxd-14 = napB (aeg-46.5). Two other fusions correspond to previously unknown loci: oxd-2 encodes an acetate/propionate kinase, and oxd-6 encodes a putative ABC transporter present in S. typhimurium but not in E. coli.

scholarly journals Sequence Analysis and Characterization of a Transferable Hybrid Plasmid Encoding Multidrug Resistance and Enabling Zoonotic Potential for Extraintestinal Escherichia coli

2010 ◽  
Vol 78 (5) ◽  
pp. 1931-1942 ◽  
Author(s):  
Timothy J. Johnson ◽  
Dianna Jordan ◽  
Subhashinie Kariyawasam ◽  
Adam L. Stell ◽  
Nathan P. Bell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistance ◽  
Sequence Analysis ◽  
Rat Model ◽  
Antimicrobial Agents ◽  
Neonatal Meningitis ◽  
E Coli ◽  
High Level ◽  
Plasmid Backbone

ABSTRACT ColV plasmids of extraintestinal pathogenic Escherichia coli (ExPEC) encode a variety of fitness and virulence factors and have long been associated with septicemia and avian colibacillosis. These plasmids are found significantly more often in ExPEC, including ExPEC associated with human neonatal meningitis and avian colibacillosis, than in commensal E. coli. Here we describe pAPEC-O103-ColBM, a hybrid RepFIIA/FIB plasmid harboring components of the ColV pathogenicity island and a multidrug resistance (MDR)-encoding island. This plasmid is mobilizable and confers the ability to cause septicemia in chickens, the ability to cause bacteremia resulting in meningitis in the rat model of human disease, and the ability to resist the killing effects of multiple antimicrobial agents and human serum. The results of a sequence analysis of this and other ColV plasmids supported previous findings which indicated that these plasmid types arose from a RepFIIA/FIB plasmid backbone on multiple occasions. Comparisons of pAPEC-O103-ColBM with other sequenced ColV and ColBM plasmids indicated that there is a core repertoire of virulence genes that might contribute to the ability of some ExPEC strains to cause high-level bacteremia and meningitis in a rat model. Examination of a neonatal meningitis E. coli (NMEC) population revealed that approximately 58% of the isolates examined harbored ColV-type plasmids and that 26% of these plasmids had genetic contents similar to that of pAPEC-O103-ColBM. The linkage of the ability to confer MDR and the ability contribute to multiple forms of human and animal disease on a single plasmid presents further challenges for preventing and treating ExPEC infections.

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