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Gonyar LA, Sauder AB, Mortensen L, Willsey GG, Kendall MM. The yad and yeh fimbrial loci influence gene expression and virulence in enterohemorrhagic Escherichia coli O157:H7. mSphere 2024; 9:e0012424. [PMID: 38904402 PMCID: PMC11287998 DOI: 10.1128/msphere.00124-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 05/15/2024] [Indexed: 06/22/2024] Open
Abstract
Fimbriae are essential virulence factors for many bacterial pathogens. Fimbriae are extracellular structures that attach bacteria to surfaces. Thus, fimbriae mediate a critical step required for any pathogen to establish infection by anchoring a bacterium to host tissue. The human pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7encodes 16 fimbriae that may be important for EHEC to initiate infection and allow for productive expression of virulence traits important in later stages of infection, including a type III secretion system (T3SS) and Shiga toxin; however, the roles of most EHEC fimbriae are largely uncharacterized. Here, we provide evidence that two EHEC fimbriae, Yad and Yeh, modulate expression of diverse genes including genes encoding T3SS and Shiga toxin and that these fimbriae are required for robust colonization of the gastrointestinal tract. These findings reveal a significant and previously unappreciated role for fimbriae in bacterial pathogenesis as important determinants of virulence gene expression.IMPORTANCEFimbriae are extracellular proteinaceous structures whose defining role is to anchor bacteria to surfaces. This is a fundamental step for bacterial pathogens to establish infection in a host. Here, we show that the contributions of fimbriae to pathogenesis are more complex. Specifically, we demonstrate that fimbriae influence expression of virulence traits essential for disease progression in the intestinal pathogen enterohemorrhagic Escherichia coli. Gram-positive and Gram-negative bacteria express multiple fimbriae; therefore, these findings may have broad implications for understanding how pathogens use fimbriae, beyond adhesion, to initiate infection and coordinate gene expression, which ultimately results in disease.
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Affiliation(s)
- Laura A. Gonyar
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Amber B. Sauder
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Lindsay Mortensen
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Graham G. Willsey
- Department of Microbiology and Molecular Genetics, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Melissa M. Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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2
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Downing T, Lee MJ, Archbold C, McDonnell A, Rahm A. Informing plasmid compatibility with bacterial hosts using protein-protein interaction data. Genomics 2022; 114:110509. [PMID: 36273742 DOI: 10.1016/j.ygeno.2022.110509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/23/2022] [Accepted: 10/19/2022] [Indexed: 01/15/2023]
Abstract
The compatibility of plasmids with new host cells is significant given their role in spreading antimicrobial resistance (AMR) and virulence factor genes. Evaluating this using in vitro screening is laborious and can be informed by computational analyses of plasmid-host compatibility through rates of protein-protein interactions (PPIs) between plasmid and host cell proteins. We identified large excesses of such PPIs in eight important plasmids, including pOXA-48, using most known bacteria (n = 4363). 23 species had high rates of interactions with four blaOXA-48-positive plasmids. We also identified 48 species with high interaction rates with plasmids common in Escherichia coli. We found a strong association between one plasmid and the fimbrial adhesin operon pil, which could enhance host cell adhesion in aqueous environments. An excess rate of PPIs could be a sign of host-plasmid compatibility, which is important for AMR control given that plasmids like pOXA-48 move between species with ease.
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Affiliation(s)
- Tim Downing
- School of Biotechnology, Dublin City University, Dublin, Ireland; The Pirbright Institute, UK.
| | - Min Jie Lee
- School of Biotechnology, Dublin City University, Dublin, Ireland
| | - Conor Archbold
- School of Biotechnology, Dublin City University, Dublin, Ireland
| | - Adam McDonnell
- School of Biotechnology, Dublin City University, Dublin, Ireland
| | - Alexander Rahm
- GAATI Lab, University of French Polynesia, Tahiti, French Polynesia
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3
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Ageorges V, Monteiro R, Leroy S, Burgess CM, Pizza M, Chaucheyras-Durand F, Desvaux M. Molecular determinants of surface colonisation in diarrhoeagenic Escherichia coli (DEC): from bacterial adhesion to biofilm formation. FEMS Microbiol Rev 2021; 44:314-350. [PMID: 32239203 DOI: 10.1093/femsre/fuaa008] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/31/2020] [Indexed: 12/11/2022] Open
Abstract
Escherichia coli is primarily known as a commensal colonising the gastrointestinal tract of infants very early in life but some strains being responsible for diarrhoea, which can be especially severe in young children. Intestinal pathogenic E. coli include six pathotypes of diarrhoeagenic E. coli (DEC), namely, the (i) enterotoxigenic E. coli, (ii) enteroaggregative E. coli, (iii) enteropathogenic E. coli, (iv) enterohemorragic E. coli, (v) enteroinvasive E. coli and (vi) diffusely adherent E. coli. Prior to human infection, DEC can be found in natural environments, animal reservoirs, food processing environments and contaminated food matrices. From an ecophysiological point of view, DEC thus deal with very different biotopes and biocoenoses all along the food chain. In this context, this review focuses on the wide range of surface molecular determinants acting as surface colonisation factors (SCFs) in DEC. In the first instance, SCFs can be broadly discriminated into (i) extracellular polysaccharides, (ii) extracellular DNA and (iii) surface proteins. Surface proteins constitute the most diverse group of SCFs broadly discriminated into (i) monomeric SCFs, such as autotransporter (AT) adhesins, inverted ATs, heat-resistant agglutinins or some moonlighting proteins, (ii) oligomeric SCFs, namely, the trimeric ATs and (iii) supramolecular SCFs, including flagella and numerous pili, e.g. the injectisome, type 4 pili, curli chaperone-usher pili or conjugative pili. This review also details the gene regulatory network of these numerous SCFs at the various stages as it occurs from pre-transcriptional to post-translocational levels, which remains to be fully elucidated in many cases.
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Affiliation(s)
- Valentin Ageorges
- Université Clermont Auvergne, INRAE, MEDiS, F-63000 Clermont-Ferrand, France
| | - Ricardo Monteiro
- Université Clermont Auvergne, INRAE, MEDiS, F-63000 Clermont-Ferrand, France.,GSK, Via Fiorentina 1, 53100 Siena, Italy
| | - Sabine Leroy
- Université Clermont Auvergne, INRAE, MEDiS, F-63000 Clermont-Ferrand, France
| | - Catherine M Burgess
- Food Safety Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland
| | | | - Frédérique Chaucheyras-Durand
- Université Clermont Auvergne, INRAE, MEDiS, F-63000 Clermont-Ferrand, France.,Lallemand Animal Nutrition SAS, F-31702 Blagnac Cedex, France
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRAE, MEDiS, F-63000 Clermont-Ferrand, France
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4
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Decano AG, Tran N, Al-Foori H, Al-Awadi B, Campbell L, Ellison K, Mirabueno LP, Nelson M, Power S, Smith G, Smyth C, Vance Z, Woods C, Rahm A, Downing T. Plasmids shape the diverse accessory resistomes of Escherichia coli ST131. Access Microbiol 2020; 3:acmi000179. [PMID: 33997610 PMCID: PMC8115979 DOI: 10.1099/acmi.0.000179] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 10/27/2020] [Indexed: 12/22/2022] Open
Abstract
The human gut microbiome includes beneficial, commensal and pathogenic bacteria that possess antimicrobial resistance (AMR) genes and exchange these predominantly through conjugative plasmids. Escherichia coli is a significant component of the gastrointestinal microbiome and is typically non-pathogenic in this niche. In contrast, extra-intestinal pathogenic E. coli (ExPEC) including ST131 may occupy other environments like the urinary tract or bloodstream where they express genes enabling AMR and host cell adhesion like type 1 fimbriae. The extent to which commensal E. coli and uropathogenic ExPEC ST131 share AMR genes remains understudied at a genomic level, and we examined this here using a preterm infant resistome. We found that individual ST131 had small differences in AMR gene content relative to a larger shared resistome. Comparisons with a range of plasmids common in ST131 showed that AMR gene composition was driven by conjugation, recombination and mobile genetic elements. Plasmid pEK499 had extended regions in most ST131 Clade C isolates, and it had evidence of a co-evolutionary signal based on protein-level interactions with chromosomal gene products, as did pEK204 that had a type IV fimbrial pil operon. ST131 possessed extensive diversity of selective type 1, type IV, P and F17-like fimbriae genes that was highest in subclade C2. The structure and composition of AMR genes, plasmids and fimbriae vary widely in ST131 Clade C and this may mediate pathogenicity and infection outcomes.
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Affiliation(s)
- Arun Gonzales Decano
- School of Biotechnology, Dublin City University, Ireland.,Present address: School of Medicine, University of St., Andrews, UK
| | - Nghia Tran
- School of Maths, Applied Maths and Statistics, National University of Ireland Galway, Ireland
| | | | | | | | - Kevin Ellison
- School of Biotechnology, Dublin City University, Ireland
| | - Louisse Paolo Mirabueno
- School of Biotechnology, Dublin City University, Ireland.,Present address: National Institute of Agricultural Botany - East Malling Research, Kent, UK
| | - Maddy Nelson
- School of Biotechnology, Dublin City University, Ireland
| | - Shane Power
- School of Biotechnology, Dublin City University, Ireland
| | | | - Cian Smyth
- School of Biotechnology, Dublin City University, Ireland.,Present address: Dept of Biology, Maynooth University, Dublin, Ireland
| | - Zoe Vance
- School of Genetics & Microbiology, Trinity College Dublin, Ireland
| | | | - Alexander Rahm
- School of Maths, Applied Maths and Statistics, National University of Ireland Galway, Ireland.,Present address: GAATI Lab, Université de la Polynésie Française, Puna'auia, French Polynesia
| | - Tim Downing
- School of Biotechnology, Dublin City University, Ireland
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5
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Li B, Huang Q, Cui A, Liu X, Hou B, Zhang L, Liu M, Meng X, Li S. Overexpression of Outer Membrane Protein X (OmpX) Compensates for the Effect of TolC Inactivation on Biofilm Formation and Curli Production in Extraintestinal Pathogenic Escherichia coli (ExPEC). Front Cell Infect Microbiol 2018; 8:208. [PMID: 29988395 PMCID: PMC6024092 DOI: 10.3389/fcimb.2018.00208] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 06/05/2018] [Indexed: 11/24/2022] Open
Abstract
Our previous study showed that the inactivation of the efflux pump TolC could abolish biofilm formation and curli production of extraintestinal pathogenic Escherichia coli (ExPEC) strain PPECC42 under hyper-osmotic conditions. In this study we investigated the role of OmpX in biofilm formation and curli production of ExPEC PPECC42. Our data showed that OmpX disruption or overexpression didn't significantly affect the biofilm formation and curli production of the wild-type strain. However, in the tolC-deleted mutant, overexpressing OmpX suppressed the effect of TolC inactivation on ExPEC biofilm formation and curli production under hyper-osmotic growth conditions. Real-time qRT-PCR confirmed that OmpX overexpression affected curli production by regulating the transcription of the curli biosynthesis-related genes in the ΔtolC strain. Our findings suggest that OmpX is involved in biofilm formation and curli production.
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Affiliation(s)
- Binyou Li
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Qi Huang
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Ailian Cui
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xueling Liu
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Bo Hou
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Liyuan Zhang
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Mei Liu
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xianrong Meng
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Shaowen Li
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
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6
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Abstract
Extraintestinal pathogenic E. coli (ExPEC) present a major clinical problem that has emerged in the past years. Most of the infections are hospital or community-acquired and involve patients with a compromised immune system. The infective agents belong to a large number of strains of different serotypes that do not cross react. The seriousness of the infection is due to the fact that most of the infecting bacteria are highly antibiotic resistant. Here, we discuss the bacterial factors responsible for pathogenesis and potential means to combat the infections.
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Affiliation(s)
- Dvora Biran
- Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, 39978, Tel Aviv, Israel
| | - Eliora Z Ron
- Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, 39978, Tel Aviv, Israel.
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7
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Mandal J. Significance of Asymptomatic Bacteriuria. EUROPEAN MEDICAL JOURNAL 2017. [DOI: 10.33590/emj/10310957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Since the recognition of asymptomatic bacteriuria (ABU), several studies have questioned its significance. It is a very common condition, observed in many healthy individuals. Current guidelines mandate that ABU should not be treated in all cases, as it does not seem to improve the outcome. Conditional restrictions for treatment of ABU can be relaxed in certain situations, with minimal exceptions to the rule.
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Affiliation(s)
- Jharna Mandal
- Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India
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8
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Marshall J, Rossez Y, Mainda G, Gally DL, Daniell TJ, Holden NJ. Alternate thermoregulation and functional binding ofEscherichia colitype 1 fimbriae in environmental and animal isolates. FEMS Microbiol Lett 2016; 363:fnw251. [DOI: 10.1093/femsle/fnw251] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/24/2016] [Accepted: 11/02/2016] [Indexed: 11/14/2022] Open
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9
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Crozier L, Hedley PE, Morris J, Wagstaff C, Andrews SC, Toth I, Jackson RW, Holden NJ. Whole-Transcriptome Analysis of Verocytotoxigenic Escherichia coli O157:H7 (Sakai) Suggests Plant-Species-Specific Metabolic Responses on Exposure to Spinach and Lettuce Extracts. Front Microbiol 2016; 7:1088. [PMID: 27462311 PMCID: PMC4940412 DOI: 10.3389/fmicb.2016.01088] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/29/2016] [Indexed: 12/11/2022] Open
Abstract
Verocytotoxigenic Escherichia coli (VTEC) can contaminate crop plants, potentially using them as secondary hosts, which can lead to food-borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonization. As such, we compared the ability of the VTEC strain, E. coli O157:H7 'Sakai,' to colonize the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea), lettuce (Lactuca sativa), vining green pea (Pisum sativum), and prickly lettuce (Lactuca serriola), a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analyzed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce). Plant extracts were used to reduce heterogeneity inherent in plant-microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonization. Results showed that both the plant tissue type and the plant species strongly influence the short-term (1 h) transcriptional response to extracts as well as longer-term (10 days) plant colonization or persistence. We show that propagation temperature (37 vs. 18°C) has a major impact on the expression profile and therefore pre-adaptation of bacteria to a plant-relevant temperature is necessary to avoid misleading temperature-dependent wholescale gene-expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated) differentially regulated genes were associated with metabolism. However, large-scale differences in the metabolic and biosynthetic pathways between treatment types indicate specificity in substrate utilization. Induction of stress-response genes reflected the apparent physiological status of the bacterial genes in each extract, as a result of glutamate-dependent acid resistance, nutrient stress, or translational stalling. A large proportion of differentially regulated genes are uncharacterized (annotated as hypothetical), which could indicate yet to be described functional roles associated with plant interaction for E. coli O157:H7 Sakai.
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Affiliation(s)
- Louise Crozier
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Pete E. Hedley
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Jenny Morris
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Carol Wagstaff
- School of Chemistry, Food and Pharmacy, The University of ReadingReading, UK
| | - Simon C. Andrews
- School of Biological Sciences, The University of ReadingReading, UK
| | - Ian Toth
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | | | - Nicola J. Holden
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
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10
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Stephenson SAM, Brown PD. Epigenetic Influence of Dam Methylation on Gene Expression and Attachment in Uropathogenic Escherichia coli. Front Public Health 2016; 4:131. [PMID: 27446897 PMCID: PMC4921776 DOI: 10.3389/fpubh.2016.00131] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 06/09/2016] [Indexed: 11/13/2022] Open
Abstract
Urinary tract infections (UTI) are among the most frequently encountered infections in clinical practice globally. Predominantly a burden among female adults and infants, UTIs primarily caused by uropathogenic Escherichia coli (UPEC) results in high morbidity and fiscal health strains. During pathogenesis, colonization of the urinary tract via fimbrial adhesion to mucosal cells is the most critical point in infection and has been linked to DNA methylation. Furthermore, with continuous exposure to antibiotics as the standard therapeutic strategy, UPEC has evolved to become highly adaptable in circumventing the effect of antimicrobial agents and host defenses. Hence, the need for alternative treatment strategies arises. Since differential DNA methylation is observed as a critical precursor to virulence in various pathogenic bacteria, this body of work sought to assess the influence of the DNA adenine methylase (dam) gene on gene expression and cellular adhesion in UPEC and its potential as a therapeutic target. To monitor the influence of dam on attachment and FQ resistance, selected UPEC dam mutants created via one-step allelic exchange were transformed with cloned qnrA and dam complement plasmid for comparative analysis of growth rate, antimicrobial susceptibility, biofilm formation, gene expression, and mammalian cell attachment. The absence of DNA methylation among dam mutants was apparent. Varying deficiencies in cell growth, antimicrobial resistance and biofilm formation, alongside low-level increases in gene expression (recA and papI), and adherence to HEK-293 and HTB-9 mammalian cells were also detected as a factor of SOS induction to result in increased mutability. Phenotypic characteristics of parental strains were restored in dam complement strains. Dam's vital role in DNA methylation and gene expression in local UPEC isolates was confirmed. Similarly to dam-deficient Enterohemorrhagic E. coli (EHEC), these findings suggest unsuccessful therapeutic use of Dam inhibitors against UPEC or dam-deficient UPEC strains as attenuated live vaccines. However, further investigations are necessary to determine the post-transcriptional influence of dam on the regulatory network of virulence genes central to pathogenesis.
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Affiliation(s)
| | - Paul D Brown
- Department of Basic Medical Sciences, Faculty of Medical Sciences, University of West Indies , Jamaica
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11
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Zhang H, Susanto TT, Wan Y, Chen SL. Comprehensive mutagenesis of the fimS promoter regulatory switch reveals novel regulation of type 1 pili in uropathogenic Escherichia coli. Proc Natl Acad Sci U S A 2016; 113:4182-7. [PMID: 27035967 PMCID: PMC4839427 DOI: 10.1073/pnas.1522958113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Type 1 pili (T1P) are major virulence factors for uropathogenic Escherichia coli (UPEC), which cause both acute and recurrent urinary tract infections. T1P expression therefore is of direct relevance for disease. T1P are phase variable (both piliated and nonpiliated bacteria exist in a clonal population) and are controlled by an invertible DNA switch (fimS), which contains the promoter for the fim operon encoding T1P. Inversion of fimS is stochastic but may be biased by environmental conditions and other signals that ultimately converge at fimS itself. Previous studies of fimS sequences important for T1P phase variation have focused on laboratory-adapted E coli strains and have been limited in the number of mutations or by alteration of the fimS genomic context. We surmounted these limitations by using saturating genomic mutagenesis of fimS coupled with accurate sequencing to detect both mutations and phase status simultaneously. In addition to the sequences known to be important for biasing fimS inversion, our method also identifies a previously unknown pair of 5' UTR inverted repeats that act by altering the relative fimA levels to control phase variation. Thus we have uncovered an additional layer of T1P regulation potentially impacting virulence and the coordinate expression of multiple pilus systems.
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Affiliation(s)
- Huibin Zhang
- Infectious Diseases Group, Genome Institute of Singapore, Singapore 138672
| | - Teodorus T Susanto
- Stem Cell and Development, Genome Institute of Singapore, Singapore 138672
| | - Yue Wan
- Stem Cell and Development, Genome Institute of Singapore, Singapore 138672
| | - Swaine L Chen
- Infectious Diseases Group, Genome Institute of Singapore, Singapore 138672; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074
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12
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Abstract
Pyelonephritis represents a subset of urinary tract infections that occur from bacteria ascending from the lower to the upper reaches of the genitourinary system, such as the kidney. The renal system contains a range of hydrodynamically and immunologically challenging, interconnected microenvironments where the invading pathogen may populate during the course of the infection. The situation at the infection foci changes dynamically, vacillating between bacterial colonization and clearance, to which the outcome is a summation of all host-pathogen elements in play. A selection of important determinants includes factors of microbial origin, effects of eukaryotic cell signaling, physiological facets of the infected organ, and signals from distal organs. Improved understanding of the multifactorial aspects of molecular pathogenesis of infection requires intravital, cross-disciplinary approaches with high spatio-temporal resolution. The advancement of such approaches promises to eventually provide a comprehensive understanding of the integrated pathophysiology of pyelonephritis.
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13
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Khandige S, Møller-Jensen J. Fimbrial phase variation: stochastic or cooperative? Curr Genet 2015; 62:237-41. [DOI: 10.1007/s00294-015-0529-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 02/07/2023]
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14
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Wurpel DJ, Totsika M, Allsopp LP, Webb RI, Moriel DG, Schembri MA. Comparative proteomics of uropathogenic Escherichia coli during growth in human urine identify UCA-like (UCL) fimbriae as an adherence factor involved in biofilm formation and binding to uroepithelial cells. J Proteomics 2015; 131:177-189. [PMID: 26546558 DOI: 10.1016/j.jprot.2015.11.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 10/23/2015] [Accepted: 11/02/2015] [Indexed: 01/15/2023]
Abstract
Uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infection (UTI) in humans. For the successful colonisation of the human urinary tract, UPEC employ a diverse collection of secreted or surface-exposed virulence factors including toxins, iron acquisition systems and adhesins. In this study, a comparative proteomic approach was utilised to define the UPEC pan and core surface proteome following growth in pooled human urine. Identified proteins were investigated for subcellular origin, prevalence and homology to characterised virulence factors. Fourteen core surface proteins were identified, as well as eleven iron uptake receptor proteins and four distinct fimbrial types, including type 1, P, F1C/S and a previously uncharacterised fimbrial type, designated UCA-like (UCL) fimbriae in this study. These pathogenicity island (PAI)-associated fimbriae are related to UCA fimbriae of Proteus mirabilis, associated with UPEC and exclusively found in members of the E. coli B2 and D phylogroup. We further demonstrated that UCL fimbriae promote significant biofilm formation on abiotic surfaces and mediate specific attachment to exfoliated human uroepithelial cells. Combined, this study has defined the surface proteomic profiles and core surface proteome of UPEC during growth in human urine and identified a new type of fimbriae that may contribute to UTI.
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Affiliation(s)
- Daniël J Wurpel
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Makrina Totsika
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Luke P Allsopp
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Richard I Webb
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Australia
| | - Danilo G Moriel
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Mark A Schembri
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.
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15
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Ross BN, Rojas-Lopez M, Cieza RJ, McWilliams BD, Torres AG. The Role of Long Polar Fimbriae in Escherichia coli O104:H4 Adhesion and Colonization. PLoS One 2015; 10:e0141845. [PMID: 26517878 PMCID: PMC4636846 DOI: 10.1371/journal.pone.0141845] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/13/2015] [Indexed: 01/12/2023] Open
Abstract
A renewed interest in Shiga toxin-producing Escherichia coli (STEC) strains was sparked due to the appearance of an outbreak in 2011, causing 3,816 diarrheal cases and some deaths in Europe. The causative strain was classified as enteroaggregative E. coli of serotype O104:H4 that had acquired Shiga toxin genes. The ability of STEC O104:H4 to cause disease relies greatly on the bacteria’s capacity to colonize, persist, and produce Shiga toxin. However, not much is known about the colonization factors of this strain. Because long polar fimbriae (lpf) lpf1 and lpf2 operons encode important colonization factors in other STEC isolates and E. coli O104:H4 possesses both loci, we hypothesized that Lpf is required for adhesion and colonization. In this study, isogenic lpfA1 and lpfA2 major fimbrial subunit mutants were constructed. To determine their role in O104:H4’s virulence, we assessed their ability to adhere to non-polarized and polarized intestinal epithelial cells. The ΔlpfA1 showed decreased adherence in both cell systems, while the ΔlpfA2 only showed a decrease in adherence to polarized Caco-2 cells. We also tested the O104:H4 mutants’ ability to form biofilm and found that the ΔlpfA1 was unable to form a stable biofilm. In an in vivo murine model of intestinal colonization, the ΔlpfA1 had a reduced ability to colonize the cecum and large intestine, consistent with the in vitro data. Further, we tested the lpfA1 mutants’ ability to compete against the wild type. We found that in the in vitro and in vivo models, the presence of the wild type O104:H4 facilitates increased adherence of the ΔlpfA1 to levels exceeding that of the wild type. Overall, our data demonstrated that Lpf1 is one of the factors responsible for O104:H4 intestinal adhesion and colonization.
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Affiliation(s)
- Brittany N. Ross
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
| | - Maricarmen Rojas-Lopez
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
| | - Roberto J. Cieza
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
| | - Brian D. McWilliams
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, 77555–1070, United States of America
- * E-mail:
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sRNA-Mediated Regulation of P-Fimbriae Phase Variation in Uropathogenic Escherichia coli. PLoS Pathog 2015; 11:e1005109. [PMID: 26291711 PMCID: PMC4546395 DOI: 10.1371/journal.ppat.1005109] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 07/24/2015] [Indexed: 12/21/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) are capable of occupying physiologically distinct intracellular and extracellular niches within the urinary tract. This feat requires the timely regulation of gene expression and small RNAs (sRNAs) are known to mediate such rapid adjustments in response to changing environmental cues. This study aimed to uncover sRNA-mediated gene regulation in the UPEC strain UTI89, during infection of bladder epithelial cells. Hfq is an RNA chaperone known to facilitate and stabilize sRNA and target mRNA interactions with bacterial cells. The co-immunoprecipitation and high throughput RNA sequencing of Hfq bound sRNAs performed in this study, revealed distinct sRNA profiles in UPEC in the extracellular and intracellular environments. Our findings emphasize the importance of studying regulatory sRNAs in a biologically relevant niche. This strategy also led to the discovery of a novel virulence-associated trans-acting sRNA—PapR. Deletion of papR was found to enhance adhesion of UTI89 to both bladder and kidney cell lines in a manner independent of type-1 fimbriae. We demonstrate PapR mediated posttranscriptional repression of the P-fimbriae phase regulator gene papI and postulate a role for such regulation in fimbrial cross-talk at the population level in UPEC. Our results further implicate the Leucine responsive protein (LRP) as a transcriptional activator regulating PapR expression. Our study reports, for the first time, a role for sRNAs in regulation of P-fimbriae phase variation and emphasizes the importance of studying pathogenesis-specific sRNAs within a relevant biological niche. Recent years have seen an increasing emphasis placed on the role of small RNAs (sRNAs) in the regulation of bacterial gene expression and stress adaptation. The advent of high-throughput sequencing methods has now made it possible to directly monitor the appearance of potentially virulence-associated sRNAs that may contribute to rapid adaptation of the pathogen to a changing environment during infection. Uropathogenic Escherichia coli (UPEC) are presumably exposed to a deluge of stimuli from epithelial cell contact, urine and host immune factors and we asked if any regulatory sRNAs would play a role in the transition of UPEC from the extracellular niche to the intracellular one. This study employs co-immunoprecipitation using the RNA chaperone Hfq to identify novel virulence-associated sRNAs in intracellular UPEC, followed by high-throughput RNA-seq. We report the identification of a novel sRNA that we designate PapR (P-fimbriae regulator) and elaborate on this discovery by demonstrating a role for PapR in regulation of P-fimbriae—a UPEC surface virulence factor. The results presented in this study offer new insights into the molecular mechanisms of UPEC pathogenesis and a role for sRNA mediated regulation of virulence factors.
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Zalmanovici Trestioreanu A, Lador A, Sauerbrun‐Cutler M, Leibovici L. Antibiotics for asymptomatic bacteriuria. Cochrane Database Syst Rev 2015; 4:CD009534. [PMID: 25851268 PMCID: PMC8407041 DOI: 10.1002/14651858.cd009534.pub2] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Asymptomatic bacteriuria is commonly detected in women aged up to 60 years, patients with diabetes, and the elderly. The benefit of antibiotic treatment for this condition is controversial. OBJECTIVES To assess the effectiveness and safety of antibiotics treatment for asymptomatic bacteriuria in adults. Specific objectives were to assess 1) the effectiveness of antibiotics for preventing development of symptomatic UTI, UTI-related complications, overall mortality, UTI-related mortality, and resolution of bacteriuria; 2) the development of resistance to antibiotic treatment by comparing resistance of grown bacteria in urine before and after therapy; and 3) the frequency of adverse events. SEARCH METHODS We searched the Cochrane Renal Group's Specialised Register up to 24 February 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. SELECTION CRITERIA Randomised controlled trials (RCTs) and quasi-RCTs comparing antibiotics to placebo or no treatment for asymptomatic bacteriuria in adults were included. The outcomes of interest were the development of symptomatic urinary tract infection (UTI), complications, death, any adverse event, development of antibiotic resistance, bacteriological cure, and decline in kidney function. DATA COLLECTION AND ANALYSIS Two authors independently extracted the data and assessed study quality. Statistical analyses were performed using the random effects model and the results expressed as risk ratios (RR) with 95% confidence intervals (CI). MAIN RESULTS We included nine studies (1614 participants) in this review. Symptomatic UTI (RR 1.11, 95% CI 0.51 to 2.43), complications (RR 0.78, 95% CI 0. 35 to 1.74), and death (RR 0.99, 95% CI 0.70 to 1.41) were similar between the antibiotic and placebo or no treatment arms. Antibiotics were more effective for bacteriological cure (RR 2.32, 95% CI 1.11 to 4.83) but also more adverse events developed in this group (RR 3.77, 95% CI 1.40 to 10.15). No decline in the kidney function was observed across the studies; minimal data were available on the emergence of resistant strains after antimicrobial treatment.The included studies were of medium and high quality, used different treatments for different durations of treatment and follow-up, different populations, but this did not appear to influence the results of review. AUTHORS' CONCLUSIONS No differences were observed between antibiotics versus no treatment of asymptomatic bacteriuria for the development of symptomatic UTI, complications or death. Antibiotics were superior to no treatment for the bacteriological cure but with significantly more adverse events. There was no clinical benefit from treating asymptomatic bacteriuria in the studies included in this review.
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Affiliation(s)
| | - Adi Lador
- Beilinson Hospital, Rabin Medical CenterDepartment of Medicine E39 Jabotinski StreetPetah TikvaIsrael49100
| | | | - Leonard Leibovici
- Beilinson Hospital, Rabin Medical CenterDepartment of Medicine E39 Jabotinski StreetPetah TikvaIsrael49100
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Kudirkienė E, Bager RJ, Johnson TJ, Bojesen AM. Chaperone-usher fimbriae in a diverse selection of Gallibacterium genomes. BMC Genomics 2014; 15:1093. [PMID: 25495603 PMCID: PMC4299563 DOI: 10.1186/1471-2164-15-1093] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/03/2014] [Indexed: 12/24/2022] Open
Abstract
Background Fimbriae are bacterial cell surface organelles involved in the pathogenesis of many bacterial species, including Gallibacterium anatis, in which a F17-like fimbriae of the chaperone-usher (CU) family was recently shown to be an important virulence factor and vaccine candidate. To reveal the distribution and variability of CU fimbriae 22 genomes of the avian host-restricted bacteria Gallibacterium spp. were investigated. Fimbrial clusters were classified using phylogeny-based and conserved domain (CD) distribution-based approaches. To characterize the fimbriae in depth evolutionary analysis and in vitro expression of the most prevalent fimbrial clusters was performed. Results Overall 48 CU fimbriae were identified in the genomes of the examined Gallibacterium isolates. All fimbriae were assigned to γ4 clade of the CU fimbriae of Gram-negative bacteria and were organized in four-gene clusters encoding a putative major fimbrial subunit, a chaperone, an usher and a fimbrial adhesin. Five fimbrial clusters (Flf-Flf4) and eight conserved domain groups were defined to accommodate the identified fimbriae. Although, the number of different fimbrial clusters in individual Gallibacterium genomes was low, there was substantial amino acid sequence variability in the major fimbrial subunit and the adhesin proteins. The distribution of CDs among fimbrial clusters, analysis of their flanking regions, and evolutionary comparison of the strains revealed that Gallibacterium fimbrial clusters likely underwent evolutionary divergence resulting in highly host adapted and antigenically variable fimbriae. In vitro, only the fimbrial subunit FlfA was expressed in most Gallibacterium strains encoding this protein. The absence or scarce expression of the two other common fimbrial subunits (Flf1A and Flf3A) indicates that their expression may require other in vitro or in vivo conditions. Conclusions This is the first approach establishing a systematic fimbria classification system within Gallibacterium spp., which indicates a species-wide distribution of γ4 CU fimbriae among a diverse collection of Gallibacterium isolates. The expression of only one out of up to three fimbriae present in the individual genomes in vitro suggests that fimbriae expression in Gallibacterium is highly regulated. This information is important for future attempts to understand the role of Gallibacterium fimbriae in pathogenesis, and may prove useful for improved control of Gallibacterium infections in chickens. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1093) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Anders M Bojesen
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Denmark.
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19
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Abstract
Chaperone-usher pathway (CUP) pili are extracellular organelles produced by Gram-negative bacteria that mediate bacterial pathogenesis. Small-molecule inhibitors of CUP pili, termed pilicides, were rationally designed and shown to inhibit type 1 or P piliation. Here, we show that pilicide ec240 decreased the levels of type 1, P, and S piliation. Transcriptomic and proteomic analyses using the cystitis isolate UTI89 revealed that ec240 dysregulated CUP pili and decreased motility. Paradoxically, the transcript levels of P and S pilus genes were increased during growth in ec240, even though the level of P and S piliation decreased. In contrast, the most downregulated transcripts after growth in ec240 were from the type 1 pilus genes. Type 1 pilus expression is controlled by inversion of the fimS promoter element, which can oscillate between phase on and phase off orientations. ec240 induced the fimS phase off orientation, and this effect was necessary for the majority of ec240’s inhibition of type 1 piliation. ec240 increased levels of the transcriptional regulators SfaB and PapB, which were shown to induce the fimS promoter phase off orientation. Furthermore, the effect of ec240 on motility was abolished in the absence of the SfaB, PapB, SfaX, and PapX regulators. In contrast to the effects of ec240, deletion of the type 1 pilus operon led to increased S and P piliation and motility. Thus, ec240 dysregulated several uropathogenic Escherichia coli (UPEC) virulence factors through different mechanisms and independent of its effects on type 1 pilus biogenesis and may have potential as an antivirulence compound. CUP pili and flagella play active roles in the pathogenesis of a variety of Gram-negative bacterial infections, including urinary tract infections mediated by UPEC. These are extremely common infections that are often recurrent and increasingly caused by antibiotic-resistant organisms. Preventing piliation and motility through altered regulation and assembly of these important virulence factors could aid in the development of novel therapeutics. This study increases our understanding of the regulation of these virulence factors, providing new avenues by which to target their expression.
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20
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Vollmerhausen TL, Woods JL, Faoagali J, Katouli M. Interactions of uroseptic Escherichia coli with renal (A-498) and gastrointestinal (HT-29) cell lines. J Med Microbiol 2014; 63:1575-1583. [PMID: 25298161 DOI: 10.1099/jmm.0.076562-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the ability of Escherichia coli isolated from septic patients with urinary tract infection (UTI) to translocate through the gastrointestinal (GI) tract of the same patients using cell-culture models. Forty-seven hospitalized patients with urosepsis were included in this study. E. coli was isolated from their urine and blood (total 94 isolates) and investigated for genetic relatedness and interaction with the cell lines A-498 and HT-29. An initial comparison of the strains isolated from urine and blood showed that 44 out of 47 patients (94 %) had identical strains in their blood and urine. The blood isolates adhered to both cell lines, although their rate of adherence to A-498 cells was significantly higher than that to HT-29 cells (5.8±3.8 per cell vs 2.8±1.9; P<0.0001). The rate of translocation in A-498 cells was also significantly higher after 120 min (8.7×10(5) vs 2.9×10(5); P = 0.0006). Three non-identical blood isolates were unable to translocate in HT-29 cells, indicating that host immune factors might be more important than bacterial ability to translocate the GI epithelium in these patients. Our data showed that blood isolates from uroseptic patients are able to adhere to and translocate through both cell lines. This suggests that E. coli in patients with UTI may translocate from either the GI tract or the urinary tract, hence questioning the assumption that the urinary tract is the only source of septicaemia in these patients.
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Affiliation(s)
- Tara L Vollmerhausen
- Inflammation and Healing Research Cluster, School of Health and Sport Sciences, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Australia
| | - Jasmine L Woods
- Inflammation and Healing Research Cluster, School of Health and Sport Sciences, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Australia
| | - Joan Faoagali
- Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Mohammad Katouli
- Inflammation and Healing Research Cluster, School of Health and Sport Sciences, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Australia
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21
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Teh AHT, Wang Y, Dykes GA. The influence of antibiotic resistance gene carriage on biofilm formation by two Escherichia coli strains associated with urinary tract infections. Can J Microbiol 2014; 60:105-11. [DOI: 10.1139/cjm-2013-0633] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Urinary tract infections (UTI) caused by uropathogenic Escherichia coli are one of the most common forms of human disease. In this study, the effect of the presence of newly acquired antibiotic resistance genes on biofilm formation of UTI-associated E. coli strains was examined. Two clinical UTI-associated E. coli strains (SMC18 and SMC20) carrying different combinations of virulence genes were transformed with pGEM-T, pGEM-T::KmΔAmp, or pGEM-T::Km to construct ampicillin-resistant (KmSAmpR), kanamycin-resistant (KmRAmpS), or ampicillin- and kanamycin-resistant (KmRAmpR) strains. Transformed and wild-type strains were characterized for biofilm formation, bacterial surface hydrophobicity, auto-aggregation, morphology, and attachment to abiotic surfaces. Transformation with a plasmid carrying an ampicillin resistance gene alone decreased (p < 0.05) biofilm formation by SMC18 (8 virulence marker genes) but increased (p < 0.05) biofilm formation by SMC20 (5 virulence marker genes). On the other hand, transformation with a plasmid carrying a kanamycin resistance gene alone or both ampicillin and kanamycin resistance genes resulted in a decrease (p < 0.05) in biofilm formation by SMC18 but did not affect (p > 0.05) the biofilm formation by SMC20. Our results suggest that transformation of UTI-associated E. coli with plasmids carrying different antibiotic resistance gene(s) had a significant impact on biofilm formation and that these effects were both strain dependent and varied between different antibiotics.
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Affiliation(s)
- Amy Huei Teen Teh
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway 46150, Selangor Darul Ehsan, Malaysia
| | - Yi Wang
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway 46150, Selangor Darul Ehsan, Malaysia
| | - Gary A. Dykes
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway 46150, Selangor Darul Ehsan, Malaysia
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22
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Hung C, Marschall J, Burnham CAD, Byun AS, Henderson JP. The bacterial amyloid curli is associated with urinary source bloodstream infection. PLoS One 2014; 9:e86009. [PMID: 24465838 PMCID: PMC3896446 DOI: 10.1371/journal.pone.0086009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/03/2013] [Indexed: 12/20/2022] Open
Abstract
Urinary tract infections are the most common cause of E. coli bloodstream infections (BSI) but the mechanism of bloodstream invasion is poorly understood. Some clinical isolates have been observed to shield themselves with extracellular amyloid fibers called curli at physiologic temperature. We hypothesize that curli fiber assembly at 37°C promotes bacteremic progression by urinary E. coli strains. Curli expression by cultured E. coli isolates from bacteriuric patients in the presence and absence of bacteremia were compared using Western blotting following amyloid fiber disruption with hexafluoroisopropanol. At 37°C, urinary isolates from bacteremic patients were more likely to express curli than those from non-bacteremic patients [16/22 (73%) vs. 7/21 (33%); p = 0.01]. No significant difference in curli expression was observed at 30°C [86% (19/22) vs. 76% (16/21); p = 0.5]. Isolates were clonally diverse between patients, indicating that this phenotype is distributed across multiple lineages. Most same-patient urine and blood isolates were highly related, consistent with direct invasion of urinary bacteria into the bloodstream. 37°C curli expression was associated with bacteremic progression of urinary E. coli isolates in this population. These findings suggest new future diagnostic and virulence-targeting therapeutic approaches.
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Affiliation(s)
- Chia Hung
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jonas Marschall
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Infectious Diseases, Bern University Hospital, Bern, Switzerland
| | - Carey-Ann D. Burnham
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Albert S. Byun
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jeffrey P. Henderson
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Center for Women’s Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Expression and purification of SfaX(II), a protein involved in regulating adhesion and motility genes in extraintestinal pathogenic Escherichia coli. Protein Expr Purif 2012; 86:127-34. [PMID: 23022032 DOI: 10.1016/j.pep.2012.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 09/14/2012] [Accepted: 09/17/2012] [Indexed: 11/21/2022]
Abstract
Pathogenic Escherichia coli strains commonly harbor genes involved in formation of fimbriae, such as the sfa(II) fimbrial gene cluster found in uropathogenic and newborn meningitis isolates. The sfaX(II) gene, located at the distal end of the sfa(II) operon, was recently shown to play a role in controlling virulence-related gene expression in extraintestinal pathogenic E. coli (ExPEC). Until now, detailed characterization of the SfaX(II) protein has been hampered by difficulties in obtaining large quantities of soluble protein. By a rational modeling approach, we engineered a Cys70Ser mutation, which successfully improved solubility of the protein. Here, we present the expression, purification, and initial characterization of the recombinant SfaX(IIC70S) mutant. The protein was produced in E. coli BL21 (DE3) cells grown in autoinduction culture media. The plasmid vector harbored DNA encoding the SfaX(IIC70S) protein N-terminally fused with a six histidine (H6) sequence followed by a ZZ tag (a derivative of the Staphylococcus protein A) (H6-ZZ tag). The H6-ZZ tag was cleaved off with Tobacco Etch Virus (TEV) protease and the 166 amino acid full-length homo-dimeric protein was purified using affinity and size-exclusion chromatography. Electrophoretic mobility gel shift assays and atomic force microscopy demonstrated that the protein possesses DNA-binding properties, suggesting that the transcriptional regulatory activity of SfaX(II) can be mediated via direct binding to DNA.
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24
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Liu Z, Treviño J, Ramirez-Peña E, Sumby P. The small regulatory RNA FasX controls pilus expression and adherence in the human bacterial pathogen group A Streptococcus. Mol Microbiol 2012; 86:140-54. [PMID: 22882718 DOI: 10.1111/j.1365-2958.2012.08178.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Bacterial pathogens use cell surface-associated adhesion molecules to promote host attachment and colonization, and the ability to modulate adhesion expression is critical to pathogen success. Here, we show that the human-specific pathogen the group A Streptococcus (GAS) uses a small regulatory RNA (sRNA) to regulate the expression of adhesive pili. The fibronectin/fibrinogen-binding/haemolytic-activity/streptokinase-regulator-X (FasX) sRNA, previously shown to positively regulate expression of the secreted virulence factor streptokinase (SKA), negatively regulates the production of pili on the GAS cell surface. FasX base pairs to the extreme 5' end of mRNA from the pilus biosynthesis operon, and this RNA:RNA interaction reduces the stability of the mRNA, while also inhibiting translation of at least the first gene in the pilus biosynthesis operon (cpa, which encodes a minor pilin protein). The negative regulation of pilus expression by FasX reduces the ability of GAS to adhere to human keratinocytes. Our findings cement FasX sRNA as an important regulator of virulence factor production in GAS and identify that FasX uses at least three distinct mechanisms, positive (ska mRNA) and negative (pilus operon mRNA) regulation of mRNA stability, and negative regulation of mRNA translation (cpa mRNA), to post-transcriptionally regulate target mRNAs during infection.
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Affiliation(s)
- Zhuyun Liu
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas, USA
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25
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Transcriptional regulation of the ecp operon by EcpR, IHF, and H-NS in attaching and effacing Escherichia coli. J Bacteriol 2012; 194:5020-33. [PMID: 22797761 DOI: 10.1128/jb.00915-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli are clinically important diarrheagenic pathogens that adhere to the intestinal epithelial surface. The E. coli common pili (ECP), or meningitis-associated and temperature-regulated (MAT) fimbriae, are ubiquitous among both commensal and pathogenic E. coli strains and play a role as colonization factors by promoting the interaction between bacteria and host epithelial cells and favoring interbacterial interactions in biofilm communities. The first gene of the ecp operon encodes EcpR (also known as MatA), a proposed regulatory protein containing a LuxR-like C-terminal helix-turn-helix (HTH) DNA-binding motif. In this work, we analyzed the transcriptional regulation of the ecp genes and the role of EcpR as a transcriptional regulator. EHEC and EPEC ecpR mutants produce less ECP, while plasmids expressing EcpR increase considerably the expression of EcpA and production of ECP. The ecp genes are transcribed as an operon from a promoter located 121 bp upstream of the start codon of ecpR. EcpR positively regulates this promoter by binding to two TTCCT boxes distantly located upstream of the ecp promoter, thus enhancing expression of downstream ecp genes, leading to ECP production. EcpR mutants in the putative HTH DNA-binding domain are no longer able to activate ecp expression or bind to the TTCCT boxes. EcpR-mediated activation is aided by integration host factor (IHF), which is essential for counteracting the repression exerted by histone-like nucleoid-structuring protein (H-NS) on the ecp promoter. This work demonstrates evidence about the interplay between a novel member of a diverse family of regulatory proteins and global regulators in the regulation of a fimbrial operon.
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Miyashita A, Iyoda S, Ishii K, Hamamoto H, Sekimizu K, Kaito C. Lipopolysaccharide O-antigen of enterohemorrhagic Escherichia coli O157:H7 is required for killing both insects and mammals. FEMS Microbiol Lett 2012; 333:59-68. [DOI: 10.1111/j.1574-6968.2012.02599.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 05/14/2012] [Indexed: 01/08/2023] Open
Affiliation(s)
- Atsushi Miyashita
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Hongo; Bunkyo-ku; Tokyo; Japan
| | - Sunao Iyoda
- Department of Bacteriology; National Institute of Infectious Diseases; Shinjuku-ku; Tokyo; Japan
| | - Kenichi Ishii
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Hongo; Bunkyo-ku; Tokyo; Japan
| | - Hiroshi Hamamoto
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Hongo; Bunkyo-ku; Tokyo; Japan
| | - Kazuhisa Sekimizu
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Hongo; Bunkyo-ku; Tokyo; Japan
| | - Chikara Kaito
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Hongo; Bunkyo-ku; Tokyo; Japan
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27
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Lloyd SJ, Ritchie JM, Torres AG. Fimbriation and curliation in Escherichia coli O157:H7: a paradigm of intestinal and environmental colonization. Gut Microbes 2012; 3:272-6. [PMID: 22614704 PMCID: PMC3427220 DOI: 10.4161/gmic.20661] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) serotypes, particularly E. coli O157:H7, possess a variety of fimbrial and afimbrial adhesins which have emerged as important contributors to intestinal colonization. E. coli O157:H7 possesses two chromosomal operons encoding long polar fimbriae (Lpf), which have been found to influence adherence in vitro and colonization in vivo. In a recent Infection and Immunity paper, we further explored the role of Lpf in E. coli O157:H7 intestinal colonization by using the infant rabbit model of STEC infection. We found that an E. coli O157:H7 Lpf-deficient mutant was outcompeted in the rabbit intestine by its parental strain, which may suggest that Lpf contributes to colonization. In contrast, the Lpf-deficient mutant showed an increased adherence to cultured intestinal epithelial cells, and we discovered that this strain overexpressed curli fibers. In this addendum article, we provide a continued perspective on the predicted roles of Lpf and curli, both in vivo and in vitro.
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Affiliation(s)
- Sonja J. Lloyd
- Department of Microbiology and Immunology; University of Texas Medical Branch; Galveston, TX USA
| | - Jennifer M. Ritchie
- Faculty of Health and Medical Sciences; University of Surrey; Guildford, Surrey UK
| | - Alfredo G. Torres
- Department of Microbiology and Immunology; University of Texas Medical Branch; Galveston, TX USA,Department of Pathology; Sealy Center for Vaccine Development; University of Texas Medical Branch; Galveston, TX USA,Correspondence to: Alfredo G. Torres ;
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Effect of periodic fluctuation in the osmotic environment on the adaptation of Salmonella. Food Microbiol 2011; 30:298-302. [PMID: 22265315 DOI: 10.1016/j.fm.2011.09.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 11/23/2022]
Abstract
The growth of Salmonella from different osmotic histories was studied in low water activity conditions. Cell cultures were successively diluted and grown in batch, in minimal medium, without and then with added NaCl, several times and from different inoculum levels. The viable count curves obtained in low water activity conditions showed an initial decline after which the culture either died out or recovered and entered the exponential phase. After the first batch with NaCl added, the subsequent curves at low water activity showed progressively smaller initial decline and shorter lag time as the number of transfers from high to low water activity conditions increased. The observed curves were analyzed by F-tests applying an extension of the model of Baranyi and Roberts (1994). The results suggest that periodic, systematic "training" can improve the adaptation capability of the organism without resulting in higher specific growth rate.
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Rader BA, Wreden C, Hicks KG, Sweeney EG, Ottemann KM, Guillemin K. Helicobacter pylori perceives the quorum-sensing molecule AI-2 as a chemorepellent via the chemoreceptor TlpB. MICROBIOLOGY-SGM 2011; 157:2445-2455. [PMID: 21602215 DOI: 10.1099/mic.0.049353-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Helicobacter pylori moves in response to environmental chemical cues using a chemotaxis two-component signal-transduction system. Autoinducer-2 (AI-2) is a quorum-sensing signal produced by the LuxS protein that accumulates in the bacterial environment in a density-dependent manner. We showed previously that a H. pylori luxS mutant was defective in motility on soft agar plates. Here we report that deletion of the luxS gene resulted in swimming behaviour with a reduced frequency of stops as compared to the wild-type strain. Stopping frequency was restored to wild-type levels by genetic complementation of the luxS mutation or by addition of synthetic 4,5-dihydroxy-2,3-pentanedione (DPD), which cyclizes to form AI-2. Synthetic DPD also increased the frequency of stops in wild-type H. pylori, similar to the behaviour induced by the known chemorepellent HCl. We found that whereas mutants lacking the chemoreceptor genes tlpA, tlpC or tlpD responded to an exogenous source of synthetic DPD, the chemoreceptor mutant tlpB was non-responsive to a gradient or uniform distribution of the chemical. Furthermore, a double mutant lacking both tlpB and luxS exhibited chemotactic behaviour similar to the tlpB single mutant, whereas a double mutant lacking both tlpB and the chemotransduction gene cheA behaved like a nonchemotactic cheA single mutant, supporting the model that tlpB functions in a signalling pathway downstream of luxS and upstream of cheA. We conclude that H. pylori perceives LuxS-produced AI-2 as a chemorepellent via the chemoreceptor TlpB.
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Affiliation(s)
- Bethany A Rader
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Christopher Wreden
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Kevin G Hicks
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | | | - Karen M Ottemann
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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Melican K, Sandoval RM, Kader A, Josefsson L, Tanner GA, Molitoris BA, Richter-Dahlfors A. Uropathogenic Escherichia coli P and Type 1 fimbriae act in synergy in a living host to facilitate renal colonization leading to nephron obstruction. PLoS Pathog 2011; 7:e1001298. [PMID: 21383970 PMCID: PMC3044688 DOI: 10.1371/journal.ppat.1001298] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 01/18/2011] [Indexed: 12/03/2022] Open
Abstract
The progression of a natural bacterial infection is a dynamic process influenced by the physiological characteristics of the target organ. Recent developments in live animal imaging allow for the study of the dynamic microbe-host interplay in real-time as the infection progresses within an organ of a live host. Here we used multiphoton microscopy-based live animal imaging, combined with advanced surgical procedures, to investigate the role of uropathogenic Escherichia coli (UPEC) attachment organelles P and Type 1 fimbriae in renal bacterial infection. A GFP+ expressing variant of UPEC strain CFT073 and genetically well-defined isogenic mutants were microinfused into rat glomerulus or proximal tubules. Within 2 h bacteria colonized along the flat squamous epithelium of the Bowman's capsule despite being exposed to the primary filtrate. When facing the challenge of the filtrate flow in the proximal tubule, the P and Type 1 fimbriae appeared to act in synergy to promote colonization. P fimbriae enhanced early colonization of the tubular epithelium, while Type 1 fimbriae mediated colonization of the center of the tubule via a mechanism believed to involve inter-bacterial binding and biofilm formation. The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h. Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen. Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis. When bacteria such as uropathogenic Escherichia coli (UPEC) infect a living kidney, they face numerous physiological challenges such as the flow of urine. Bacteria need to attach themselves to the epithelial linings of the kidney to withstand this flow. In this work we use a live animal imaging model to study how UPEC colonize a living kidney despite the physiological challenges they face. We show that P and Type 1 fimbriae, two of the most well described UPEC adhesion factors, work together to promote successful bacterial colonization. P fimbriae mediate binding between the bacteria and the epithelial cells lining the tubules, while Type 1 appears to play a role in inter-bacterial binding and biofilm formation in the center parts of the lumen. The heterogeneous bacterial community which filled the tubule was subsequently shown to effect nephron filtration and resulted in a total loss of filtrate flow i.e. obstruction. This work demonstrates the interplay between the bacterial and host aspects, indicating how factors such as filtration may affect bacterial adhesion and vice versa. It also highlights the multifactorial basis of kidney infection, demonstrating how physiological injuries such as obstruction may contribute towards the full pathophysiology of pyelonephritis.
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Affiliation(s)
- Keira Melican
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - Ruben M. Sandoval
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Abdul Kader
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - Lina Josefsson
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - George A. Tanner
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Bruce A. Molitoris
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Agneta Richter-Dahlfors
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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Klemm P, Hancock V, Schembri MA. Fimbrial adhesins from extraintestinal Escherichia coli. ENVIRONMENTAL MICROBIOLOGY REPORTS 2010; 2:628-640. [PMID: 23766248 DOI: 10.1111/j.1758-2229.2010.00166.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Extraintestinal pathogenic Escherichia coli (ExPEC) represent an important subclass of E. coli that cause a wide spectrum of diseases in human and animal hosts. Fimbriae are key virulence factors of ExPEC strains. These long surface located rod-shaped organelles mediate receptor-specific attachment to host tissue surfaces (tissue tropism). Some ExPEC fimbriae have additional functions such as the promotion of biofilm formation, cell aggregation and adherence to abiotic surfaces. Here we review the structure, function and contribution to virulence of fimbriae associated with ExPEC strains.
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Affiliation(s)
- Per Klemm
- Microbial Adhesion Group, DTU Food, Technical University of Denmark, Lyngby, Denmark. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia
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Somvanshi VS, Kaufmann-Daszczuk B, Kim KS, Mallon S, Ciche TA. Photorhabdus phase variants express a novel fimbrial locus, mad, essential for symbiosis. Mol Microbiol 2010; 77:1021-38. [PMID: 20572934 DOI: 10.1111/j.1365-2958.2010.07270.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fimbriae are adhesive organelles known to enable pathogens to colonize animal tissue, but little is known of their function in mutualistic symbioses. Photorhabdus colonization of Heterorhabditis bacteriophora nematodes is essential for the pair's insect pathogenic lifestyle. Maternal nematodes acquire Photorhabdus symbionts as a persistent intestinal biofilm prior to transmission to infective juvenile (IJ) stage offspring developing inside the maternal body. Screening 8000 Photorhabdus mutants for defects in IJ colonization revealed that a single fimbrial locus, named mad for maternal adhesion defective, is essential. The mad genes encode a novel usher/chaperone assembled fimbria regulated by an ON/OFF invertible promoter switch. Adherent Photorhabdus cells in maternal nematode intestines had the switch ON opposite to the OFF orientation of most other cells. A ΔmadA mutant failed to adhere to maternal intestines and be transmitted to the IJs. Mad fimbriae were detected on TT01 phase ON cells but not on ΔmadA phase ON cells. Also required for transmission is madJ, predicted to encode a transcriptional activator related to GrlA. Expression of madA-K or madIJK restored the ability of madJ mutant to adhere. The Mad fimbriae were not required for insect pathogenesis, indicating the specialized function of Mad fimbriae for symbiosis.
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Affiliation(s)
- Vishal S Somvanshi
- Department of Microbiology and Molecular Genetics and the Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI 48824, USA
| | - Bettina Kaufmann-Daszczuk
- Department of Microbiology and Molecular Genetics and the Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI 48824, USA
| | - Kwi-Suk Kim
- Department of Microbiology and Molecular Genetics and the Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI 48824, USA
| | - Shane Mallon
- Department of Microbiology and Molecular Genetics and the Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI 48824, USA
| | - Todd A Ciche
- Department of Microbiology and Molecular Genetics and the Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI 48824, USA
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Hultdin UW, Lindberg S, Grundström C, Allgardsson A, Huang S, Stier G, Öhman A, Uhlin BE, Sauer-Eriksson AE. Purification, crystallization and preliminary data analysis of FocB, a transcription factor regulating fimbrial adhesin expression in uropathogenic Escherichia coli. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:337-41. [PMID: 20208176 PMCID: PMC2833052 DOI: 10.1107/s1744309110002204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 01/18/2010] [Indexed: 05/28/2023]
Abstract
The transcription factor FocB belongs to a family of regulators encoded by several different fimbriae gene clusters in uropathogenic Escherichia coli. Recent findings suggest that FocB-family proteins may form different protein-protein complexes and that they may exert both positive and negative effects on the transcription of fimbriae genes. However, little is known about the actual role and mode of action when these proteins interact with the fimbriae operons. The 109-amino-acid FocB transcription factor from the foc gene cluster in E. coli strain J96 has been cloned, expressed and purified. The His(6)-tagged fusion protein was captured by Ni(2+)-affinity chromatography, cleaved with tobacco etch virus protease and purified by gel filtration. The purified protein is oligomeric, most likely in the form of dimers. NMR analysis guided the crystallization attempts by showing that probable conformational exchange or oligomerization is reduced at temperatures above 293 K and that removal of the highly flexible His(6) tag is advantageous. The protein was crystallized using the hanging-drop vapour-diffusion method at 295 K. A native data set to 2.0 A resolution was collected at 100 K using synchrotron radiation.
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Affiliation(s)
| | - Stina Lindberg
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-901 87 Umeå, Sweden
| | | | - Anders Allgardsson
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-901 87 Umeå, Sweden
| | - Shenghua Huang
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Gunter Stier
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, DE-69117 Heidelberg, Germany
| | - Anders Öhman
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-901 87 Umeå, Sweden
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Unfolding and refolding properties of S pili on extraintestinal pathogenic Escherichia coli. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:1105-15. [DOI: 10.1007/s00249-009-0552-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 10/02/2009] [Accepted: 10/09/2009] [Indexed: 01/19/2023]
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Dalal S, Nicolle L, Marrs CF, Zhang L, Harding G, Foxman B. Long-term Escherichia coli asymptomatic bacteriuria among women with diabetes mellitus. Clin Infect Dis 2009; 49:491-7. [PMID: 19583518 DOI: 10.1086/600883] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Persistent Escherichia coli asymptomatic bacteriuria (ASB) is common among persons with diabetes mellitus, but the duration of colonization and the rates of recolonization are unknown. We estimated the duration of colonization and the rate of recolonization among successively isolated E. coli from diabetic women with ASB and compared the virulence profiles with uropathogenic and commensal E. coli. METHODS A total of 105 women with diabetes were enrolled in a randomized, controlled clinical trial for treatment of ASB in Manitoba, Canada, and were observed at least every 3 months for up to 3 years. We analyzed 517 isolates from 70 women with repeated E. coli ASB for genetic similarity using enterobacterial repetitive intergenic consensus polymerase chain reaction. Unique strains were screened for uropathogenic virulence characteristics using dot blot hybridization and compared with different collections of E. coli isolates. RESULTS On average, differences were found among women assigned to treatment for ASB, those treated only for symptomatic infections, and untreated women in (1) follow-up time with bacteriuria (29%, 31%, and 66%, respectively; P<.001), (2) duration of bacteriuria (2.2, 2.5, and 3.7 months, respectively; P=.04), and (3) carriage of unique isolates (2.4, 2.8, and 4 months, respectively; P=.03). Women assigned to antibiotic treatment usually had recurrent infection (76%), 64% of the time with a genetically new E. coli strain. Virulence characteristics of these isolates were comparable to those of fecal isolates from healthy women. CONCLUSIONS Treatment may reduce the overall proportion of time infected in the long term and carriage of a unique strain, but most treatment regimens were followed by subsequent recolonization. Infecting strains did not have virulence factors characteristic of uropathogenic E. coli.
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Affiliation(s)
- Shona Dalal
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA
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Identification of a conserved chromosomal region encoding Klebsiella pneumoniae type 1 and type 3 fimbriae and assessment of the role of fimbriae in pathogenicity. Infect Immun 2009; 77:5016-24. [PMID: 19703972 DOI: 10.1128/iai.00585-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Type 3 fimbriae are expressed by most clinical Klebsiella pneumoniae isolates and mediate adhesion to host structures in vitro. However, the role of type 3 fimbriae in K. pneumoniae virulence has not been evaluated by use of in vivo infection models. In this study, the type 3 fimbrial gene cluster (mrk) of the clinical isolate C3091 is described in detail. The mrk gene cluster was revealed to be localized in close proximity to the type 1 fimbrial gene cluster. Thus, a 20.4-kb fimbria-encoding region was identified and found to be highly conserved among different K. pneumoniae isolates. Interestingly, a homologue to PecS, known as a global regulator of virulence in Erwinia chrysanthemi, was identified in the fimbria-encoding region. Comparison to the previously characterized plasmid encoded mrk gene cluster revealed significant differences, and it is established here that the putative regulatory gene mrkE is not a part of the chromosomally encoded type 3 fimbrial gene cluster. To evaluate the role of type 3 fimbriae in virulence, a type 3 fimbria mutant and a type 1 and type 3 fimbria double mutant was constructed. Type 3 fimbria expression was found to strongly promote biofilm formation. However, the fimbria mutants were as effective at colonizing the intestine as the wild type, and their virulence was not attenuated in a lung infection model. Also, in a urinary tract infection model, type 3 fimbriae did not influence the virulence, whereas type 1 fimbriae were verified as an essential virulence factor. Thus, type 3 fimbriae were established not to be a virulence factor in uncomplicated K. pneumoniae infections. However, since type 3 fimbriae promote biofilm formation, their role in development of infections in catheterized patients needs to be elucidated.
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Visco P, Allen RJ, Evans MR. Statistical physics of a model binary genetic switch with linear feedback. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:031923. [PMID: 19391987 DOI: 10.1103/physreve.79.031923] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Indexed: 05/27/2023]
Abstract
We study the statistical properties of a simple genetic regulatory network that provides heterogeneity within a population of cells. This network consists of a binary genetic switch in which stochastic flipping between the two switch states is mediated by a "flipping" enzyme. Feedback between the switch state and the flipping rate is provided by a linear feedback mechanism: the flipping enzyme is only produced in the on switch state and the switching rate depends linearly on the copy number of the enzyme. This work generalizes the model of Visco [Phys. Rev. Lett. 101, 118104 (2008)] to a broader class of linear feedback systems. We present a complete analytical solution for the steady-state statistics of the number of enzyme molecules in the on and off states, for the general case where the enzyme can mediate flipping in either direction. For this general case we also solve for the flip time distribution, making a connection to first passage and persistence problems in statistical physics. We show that the statistics are non-Poissonian, leading to a peak in the flip time distribution. The occurrence of such a peak is analyzed as a function of the parameter space. We present a relation between the flip time distributions measured for two relevant choices of initial condition. We also introduce a correlation measure and use this to show that this model can exhibit long-lived temporal correlations, thus providing a primitive form of cellular memory. Motivated by DNA replication as well as by evolutionary mechanisms involving gene duplication, we study the case of two switches in the same cell. This results in correlations between the two switches; these can be either positive or negative depending on the parameter regime.
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Affiliation(s)
- Paolo Visco
- SUPA, School of Physics and Astronomy, The University of Edinburgh, James Clerk Maxwell Building, The King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
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Sjöström AE, Balsalobre C, Emödy L, Westerlund-Wikström B, Hacker J, Uhlin BE. The SfaXII protein from newborn meningitis E. coli is involved in regulation of motility and type 1 fimbriae expression. Microb Pathog 2009; 46:243-52. [PMID: 19486641 DOI: 10.1016/j.micpath.2009.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 01/16/2009] [Accepted: 01/22/2009] [Indexed: 02/07/2023]
Abstract
The genomes of pathogenic Escherichia coli may contain several different fimbrial operons. How bacteria regulate and coordinate the choice of fimbrial expression under different circumstances remains largely unanswered. In this report we have investigated the role of the sfaX(II) gene associated to the Sfa(II) fimbrial determinant in the E. coli isolate IHE3034. sfaX(II) belongs to a subfamily of genes, the 17k Da genes, located near different fimbrial operons in uropathogenic and newborn meningitis E. coli (NMEC) strains. Using the NMEC isolate IHE3034 and non-pathogenic E. coli strains we found that the sfaX(II) gene had an inhibitory effect on type 1 fimbriae expression. Down-regulation of type 1 fimbriae was exerted at transcriptional level both by inhibiting expression from the fimA promoter and by reducing the frequency of OFF-to-ON switching. The effect of sfaX(II) on expression of the recombinase FimB that catalyzes OFF-to-ON switching might explain the described reduction in percentage of ON cells. Moreover, expression of the sfaX(II) gene strongly influenced motility and flagella production of the NMEC isolate IHE3034. We propose that the sfaX(II) gene, and presumably other members in the 17 kDa gene family, may play a role in the control of virulence related gene expression in pathogenic E. coli.
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Affiliation(s)
- Annika E Sjöström
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden, Umeå University, S-90187 Umeå, Sweden
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Knight SD, Bouckaert J. Structure, Function, and Assembly of Type 1 Fimbriae. GLYCOSCIENCE AND MICROBIAL ADHESION 2009; 288:67-107. [DOI: 10.1007/128_2008_13] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
Antigen 43 (Ag43) is an abundant outer membrane protein in Escherichia coli belonging to the autotransporter family. Structure-function relationships of Ag43 proposed on the basis of experimental work and in silico analysis are discussed in context of insights derived from molecular modeling. New sequence analysis sheds light on the phylogeny of the allelic variants of the Ag43-encoding gene and identifies two distinct families that appear to be distributed between specific pathogenic and commensal isolates. The molecular mechanism that controls expression by phase variation to create population heterogeneity is discussed. Proposed roles of Ag43 expression for E. coli are summarized and the studies are put into perspective regarding the role of allelic variants, genetic background of the bacterial strain, and control of expression by phase variation. We conclude that future studies need to take into account these variables to obtain a complete understanding of the contribution of Ag43 expression to E. coli biology.
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Affiliation(s)
- Marjan W van der Woude
- Department of Biology and the Hull York Medical School, University of York, York Y010 5YW, United Kingdom.
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41
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Hendrickx APA, Bonten MJM, van Luit-Asbroek M, Schapendonk CME, Kragten AHM, Willems RJL. Expression of two distinct types of pili by a hospital-acquired Enterococcus faecium isolate. MICROBIOLOGY-SGM 2008; 154:3212-3223. [PMID: 18832326 DOI: 10.1099/mic.0.2008/020891-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Surface filamentous structures designated pili, and implicated in virulence, have been found on the surfaces of several Gram-positive pathogens. This work describes the conditional expression of two phenotypically distinct pilus-like structures, designated PilA and PilB, on the surface of a hospital-adapted Enterococcus faecium bloodstream isolate. E. faecium is an emerging Gram-positive opportunistic pathogen that can cause severe disease, particularly in immunocompromised patients. Expression of PilA- and PilB-type pili was analysed during different phases of growth in broth culture. During growth, PilA and PilB pilin subunits were expressed around the cross-wall in early-exponential-phase cells. Polymerization and migration of short PilB-type pili towards the poles occurred in cells from the exponential phase and long polymerized pili were expressed at the poles of cells grown to stationary phase. In contrast, PilA-type pili were not expressed in broth culture, but only when cells were grown on solid media. Furthermore, surface expression of the PilA- and PilB-type pili was regulated in a temperature-dependent manner, as polymerization of two distinct types of pili at the surface only occurred when cells were grown at 37 degrees C; no pili were observed on cells grown at 21 degrees C. Hospital-aquired E. faecium isolates were specifically enriched in pilin gene clusters, suggesting that conditional expression of pili may contribute to E. faecium pathogenesis.
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Affiliation(s)
- Antoni P A Hendrickx
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Marc J M Bonten
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.,Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Miranda van Luit-Asbroek
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Claudia M E Schapendonk
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Angela H M Kragten
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Rob J L Willems
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
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Visco P, Allen RJ, Evans MR. Exact solution of a model DNA-inversion genetic switch with orientational control. PHYSICAL REVIEW LETTERS 2008; 101:118104. [PMID: 18851337 DOI: 10.1103/physrevlett.101.118104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Indexed: 05/26/2023]
Abstract
DNA inversion is an important mechanism by which bacteria and bacteriophage switch reversibly between phenotypic states. In such switches, the orientation of a short DNA element is flipped by a site-specific recombinase enzyme. We propose a simple model for a DNA-inversion switch in which recombinase production is dependent on the switch state (orientational control). Our model is inspired by the fim switch in E. coli. We present an exact analytical solution of the chemical master equation for the model switch, as well as stochastic simulations. Orientational control causes the switch to deviate from Poissonian behavior: the distribution of times in the on state shows a peak and successive flip times are correlated.
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Affiliation(s)
- Paolo Visco
- SUPA, School of Physics, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
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43
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Origins and virulence mechanisms of uropathogenic Escherichia coli. Exp Mol Pathol 2008; 85:11-9. [PMID: 18482721 DOI: 10.1016/j.yexmp.2008.03.007] [Citation(s) in RCA: 381] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 03/02/2008] [Indexed: 11/23/2022]
Abstract
Strains of uropathogenic E. coli (UPEC) are the primary cause of urinary tract infections, including both cystitis and pyelonephritis. These bacteria have evolved a multitude of virulence factors and strategies that facilitate bacterial growth and persistence within the adverse settings of the host urinary tract. Expression of adhesive organelles like type 1 and P pili allow UPEC to bind and invade host cells and tissues within the urinary tract while expression of iron-chelating factors (siderophores) enable UPEC to pilfer host iron stores. Deployment of an array of toxins, including hemolysin and cytotoxic necrotizing factor 1, provide UPEC with the means to inflict extensive tissue damage, facilitating bacterial dissemination as well as releasing host nutrients and disabling immune effector cells. These toxins also have the capacity to modulate, in more subtle ways, host signaling pathways affecting myriad processes, including inflammatory responses, host cell survival, and cytoskeletal dynamics. Here, we discuss the mechanisms by which these and other virulence factors promote UPEC survival and growth within the urinary tract. Comparisons are also made between UPEC and other strains of extraintestinal pathogenic E. coli that, although closely related to UPEC, are distinct in their abilities to colonize the host and cause disease.
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Hazes B, Frost L. Towards a systems biology approach to study type II/IV secretion systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1839-50. [PMID: 18406342 DOI: 10.1016/j.bbamem.2008.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 02/22/2008] [Accepted: 03/17/2008] [Indexed: 10/22/2022]
Abstract
Many gram-negative bacteria produce thin protein filaments, named pili, which extend beyond the confines of the outer membrane. The importance of these pili is illustrated by the fact that highly complex, multi-protein pilus-assembly machines have evolved, not once, but several times. Their many functions include motility, adhesion, secretion, and DNA transfer, all of which can contribute to the virulence of bacterial pathogens or to the spread of virulence factors by horizontal gene transfer. The medical importance has stimulated extensive biochemical and genetic studies but the assembly and function of pili remains an enigma. It is clear that progress in this field requires a more holistic approach where the entire molecular apparatus that forms the pilus is studied as a system. In recent years systems biology approaches have started to complement classical studies of pili and their assembly. Moreover, continued progress in structural biology is building a picture of the components that make up the assembly machine. However, the complexity and multiple-membrane spanning nature of these secretion systems pose formidable technical challenges, and it will require a concerted effort before we can create comprehensive and predictive models of these remarkable molecular machines.
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Affiliation(s)
- Bart Hazes
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
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Totsika M, Beatson SA, Holden N, Gally DL. Regulatory interplay between pap operons in uropathogenic Escherichia coli. Mol Microbiol 2008; 67:996-1011. [DOI: 10.1111/j.1365-2958.2007.06098.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Wolf DM, Fontaine-Bodin L, Bischofs I, Price G, Keasling J, Arkin AP. Memory in microbes: quantifying history-dependent behavior in a bacterium. PLoS One 2008; 3:e1700. [PMID: 18324309 PMCID: PMC2264733 DOI: 10.1371/journal.pone.0001700] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 01/28/2008] [Indexed: 11/19/2022] Open
Abstract
Memory is usually associated with higher organisms rather than bacteria. However, evidence is mounting that many regulatory networks within bacteria are capable of complex dynamics and multi-stable behaviors that have been linked to memory in other systems. Moreover, it is recognized that bacteria that have experienced different environmental histories may respond differently to current conditions. These “memory” effects may be more than incidental to the regulatory mechanisms controlling acclimation or to the status of the metabolic stores. Rather, they may be regulated by the cell and confer fitness to the organism in the evolutionary game it participates in. Here, we propose that history-dependent behavior is a potentially important manifestation of memory, worth classifying and quantifying. To this end, we develop an information-theory based conceptual framework for measuring both the persistence of memory in microbes and the amount of information about the past encoded in history-dependent dynamics. This method produces a phenomenological measure of cellular memory without regard to the specific cellular mechanisms encoding it. We then apply this framework to a strain of Bacillus subtilis engineered to report on commitment to sporulation and degradative enzyme (AprE) synthesis and estimate the capacity of these systems and growth dynamics to ‘remember’ 10 distinct cell histories prior to application of a common stressor. The analysis suggests that B. subtilis remembers, both in short and long term, aspects of its cell history, and that this memory is distributed differently among the observables. While this study does not examine the mechanistic bases for memory, it presents a framework for quantifying memory in cellular behaviors and is thus a starting point for studying new questions about cellular regulation and evolutionary strategy.
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Affiliation(s)
- Denise M. Wolf
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * To whom correspondence should be addressed. E-mail: (DW); (AA)
| | - Lisa Fontaine-Bodin
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, California, United States of America
| | - Ilka Bischofs
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, California, United States of America
| | - Gavin Price
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, California, United States of America
| | - Jay Keasling
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, California, United States of America
- Department of Chemical Engineering, University of California, Berkeley, California, United States of America
| | - Adam P. Arkin
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, California, United States of America
- * To whom correspondence should be addressed. E-mail: (DW); (AA)
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Abstract
Escherichia coli is a predominant species among facultative anaerobic bacteria of the gastrointestinal tract. Both its frequent community lifestyle and the availability of a wide array of genetic tools contributed to establish E. coli as a relevant model organism for the study of surface colonization. Several key factors, including different extracellular appendages, are implicated in E. coli surface colonization and their expression and activity are finely regulated, both in space and time, to ensure productive events leading to mature biofilm formation. This chapter will present known molecular mechanisms underlying biofilm development in both commensal and pathogenic E. coli.
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Affiliation(s)
- C Beloin
- Groupe de Génétique des Biofilms, Institut Pasteur, CNRS URA 2172, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
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Nart P, Holden N, McAteer SP, Wang D, Flockhart AF, Naylor SW, Low JC, Gally DL, Huntley JF. Mucosal antibody responses of colonized cattle to Escherichia coli O157-secreted proteins, flagellin, outer membrane proteins and lipopolysaccharide. ACTA ACUST UNITED AC 2007; 52:59-68. [PMID: 17995963 DOI: 10.1111/j.1574-695x.2007.00341.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The aim of this work was to characterize adaptive mucosal immune responses to Escherichia coli O157:H7 at the principal site of colonization in the bovine species. Following experimental infection, extracts from terminal rectum mucosal samples were tested for IgA antibodies by immunoblotting against different bacterial antigens including: whole-cell E. coli O157:H7 with and without proteinase treatment, outer membrane and cytoplasmic preparations, secreted protein supernatants and purified E. coli O157 lipopolysaccharide and H7 flagellin. Lipopolysaccharide and H7 flagellin preparations were also used to coat enzyme-linked immunosorbent assay plates to determine mucosal IgG1 and IgA antibody titers. In this work, evidence is presented of strong local IgA immune responses induced following infection at the bovine terminal rectal mucosa directed against multiple antigens including type III secretion-dependent proteins, O157 lipopolysaccharide, H7 flagellin and OmpC.
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Affiliation(s)
- Pablo Nart
- Centre for Infectious Diseases, School of Veterinary Medicine, University of Edinburgh, Edinburgh, UK
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Ulett GC, Mabbett AN, Fung KC, Webb RI, Schembri MA. The role of F9 fimbriae of uropathogenic Escherichia coli in biofilm formation. Microbiology (Reading) 2007; 153:2321-2331. [PMID: 17600076 DOI: 10.1099/mic.0.2006/004648-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI) in the developed world. The major factors associated with virulence of UPEC are fimbrial adhesins, which mediate attachment to specific receptors, enhance persistence and trigger innate host responses. UPEC produce a range of fimbrial adhesins, with type 1 and P fimbriae of the chaperone-usher subclass being the best characterized. The prototype UPEC strain CFT073 contains ten gene clusters that contain genes characteristic of this class of fimbriae. However, only five of these gene clusters have been characterized in detail. In this study the F9 fimbrial gene cluster (c1931-c1936) from CFT073 has been characterized. The F9 fimbriae-encoding genes were PCR amplified, cloned and expressed in a K-12 background devoid of type 1 fimbriae. While F9 fimbrial expression was not associated with any haemagglutination or cellular adherence properties, a role in biofilm formation was observed. E. coli K-12 cells expressing F9 fimbriae produced a dense and uniform biofilm in both microtitre plate and continuous-flow biofilm model systems. In wild-type UPEC CFT073, expression of the F9 major subunit-encoding gene was detected during exponential growth in M9 minimal medium. F9 expression could also be detected following selection and enrichment for pellicle growth in a CFT073fim foc double mutant. The F9 genes appear to be common in UPEC and other types of pathogenic E. coli. However, their precise contribution to disease remains to be determined.
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Affiliation(s)
- Glen C Ulett
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Amanda N Mabbett
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Khe C Fung
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Richard I Webb
- Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark A Schembri
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
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50
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Magnusson LU, Gummesson B, Joksimović P, Farewell A, Nyström T. Identical, independent, and opposing roles of ppGpp and DksA in Escherichia coli. J Bacteriol 2007; 189:5193-202. [PMID: 17496080 PMCID: PMC1951846 DOI: 10.1128/jb.00330-07] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recent discovery that the protein DksA acts as a coregulator of genes controlled by ppGpp led us to investigate the similarities and differences between the relaxed phenotype of a ppGpp-deficient mutant and the phenotype of a strain lacking DksA. We demonstrate that the absence of DksA and ppGpp has similar effects on many of the observed phenotypes but that DksA and ppGpp also have independent and sometimes opposing roles in the cell. Specifically, we show that overexpression of DksA can compensate for the loss of ppGpp with respect to transcription of the promoters P(uspA), P(livJ), and P(rrnBP1) as well as amino acid auxotrophy, cell-cell aggregation, motility, filamentation, and stationary phase morphology, suggesting that DksA can function without ppGpp in regulating gene expression. In addition, ppGpp and DksA have opposing effects on adhesion. In the course of our analysis, we also discovered new features of the relaxed mutant, namely, defects in cell-cell aggregation and motility.
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Affiliation(s)
- Lisa U Magnusson
- Department of Cell and Molecular Biology-Microbiology, Göteborg University, Box 462, 405 30 Göteborg, Sweden.
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