scholarly journals Specific Properties of Enteropathogenic Escherichia coli Isolates from Diarrheal Patients and Comparison to Strains from Foods and Fecal Specimens from Cattle, Swine, and Healthy Carriers in Osaka City, Japan

2012 ◽  
Vol 79 (4) ◽  
pp. 1232-1240 ◽  
Author(s):  
Lili Wang ◽  
Mitsuko Wakushima ◽  
Tetsu Aota ◽  
Yuka Yoshida ◽  
Toshimasa Kita ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Domestic Animals ◽  
Content Type ◽  
E Coli ◽  
Membrane Filters ◽  
Healthy Humans ◽  
Group I ◽  
Virulence Group ◽  
Healthy Carriers

ABSTRACTFor exhaustive detection of diarrheagenicEscherichia coli, we previously developed a colony-hybridization method using hydrophobic grid-membrane filters in combination with multiplex real-time PCR. To assess the role of domestic animals as the source of atypical enteropathogenicE. coli(aEPEC), a total of 679 samples (333 from foods, fecal samples from 227 domestic animals, and 119 from healthy people) were examined. Combining 48 strains previously isolated from patients and carriers, 159 aEPEC strains were classified by phylogroup, virulence profile, and intimin typing. Phylogroup B1 was significantly more prevalent among aEPEC from patients (50%) and bovine samples (79%) than from healthy carriers (16%) and swine strains (23%), respectively. Intimin type β1 was predominant in phylogroup B1; B1-β1 strains comprised 26% of bovine strains and 25% of patient strains. The virulence profile groups Ia and Ib were also observed more frequently among bovine strains than among porcine strains. Similarly, virulence group Ia was detected more frequently among patient strains than strains of healthy carriers. A total of 85 strains belonged to virulence group I, and 63 of these strains (74%) belonged to phylogroup B1. The present study suggests that the etiologically important aEPEC in diarrheal patients could be distinguished from aEPEC strains indigenous to humans based on type, such as B1, Ia, and β1/γ1, which are shared with bovine strains, while the aEPEC strains in healthy humans are different, and some of these were also present in porcine samples.

scholarly journals Role of the Vpe Carbohydrate Permease in Escherichia coli Urovirulence and FitnessIn Vivo

2012 ◽  
Vol 80 (8) ◽  
pp. 2655-2666 ◽  
Author(s):  
Vanessa Martinez-Jéhanne ◽  
Christophe Pichon ◽  
Laurence du Merle ◽  
Olivier Poupel ◽  
Nadège Cayet ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mouse Model ◽  
Sugar Transport ◽  
Gene Clusters ◽  
Content Type ◽  
E Coli ◽  
Healthy Humans ◽  
Gut Colonization

ABSTRACTUropathogenicEscherichia coli(UPEC) strains are a leading cause of infections in humans, but the mechanisms governing host colonization by this bacterium remain poorly understood. Previous studies have identified numerous gene clusters encoding proteins involved in sugar transport, in pathogen-specific islands. We investigated the role in fitness and virulence of thevpeoperon encoding an EII complex of the phosphotransferase (PTS) system, which is found more frequently in human strains from infected urine and blood (45%) than inE. coliisolated from healthy humans (15%). We studied the role of this locusin vivo, using the UPECE. colistrain AL511, mutants, and complemented derivatives in two experimental mouse models of infection. Mutant strains displayed attenuated virulence in a mouse model of sepsis. A role in kidney colonization was also demonstrated by coinfection experiments in a mouse model of pyelonephritis. Electron microscopy examinations showed that thevpeBCmutant produced much smaller amounts of a capsule-like surface material than the wild type, particularly when growing in human urine. Complementation of thevpeBCmutation led to an increase in the amount of exopolysaccharide, resistance to serum killing, and virulence. It was therefore clear that the loss ofvpegenes was responsible for all the observed phenotypes. We also demonstrated the involvement of thevpelocus in gut colonization in the streptomycin-treated mouse model of intestinal colonization. These findings confirm that carbohydrate transport and metabolism underlie the ability of UPEC strains to colonize the host intestine and to infect various host sites.

scholarly journals Genotypic and Phenotypic Traits That Distinguish Neonatal Meningitis-Associated Escherichia coli from Fecal E. coli Isolates of Healthy Human Hosts

2012 ◽  
Vol 78 (16) ◽  
pp. 5824-5830 ◽  
Author(s):  
Catherine M. Logue ◽  
Curt Doetkott ◽  
Paul Mangiamele ◽  
Yvonne M. Wannemuehler ◽  
Timothy J. Johnson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Phylogenetic Group ◽  
Neonatal Meningitis ◽  
Phenotypic Traits ◽  
Healthy Human ◽  
Content Type ◽  
Plasmid Content ◽  
E Coli ◽  
Healthy Humans ◽  
Definition Of

ABSTRACTNeonatal meningitisEscherichia coli(NMEC) is one of the top causes of neonatal meningitis worldwide. Here, 85 NMEC and 204 fecalE. coliisolates from healthy humans (HFEC) were compared for possession of traits related to virulence, antimicrobial resistance, and plasmid content. This comparison was done to identify traits that typify NMEC and distinguish it from commensal strains to refine the definition of the NMEC subpathotype, identify traits that might contribute to NMEC pathogenesis, and facilitate choices of NMEC strains for future study. A large number ofE. colistrains from both groups were untypeable, with the most common serogroups occurring among NMEC being O18, followed by O83, O7, O12, and O1. NMEC strains were more likely than HFEC strains to be assigned to the B2 phylogenetic group. Few NMEC or HFEC strains were resistant to antimicrobials. Genes that best discriminated between NMEC and HFEC strains and that were present in more than 50% of NMEC isolates were mainly from extraintestinal pathogenicE. coligenomic and plasmid pathogenicity islands. Several of these defining traits had not previously been associated with NMEC pathogenesis, are of unknown function, and are plasmid located. Several genes that had been previously associated with NMEC virulence did not dominate among the NMEC isolates. These data suggest that there is much about NMEC virulence that is unknown and that there are pitfalls to studying single NMEC isolates to represent the entire subpathotype.

scholarly journals Molecular Characterization of Commensal Escherichia coli Adapted to Different Compartments of the Porcine Gastrointestinal Tract

2012 ◽  
Vol 78 (19) ◽  
pp. 6799-6803 ◽  
Author(s):  
Sam Abraham ◽  
David M. Gordon ◽  
James Chin ◽  
Huub J. M. Brouwers ◽  
Peter Njuguna ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Tract ◽  
Random Amplified Polymorphic Dna ◽  
Content Type ◽  
E Coli ◽  
Plasmid Replicon ◽  
Different Strains ◽  
Different Characteristics

ABSTRACTThe role ofEscherichia colias a pathogen has been the focus of considerable study, while much less is known about it as a commensal and how it adapts to and colonizes different environmental niches within the mammalian gut. In this study, we characterizeEscherichia coliorganisms (n= 146) isolated from different regions of the intestinal tracts of eight pigs (dueodenum, ileum, colon, and feces). The isolates were typed using the method of random amplified polymorphic DNA (RAPD) and screened for the presence of bacteriocin genes and plasmid replicon types. Molecular analysis of variance using the RAPD data showed thatE. coliisolates are nonrandomly distributed among different gut regions, and that gut region accounted for 25% (P< 0.001) of the observed variation among strains. Bacteriocin screening revealed that a bacteriocin gene was detected in 45% of the isolates, with 43% carrying colicin genes and 3% carrying microcin genes. Of the bacteriocins observed (H47, E3, E1, E2, E7, Ia/Ib, and B/M), the frequency with which they were detected varied with respect to gut region for the colicins E2, E7, Ia/Ib, and B/M. The plasmid replicon typing gave rise to 25 profiles from the 13 Inc types detected. Inc F types were detected most frequently, followed by Inc HI1 and N types. Of the Inc types detected, 7 were nonrandomly distributed among isolates from the different regions of the gut. The results of this study indicate that not only may the different regions of the gastrointestinal tract harbor different strains ofE. colibut also that strains from different regions have different characteristics.

scholarly journals Transcription of the Subtilase Cytotoxin Gene subAB1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns

2019 ◽  
Vol 85 (20) ◽  
Author(s):  
Laura Heinisch ◽  
Katharina Zoric ◽  
Maike Krause ◽  
Herbert Schmidt
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Shiga Toxin ◽  
Promoter Activity ◽  
Deletion Mutants ◽  
Content Type ◽  
E Coli ◽  
Intensive Investigation ◽  
Subtilase Cytotoxin

ABSTRACT Certain foodborne Shiga toxin-producing Escherichia coli (STEC) strains carry genes encoding the subtilase cytotoxin (SubAB). Although the mode of action of SubAB is under intensive investigation, information about the regulation of subAB gene expression is currently not available. In this study, we investigated the regulation of the chromosomal subAB1 gene in laboratory E. coli strain DH5α and STEC O113:H21 strain TS18/08 using a luciferase reporter gene assay. Special emphasis was given to the role of the global regulatory protein genes hfq and hns in subAB1 promoter activity. Subsequently, quantitative real-time PCR was performed to analyze the expression of Shiga toxin 2a (Stx2a), SubAB1, and cytolethal distending toxin V (Cdt-V) genes in STEC strain TS18/08 and its isogenic hfq and hns deletion mutants. The deletion of hfq led to a significant increase of up to 2-fold in subAB1 expression, especially in the late growth phase, in both strains. However, deletion of hns showed different effects on the promoter activity during the early and late exponential growth phases in both strains. Furthermore, upregulation of stx2a and cdt-V was demonstrated in hfq and hns deletion mutants in TS18/08. These data showed that the expression of subAB1, stx2a, and cdt-V is integrated in the regulatory network of global regulators Hfq and H-NS in Escherichia coli. IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) strains are responsible for outbreaks of foodborne diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. The pathogenicity of those strains can be attributed to, among other factors, the production of toxins. Recently, the subtilase cytotoxin was detected in locus of enterocyte effacement (LEE)-negative STEC, and it was confirmed that it contributes to the cytotoxicity of those STEC strains. Although the mode of action of SubAB1 is under intensive investigation, the regulation of gene expression is currently not known. The global regulatory proteins H-NS and Hfq have impact on many cellular processes and have been described to regulate virulence factors as well. Here, we investigate the role of hns and hfq in expression of subAB1 as well as stx2a and cdt-V in an E. coli laboratory strain as well as in wild-type STEC strain TS18/08.

scholarly journals Bacterial Dose-Dependent Role of G Protein-Coupled Receptor Kinase 5 in Escherichia coli-Induced Pneumonia

2016 ◽  
Vol 84 (5) ◽  
pp. 1633-1641 ◽  
Author(s):  
Nandakumar Packiriswamy ◽  
Michael Steury ◽  
Ian C. McCabe ◽  
Scott D. Fitzgerald ◽  
Narayanan Parameswaran
Keyword(s):  
Escherichia Coli ◽  
G Protein ◽  
Lethal Dose ◽  
Neutrophil Recruitment ◽  
Sublethal Dose ◽  
Receptor Kinase ◽  
Content Type ◽  
E Coli ◽  
G Protein Coupled

G protein-coupled receptor kinase 5 (GRK5) is a serine/threonine kinase previously shown to mediate polymicrobial sepsis-induced inflammation. The goal of the present study was to examine the role of GRK5 in monomicrobial pulmonary infection by using an intratrachealEscherichia coliinfection model of pneumonia. We used sublethal and lethal doses ofE. colito examine the mechanistic differences between low-grade and high-grade inflammation induced byE. coliinfection. With a sublethal dose ofE. coli, GRK5 knockout (KO) mice exhibited higher plasma CXCL1/KC levels and enhanced lung neutrophil recruitment early after infection, and lower bacterial loads, than wild-type (WT) mice. The inflammatory response was also diminished, and resolution of inflammation advanced, in the lungs of GRK5 KO mice. In contrast to the reduced bacterial loads in GRK5 KO mice following a sublethal dose, at a lethal dose ofE. coli, the bacterial burdens remained high in GRK5 KO mice relative to those in WT mice. This occurred in spite of enhanced plasma CXCL1 levels as well as neutrophil recruitment in the KO mice. But the recruited neutrophils (following high-dose infection) exhibited decreased CD11b expression and reduced reactive oxygen species production, suggesting decreased neutrophil activation or increased neutrophil exhaustion in the GRK5 KO mice. In agreement with the increased bacterial burden, KO mice showed poorer survival than WT mice followingE. coliinfection at a lethal dose. Overall, our data suggest that GRK5 negatively regulates CXCL1/KC levels during bacterial pneumonia but that the role of GRK5 in the clinical outcome in this model is dependent on the bacterial dose.

scholarly journals Association of ω with the C-Terminal Region of the β′ Subunit Is Essential for Assembly of RNA Polymerase in Mycobacterium tuberculosis

2018 ◽  
Vol 200 (12) ◽  
Author(s):  
Chunyou Mao ◽  
Yan Zhu ◽  
Pei Lu ◽  
Lipeng Feng ◽  
Shiyun Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Essential Role ◽  
Β Subunit ◽  
Content Type ◽  
E Coli ◽  
Core Enzyme ◽  
Loop Region

ABSTRACT The ω subunit is the smallest subunit of bacterial RNA polymerase (RNAP). Although homologs of ω are essential in both eukaryotes and archaea, this subunit has been known to be dispensable for RNAP in Escherichia coli and in other bacteria. In this study, we characterized an indispensable role of the ω subunit in Mycobacterium tuberculosis . Unlike the well-studied E. coli RNAP, the M. tuberculosis RNAP core enzyme cannot be functionally assembled in the absence of the ω subunit. Importantly, substitution of M. tuberculosis ω with ω subunits from E. coli or Thermus thermophilus cannot restore the assembly of M. tuberculosis RNAP. Furthermore, by replacing different regions in M. tuberculosis ω with the corresponding regions from E. coli ω, we found a nonconserved loop region in M. tuberculosis ω essential for its function in RNAP assembly. From RNAP structures, we noticed that the location of the C-terminal region of the β′ subunit (β′CTD) in M. tuberculosis RNAP but not in E. coli or T. thermophilus RNAP is close to the ω loop region. Deletion of this β′CTD in M. tuberculosis RNAP destabilized the binding of M. tuberculosis ω on RNAP and compromised M. tuberculosis core assembly, suggesting that these two regions may function together to play a role in ω-dependent RNAP assembly in M. tuberculosis . Sequence alignment of the ω loop and the β′CTD regions suggests that the essential role of ω is probably restricted to mycobacteria. Together, our study characterized an essential role of M. tuberculosis ω and highlighted the importance of the ω loop region in M. tuberculosis RNAP assembly. IMPORTANCE DNA-dependent RNA polymerase (RNAP), which consists of a multisubunit core enzyme (α 2 ββ′ω) and a dissociable σ subunit, is the only enzyme in charge of transcription in bacteria. As the smallest subunit, the roles of ω remain the least well studied. In Escherichia coli and some other bacteria, the ω subunit is known to be nonessential for RNAP. In this study, we revealed an essential role of the ω subunit for RNAP assembly in the human pathogen Mycobacterium tuberculosis , and a mycobacterium-specific ω loop that plays a role in this function was also characterized. Our study provides fresh insights for further characterizing the roles of bacterial ω subunit.

scholarly journals The Ribosomal S10 Protein Is a General Target for Decreased Tigecycline Susceptibility

2015 ◽  
Vol 59 (9) ◽  
pp. 5561-5566 ◽  
Author(s):  
Kathryn Beabout ◽  
Troy G. Hammerstrom ◽  
Anisha Maria Perez ◽  
Bárbara Freitas Magalhães ◽  
Amy G. Prater ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Binding Pocket ◽  
Gram Positive ◽  
Content Type ◽  
E Coli ◽  
Species Cluster ◽  
Wide Range ◽  
Translational Inhibitor

ABSTRACTTigecycline is a translational inhibitor with efficacy against a wide range of pathogens. Using experimental evolution, we adaptedAcinetobacter baumannii,Enterococcus faecium,Escherichia coli, andStaphylococcus aureusto growth in elevated tigecycline concentrations. At the end of adaptation, 35 out of 47 replicate populations had clones with a mutation inrpsJ, the gene that encodes the ribosomal S10 protein. To validate the role of mutations inrpsJin conferring tigecycline resistance, we showed that mutation ofrpsJalone inEnterococcus faecaliswas sufficient to increase the tigecycline MIC to the clinical breakpoint of 0.5 μg/ml. Importantly, we also report the first identification ofrpsJmutations associated with decreased tigecycline susceptibility inA. baumannii,E. coli, andS. aureus. The identified S10 mutations across both Gram-positive and -negative species cluster in the vertex of an extended loop that is located near the tigecycline-binding pocket within the 16S rRNA. These data indicate that S10 is a general target of tigecycline adaptation and a relevant marker for detecting reduced susceptibility in both Gram-positive and -negative pathogens.

scholarly journals Distinct Requirements for Tail-Anchored Membrane Protein Biogenesis in Escherichia coli

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Markus Peschke ◽  
Mélanie Le Goff ◽  
Gregory M. Koningstein ◽  
Norbert O. Vischer ◽  
Abbi Abdel-Rehim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Transmembrane Domain ◽  
Signal Recognition Particle ◽  
Membrane Insertion ◽  
Type Ii ◽  
Content Type ◽  
E Coli ◽  
C Terminus

ABSTRACT Tail-anchored membrane proteins (TAMPs) are a distinct subset of inner membrane proteins (IMPs) characterized by a single C-terminal transmembrane domain (TMD) that is responsible for both targeting and anchoring. Little is known about the routing of TAMPs in bacteria. Here, we have investigated the role of TMD hydrophobicity in tail-anchor function in Escherichia coli and its influence on the choice of targeting/insertion pathway. We created a set of synthetic, fluorescent TAMPs that vary in the hydrophobicity of their TMDs and corresponding control polypeptides that are extended at their C terminus to create regular type II IMPs. Surprisingly, we observed that TAMPs have a much lower TMD hydrophobicity threshold for efficient targeting and membrane insertion than their type II counterparts. Using strains conditional for the expression of known membrane-targeting and insertion factors, we show that TAMPs with strongly hydrophobic TMDs require the signal recognition particle (SRP) for targeting. Neither the SecYEG translocon nor YidC appears to be essential for the membrane insertion of any of the TAMPs studied. In contrast, corresponding type II IMPs with a TMD of sufficient hydrophobicity to promote membrane insertion followed an SRP- and SecYEG translocon-dependent pathway. Together, these data indicate that the capacity of a TMD to promote the biogenesis of E. coli IMPs is strongly dependent upon the polypeptide context in which it is presented. IMPORTANCE A subset of membrane proteins is targeted to and inserted into the membrane via a hydrophobic transmembrane domain (TMD) that is positioned at the very C terminus of the protein. The biogenesis of these so-called tail-anchored proteins (TAMPs) has been studied in detail in eukaryotic cells. Various partly redundant pathways were identified, the choice for which depends in part on the hydrophobicity of the TMD. Much less is known about bacterial TAMPs. The significance of our research is in identifying the role of TMD hydrophobicity in the routing of E. coli TAMPs. Our data suggest that both the nature of the TMD and its role in routing can be very different for TAMPs versus “regular” membrane proteins. Elucidating these position-specific effects of TMDs will increase our understanding of how prokaryotic cells face the challenge of producing a wide variety of membrane proteins.

scholarly journals ThechbGGene of the Chitobiose (chb) Operon of Escherichia coli Encodes a Chitooligosaccharide Deacetylase

2012 ◽  
Vol 194 (18) ◽  
pp. 4959-4971 ◽  
Author(s):  
Subhash Chandra Verma ◽  
Subramony Mahadevan
Keyword(s):  
Escherichia Coli ◽  
Metal Binding ◽  
Inflammatory Diseases ◽  
Regulatory Protein ◽  
Loss Of Function ◽  
Content Type ◽  
Reading Frame ◽  
E Coli ◽  
Evolutionarily Conserved

ABSTRACTThechboperon ofEscherichia coliis involved in the utilization of the β-glucosides chitobiose and cellobiose. The function ofchbG(ydjC), the sixth open reading frame of the operon that codes for an evolutionarily conserved protein is unknown. We show thatchbGencodes a monodeacetylase that is essential for growth on the acetylated chitooligosaccharides chitobiose and chitotriose but is dispensable for growth on cellobiose and chitosan dimer, the deacetylated form of chitobiose. The predicted active site of the enzyme was validated by demonstrating loss of function upon substitution of its putative metal-binding residues that are conserved across the YdjC family of proteins. We show that activation of thechbpromoter by the regulatory protein ChbR is dependent on ChbG, suggesting that deacetylation of chitobiose-6-P and chitotriose-6-P is necessary for their recognition by ChbR as inducers. Strains carrying mutations inchbRconferring the ability to grow on both cellobiose and chitobiose are independent ofchbGfunction for induction, suggesting that gain of function mutations in ChbR allow it to recognize the acetylated form of the oligosaccharides. ChbR-independent expression of the permease and phospho-β-glucosidase from a heterologous promoter did not support growth on both chitobiose and chitotriose in the absence ofchbG, suggesting an additional role ofchbGin the hydrolysis of chitooligosaccharides. The homologs ofchbGin metazoans have been implicated in development and inflammatory diseases of the intestine, indicating that understanding the function ofE. colichbGhas a broader significance.

scholarly journals Role of Enteroaggregative Escherichia coli Virulence Factors in Uropathogenesis

2013 ◽  
Vol 81 (4) ◽  
pp. 1164-1171 ◽  
Author(s):  
Erik J. Boll ◽  
Carsten Struve ◽  
Nadia Boisen ◽  
Bente Olesen ◽  
Steen G. Stahlhut ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Outbreak Strain ◽  
Content Type ◽  
E Coli ◽  
Abiotic Surfaces ◽  
Extraintestinal Disease ◽  
First Time ◽  
Specific Virulence

ABSTRACTA multiresistant clonalEscherichia coliO78:H10 strain qualifying molecularly as enteroaggregativeEscherichia coli(EAEC) was recently shown to be the cause of a community-acquired outbreak of urinary tract infection (UTI) in greater Copenhagen, Denmark, in 1991. This marks the first time EAEC has been associated with an extraintestinal disease outbreak. Importantly, the outbreak isolates were recovered from the urine of patients with symptomatic UTI, strongly implying urovirulence. Here, we sought to determine the uropathogenic properties of the Copenhagen outbreak strain and whether these properties are conferred by the EAEC-specific virulence factors. We demonstrated that through expression of aggregative adherence fimbriae, the principal adhesins of EAEC, the outbreak strain exhibited pronouncedly increased adherence to human bladder epithelial cells compared to prototype uropathogenic strains. Moreover, the strain was able to produce distinct biofilms on abiotic surfaces, including urethral catheters. These findings suggest that EAEC-specific virulence factors increase uropathogenicity and may have played a significant role in the ability of the strain to cause a community-acquired outbreak of UTI. Thus, inclusion of EAEC-specific virulence factors is warranted in future detection and characterization of uropathogenicE. coli.

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