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Machado MAM, Chapartegui-González I, Castro VS, Figueiredo EEDS, Conte-Junior CA, Torres AG. Biofilm-producing Escherichia coli O104:H4 overcomes bile salts toxicity by expressing virulence and resistance proteins. Lett Appl Microbiol 2024; 77:ovae032. [PMID: 38573831 DOI: 10.1093/lambio/ovae032] [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: 11/09/2023] [Revised: 02/15/2024] [Accepted: 04/03/2024] [Indexed: 04/06/2024]
Abstract
We investigated bile salts' ability to induce phenotypic changes in biofilm production and protein expression of pathogenic Escherichia coli strains. For this purpose, 82 pathogenic E. coli strains isolated from humans (n = 70), and animals (n = 12), were examined for their ability to form biofilms in the presence or absence of bile salts. We also identified bacterial proteins expressed in response to bile salts using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-electrophoresis) and liquid chromatography-mass spectrometry (LC-MS/MS). Lastly, we evaluated the ability of these strains to adhere to Caco-2 epithelial cells in the presence of bile salts. Regarding biofilm formation, two strains isolated from an outbreak in Republic of Georgia in 2009 were the only ones that showed a high and moderate capacity to form biofilm in the presence of bile salts. Further, we observed that those isolates, when in the presence of bile salts, expressed different proteins identified as outer membrane proteins (i.e. OmpC), and resistance to adverse growth conditions (i.e. F0F1, HN-S, and L7/L12). We also found that these isolates exhibited high adhesion to epithelial cells in the presence of bile salts. Together, these results contribute to the phenotypic characterization of E. coli O104: H4 strains.
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Affiliation(s)
- Maxsueli Aparecida Moura Machado
- Food Science Program (PPGCAL), Chemistry Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-909, Brazil
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), Cidade Universitaria, Rio de Janeiro 21941-598, RJ, Brazil
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), Cidade Universitaria, Rio de Janeiro 21941-909, RJ, Brazil
| | - Itziar Chapartegui-González
- Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, United States
| | - Vinicius Silva Castro
- Animal Science Program (PPGCA). Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso 78060-900, Brazil
- Nutrition, Food and Metabolism Program (PPGNAM). Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso 78060-900, Brazil
| | - Eduardo Eustáquio de Souza Figueiredo
- Animal Science Program (PPGCA). Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso 78060-900, Brazil
- Nutrition, Food and Metabolism Program (PPGNAM). Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso 78060-900, Brazil
| | - Carlos Adam Conte-Junior
- Food Science Program (PPGCAL), Chemistry Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-909, Brazil
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), Cidade Universitaria, Rio de Janeiro 21941-598, RJ, Brazil
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), Cidade Universitaria, Rio de Janeiro 21941-909, RJ, Brazil
| | - Alfredo G Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, TX 77555, United States
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Rodriguez-Valverde D, Giron JA, Hu Y, Nataro JP, Ruiz-Perez F, Santiago AE. Highly-conserved regulatory activity of the ANR family in the virulence of diarrheagenic bacteria through interaction with master and global regulators. Sci Rep 2023; 13:7024. [PMID: 37120613 PMCID: PMC10148876 DOI: 10.1038/s41598-023-33997-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 04/22/2023] [Indexed: 05/01/2023] Open
Abstract
ANR (AraC negative regulators) are a novel class of small regulatory proteins commonly found in enteric pathogens. Aar (AggR-activated regulator), the best-characterized member of the ANR family, regulates the master transcriptional regulator of virulence AggR and the global regulator HNS in enteroaggregative Escherichia coli (EAEC) by protein-protein interactions. On the other hand, Rnr (RegA-negative regulator) is an ANR homolog identified in attaching and effacing (AE) pathogens, including Citrobacter rodentium and enteropathogenic Escherichia coli (EPEC), sharing only 25% identity with Aar. We previously found that C. rodentium lacking Rnr exhibits prolonged shedding and increased gut colonization in mice compared to the parental strain. To gain mechanistic insights into this phenomenon, we characterized the regulatory role of Rnr in the virulence of prototype EPEC strain E2348/69 by genetic, biochemical, and human organoid-based approaches. Accordingly, RNA-seq analysis revealed more than 500 genes differentially regulated by Rnr, including the type-3 secretion system (T3SS). The abundance of EspA and EspB in whole cells and bacterial supernatants confirmed the negative regulatory activity of Rnr on T3SS effectors. We found that besides HNS and Ler, twenty-six other transcriptional regulators were also under Rnr control. Most importantly, the deletion of aar in EAEC or rnr in EPEC increases the adherence of these pathogens to human intestinal organoids. In contrast, the overexpression of ANR drastically reduces bacterial adherence and the formation of AE lesions in the intestine. Our study suggests a conserved regulatory mechanism and a central role of ANR in modulating intestinal colonization by these enteropathogens despite the fact that EAEC and EPEC evolved with utterly different virulence programs.
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Affiliation(s)
- Diana Rodriguez-Valverde
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Jorge A Giron
- Centro de Detección Biomolecular, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
- Translational Genomics Research Institute, 445 N. 5th St, Phoenix, AZ, 85004, USA
| | - Yang Hu
- CD Genomics, Shirley, NY, USA
| | - James P Nataro
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Fernando Ruiz-Perez
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Araceli E Santiago
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA.
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3
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The deletion of yeaJ gene facilitates Escherichia coli escape from immune recognition. J Bacteriol 2021; 203:e0033621. [PMID: 34309400 DOI: 10.1128/jb.00336-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mammary gland-derived Escherichia coli (E. coli) is an important pathogen causing dairy cow mastitis. Mammary gland mucosal immunity against infectious E. coli mainly depends on recognition of pathogen-associated molecular patterns by innate receptors. Stimulator of interferon (IFN) gene (STING) has recently been the dominant mediator in reacting to bacterial intrusion and preventing inflammatory disorders. In this study, we firstly proved that diguanylate cyclase YeaJ relieves mouse mammary gland pathological damage by changing E. coli phenotypic and host STING-dependent innate immunity response. YeaJ decreases mammary gland circular vacuoles, bleeding and degeneration in mice. In addition, YeaJ participates in STING-IRF3 signaling to regulate inflammation in vivo. While in vitro, YeaJ decreases damage to macrophages (RAW264.7) but not to mouse mammary epithelial cells (EpH4-Ev). Consistent with the results in mouse mammary gland, yeaJ significantly activates STING/TBK1/IRF3 pathway in RAW264.7 as well. In conclusion, the deletion of yeaJ gene facilitates E. coli NJ17 escape from STING-dependent innate immunity recognition in vitro and in vivo. This study highlights a novel role for YeaJ in E. coli infection, which provides a better understanding of host-bacteria interactions and potential prophylactic strategies for infections. IMPORTANCE E. coli is the etiological agent of environmental mastitis in dairy cows, which cause massive financial losses worldwide. However, the pathophysiological role of yeaJ in the interaction between E. coli and host remains unclear. We found that YeaJ significantly influences various biological characteristics and suppresses severe inflammatory response as well as greater damage. YeaJ alleviates damage to macrophages (RAW264.7) and mouse mammary gland. Moreover, these effects of YeaJ are achieved at least partial by mediating the STING-IRF3 signaling pathway. In conclusion, the deletion of yeaJ gene facilitates E. coli NJ17 escape from STING-dependent innate immunity recognition in vitro and in vivo. This study is the basis for further research to better understand host-bacteria interactions and provides potential prophylactic strategies for infections.
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Enterohemorrhagic Escherichia coli pathogenesis: role of Long polar fimbriae in Peyer's patches interactions. Sci Rep 2017; 7:44655. [PMID: 28317910 PMCID: PMC5357955 DOI: 10.1038/srep44655] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 02/13/2017] [Indexed: 11/14/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are major food-borne pathogens whose survival and virulence in the human digestive tract remain unclear owing to paucity of relevant models. EHEC interact with the follicle-associated epithelium of Peyer’s patches of the distal ileum and translocate across the intestinal epithelium via M-cells, but the underlying molecular mechanisms are still unknown. Here, we investigated the involvement of Long polar fimbriae (Lpf) in EHEC pathogenesis. Of the 236 strains tested, a significant association was observed between the presence of lpf operons and pathogenicity. In sophisticated in vitro models of the human gastro-intestinal tract, lpf expression was induced during transit through the simulated stomach and small intestine, but not in the colonic compartment. To investigate the involvement of Lpf in EHEC pathogenesis, lpf isogenic mutants and their relative trans-complemented strains were generated. Translocation across M-cells, interactions with murine ileal biopsies containing Peyer’s patches and the number of hemorrhagic lesions were significantly reduced with the lpf mutants compared to the wild-type strain. Complementation of lpf mutants fully restored the wild-type phenotypes. Our results indicate that (i) EHEC might colonize the terminal ileum at the early stages of infection, (ii) Lpf are an important player in the interactions with Peyer’s patches and M-cells, and could contribute to intestinal colonization.
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Virulence traits and different nle profiles in cattle and human verotoxin-producing Escherichia coli O157:H7 strains from Argentina. Microb Pathog 2017; 102:102-108. [DOI: 10.1016/j.micpath.2016.11.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/28/2016] [Accepted: 11/29/2016] [Indexed: 12/22/2022]
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6
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Monteiro R, Ageorges V, Rojas-Lopez M, Schmidt H, Weiss A, Bertin Y, Forano E, Jubelin G, Henderson IR, Livrelli V, Gobert AP, Rosini R, Soriani M, Desvaux M. A secretome view of colonisation factors in Shiga toxin-encodingEscherichia coli(STEC): from enterohaemorrhagicE. coli(EHEC) to related enteropathotypes. FEMS Microbiol Lett 2016; 363:fnw179. [DOI: 10.1093/femsle/fnw179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2016] [Indexed: 12/25/2022] Open
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7
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Kennedy NM, Mukherjee N, Banerjee P. Escherichia coli O157:H7 Cells Exposed to Lettuce Leaf Lysate in Refrigerated Conditions Exhibit Differential Expression of Selected Virulence and Adhesion-Related Genes with Altered Mammalian Cell Adherence. J Food Prot 2016; 79:1259-65. [PMID: 27357048 DOI: 10.4315/0362-028x.jfp-15-504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Contamination by and persistence of pathogenic bacteria in ready-to-eat produce have emerged as significant food safety and public health concerns. Viable produceborne pathogens cope with several stresses (e.g., temperature fluctuations and lowtemperature storage) during production and storage of the commodities. In this study, we investigated the impact of transient cold shock on Escherichia coli O157:H7 (EcO157) cells in a produce matrix (romaine lettuce leaf lysate). EcO157 cells were exposed to 25°C for 1 h, 4°C for 1 h, and 4°C for 10 min in lettuce lysate. The expression of selected genes coding for virulence, stress response, and heat and cold shock proteins was quantified by real-time quantitative reverse transcription PCR assay. Treated EcO157 cells adhered to MAC-T mammalian cells were enumerated by in vitro bioassay. Expression of the Shiga toxin 1 gene (stx1a) was upregulated significantly (P < 0.05) upon cold shock treatments, but virulence genes related to EcO157 attachment (eaeA, lpfA, and hcpA) were down-regulated. Two key members of the cold shock regulon, cold shock protein (cspA) and gyrA, were significantly induced (P < 0.05) at the refrigeration temperature (4°C). Significant upregulation of an SOS response gene, recA, was also observed. E. coli heat shock regulon member grpE was induced, but a universal stress protein (uspA) was downregulated at the refrigeration temperatures in lettuce lysate. The adhesion assay revealed a temperature-dependent reduction in the attachment of cold-shocked EcO157 cells. The results of the current study indicate a reduction in the attachment of cold-shocked EcO157 to epithelial cells and higher levels of Shiga toxin gene expression at the molecular level.
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Affiliation(s)
- Nicole M Kennedy
- Department of Food and Animal Sciences, Alabama A&M University, Huntsville, Alabama 35762, USA
| | - Nabanita Mukherjee
- Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, Tennessee 38152, USA
| | - Pratik Banerjee
- Department of Food and Animal Sciences, Alabama A&M University, Huntsville, Alabama 35762, USA; Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, Tennessee 38152, USA.
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8
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Regulation of Expression of Uropathogenic Escherichia coli Nonfimbrial Adhesin TosA by PapB Homolog TosR in Conjunction with H-NS and Lrp. Infect Immun 2016; 84:811-21. [PMID: 26755158 DOI: 10.1128/iai.01302-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/31/2015] [Indexed: 12/11/2022] Open
Abstract
Urinary tract infections (UTIs) are a major burden to human health. The overwhelming majority of UTIs are caused by uropathogenic Escherichia coli (UPEC) strains. Unlike some pathogens, UPEC strains do not have a fixed core set of virulence and fitness factors but do have a variety of adhesins and regulatory pathways. One such UPEC adhesin is the nonfimbrial adhesin TosA, which mediates adherence to the epithelium of the upper urinary tract. The tos operon is AT rich, resides on pathogenicity island aspV, and is not expressed under laboratory conditions. Because of this, we hypothesized that tosA expression is silenced by H-NS. Lrp, based on its prominent function in the regulation of other adhesins, is also hypothesized to contribute to tos operon regulation. Using a variety of in vitro techniques, we mapped both the tos operon promoter and TosR binding sites. We have now identified TosR as a dual regulator of the tos operon, which could control the tos operon in association with H-NS and Lrp. H-NS is a negative regulator of the tos operon, and Lrp positively regulates the tos operon. Exogenous leucine also inhibits Lrp-mediated tos operon positive regulation. In addition, TosR binds to the pap operon, which encodes another important UPEC adhesin, P fimbria. Induction of TosR synthesis reduces production of P fimbria. These studies advance our knowledge of regulation of adhesin expression associated with uropathogen colonization of a host.
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Finding Regulators Associated with the Expression of the Long Polar Fimbriae in Enteropathogenic Escherichia coli. J Bacteriol 2015; 197:3658-65. [PMID: 26350135 DOI: 10.1128/jb.00509-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/02/2015] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Enteropathogenic Escherichia coli (EPEC) is a human pathogen that requires initial adhesion to the intestine in order to cause disease. Multiple adhesion factors have been identified in E. coli strains, among them the long polar fimbriae (Lpf), a colonization factor associated with intestinal adhesion. The conditions of Lpf expression are well understood in enterohemorrhagic E. coli (EHEC); however, the expression of EPEC lpf has been found to be repressed under any in vitro condition tested. Therefore, we decided to identify those factors silencing expression of EPEC lpf. Because histone-like nucleoid structuring protein (H-NS) is a known repressor of EHEC lpf, we tested it and found that H-NS is a repressor of EPEC lpf. We also found that the adhesion of the EPEC Δhns strain was significantly enhanced compared to the wild-type strain. Because lpf expression was modestly increased in the hns mutant, transposon mutagenesis was performed to find a strain displaying higher lpf expression than EPEC Δhns. One Tn5 insertion was identified within the yhjX gene, and further in vitro characterization revealed increased lpf expression and adhesion to Caco-2 cells compared with EPEC Δhns. However, in a murine model of intestinal infection, the EPEC Δhns and EPEC Δhns Tn5 mutants had only a slight change in colonization pattern compared to the wild-type strain. Our data showed that EPEC Lpf is transcribed, but its role in EPEC intestinal colonization requires further analysis. IMPORTANCE Data are presented demonstrating that the long polar fimbriae (lpf) operon in enteropathogenic E. coli (EPEC) is highly regulated; however, derepression occurs by mutagenizing two proteins associated with its control. The study demonstrates that the EPEC lpf operon can be expressed and, therefore, participates in the EPEC adherence phenotype.
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Hu J, Zhu MJ. Defects in polynucleotide phosphorylase impairs virulence in Escherichia coli O157:H7. Front Microbiol 2015; 6:806. [PMID: 26347717 PMCID: PMC4538292 DOI: 10.3389/fmicb.2015.00806] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 07/22/2015] [Indexed: 01/31/2023] Open
Abstract
Polynucleotide phosphorylase (PNPase) is reported to regulate virulence in Salmonella, Yersinia sp. and Campylobacter jejuni, yet its role in Escherichia coli O157:H7 has not been investigated. To gain insights into its roles in E. coli O157:H7 virulence, pnp deletion mutants were generated and the major virulence factors were compared to their parental wild type strains. Deletion of pnp in E. coli O157:H7 dramatically decreased stx2 mRNA expression and Stx2 protein production, and impaired lambdoid prophage activation in E. coli O157:H7. Quantitative PCR further confirmed that the Stx2 phage lytic growth was repressed by pnp deletion. Consistent with reduced Stx2 production and Stx2 phage activation, the transcriptional levels of genes involved in phage lysis and replication were down-regulated. In addition, disruption of pnp in E. coli O157:H7 decreased its adhesion to intestinal epithelial cells as well as cattle colonic explant tissues. On the other hand, PNPase inactivation in E. coli O157:H7 enhanced Tir protein content and the transcription of type three secretion system components, including genes encoding intimin, Tir, and EspB as well as locus of enterocyte and effacement positive regulator, Ler. Collectively, data indicate that PNPase has pleiotropic effects on the virulence of E. coli O157:H7.
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Affiliation(s)
- Jia Hu
- School of Food Science, Washington State University, Pullman, WA USA ; Department of Animal Science, University of Wyoming, Laramie, WY USA
| | - Mei-Jun Zhu
- School of Food Science, Washington State University, Pullman, WA USA
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Abstract
Adhesins are a group of proteins in enterohemorrhagic Escherichia coli (EHEC) that are involved in the attachment or colonization of this pathogen to abiotic (plastic or steel) and biological surfaces, such as those found in bovine and human intestines. This review provides the most up-to-date information on these essential adhesion factors, summarizing important historical discoveries and analyzing the current and future state of this research. In doing so, the proteins intimin and Tir are discussed in depth, especially regarding their role in the development of attaching and effacing lesions and in EHEC virulence. Further, a series of fimbrial proteins (Lpf1, Lpf2, curli, ECP, F9, ELF, Sfp, HCP, and type 1 fimbriae) are also described, emphasizing their various contributions to adherence and colonization of different surfaces and their potential use as genetic markers in detection and classification of different EHEC serotypes. This review also discusses the role of several autotransporter proteins (EhaA-D, EspP, Saa and Sab, and Cah), as well as other proteins associated with adherence, such as flagella, EibG, Iha, and OmpA. While these proteins have all been studied to varying degrees, all of the adhesins summarized in this chapter have been linked to different stages of the EHEC life cycle, making them good targets for the development of more effective diagnostics and therapeutics.
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Affiliation(s)
- Brian D. McWilliams
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, 77555. USA
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Abstract
ABSTRACT
Coordinated expression of enterohemorrhagic
Escherichia coli
virulence genes enables the bacterium to cause hemorrhagic colitis and the complication known as hemolytic-uremic syndrome. Horizontally acquired genes and those common to
E. coli
contribute to the disease process, and increased virulence gene expression is correlated with more severe disease in humans. Researchers have gained considerable knowledge about how the type III secretion system, secreted effectors, adhesin molecules, and the Shiga toxins are regulated by environmental signals and multiple genetic pathways. Also emergent from the data is an understanding of how enterohemorrhagic
E. coli
regulates response to acid stress, the role of flagellar motility, and how passage through the human host and bovine intestinal tract causes disease and supports carriage in the cattle reservoir, respectively. Particularly exciting areas of discovery include data suggesting how expression of the myriad effectors is coordinately regulated with their cognate type III secretion system and how virulence is correlated with bacterial metabolism and gut physiology.
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Levine JA, Hansen AM, Michalski JM, Hazen TH, Rasko DA, Kaper JB. H-NST induces LEE expression and the formation of attaching and effacing lesions in enterohemorrhagic Escherichia coli. PLoS One 2014; 9:e86618. [PMID: 24466172 PMCID: PMC3897749 DOI: 10.1371/journal.pone.0086618] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 12/17/2013] [Indexed: 11/19/2022] Open
Abstract
Background Enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli are important causes of morbidity and mortality worldwide. These enteric pathogens contain a type III secretion system (T3SS) responsible for the attaching and effacing (A/E) lesion phenotype. The T3SS is encoded by the locus of enterocyte effacement (LEE) pathogenicity island. The H-NS-mediated repression of LEE expression is counteracted by Ler, the major activator of virulence gene expression in A/E pathogens. A regulator present in EPEC, H-NST, positively affects expression of H-NS regulon members in E. coli K-12, although the effect of H-NST on LEE expression and virulence of A/E pathogens has yet-to-be determined. Results We examine the effect of H-NST on LEE expression and A/E lesion formation on intestinal epithelial cells. We find that H-NST positively affects the levels of LEE-encoded proteins independently of ler and induces A/E lesion formation. We demonstrate H-NST binding to regulatory regions of LEE1 and LEE3, the first report of DNA-binding by H-NST. We characterize H-NST mutants substituted at conserved residues including Ala16 and residues Arg60 and Arg63, which are part of a potential DNA-binding domain. The single mutants A16V, A16L, R60Q and the double mutant R60Q/R63Q exhibit a decreased effect on LEE expression and A/E lesion formation. DNA mobility shift assays reveal that these residues are important for H-NST to bind regulatory LEE DNA targets. H-NST positively affects Ler binding to LEE DNA in the presence of H-NS, and thereby potentially helps Ler displace H-NS bound to DNA. Conclusions H-NST induces LEE expression and A/E lesion formation likely by counteracting H-NS-mediated repression. We demonstrate that H-NST binds to DNA and identify arginine residues that are functionally important for DNA-binding. Our study suggests that H-NST provides an additional means for A/E pathogens to alleviate repression of virulence gene expression by H-NS to promote virulence capabilities.
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Affiliation(s)
- Jonathan A. Levine
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Graduate Program in Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, United States of America
| | - Anne-Marie Hansen
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jane M. Michalski
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Tracy H. Hazen
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - David A. Rasko
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James B. Kaper
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Role of sortase-dependent pili of Bifidobacterium bifidum PRL2010 in modulating bacterium-host interactions. Proc Natl Acad Sci U S A 2013; 110:11151-6. [PMID: 23776216 DOI: 10.1073/pnas.1303897110] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Bifidobacteria represent one of the dominant groups of microorganisms colonizing the human infant intestine. Commensal bacteria that interact with a eukaryotic host are believed to express adhesive molecules on their cell surface that bind to specific host cell receptors or soluble macromolecules. Whole-genome transcription profiling of Bifidobacterium bifidum PRL2010, a strain isolated from infant stool, revealed a small number of commonly expressed extracellular proteins, among which were genes that specify sortase-dependent pili. Expression of the coding sequences of these B. bifidum PRL2010 appendages in nonpiliated Lactococcus lactis enhanced adherence to human enterocytes through extracellular matrix protein and bacterial aggregation. Furthermore, such piliated L. lactis cells evoked a higher TNF-α response during murine colonization compared with their nonpiliated parent, suggesting that bifidobacterial sortase-dependent pili not only contribute to adherence but also display immunomodulatory activity.
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Sváb D, Galli L, Horváth B, Maróti G, Dobrindt U, Torres AG, Rivas M, Tóth I. The long polar fimbriae operon and its flanking regions in bovine Escherichia coli O157:H43 and STEC O136:H12 strains. Pathog Dis 2013; 68:1-7. [PMID: 23620202 DOI: 10.1111/2049-632x.12038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/07/2012] [Accepted: 02/23/2013] [Indexed: 11/30/2022] Open
Abstract
Long polar fimbriae (Lpf) are intestinal adhesins and important virulence factors of pathogenic Escherichia coli strains. We cloned and sequenced the lpf2-1 operon (lpf2ABCD) and its flanking regions of an intimin- and Shiga toxin-negative atypical E. coli O157:H43 strain of bovine origin and also sequenced the lpf2-1 operon of six additional atypical O157 bovine E. coli strains of various serotypes. Nucleotide sequence comparison of these lpf operons showed sequence conservation as they contained only four polymorphic nucleotide positions. Investigation of these O157 strains as well as 13 E. coli Reference Collection (ECOR) strains carrying the lpf2-1 allele revealed high degree of sequence conservation in the lpf2 flanking regions. The lpf2-1 allele is also present in a bovine Shiga toxin-producing E. coli STEC O136:H12 strain, and in vitro adherence assays revealed that the absence of lpf2-1 in this strain did not affect its host cell-binding properties. Our data indicate that lpf2 loci are highly conserved in E. coli isolates; however, its role in adherence might be masked by other uncharacterized adhesins.
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Affiliation(s)
- Domonkos Sváb
- Centre for Agricultural Research, Institute for Veterinary Medical Research, Hungarian Academy of Sciences, Budapest, Hungary
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16
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Hu J, Wang B, Fang X, Means WJ, McCormick RJ, Gomelsky M, Zhu MJ. c-di-GMP signaling regulates E. coli O157:H7 adhesion to colonic epithelium. Vet Microbiol 2013; 164:344-51. [PMID: 23528649 DOI: 10.1016/j.vetmic.2013.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/23/2013] [Accepted: 02/23/2013] [Indexed: 12/01/2022]
Abstract
Escherichia coli O157:H7 is an important foodborne pathogen that causes serious illness in humans at low infectious doses. The main source of infections is beef or greens contaminated with E. coli O157:H7 shed by cattle. Here we investigated the role of c-di-GMP-dependent signal transduction in cattle gut colonization of E. coli O157:H7. To manipulate intracellular c-di-GMP levels, we introduced into E. coli O157:H7 a c-di-GMP specific phosphodiesterase (PDE). Liquid chromatography tandem mass spectrometry analysis confirmed that in E. coli O157:H7, over-expression of PDE decreased c-di-GMP level. Consistent with the altered c-di-GMP level, PDE overexpression resulted in decreased biofilm formation in E. coli O157:H7. Furthermore, this diminished c-di-GMP levels reduced adhesion of E. coli O157:H7 to both cultured HT-29 cells and cattle colon explants. Consistently, mRNA levels of genes involved in adhesion were down-regulated including genes encoding E. coli common pili, long polar fimbriae 1, hemorrhagic coli pilus, as well as intimin and tir. We further observed decreased curli fimbriae synthesis in the strain with decreased c-di-GMP levels, which was supported by the reduction in the transcription of curli large subunit gene csgA and the curli expression regulator gene csgD. Genes for enterocyte effacement encoded regulator (Ler) and type III secretion system effectors, EspA and EspB, were also down-regulated. Collectively, data indicated that c-di-GMP signaling positively regulates E. coli O157:H7 intestinal epithelial cell and tissue colonization and expression of associated adhesion factors.
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Affiliation(s)
- Jia Hu
- Department of Animal Science, University of Wyoming, Laramie, WY 82071, USA
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17
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Hansen AM, Jin DJ. SspA up-regulates gene expression of the LEE pathogenicity island by decreasing H-NS levels in enterohemorrhagic Escherichia coli. BMC Microbiol 2012; 12:231. [PMID: 23051860 PMCID: PMC3539938 DOI: 10.1186/1471-2180-12-231] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/09/2012] [Indexed: 11/29/2022] Open
Abstract
Background Enterohemorrhagic Escherichia coli (EHEC) colonizes the intestinal epithelium and causes attaching and effacing (A/E) lesions. Expression of virulence genes, particularly those from the locus of the enterocyte effacement (LEE) pathogenicity island is required for the formation of a type three secretion system, which induces A/E lesion formation. Like other horizontally acquired genetic elements, expression of the LEE is negatively regulated by H-NS. In the non-pathogenic Escherichia coli K-12 strain the stringent starvation protein A (SspA) inhibits accumulation of H-NS, and thereby allows de-repression of the H-NS regulon during the stationary phase of growth. However, the effect of SspA on the expression of H-NS-controlled virulence genes in EHEC is unknown. Results Here we assess the effect of SspA on virulence gene expression in EHEC. We show that transcription of virulence genes including those of the LEE is decreased in an sspA mutant, rendering the mutant strain defective in forming A/E lesions. A surface exposed pocket of SspA is functionally important for the regulation of the LEE and for the A/E phenotype. Increased expression of ler alleviates LEE expression in an sspA mutant, suggesting that the level of Ler in the mutant is insufficient to counteract H-NS-mediated repression. We demonstrate that the H-NS level is two-fold higher in an sspA mutant compared to wild type, and that the defects of the sspA mutant are suppressed by an hns null mutation, indicating that hns is epistatic to sspA in regulating H-NS repressed virulence genes. Conclusions SspA positively regulates the expression of EHEC virulence factors by restricting the intracellular level of H-NS. Since SspA is conserved in many bacterial pathogens containing horizontally acquired pathogenicity islands controlled by H-NS, our study suggests a common mechanism whereby SspA potentially regulates the expression of virulence genes in these pathogens.
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Affiliation(s)
- Anne-Marie Hansen
- Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory, Frederick National Laboratory for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
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18
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Chingcuanco F, Yu Y, Kus JV, Que L, Lackraj T, Lévesque CM, Barnett Foster D. Identification of a novel adhesin involved in acid-induced adhesion of enterohaemorrhagic Escherichia coli O157 : H7. Microbiology (Reading) 2012; 158:2399-2407. [DOI: 10.1099/mic.0.056374-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Frances Chingcuanco
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Yijing Yu
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Julianne V. Kus
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Lynn Que
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Tracy Lackraj
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Céline M. Lévesque
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
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19
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Chassaing B, Etienne-Mesmin L, Bonnet R, Darfeuille-Michaud A. Bile salts induce long polar fimbriae expression favouring Crohn's disease-associated adherent-invasive Escherichia coli interaction with Peyer's patches. Environ Microbiol 2012; 15:355-71. [PMID: 22789019 DOI: 10.1111/j.1462-2920.2012.02824.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ileal lesions of patients with Crohn's disease are colonized by adherent-invasive Escherichia coli (AIEC). The earliest lesions of recurrent Crohn's disease are erosions of Peyer's patches (PP). We recently reported the presence of a functional lpf operon in AIEC, encoding long polar fimbriae (LPF), that allows AIEC bacteria to interact with PP and to translocate across M cells. The aim of this study was to analyse the effect of gastrointestinal conditions on LPF expression in AIEC strains. The LF82 bacterial growth in an acid pH medium or at high osmolarity medium had no effect on lpf transcription level, in contrast to bacterial growth in the presence of bile salts, which promoted activation of lpf transcription. When cultured in the presence of bile salt, LF82 wild-type bacteria, but not the isogenic mutant deleted for lpfA, exhibited a higher level of interaction with PP and a higher level of translocation through M cell monolayers. The FhlA transcriptional factor was found to be a key bacterial regulator at the origin of LPF expression in the presence of bile salts.
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Affiliation(s)
- Benoit Chassaing
- Clermont Université, UMR 1071 Inserm/Université Auvergne, Clermont-Ferrand 63000, France
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20
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Nara JM, Pimenta DC, Abe CM, Abreu PAE, Moraes CTP, Freitas NC, Elias WP, Piazza RMF. Low-molecular mass comparative proteome of four atypical enteropathogenic Escherichia coli isolates showing different adherence patterns. Comp Immunol Microbiol Infect Dis 2012; 35:539-49. [PMID: 22768807 DOI: 10.1016/j.cimid.2012.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/04/2012] [Accepted: 06/10/2012] [Indexed: 11/19/2022]
Abstract
Atypical enteropathogenic Escherichia coli (aEPEC) are heterogeneous in terms of serotypes, adherence patterns and the presence of non-locus of enterocyte effacement virulence factors. In this study, the low-molecular mass proteomes of four representative aEPEC, comprising three different adhesion phenotypes (localized-like, aggregative and diffuse) and one non-adherent isolate, were analyzed and compared by 2D gel electrophoresis and LC-MS/MS. By mass spectrometry, a total of 59 proteins were identified according to their annotated function, with most of them being involved in metabolism, protection, and transport; some of them still classified as hypothetical proteins. Thus, in this comparative proteomic analysis of low-molecular mass extracted proteins from different aEPEC isolates, the proteins identified are mainly involved in key metabolic pathways. Also, the majority of the hypothetical and filamentous proteins identified in the isolates studied are products of genes originally identified in the genome of enterohemorrhagic E. coli.
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Affiliation(s)
- Júlia M Nara
- Laboratório de Bacteriologia, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900, São Paulo, SP, Brazil
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21
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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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22
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Lloyd SJ, Ritchie JM, Rojas-Lopez M, Blumentritt CA, Popov VL, Greenwich JL, Waldor MK, Torres AG. A double, long polar fimbria mutant of Escherichia coli O157:H7 expresses Curli and exhibits reduced in vivo colonization. Infect Immun 2012; 80:914-20. [PMID: 22232190 PMCID: PMC3294650 DOI: 10.1128/iai.05945-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 12/27/2011] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 causes food and waterborne enteric infections that can result in hemorrhagic colitis and life-threatening hemolytic uremic syndrome. Intimate adherence of the bacteria to intestinal epithelial cells is mediated by intimin, but E. coli O157:H7 also possess several other putative adhesins, including curli and two operons that encode long polar fimbriae (Lpf). To assess the importance of Lpf for intestinal colonization, we performed competition experiments between E. coli O157:H7 and an isogenic ΔlpfA1 ΔlpfA2 double mutant in the infant rabbit model. The mutant was outcompeted in the ileum, cecum, and midcolon, suggesting that Lpf contributes to intestinal colonization. In contrast, the ΔlpfA1 ΔlpfA2 mutant showed increased adherence to colonic epithelial cells in vitro. Transmission electron microscopy revealed curli-like structures on the surface of the ΔlpfA1 ΔlpfA2 mutant, and the presence of curli was confirmed by Congo red binding, immunogold-labeling electron microscopy, immunoblotting, and quantitative real-time reverse transcription-PCR (qRT-PCR) measuring csgA expression. However, deletion of csgA, which encodes the major curli subunit, does not appear to affect intestinal colonization. In addition to suggesting that Lpf can contribute to EHEC intestinal colonization, our observations indicate that the regulatory pathways governing the expression of Lpf and curli are interdependent.
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Affiliation(s)
| | - Jennifer M. Ritchie
- Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | | | | | | | - Jennifer L. Greenwich
- Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew K. Waldor
- Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Alfredo G. Torres
- Departments of Microbiology and Immunology
- Pathology
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, USA
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23
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Farfan MJ, Torres AG. Molecular mechanisms that mediate colonization of Shiga toxin-producing Escherichia coli strains. Infect Immun 2012; 80:903-13. [PMID: 22144484 PMCID: PMC3294676 DOI: 10.1128/iai.05907-11] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a group of pathogens which cause gastrointestinal disease in humans and have been associated with numerous food-borne outbreaks worldwide. The intimin adhesin has been considered for many years to be the only colonization factor in these strains. However, the rapid progress in whole-genome sequencing of different STEC serotypes has accelerated the discovery of other adhesins (fimbrial and afimbrial), which have emerged as important contributors to the intestinal colonization occurring during STEC infection. This review summarizes recent progress to identify and characterize, at the molecular level, novel adhesion and colonization factors in STEC strains, with an emphasis on their contribution to virulence traits, their host-pathogen interactions, the regulatory mechanisms controlling their expression, and their role as targets eliciting immune responses in the host.
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Affiliation(s)
- Mauricio J. Farfan
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, Department of Pathology, Sealy Center for Vaccine Development, and Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, USA
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24
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Sváb D, Tóth I. Allelic types of long polar fimbriae in bovine and human Escherichia coli O157 strains. Acta Vet Hung 2012; 60:1-15. [PMID: 22366128 DOI: 10.1556/avet.2012.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Long polar fimbriae (Lpf) are recently discovered adhesins and increasingly important genetic markers of pathogenic Escherichia coli strains. The presence and genotype diversity of Lpf operons was screened in a collection of 97 Escherichia coli O157 strains representing different pathotypes, isolated from healthy cattle (n = 43) and human patients (n = 54) in several countries. Individual structural genes of Lpf were scanned by PCR, and allelic variants were detected with a recently developed typing scheme. Ninety-five strains carried at least one whole Lpf operon (genes lpfABCD and/or lpfABCDE). The 64 enterohaemorrhagic (EHEC) and 24 enteropathogenic (EPEC) strains all carried two Lpf operons, allele 3 of lpfA1 and allele 2 of lpfA2, a combination characteristic of the O157:H7/NM serotype. Out of the 9 bovine atypical (AT; stx-, eae-) strains, 7 carried one complete Lpf operon, allele 1 of lpfA2. The atypical strains belonged to main phylogenetic groups A and B1, while the EHEC and EPEC strains were from group D. Lpf variants carried by the 72 strains of the Escherichia coli Reference Collection (ECOR) were determined with the same typing scheme. Alleles were detected in 25 strains, of which 6 were found negative for the respective Lpf operons in earlier studies. The marker value of the Lpf allelic combination for the O157:H7/NM serotype was confirmed, and further evidence was given for the presence of at least two different genetic lineages of atypical bovine E. coli O157 strains.
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Affiliation(s)
- Domonkos Sváb
- 1 Hungarian Academy of Sciences Veterinary Medical Research Institute Hungária krt. 21 H-1143 Budapest Hungary
| | - István Tóth
- 1 Hungarian Academy of Sciences Veterinary Medical Research Institute Hungária krt. 21 H-1143 Budapest Hungary
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25
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Kudva I, Dean-Nystrom E. Bovine recto-anal junction squamous epithelial (RSE) cell adhesion assay for studying Escherichia coli O157 adherence. J Appl Microbiol 2011; 111:1283-94. [DOI: 10.1111/j.1365-2672.2011.05139.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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26
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Etienne-Mesmin L, Chassaing B, Sauvanet P, Denizot J, Blanquet-Diot S, Darfeuille-Michaud A, Pradel N, Livrelli V. Interactions with M cells and macrophages as key steps in the pathogenesis of enterohemorrhagic Escherichia coli infections. PLoS One 2011; 6:e23594. [PMID: 21858177 PMCID: PMC3157389 DOI: 10.1371/journal.pone.0023594] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 07/21/2011] [Indexed: 12/13/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are food-borne pathogens that can cause serious infections ranging from diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Translocation of Shiga-toxins (Stx) from the gut lumen to underlying tissues is a decisive step in the development of the infection, but the mechanisms involved remain unclear. Many bacterial pathogens target the follicle-associated epithelium, which overlies Peyer's patches (PPs), cross the intestinal barrier through M cells and are captured by mucosal macrophages. Here, translocation across M cells, as well as survival and proliferation of EHEC strains within THP-1 macrophages were investigated using EHEC O157:H7 reference strains, isogenic mutants, and 15 EHEC strains isolated from HC/HUS patients. We showed for the first time that E. coli O157:H7 strains are able to interact in vivo with murine PPs, to translocate ex vivo through murine ileal mucosa with PPs and across an in vitro human M cell model. EHEC strains are also able to survive and to produce Stx in macrophages, which induce cell apoptosis and Stx release. In conclusion, our results suggest that the uptake of EHEC by M cells and underlying macrophages in the PP may be a critical step in Stx translocation and release in vivo. A new model for EHEC infection in humans is proposed that could help in a fuller understanding of EHEC-associated diseases.
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Affiliation(s)
- Lucie Etienne-Mesmin
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception, Ingénierie et Développement de l'Aliment et du Médicament, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
| | - Benoit Chassaing
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Pierre Sauvanet
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- CHU Clermont Ferrand, Pôle des Pathologies Digestives, Clermont-Ferrand, France
| | - Jérémy Denizot
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Stéphanie Blanquet-Diot
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception, Ingénierie et Développement de l'Aliment et du Médicament, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
| | - Arlette Darfeuille-Michaud
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Nathalie Pradel
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Valérie Livrelli
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
- CHU Clermont-Ferrand, Service Bactériologie Mycologie Parasitologie, Clermont-Ferrand, France
- * E-mail:
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27
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Long polar fimbriae of enterohemorrhagic Escherichia coli O157:H7 bind to extracellular matrix proteins. Infect Immun 2011; 79:3744-50. [PMID: 21708988 DOI: 10.1128/iai.05317-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Adherence to intestinal cells is a key process in infection caused by enterohemorrhagic Escherichia coli (EHEC). Several adhesion factors that mediate the binding of EHEC to intestinal cells have been described, but the receptors involved in their recognition are not fully characterized. Extracellular matrix (ECM) proteins might act as receptors involved in the recognition of enteric pathogens, including EHEC. In this study, we sought to characterize the binding of EHEC O157:H7 to ECM proteins commonly present in the intestine. We found that EHEC prototype strains as well as other clinical isolates adhered more abundantly to surfaces coated with fibronectin, laminin, and collagen IV. Further characterization of this phenotype, by using antiserum raised against the LpfA1 putative major fimbrial subunit and by addition of mannose, showed that a reduced binding of EHEC to ECM proteins was observed in a long polar fimbria (lpf) mutant. We also found that the two regulators, H-NS and Ler, had an effect in EHEC Lpf-mediated binding to ECM, supporting the roles of these tightly regulated fimbriae as adherence factors. Purified Lpf major subunit bound to all of the ECM proteins tested. Finally, increased bacterial adherence was observed when T84 cells, preincubated with ECM proteins, were infected with EHEC. Taken together, these findings suggest that the interaction of Lpf and ECM proteins contributes to the EHEC colonization of the gastrointestinal tract.
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28
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Liu J, Sun Y, Feng S, Zhu L, Guo X, Qi C. Towards an attenuated enterohemorrhagic Escherichia coli O157:H7 vaccine characterized by a deleted ler gene and containing apathogenic Shiga toxins. Vaccine 2009; 27:5929-35. [DOI: 10.1016/j.vaccine.2009.07.097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 07/20/2009] [Accepted: 07/24/2009] [Indexed: 11/16/2022]
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29
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Genes related to long polar fimbriae of pathogenic Escherichia coli strains as reliable markers to identify virulent isolates. J Clin Microbiol 2009; 47:2442-51. [PMID: 19494071 DOI: 10.1128/jcm.00566-09] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Lpf (stands for long polar fimbriae) is one of the few adhesive factors of enterohemorrhagic Escherichia coli O157:H7 associated with colonization of the intestine. E. coli O157:H7 strains possess two lpf loci encoding highly regulated fimbrial structures. Database analysis of the genes encoding the major fimbrial subunits demonstrated that they are present in commensal as well as pathogenic (both intestinal and extraintestinal) E. coli strains and in Salmonella strains and that the lpfA1 and lpfA2 genes are highly prevalent among LEE (locus of enterocyte effacement)-positive E. coli strains associated with severe and/or epidemic disease. Further DNA sequence analysis of the lpfA1 and lpfA2 genes from different attaching-and-effacing E. coli strains has led us to the identification of several polymorphisms and the classification of the major fimbrial subunits into distinct variants. Using collections of pathogenic E. coli isolates from Europe and Latin America, we demonstrated that the different lpfA types are associated with the presence of specific intimin (eae) adhesin variants and, most importantly, that they are found in specific E. coli pathotypes. Our results showed that the use of these fimbrial genes as markers, in combination with the different intimin types, resulted in a specific test for the identification of E. coli O157:H7, distinguishing it from other pathogenic E. coli strains.
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