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Izquierdo M, Lopez J, Gallardo P, Vidal RM, Ossa JC, Farfan MJ. Bacteria from gut microbiota associated with diarrheal infections in children promote virulence of Shiga toxin-producing and enteroaggregative Escherichia coli pathotypes. Front Cell Infect Microbiol 2022; 12:867205. [PMID: 36017363 PMCID: PMC9396624 DOI: 10.3389/fcimb.2022.867205] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/07/2022] [Indexed: 11/26/2022] Open
Abstract
Background Diarrheagenic E. coli (DEC) pathogenicity relies on the interaction of bacteria with the host’s gut environment, which is regulated by the resident microbiota. Previously, we identified indicative bacterial species of gut microbiota in DEC-positive stool samples from children. Here, we evaluated the role of two indicative species, Citrobacter werkmanii (CW) and Escherichia albertii (EA), in the virulence of two DEC pathotypes, Shiga toxin-producing (STEC) and enteroaggregative (EAEC) Escherichia coli. Methods We determined the effect of supernatants obtained from CW and EA cultures on the gene expression of STEC strain 86-24 and EAEC strain 042 by RNA-seq analysis. We evaluated IL-8 secretion from T84 cells infected with these DEC strains in the presence or absence of the supernatant from EA. The effect of the supernatant from EA on the growth and adherence of STEC and EAEC to cells was also evaluated. Finally, we studied the effect of the EA supernatant on the STEC-induced inflammation mediated by the long polar fimbriae (Lpf) in T84 cells and the expression of plasmid-encoded toxin (Pet) in EAEC. Results RNA-seq analysis revealed that several virulence factors in STEC and EAEC were upregulated in the presence of supernatants from CW and EA. Interestingly, an increase in the secretion of IL-8 was observed in cells infected with STEC or EAEC in the presence of a supernatant from EA. Similar results were observed with the supernatants obtained from clinical strains of E. albertii. The supernatant from EA had no effect on the growth of STEC and EAEC, or on the ability of these DEC strains to adhere to cells. We found that Pet toxin in EAEC was upregulated in the presence of a supernatant from EA. In STEC, using mutant strains for Lpf fimbriae, our data suggested that these fimbriae might be participating in the increase in IL-8 induced by STEC in cells in the presence of a supernatant from EA. Conclusion Supernatant obtained from an indicative species of DEC-positive diarrhea could modulate gene expression in STEC and EAEC, and IL-8 secretion induced by these bacteria. These data provide new insights into the effect of gut microbiota species in the pathogenicity of STEC and EAEC.
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Affiliation(s)
- Mariana Izquierdo
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Joaquín Lopez
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Pablo Gallardo
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Roberto M. Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Juan C. Ossa
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Mauricio J. Farfan
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- *Correspondence: Mauricio J. Farfan,
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Ma R, Liu Y, Gan J, Qiao H, Ma J, Zhang Y, Bu Y, Shao S, Zhang Y, Wang Q. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3777-3798. [PMID: 35325196 PMCID: PMC9023278 DOI: 10.1093/nar/gkac180] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/25/2022] [Accepted: 03/07/2022] [Indexed: 11/14/2022] Open
Affiliation(s)
| | | | | | - Haoxian Qiao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jiabao Ma
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yi Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yifan Bu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Shuai Shao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Qiyao Wang
- To whom correspondence should be addressed. Tel: +86 21 64253306; Fax: +86 21 64253306;
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Pfeifer E, Hünnefeld M, Popa O, Frunzke J. Impact of Xenogeneic Silencing on Phage-Host Interactions. J Mol Biol 2019; 431:4670-4683. [PMID: 30796986 PMCID: PMC6925973 DOI: 10.1016/j.jmb.2019.02.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 01/21/2023]
Abstract
Phages, viruses that prey on bacteria, are the most abundant and diverse inhabitants of the Earth. Temperate bacteriophages can integrate into the host genome and, as so-called prophages, maintain a long-term association with their host. The close relationship between host and virus has significantly shaped microbial evolution and phage elements may benefit their host by providing new functions. Nevertheless, the strong activity of phage promoters and potentially toxic gene products may impose a severe fitness burden and must be tightly controlled. In this context, xenogeneic silencing (XS) proteins, which can recognize foreign DNA elements, play an important role in the acquisition of novel genetic information and facilitate the evolution of regulatory networks. Currently known XS proteins fall into four classes (H-NS, MvaT, Rok and Lsr2) and have been shown to follow a similar mode of action by binding to AT-rich DNA and forming an oligomeric nucleoprotein complex that silences gene expression. In this review, we focus on the role of XS proteins in phage-host interactions by highlighting the important function of XS proteins in maintaining the lysogenic state and by providing examples of how phages fight back by encoding inhibitory proteins that disrupt XS functions in the host. Sequence analysis of available phage genomes revealed the presence of genes encoding Lsr2-type proteins in the genomes of phages infecting Actinobacteria. These data provide an interesting perspective for future studies to elucidate the impact of phage-encoded XS homologs on the phage life cycle and phage-host interactions.
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Affiliation(s)
- Eugen Pfeifer
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany.
| | - Max Hünnefeld
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany
| | - Ovidiu Popa
- Heinrich Heine Universität Düsseldorf, Institute for Quantitative and Theoretical Biology, 40223 Düsseldorf, Germany
| | - Julia Frunzke
- Forschungszentrum Jülich GmbH, Institute for Bio- and Geosciences 1, IBG1, 52425 Jülich, Germany.
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Abstract
The H-NS (heat-stable nucleoid structuring) protein affects both nucleoid compaction and global gene regulation. H-NS appears to act primarily as a silencer of AT-rich genetic material acquired by horizontal gene transfer. As such, it is key in the regulation of most genes involved in virulence and in adaptation to new environmental niches. Here we review recent progress in understanding the biochemistry of H-NS and how xenogeneic silencing affects bacterial evolution. We highlight the strengths and weaknesses of some of the models proposed in H-NS-mediated nucleoprotein complex formation. Based on recent single-molecule studies, we also propose a novel mode of DNA compaction by H-NS termed intrabridging to explain over two decades of observations of the H-NS molecule.
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Affiliation(s)
- Kamna Singh
- Department of Molecular Genetics, University of Toronto, Ontario M5S 1A8, Canada;
| | - Joshua N Milstein
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Ontario L5L 1C6, Canada.,Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
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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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Ali SS, Soo J, Rao C, Leung AS, Ngai DHM, Ensminger AW, Navarre WW. Silencing by H-NS potentiated the evolution of Salmonella. PLoS Pathog 2014; 10:e1004500. [PMID: 25375226 PMCID: PMC4223078 DOI: 10.1371/journal.ppat.1004500] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 10/02/2014] [Indexed: 11/17/2022] Open
Abstract
The bacterial H-NS protein silences expression from sequences with higher AT-content than the host genome and is believed to buffer the fitness consequences associated with foreign gene acquisition. Loss of H-NS results in severe growth defects in Salmonella, but the underlying reasons were unclear. An experimental evolution approach was employed to determine which secondary mutations could compensate for the loss of H-NS in Salmonella. Six independently derived S. Typhimurium hns mutant strains were serially passaged for 300 generations prior to whole genome sequencing. Growth rates of all lineages dramatically improved during the course of the experiment. Each of the hns mutant lineages acquired missense mutations in the gene encoding the H-NS paralog StpA encoding a poorly understood H-NS paralog, while 5 of the mutant lineages acquired deletions in the genes encoding the Salmonella Pathogenicity Island-1 (SPI-1) Type 3 secretion system critical to invoke inflammation. We further demonstrate that SPI-1 misregulation is a primary contributor to the decreased fitness in Salmonella hns mutants. Three of the lineages acquired additional loss of function mutations in the PhoPQ virulence regulatory system. Similarly passaged wild type Salmonella lineages did not acquire these mutations. The stpA missense mutations arose in the oligomerization domain and generated proteins that could compensate for the loss of H-NS to varying degrees. StpA variants most able to functionally substitute for H-NS displayed altered DNA binding and oligomerization properties that resembled those of H-NS. These findings indicate that H-NS was central to the evolution of the Salmonellae by buffering the negative fitness consequences caused by the secretion system that is the defining characteristic of the species.
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Affiliation(s)
- Sabrina S. Ali
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Jeremy Soo
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Chitong Rao
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Andrea S. Leung
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David Hon-Man Ngai
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Dorman CJ. H-NS-like nucleoid-associated proteins, mobile genetic elements and horizontal gene transfer in bacteria. Plasmid 2014; 75:1-11. [DOI: 10.1016/j.plasmid.2014.06.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/23/2014] [Accepted: 06/25/2014] [Indexed: 11/29/2022]
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Winardhi RS, Gulvady R, Mellies JL, Yan J. Locus of enterocyte effacement-encoded regulator (Ler) of pathogenic Escherichia coli competes off histone-like nucleoid-structuring protein (H-NS) through noncooperative DNA binding. J Biol Chem 2014; 289:13739-50. [PMID: 24668810 DOI: 10.1074/jbc.m113.545954] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The locus of enterocyte effacement-encoded regulator (Ler) of enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) functions to activate transcription of virulence genes silenced by the histone-like nucleoid-structuring protein (H-NS). Despite its important role in the bacterial gene regulation, the binding mode of Ler to DNA and its mechanism in alleviating genes repressed by H-NS are largely unknown. In this study, we use magnetic tweezers to demonstrate that Ler binds extended DNA through a largely noncooperative process, which results in DNA stiffening and DNA folding depending on protein concentration. We also show that Ler can replace prebound H-NS on DNA over a range of potassium and magnesium concentrations. Our findings reveal the DNA binding properties of Ler and shed light to further understand the anti-silencing activity of Ler.
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Affiliation(s)
- Ricksen S Winardhi
- From the NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore, the Mechanobiology Institute, Singapore 117411, Singapore, the Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Ranjit Gulvady
- the Mechanobiology Institute, Singapore 117411, Singapore, the Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Jay L Mellies
- the Biology Department, Reed College, Portland, Oregon 97202, and
| | - Jie Yan
- the Mechanobiology Institute, Singapore 117411, Singapore, the Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore, the Department of Physics, National University of Singapore, Singapore 117542, Singapore
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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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AFM volumetric methods for the characterization of proteins and nucleic acids. Methods 2013; 60:113-21. [DOI: 10.1016/j.ymeth.2013.02.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/28/2013] [Accepted: 02/14/2013] [Indexed: 11/19/2022] Open
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