1
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Saleh DO, Horstmann JA, Giralt-Zúñiga M, Weber W, Kaganovitch E, Durairaj AC, Klotzsch E, Strowig T, Erhardt M. SPI-1 virulence gene expression modulates motility of Salmonella Typhimurium in a proton motive force- and adhesins-dependent manner. PLoS Pathog 2023; 19:e1011451. [PMID: 37315106 DOI: 10.1371/journal.ppat.1011451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/01/2023] [Indexed: 06/16/2023] Open
Abstract
Both the bacterial flagellum and the evolutionary related injectisome encoded on the Salmonella pathogenicity island 1 (SPI-1) play crucial roles during the infection cycle of Salmonella species. The interplay of both is highlighted by the complex cross-regulation that includes transcriptional control of the flagellar master regulatory operon flhDC by HilD, the master regulator of SPI-1 gene expression. Contrary to the HilD-dependent activation of flagellar gene expression, we report here that activation of HilD resulted in a dramatic loss of motility, which was dependent on the presence of SPI-1. Single cell analyses revealed that HilD-activation triggers a SPI-1-dependent induction of the stringent response and a substantial decrease in proton motive force (PMF), while flagellation remains unaffected. We further found that HilD activation enhances the adhesion of Salmonella to epithelial cells. A transcriptome analysis revealed a simultaneous upregulation of several adhesin systems, which, when overproduced, phenocopied the HilD-induced motility defect. We propose a model where the SPI-1-dependent depletion of the PMF and the upregulation of adhesins upon HilD-activation enable flagellated Salmonella to rapidly modulate their motility during infection, thereby enabling efficient adhesion to host cells and delivery of effector proteins.
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Affiliation(s)
- Doaa Osama Saleh
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Julia A Horstmann
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - María Giralt-Zúñiga
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Willi Weber
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Abilash Chakravarthy Durairaj
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Enrico Klotzsch
- Institute for Biology, Experimental Biophysics/Mechanobiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Till Strowig
- Department of Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Marc Erhardt
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Berlin, Germany
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
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2
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Barrila J, Yang J, Franco Meléndez KP, Yang S, Buss K, Davis TJ, Aronow BJ, Bean HD, Davis RR, Forsyth RJ, Ott CM, Gangaraju S, Kang BY, Hanratty B, Nydam SD, Nauman EA, Kong W, Steel J, Nickerson CA. Spaceflight Analogue Culture Enhances the Host-Pathogen Interaction Between Salmonella and a 3-D Biomimetic Intestinal Co-Culture Model. Front Cell Infect Microbiol 2022; 12:705647. [PMID: 35711662 PMCID: PMC9195300 DOI: 10.3389/fcimb.2022.705647] [Citation(s) in RCA: 5] [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: 05/05/2021] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
Physical forces associated with spaceflight and spaceflight analogue culture regulate a wide range of physiological responses by both bacterial and mammalian cells that can impact infection. However, our mechanistic understanding of how these environments regulate host-pathogen interactions in humans is poorly understood. Using a spaceflight analogue low fluid shear culture system, we investigated the effect of Low Shear Modeled Microgravity (LSMMG) culture on the colonization of Salmonella Typhimurium in a 3-D biomimetic model of human colonic epithelium containing macrophages. RNA-seq profiling of stationary phase wild type and Δhfq mutant bacteria alone indicated that LSMMG culture induced global changes in gene expression in both strains and that the RNA binding protein Hfq played a significant role in regulating the transcriptional response of the pathogen to LSMMG culture. However, a core set of genes important for adhesion, invasion, and motility were commonly induced in both strains. LSMMG culture enhanced the colonization (adherence, invasion and intracellular survival) of Salmonella in this advanced model of intestinal epithelium using a mechanism that was independent of Hfq. Although S. Typhimurium Δhfq mutants are normally defective for invasion when grown as conventional shaking cultures, LSMMG conditions unexpectedly enabled high levels of colonization by an isogenic Δhfq mutant. In response to infection with either the wild type or mutant, host cells upregulated transcripts involved in inflammation, tissue remodeling, and wound healing during intracellular survival. Interestingly, infection by the Δhfq mutant led to fewer transcriptional differences between LSMMG- and control-infected host cells relative to infection with the wild type strain. This is the first study to investigate the effect of LSMMG culture on the interaction between S. Typhimurium and a 3-D model of human intestinal tissue. These findings advance our understanding of how physical forces can impact the early stages of human enteric salmonellosis.
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Affiliation(s)
- Jennifer Barrila
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- *Correspondence: Jennifer Barrila, ; Cheryl A. Nickerson,
| | - Jiseon Yang
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - Karla P. Franco Meléndez
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Genomics and Bioinformatics Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Gainesville, FL, United States
| | - Shanshan Yang
- Bioinformatics Core Facility, Bioscience, Knowledge Enterprise, Arizona State University, Tempe, AZ, United States
| | - Kristina Buss
- Bioinformatics Core Facility, Bioscience, Knowledge Enterprise, Arizona State University, Tempe, AZ, United States
| | - Trenton J. Davis
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Bruce J. Aronow
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | - Heather D. Bean
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Richard R. Davis
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - Rebecca J. Forsyth
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - C. Mark Ott
- Biomedical Research and Environmental Sciences Division, NASA Johnson Space Center, Houston, TX, United States
| | - Sandhya Gangaraju
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - Bianca Y. Kang
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - Brian Hanratty
- Bioinformatics Core Facility, Bioscience, Knowledge Enterprise, Arizona State University, Tempe, AZ, United States
| | - Seth D. Nydam
- Department of Animal Care & Technologies, Arizona State University, Tempe, AZ, United States
| | - Eric A. Nauman
- School of Mechanical Engineering, Weldon School of Biomedical Engineering and Department of Basic Medical Sciences, Purdue University, West Lafayette, IN, United States
| | - Wei Kong
- Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, United States
| | - Jason Steel
- Bioinformatics Core Facility, Bioscience, Knowledge Enterprise, Arizona State University, Tempe, AZ, United States
| | - Cheryl A. Nickerson
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- *Correspondence: Jennifer Barrila, ; Cheryl A. Nickerson,
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3
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Wang J, Ma S, Li W, Wang X, Huang D, Jiang L, Feng L. Salmonella enterica Serovar Typhi Induces Host Metabolic Reprogramming to Increase Glucose Availability for Intracellular Replication. Int J Mol Sci 2021; 22:ijms221810003. [PMID: 34576166 PMCID: PMC8467381 DOI: 10.3390/ijms221810003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi) is a human-limited intracellular pathogen and the cause of typhoid fever, a severe systemic disease. Pathogen–host interaction at the metabolic level affects the pathogenicity of intracellular pathogens, but it remains unclear how S. Typhi infection influences host metabolism for its own benefit. Herein, using metabolomics and transcriptomics analyses, combined with in vitro and in vivo infection assays, we investigated metabolic responses in human macrophages during S. Typhi infection, and the impact of these responses on S. Typhi intracellular replication and systemic pathogenicity. We observed increased glucose content, higher rates of glucose uptake and glycolysis, and decreased oxidative phosphorylation in S. Typhi-infected human primary macrophages. Replication in human macrophages and the bacterial burden in systemic organs of humanized mice were reduced by either the inhibition of host glucose uptake or a mutation of the bacterial glucose uptake system, indicating that S. Typhi utilizes host-derived glucose to enhance intracellular replication and virulence. Thus, S. Typhi promotes its pathogenicity by inducing metabolic changes in host macrophages and utilizing the glucose that subsequently accumulates as a nutrient for intracellular replication. Our findings provide the first metabolic signature of S. Typhi-infected host cells and identifies a new strategy utilized by S. Typhi for intracellular replication.
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Affiliation(s)
- Jingting Wang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
| | - Shuai Ma
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
| | - Wanwu Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
| | - Xinyue Wang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
| | - Di Huang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
| | - Lingyan Jiang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Correspondence: (L.J.); (L.F.)
| | - Lu Feng
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; (J.W.); (S.M.); (W.L.); (X.W.); (D.H.)
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Correspondence: (L.J.); (L.F.)
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4
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Ko D, Choi SH. Comparative genomics reveals an SNP potentially leading to phenotypic diversity of Salmonella enterica serovar Enteritidis. Microb Genom 2021; 7. [PMID: 33952386 PMCID: PMC8209725 DOI: 10.1099/mgen.0.000572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
An SNP is a spontaneous genetic change having a potential to modify the functions of the original genes and to lead to phenotypic diversity of bacteria in nature. In this study, a phylogenetic analysis of Salmonella enterica serovar Enteritidis, a major food-borne pathogen, showed that eight strains of S. Enteritidis isolated in South Korea, including FORC_075 and FORC_078, have almost identical genome sequences. Interestingly, however, the abilities of FORC_075 to form biofilms and red, dry and rough (RDAR) colonies were significantly impaired, resulting in phenotypic differences among the eight strains. Comparative genomic analyses revealed that one of the non-synonymous SNPs unique to FORC_075 has occurred in envZ, which encodes a sensor kinase of the EnvZ/OmpR two-component system. The SNP in envZ leads to an amino acid change from Pro248 (CCG) in other strains including FORC_078 to Leu248 (CTG) in FORC_075. Allelic exchange of envZ between FORC_075 and FORC_078 identified that the SNP in envZ is responsible for the impaired biofilm- and RDAR colony-forming abilities of S. Enteritidis. Biochemical analyses demonstrated that the SNP in envZ significantly increases the phosphorylated status of OmpR in S. Enteritidis and alters the expression of the OmpR regulon. Phenotypic analyses further identified that the SNP in envZ decreases motility of S. Enteritidis but increases its adhesion and invasion to both human epithelial cells and murine macrophage cells. In addition to an enhancement of infectivity to the host cells, survival under acid stress was also elevated by the SNP in envZ. Together, these results suggest that the natural occurrence of the SNP in envZ could contribute to phenotypic diversity of S. Enteritidis, possibly improving its fitness and pathogenesis.
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Affiliation(s)
- Duhyun Ko
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul, Republic of Korea
| | - Sang Ho Choi
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul, Republic of Korea
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5
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Rosenberg G, Yehezkel D, Hoffman D, Mattioli CC, Fremder M, Ben-Arosh H, Vainman L, Nissani N, Hen-Avivi S, Brenner S, Itkin M, Malitsky S, Ohana E, Ben-Moshe NB, Avraham R. Host succinate is an activation signal for
Salmonella
virulence during intracellular infection. Science 2021; 371:400-405. [DOI: 10.1126/science.aba8026] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 08/06/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Gili Rosenberg
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dror Yehezkel
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dotan Hoffman
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | | | - Moran Fremder
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel
| | - Hadar Ben-Arosh
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Leia Vainman
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Noa Nissani
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Shelly Hen-Avivi
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Shirley Brenner
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Maxim Itkin
- Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Sergey Malitsky
- Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ehud Ohana
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel
| | - Noa Bossel Ben-Moshe
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Roi Avraham
- Department of Biological Regulation, Weizmann Institute of Science, 7610001 Rehovot, Israel
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6
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Ma S, Liu X, Ma S, Jiang L. SopA inactivation or reduced expression is selected in intracellular Salmonella and contributes to systemic Salmonella infection. Res Microbiol 2020; 172:103795. [PMID: 33347947 DOI: 10.1016/j.resmic.2020.103795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/13/2020] [Accepted: 12/14/2020] [Indexed: 11/17/2022]
Abstract
Pseudogenes are accumulated in host-restricted Salmonella enterica serovars, while pseudogenization is primarily regarded as a process that purges unnecessary genes from the genome. Here we showed that the inactivation of sopA, which encodes an effector of Salmonella Pathogenicity Island 1, in human-restricted S. enterica serovar Typhi (S. Ty) and Paratyphi A (S. PA) is under positive selection and aimed to reduce bacterial cytotoxicity toward host macrophages. Moreover, we found that the expression of sopA in Salmonella Typhimurium (S. Tm), a broad-host-range serovar which causes systemic disease in mice, was negatively regulated during mice infection and survival in murine macrophages. The sopA repression in S. Tm is mediated by IsrM, a small RNA absent from the genome of S. Ty and S. PA. Due to the lack of IsrM, sopA expression was unregulated in S. Ty and S. PA, which might have facilitated the convergent inactivation of sopA in these two serovars. In conclusion, our findings demonstrate that sopA inactivation or intracellular repression is the target of positive selection during the systemic infection caused by S. enterica serovars.
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Affiliation(s)
- Shuangshuang Ma
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin 300457, China.
| | - Xiaoqian Liu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin 300457, China.
| | - Shuai Ma
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin 300457, China.
| | - Lingyan Jiang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300457, China; TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin 300457, China.
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7
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Jing W, Liu J, Wu S, Chen Q, Li X, Liu Y. Development of a Method for Simultaneous Generation of Multiple Genetic Modification in Salmonella enterica Serovar Typhimurium. Front Genet 2020; 11:563491. [PMID: 33193646 PMCID: PMC7544003 DOI: 10.3389/fgene.2020.563491] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/19/2020] [Indexed: 01/29/2023] Open
Abstract
To comprehensively analyze bacterial gene function, it is important to simultaneously generate multiple genetic modifications within the target gene. However, current genetic engineering approaches, which mainly use suicide vector- or λ red homologous recombination-based systems, are tedious and technically difficult to perform. Here, we developed a flexible and easy method to simultaneously construct multiple modifications at the same locus on the Salmonella enterica serovar Typhimurium chromosome. The method combines an efficient seamless assembly system in vitro, red homologous recombination in vivo, and counterselection marker sacB. To test this method, with the seamless assembly system, various modification fragments for target genes cpxR, cpxA, and acrB were rapidly and efficiently constructed in vitro. sacBKan cassettes generated via polymerase chain reaction were inserted into the target loci in the genome of Salmonella Typhimurium strain CVCC541. The resulting pKD46-containing kanamycin-resistant recombinants were selected and used as intermediate strains. Multiple target gene modifications were then carried out simultaneously via allelic exchange using various homologous recombinogenic DNA fragments to replace the sacBKan cassettes in the chromosomes of the intermediate strains. Using this method, we successfully carried out site-directed mutagenesis, seamless deletion, and 3 × FLAG tagging of the target genes. This method can be used in any bacterial species that supports sacB gene activity and λ red-mediated recombination, allowing in-depth functional analysis of bacterial genes.
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Affiliation(s)
- Wenxian Jing
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Juan Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Shanshan Wu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Qiwei Chen
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Xuerui Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yongsheng Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
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8
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Abstract
Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli. Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCEEscherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.
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9
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Usage of a Bioluminescence Reporter System to Image Promoter Activity During Host Infection. Methods Mol Biol 2018. [PMID: 29288444 DOI: 10.1007/978-1-4939-7604-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Bioluminescence is the process of production and emission of light by a living organism, usually as the by-product of the oxidative enzyme, luciferase. Currently available technology allows for the exploitation of a bioluminescent reporter system to study bacterial gene regulation during rodent infection, in real time, over a large dynamic range. Here we show how this imaging system can be used to study virulence gene regulation during Salmonella enterica infection in the mouse model. To demonstrate this technique we show the ex vivo expression pattern of the gene dksA, encoding a conserved and pleotropic regulator, which plays a key role in Salmonella pathogenicity [1].
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10
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Albenne C, Ieva R. Job contenders: roles of the β-barrel assembly machinery and the translocation and assembly module in autotransporter secretion. Mol Microbiol 2017; 106:505-517. [PMID: 28887826 DOI: 10.1111/mmi.13832] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2017] [Indexed: 01/17/2023]
Abstract
In Gram-negative bacteria, autotransporters secrete effector protein domains that are linked to virulence. Although they were once thought to be simple and autonomous secretion machines, mounting evidence reveals that multiple factors of the bacterial envelope are necessary for autotransporter assembly. Secretion across the outer membrane of their soluble effector "passenger domain" is promoted by the assembly of an outer membrane-spanning "β-barrel domain". Both reactions require BamA, an essential component of the β-barrel assembly machinery (BAM complex) that catalyzes the final reaction step by which outer membrane proteins are integrated into the lipid bilayer. A large amount of data generated in the last decade has shed key insights onto the mechanistic coordination of autotransporter β-barrel domain assembly and passenger domain secretion. These results, together with the recently solved structures of the BAM complex, offer an unprecedented opportunity to discuss a detailed model of autotransporter assembly. Importantly, some autotransporters benefit from the presence of an additional machinery, the translocation and assembly module (TAM), a two-membrane spanning complex, which contains a BamA-homologous subunit. Although it remains unclear how the BAM complex and the TAM cooperate, it is evident that multiple preparatory steps are necessary for efficient autotransporter biogenesis.
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Affiliation(s)
- Cécile Albenne
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Raffaele Ieva
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
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11
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Wrobel A, Ottoni C, Leo JC, Gulla S, Linke D. The repeat structure of two paralogous genes, Yersinia ruckeri invasin (yrInv) and a "Y. ruckeri invasin-like molecule", (yrIlm) sheds light on the evolution of adhesive capacities of a fish pathogen. J Struct Biol 2017; 201:171-183. [PMID: 28888816 DOI: 10.1016/j.jsb.2017.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/18/2017] [Accepted: 08/28/2017] [Indexed: 11/18/2022]
Abstract
Inverse autotransporters comprise the recently identified type Ve secretion system and are exemplified by intimin from enterohaemorrhagic Escherichia coli and invasin from enteropathogenic Yersiniae. These proteins share a common domain architecture and promote bacterial adhesion to host cells. Here, we identified and characterized two putative inverse autotransporter genes in the fish pathogen Yersinia ruckeri NVH_3758, namely yrInv (for Y. ruckeri invasin) and yrIlm (for Y. ruckeri invasin-like molecule). When trying to clone the highly repetitive genes for structural and functional studies, we experienced problems in obtaining PCR products. PCR failures and the highly repetitive nature of inverse autotransporters prompted us to sequence the genome of Y. ruckeri NVH_3758 using PacBio sequencing, which produces some of the longest average read lengths available in the industry at this moment. According to our sequencing data, YrIlm is composed of 2603 amino acids (7812bp) and has a molecular mass of 256.4kDa. Based on the new genome information, we performed PCR analysis on four non-sequenced Y. ruckeri strains as well as the sequenced. Y. ruckeri type strain. We found that the genes are variably present in the strains, and that the length of yrIlm, when present, also varies. In addition, the length of the gene product for all strains, including the type strain, was much longer than expected based on deposited sequences. The internal repeats of the yrInv gene product are highly diverged, but represent the same bacterial immunoglobulin-like domains as in yrIlm. Using qRT-PCR, we found that yrIlm and yrInv are differentially expressed under conditions relevant for pathogenesis. In addition, we compared the genomic context of both genes in the newly sequenced Y. ruckeri strain to all available PacBio-sequenced Y. ruckeri genomes, and found indications of recent events of horizontal gene transfer. Taken together, this study demonstrates and highlights the power of Single Molecule Real-Time technology for sequencing highly repetitive proteins, and sheds light on the genetic events that gave rise to these highly repetitive genes in a commercially important fish pathogen.
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Affiliation(s)
- Agnieszka Wrobel
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Claudio Ottoni
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway; Centre for Ecological and Evolutionary Synthesis, University of Oslo, 0316, Norway
| | - Jack C Leo
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Snorre Gulla
- Norwegian Veterinary Institute, 0454 Oslo, Norway
| | - Dirk Linke
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
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12
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Guérin J, Bigot S, Schneider R, Buchanan SK, Jacob-Dubuisson F. Two-Partner Secretion: Combining Efficiency and Simplicity in the Secretion of Large Proteins for Bacteria-Host and Bacteria-Bacteria Interactions. Front Cell Infect Microbiol 2017; 7:148. [PMID: 28536673 PMCID: PMC5422565 DOI: 10.3389/fcimb.2017.00148] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/10/2017] [Indexed: 12/31/2022] Open
Abstract
Initially identified in pathogenic Gram-negative bacteria, the two-partner secretion (TPS) pathway, also known as Type Vb secretion, mediates the translocation across the outer membrane of large effector proteins involved in interactions between these pathogens and their hosts. More recently, distinct TPS systems have been shown to secrete toxic effector domains that participate in inter-bacterial competition or cooperation. The effects of these systems are based on kin vs. non-kin molecular recognition mediated by specific immunity proteins. With these new toxin-antitoxin systems, the range of TPS effector functions has thus been extended from cytolysis, adhesion, and iron acquisition, to genome maintenance, inter-bacterial killing and inter-bacterial signaling. Basically, a TPS system is made up of two proteins, the secreted TpsA effector protein and its TpsB partner transporter, with possible additional factors such as immunity proteins for protection against cognate toxic effectors. Structural studies have indicated that TpsA proteins mainly form elongated β helices that may be followed by specific functional domains. TpsB proteins belong to the Omp85 superfamily. Open questions remain on the mechanism of protein secretion in the absence of ATP or an electrochemical gradient across the outer membrane. The remarkable dynamics of the TpsB transporters and the progressive folding of their TpsA partners at the bacterial surface in the course of translocation are thought to be key elements driving the secretion process.
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Affiliation(s)
- Jeremy Guérin
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, USA
| | - Sarah Bigot
- Molecular Microbiology and Structural Biochemistry, Centre National de La Recherche Scientifique UMR 5086-Université Lyon 1, Institute of Biology and Chemistry of ProteinsLyon, France
| | - Robert Schneider
- NMR and Molecular Interactions, Université de Lille, Centre National de La Recherche Scientifique, UMR 8576-Unité de Glycobiologie Structurale et FonctionnelleLille, France
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, USA
| | - Françoise Jacob-Dubuisson
- Université de Lille, Centre National de La Recherche Scientifique, Institut National de La Santé et de La Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-Centre d'Infection et d'Immunité de LilleLille, France
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13
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Haley BJ, Kim SW, Pettengill J, Luo Y, Karns JS, Van Kessel JAS. Genomic and Evolutionary Analysis of Two Salmonella enterica Serovar Kentucky Sequence Types Isolated from Bovine and Poultry Sources in North America. PLoS One 2016; 11:e0161225. [PMID: 27695032 PMCID: PMC5047448 DOI: 10.1371/journal.pone.0161225] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 08/02/2016] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica subsp. enterica serovar Kentucky is frequently isolated from healthy poultry and dairy cows and is occasionally isolated from people with clinical disease. A genomic analysis of 119 isolates collected in the United States from dairy cows, ground beef, poultry and poultry products, and human clinical cases was conducted. Results of the analysis demonstrated that the majority of poultry and bovine-associated S. Kentucky were sequence type (ST) 152. Several bovine-associated (n = 3) and food product isolates (n = 3) collected from the United States and the majority of human clinical isolates were ST198, a sequence type that is frequently isolated from poultry and occasionally from human clinical cases in Northern Africa, Europe and Southeast Asia. A phylogenetic analysis indicated that both STs are more closely related to other Salmonella serovars than they are to each other. Additionally, there was strong evidence of an evolutionary divergence between the poultry-associated and bovine-associated ST152 isolates that was due to polymorphisms in four core genome genes. The ST198 isolates recovered from dairy farms in the United States were phylogenetically distinct from those collected from human clinical cases with 66 core genome SNPs differentiating the two groups, but more isolates are needed to determine the significance of this distinction. Identification of S. Kentucky ST198 from dairy animals in the United States suggests that the presence of this pathogen should be monitored in food-producing animals.
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Affiliation(s)
- Bradd J. Haley
- Environmental Microbial and Food Safety Laboratory, Beltsville Area Research Center, Agricultural Research Services, United States Department of Agriculture, Beltsville, MD, United States of America
| | - Seon Woo Kim
- Environmental Microbial and Food Safety Laboratory, Beltsville Area Research Center, Agricultural Research Services, United States Department of Agriculture, Beltsville, MD, United States of America
| | - James Pettengill
- Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States of America
| | - Yan Luo
- Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, United States of America
| | - Jeffrey S. Karns
- Environmental Microbial and Food Safety Laboratory, Beltsville Area Research Center, Agricultural Research Services, United States Department of Agriculture, Beltsville, MD, United States of America
| | - Jo Ann S. Van Kessel
- Environmental Microbial and Food Safety Laboratory, Beltsville Area Research Center, Agricultural Research Services, United States Department of Agriculture, Beltsville, MD, United States of America
- * E-mail:
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14
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Heinz E, Stubenrauch CJ, Grinter R, Croft NP, Purcell AW, Strugnell RA, Dougan G, Lithgow T. Conserved Features in the Structure, Mechanism, and Biogenesis of the Inverse Autotransporter Protein Family. Genome Biol Evol 2016; 8:1690-705. [PMID: 27190006 PMCID: PMC4943183 DOI: 10.1093/gbe/evw112] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The bacterial cell surface proteins intimin and invasin are virulence factors that share a common domain structure and bind selectively to host cell receptors in the course of bacterial pathogenesis. The β-barrel domains of intimin and invasin show significant sequence and structural similarities. Conversely, a variety of proteins with sometimes limited sequence similarity have also been annotated as “intimin-like” and “invasin” in genome datasets, while other recent work on apparently unrelated virulence-associated proteins ultimately revealed similarities to intimin and invasin. Here we characterize the sequence and structural relationships across this complex protein family. Surprisingly, intimins and invasins represent a very small minority of the sequence diversity in what has been previously the “intimin/invasin protein family”. Analysis of the assembly pathway for expression of the classic intimin, EaeA, and a characteristic example of the most prevalent members of the group, FdeC, revealed a dependence on the translocation and assembly module as a common feature for both these proteins. While the majority of the sequences in the grouping are most similar to FdeC, a further and widespread group is two-partner secretion systems that use the β-barrel domain as the delivery device for secretion of a variety of virulence factors. This comprehensive analysis supports the adoption of the “inverse autotransporter protein family” as the most accurate nomenclature for the family and, in turn, has important consequences for our overall understanding of the Type V secretion systems of bacterial pathogens.
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Affiliation(s)
- Eva Heinz
- Department of Microbiology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Christopher J Stubenrauch
- Department of Microbiology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Rhys Grinter
- Department of Microbiology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia Institute of Microbiology and Infection, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Nathan P Croft
- Department of Biochemistry and Molecular Biology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Anthony W Purcell
- Department of Biochemistry and Molecular Biology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Richard A Strugnell
- Department of Microbiology & Immunology, University of Melbourne, Parkville, Australia
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Trevor Lithgow
- Department of Microbiology, Infection & Immunity Program, Biomedicine Discovery Institute, Monash University, Clayton, Australia
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15
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Bakour S, Sankar SA, Rathored J, Biagini P, Raoult D, Fournier PE. Identification of virulence factors and antibiotic resistance markers using bacterial genomics. Future Microbiol 2016; 11:455-66. [PMID: 26974504 DOI: 10.2217/fmb.15.149] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In recent years, the number of multidrug-resistant bacteria has increased rapidly and several epidemics were signaled in different regions of the world. Faced with this situation that presents a major global public health concern, the development and the use of new and rapid technologies is more than urgent. The use of the next-generation sequencing platforms by microbiologists and infectious disease specialists has allowed great progress in the medical field. Here, we review the usefulness of whole-genome sequencing for the detection of virulence and antibiotic resistance associated genes.
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Affiliation(s)
- Sofiane Bakour
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Senthil Alias Sankar
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Jaishriram Rathored
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Philippe Biagini
- UMR CNRS 7268 Equipe "Emergence et coévolution virale," Etablissement Français du Sang Alpes-Méditerranée et Aix-Marseille Université, 27 Boulevard Jean Moulin, 13005 Marseille
| | - Didier Raoult
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Pierre-Edouard Fournier
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
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16
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van der Heijden J, Vogt SL, Reynolds LA, Peña-Díaz J, Tupin A, Aussel L, Finlay BB. Exploring the redox balance inside gram-negative bacteria with redox-sensitive GFP. Free Radic Biol Med 2016; 91:34-44. [PMID: 26627936 DOI: 10.1016/j.freeradbiomed.2015.11.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 11/24/2015] [Accepted: 11/24/2015] [Indexed: 12/31/2022]
Abstract
Aerobic bacteria are continuously fighting potential oxidative stress due to endogenous and exogenous reactive oxygen species (ROS). To achieve this goal, bacteria possess a wide array of defenses and stress responses including detoxifying enzymes like catalases and peroxidases; however until now, the dynamics of the intra-bacterial redox balance remained poorly understood. Herein, we used redox-sensitive GFP (roGFP2) inside a variety of gram-negative bacteria to study real-time redox dynamics immediately after a challenge with hydrogen peroxide. Using this biosensor, we determined the individual contributions of catalases and peroxidases and found that each enzyme contributes more to rapid detoxification or to prolonged catalytic activity. We also found that the total catalytic power is affected by environmental conditions. Additionally, using a Salmonella strain that is devoid of detoxifying enzymes, we examined endogenous ROS production. By measuring endogenous ROS production, we assessed the role of oxidative stress in toxicity of heavy metals and antibiotics. We found that exposure to nickel induced significant oxidative stress whereas cobalt (which was previously implicated to induce oxidative stress) did not induce ROS formation. Since a turbulent debate evolves around oxidative stress as a general killing mechanism by antibiotics (aminoglycosides, fluoroquinolones and β-lactams), we measured oxidative stress in bacteria that were challenged with these antibiotics. Our results revealed that antibiotics do not induce ROS formation in bacteria thereby disputing a role for oxidative stress as a general killing mechanism. Together, our results expose how the intra-bacterial redox balance in individual microorganisms is affected by environmental conditions and encounters with stress-inducing compounds. These findings demonstrate the significant potential of roGFP2 as a redox biosensor in gram-negative bacteria to investigate redox dynamics under a variety of circumstances.
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Affiliation(s)
- Joris van der Heijden
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stefanie L Vogt
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Lisa A Reynolds
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jorge Peña-Díaz
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Audrey Tupin
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Laurent Aussel
- Laboratoire de Chimie Bactérienne, CNRS, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - B Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
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17
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The Human Antimicrobial Protein Calgranulin C Participates in Control of Helicobacter pylori Growth and Regulation of Virulence. Infect Immun 2015; 83:2944-56. [PMID: 25964473 DOI: 10.1128/iai.00544-15] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 04/30/2015] [Indexed: 12/18/2022] Open
Abstract
During infectious processes, antimicrobial proteins are produced by both epithelial cells and innate immune cells. Some of these antimicrobial molecules function by targeting transition metals and sequestering these metals in a process referred to as "nutritional immunity." This chelation strategy ultimately starves invading pathogens, limiting their growth within the vertebrate host. Recent evidence suggests that these metal-binding antimicrobial molecules have the capacity to affect bacterial virulence, including toxin secretion systems. Our previous work showed that the S100A8/S100A9 heterodimer (calprotectin, or calgranulin A/B) binds zinc and represses the elaboration of the H. pylori cag type IV secretion system (T4SS). However, there are several other S100 proteins that are produced in response to infection. We hypothesized that the zinc-binding protein S100A12 (calgranulin C) is induced in response to H. pylori infection and also plays a role in controlling H. pylori growth and virulence. To test this, we analyzed gastric biopsy specimens from H. pylori-positive and -negative patients for S100A12 expression. These assays showed that S100A12 is induced in response to H. pylori infection and inhibits bacterial growth and viability in vitro by binding nutrient zinc. Furthermore, the data establish that the zinc-binding activity of the S100A12 protein represses the activity of the cag T4SS, as evidenced by the gastric cell "hummingbird" phenotype, interleukin 8 (IL-8) secretion, and CagA translocation assays. In addition, high-resolution field emission gun scanning electron microscopy (FEG-SEM) was used to demonstrate that S100A12 represses biogenesis of the cag T4SS. Together with our previous work, these data reveal that multiple S100 proteins can repress the elaboration of an oncogenic bacterial surface organelle.
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18
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Identification and functional characterization of the novel Edwardsiella tarda effector EseJ. Infect Immun 2015; 83:1650-60. [PMID: 25667268 DOI: 10.1128/iai.02566-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Edwardsiella tarda is a Gram-negative enteric pathogen that causes hemorrhagic septicemia in fish and gastro- and extraintestinal infections in humans. The type III secretion system (T3SS) of E. tarda has been identified as a key virulence factor that contributes to pathogenesis in fish. However, little is known about the associated effectors translocated by this T3SS. In this study, by comparing the profile of secreted proteins of the wild-type PPD130/91 and its T3SS ATPase ΔesaN mutant, we identified a new effector by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. This effector consists of 1,359 amino acids, sharing high sequence similarity with Orf29/30 of E. tarda strain EIB202, and is renamed EseJ. The secretion and translocation of EseJ depend on the T3SS. A ΔeseJ mutant strain adheres to epithelioma papillosum of carp (EPC) cells 3 to 5 times more extensively than the wild-type strain does. EseJ inhibits bacterial adhesion to EPC cells from within bacterial cells. Importantly, the ΔeseJ mutant strain does not replicate efficiently in EPC cells and fails to replicate in J774A.1 macrophages. In infected J774A.1 macrophages, the ΔeseJ mutant elicits higher production of reactive oxygen species than wild-type E. tarda. The replication defect is consistent with the attenuation of the ΔeseJ mutant in the blue gourami fish model: the 50% lethal dose (LD50) of the ΔeseJ mutant is 2.34 times greater than that of the wild type, and the ΔeseJ mutant is less competitive than the wild type in mixed infection. Thus, EseJ represents a novel effector that contributes to virulence by reducing bacterial adhesion to EPC cells and facilitating intracellular bacterial replication.
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19
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Leo JC, Oberhettinger P, Schütz M, Linke D. The inverse autotransporter family: intimin, invasin and related proteins. Int J Med Microbiol 2014; 305:276-82. [PMID: 25596886 DOI: 10.1016/j.ijmm.2014.12.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Intimin and invasin are adhesins and central virulence factors of attaching and effacing bacteria, such as enterohaemorrhagic Escherichia coli, and enteropathogenic Yersiniae, respectively. These proteins are prototypes of a large family of adhesins distributed widely in Gram-negative bacteria. It is now evident that this protein family represents a previously unrecognized autotransporter secretion system, termed type Ve secretion. In contrast to classical autotransport, where the transmembrane β-barrel domain or translocation unit is C-terminal to the extracellular region or passenger domain, type Ve-secreted proteins have an inverted topology with the passenger domain C-terminal to the translocation unit; hence the term inverse autotransporter. This minireview covers the recent advances in elucidating the structure and biogenesis of inverse autotransporters.
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Affiliation(s)
- Jack C Leo
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Philipp Oberhettinger
- Interfaculty Institute for Microbiology and Infection Medicine, University Clinics Tübingen, 72076 Tübingen, Germany
| | - Monika Schütz
- Interfaculty Institute for Microbiology and Infection Medicine, University Clinics Tübingen, 72076 Tübingen, Germany
| | - Dirk Linke
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway; Max Planck Institute for Developmental Biology, Department of Protein Evolution, 72076 Tübingen, Germany.
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20
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Nagy TA, Moreland SM, Detweiler CS. Salmonella acquires ferrous iron from haemophagocytic macrophages. Mol Microbiol 2014; 93:1314-26. [PMID: 25081030 DOI: 10.1111/mmi.12739] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2014] [Indexed: 01/21/2023]
Abstract
Bacteria harbour both ferrous and ferric iron transporters. We now report that infection of macrophages and mice with a Salmonella enterica Typhimurium strain containing an inactivated feoB-encoded ferrous iron transporter results in increased bacterial replication, compared to infection with wild type. Inactivation of other cation transporters, SitABCD or MntH, did not increase bacterial replication. The feoB mutant strain does not have an intrinsically faster growth rate. Instead, increased replication correlated with increased expression in macrophages of the fepB-encoded bacterial ferric iron transporter and also required siderophores, which capture ferric iron. Co-infection of mice with wild type and a feoB mutant strain yielded a different outcome: FeoB is clearly required for tissue colonization. In co-infected primary mouse macrophages, FeoB is required for S. Typhimurium replication if the macrophages were IFNγ treated and contain phagocytosed erythrocytes, a model for haemophagocytosis. Haemophagocytes are macrophages that have engulfed erythrocytes and/or leucocytes and can harbour Salmonella in mice. These observations suggest that Salmonella acquires ferrous iron from haemophagocytic macrophages.
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Affiliation(s)
- Toni A Nagy
- Department of Molecular, Cellular and Developmental Biology, University of Colorado-Boulder, Boulder, CO, USA
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21
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Tang F, Saier MH. Transport proteins promoting Escherichia coli pathogenesis. Microb Pathog 2014; 71-72:41-55. [PMID: 24747185 DOI: 10.1016/j.micpath.2014.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 12/26/2022]
Abstract
Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies.
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Affiliation(s)
- Fengyi Tang
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
| | - Milton H Saier
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
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22
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Abstract
Some host-adapted bacterial pathogens are capable of causing persistent infections in humans. For example, Helicobacter pylori inhabits the human gastric mucosa and persistence can be lifelong. Salmonella enterica serovar Typhi causes systemic infections that involve colonization of the reticuloendothelial system and some individuals become lifelong carriers. In this review, I compare and contrast the different lifestyles of Helicobacter and Salmonella within the host and the strategies they have evolved to persist in mammalian hosts. Persistently infected carriers serve as the reservoirs for these pathogens, and the carrier state is an essential feature that is required for survival of the bacteria within a restricted host population. Therefore, investigating the chronic carrier state should provide insight into bacterial survival strategies, as well as new therapeutic approaches for treatments.
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Affiliation(s)
- Denise M Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305
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23
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Tetracycline accelerates the temporally-regulated invasion response in specific isolates of multidrug-resistant Salmonella enterica serovar Typhimurium. BMC Microbiol 2013; 13:202. [PMID: 24020473 PMCID: PMC3854800 DOI: 10.1186/1471-2180-13-202] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 09/02/2013] [Indexed: 12/21/2022] Open
Abstract
Background Multidrug-resistant (MDR) Salmonella isolates are associated with increased morbidity compared to antibiotic-sensitive strains and are an important health and safety concern in both humans and animals. Salmonella enterica serovar Typhimurium is a prevalent cause of foodborne disease, and a considerable number of S. Typhimurium isolates from humans and livestock are resistant to three or more antibiotics. The majority of these MDR S. Typhimurium isolates are resistant to tetracycline, a commonly used and clinically and agriculturally relevant antibiotic. Because exposure of drug-resistant bacteria to antibiotics can affect cellular processes associated with virulence, such as invasion, we investigated the effect tetracycline had on the invasiveness of tetracycline-resistant MDR S. Typhimurium isolates. Results The isolates selected and tested were from two common definitive phage types of S. Typhimurium, DT104 and DT193, and were resistant to tetracycline and at least three other antibiotics. Although Salmonella invasiveness is temporally regulated and normally occurs during late-log growth phase, tetracycline exposure induced the full invasive phenotype in a cell culture assay during early-log growth in several DT193 isolates. No changes in invasiveness due to tetracycline exposure occurred in the DT104 isolates during early-log growth or in any of the isolates during late-log growth. Real-time PCR was used to test expression of the virulence genes hilA, prgH, and invF, and these genes were significantly up-regulated during early-log growth in most isolates due to tetracycline exposure; however, increased virulence gene expression did not always correspond with increased invasion, and therefore was not an accurate indicator of elevated invasiveness. This is the first report to assess DT193 isolates, as well as the early-log growth phase, in response to tetracycline exposure, and it was the combination of both parameters that was necessary to observe the induced invasion phenotype. Conclusions In this report, we demonstrate that the invasiveness of MDR S. Typhimurium can be modulated in the presence of tetracycline, and this effect is dependent on growth phase, antibiotic concentration, and strain background. Identifying the conditions necessary to establish an invasive phenotype is important to elucidate the underlying factors associated with increased virulence of MDR Salmonella.
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Odendall C, Rolhion N, Förster A, Poh J, Lamont DJ, Liu M, Freemont PS, Catling AD, Holden DW. The Salmonella kinase SteC targets the MAP kinase MEK to regulate the host actin cytoskeleton. Cell Host Microbe 2013; 12:657-68. [PMID: 23159055 PMCID: PMC3510437 DOI: 10.1016/j.chom.2012.09.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/27/2012] [Accepted: 09/25/2012] [Indexed: 01/09/2023]
Abstract
After host cell entry, Salmonella replicate in membrane-bound compartments, which accumulate a dense meshwork of F-actin through the kinase activity of the Salmonella SPI-2 type III secretion effector SteC. We find that SteC promotes actin cytoskeleton reorganization by activating a signaling pathway involving the MAP kinases MEK and ERK, myosin light chain kinase (MLCK) and Myosin IIB. Specifically, SteC phosphorylates MEK directly on serine 200 (S200), a previously unstudied phosphorylation site. S200 phosphorylation is predicted to displace a negative regulatory helix causing autophosphorylation on the known MEK activatory residues, S218 and S222. In support of this, substitution of S200 with alanine prevented phosphorylation on S218 and S222, and phosphomimetic mutations of S200 stimulated phosphorylation of these residues. Both steC-null and kinase-deficient mutant strains displayed enhanced replication in infected cells, suggesting that SteC manipulates the actin cytoskeleton to restrain bacterial growth, thereby regulating virulence.
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Affiliation(s)
- Charlotte Odendall
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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Chaudhuri RR, Morgan E, Peters SE, Pleasance SJ, Hudson DL, Davies HM, Wang J, van Diemen PM, Buckley AM, Bowen AJ, Pullinger GD, Turner DJ, Langridge GC, Turner AK, Parkhill J, Charles IG, Maskell DJ, Stevens MP. Comprehensive assignment of roles for Salmonella typhimurium genes in intestinal colonization of food-producing animals. PLoS Genet 2013; 9:e1003456. [PMID: 23637626 PMCID: PMC3630085 DOI: 10.1371/journal.pgen.1003456] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 03/02/2013] [Indexed: 11/19/2022] Open
Abstract
Chickens, pigs, and cattle are key reservoirs of Salmonella enterica, a foodborne pathogen of worldwide importance. Though a decade has elapsed since publication of the first Salmonella genome, thousands of genes remain of hypothetical or unknown function, and the basis of colonization of reservoir hosts is ill-defined. Moreover, previous surveys of the role of Salmonella genes in vivo have focused on systemic virulence in murine typhoid models, and the genetic basis of intestinal persistence and thus zoonotic transmission have received little study. We therefore screened pools of random insertion mutants of S. enterica serovar Typhimurium in chickens, pigs, and cattle by transposon-directed insertion-site sequencing (TraDIS). The identity and relative fitness in each host of 7,702 mutants was simultaneously assigned by massively parallel sequencing of transposon-flanking regions. Phenotypes were assigned to 2,715 different genes, providing a phenotype–genotype map of unprecedented resolution. The data are self-consistent in that multiple independent mutations in a given gene or pathway were observed to exert a similar fitness cost. Phenotypes were further validated by screening defined null mutants in chickens. Our data indicate that a core set of genes is required for infection of all three host species, and smaller sets of genes may mediate persistence in specific hosts. By assigning roles to thousands of Salmonella genes in key reservoir hosts, our data facilitate systems approaches to understand pathogenesis and the rational design of novel cross-protective vaccines and inhibitors. Moreover, by simultaneously assigning the genotype and phenotype of over 90% of mutants screened in complex pools, our data establish TraDIS as a powerful tool to apply rich functional annotation to microbial genomes with minimal animal use. Salmonella Typhimurium is a major cause of human diarrhoeal infections, usually acquired from chickens, pigs, cattle, or their products. To understand the basis of persistence and pathogenesis in these reservoir hosts, and to inform the design of novel vaccines and treatments, we generated a library of 7,702 S. Typhimurium mutants, each bearing an insertion at a random position in the genome. Using DNA sequencing, we identified the disrupted gene in each mutant and determined its relative abundance in a laboratory culture and after experimental infection of mice, chickens, pigs, and cattle. The method allowed large numbers of mutants to be investigated simultaneously, drastically reducing the number of animals required to perform a comprehensive screen. We identified mutants that grow in culture but do not survive in one or more of the animals. The genes disrupted in these mutants are inferred to be important for the infection process. Most of these genes were required in all three food-producing animals, but smaller subsets of genes may mediate persistence in a specific host species. The data provide the most comprehensive map of virulence-associated genes for any bacterial pathogen in natural hosts and are highly relevant for the design of control strategies.
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Affiliation(s)
- Roy R. Chaudhuri
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Eirwen Morgan
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Sarah E. Peters
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Stephen J. Pleasance
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Debra L. Hudson
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Holly M. Davies
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Jinhong Wang
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Pauline M. van Diemen
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Anthony M. Buckley
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Alison J. Bowen
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Gillian D. Pullinger
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Daniel J. Turner
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Gemma C. Langridge
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - A. Keith Turner
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Julian Parkhill
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Ian G. Charles
- The ithree institute, University of Technology Sydney, Broadway, Australia
| | - Duncan J. Maskell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | - Mark P. Stevens
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
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Genome expression analysis of nonproliferating intracellular Salmonella enterica serovar Typhimurium unravels an acid pH-dependent PhoP-PhoQ response essential for dormancy. Infect Immun 2012; 81:154-65. [PMID: 23090959 DOI: 10.1128/iai.01080-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Genome-wide expression analyses have provided clues on how Salmonella proliferates inside cultured macrophages and epithelial cells. However, in vivo studies show that Salmonella does not replicate massively within host cells, leaving the underlying mechanisms of such growth control largely undefined. In vitro infection models based on fibroblasts or dendritic cells reveal limited proliferation of the pathogen, but it is presently unknown whether these phenomena reflect events occurring in vivo. Fibroblasts are distinctive, since they represent a nonphagocytic cell type in which S. enterica serovar Typhimurium actively attenuates intracellular growth. Here, we show in the mouse model that S. Typhimurium restrains intracellular growth within nonphagocytic cells positioned in the intestinal lamina propria. This response requires a functional PhoP-PhoQ system and is reproduced in primary fibroblasts isolated from the mouse intestine. The fibroblast infection model was exploited to generate transcriptome data, which revealed that ∼2% (98 genes) of the S. Typhimurium genome is differentially expressed in nongrowing intracellular bacteria. Changes include metabolic reprogramming to microaerophilic conditions, induction of virulence plasmid genes, upregulation of the pathogenicity islands SPI-1 and SPI-2, and shutdown of flagella production and chemotaxis. Comparison of relative protein levels of several PhoP-PhoQ-regulated functions (PagN, PagP, and VirK) in nongrowing intracellular bacteria and extracellular bacteria exposed to diverse PhoP-PhoQ-inducing signals denoted a regulation responding to acidic pH. These data demonstrate that S. Typhimurium restrains intracellular growth in vivo and support a model in which dormant intracellular bacteria could sense vacuolar acidification to stimulate the PhoP-PhoQ system for preventing intracellular overgrowth.
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Prehna G, Li Y, Stoynov N, Okon M, Vuckovic M, McIntosh LP, Foster LJ, Finlay BB, Strynadka NCJ. The zinc regulated antivirulence pathway of Salmonella is a multiprotein immunoglobulin adhesion system. J Biol Chem 2012; 287:32324-37. [PMID: 22810234 DOI: 10.1074/jbc.m112.357210] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The co-evolutionary relationship between pathogen and host has led to a regulatory cycle between virulence factors needed for survival and antivirulence factors required for host transmission. This is exemplified in Salmonella spp. by the zirTS antivirulence genes: a secretion pathway comprised of the outer membrane transporter ZirT, and its secreted partner, ZirS. ZirTS act within the gastrointestinal tract to function as a virulence modulator and during Salmonella shedding in anticipation of a new host. Together, ZirT and ZirS decrease virulence by lowering bacterial colonization at systemic sites through an unknown mechanism. To understand this mechanism, we have probed the zirTS pathway both structurally and biochemically. The NMR derived structural ensemble of the C-terminal domain of ZirS reveals an immunoglobin superfamily fold (IgSF). Stable isotope labeling by amino acids in cell culture experiments show that the ZirS IgSF domain interacts with its transporter ZirT, and reveal a new protein interaction partner of the pathway, a protein encoded adjacent to zirTS that we have designated as ZirU. ZirU is secreted by ZirT and is also a predicted IgSF. Biochemical analysis delineates ZirT into an N-terminal porin-like β domain and C-terminal extracellular soluble IgSF domain, whereas biophysical characterization suggests that the transporter undergoes self-association in a concentration-dependent manner. We observe that ZirS and ZirU directly interact with each other and with the extracellular domains of ZirT. Here we show that the zir antivirulence pathway is a multiprotein immunoglobulin adhesion system consisting of a complex interplay between ZirS, ZirT, and ZirU.
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Affiliation(s)
- Gerd Prehna
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver V6T 1Z3 BC, Canada
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Abstract
ibeA is a virulence factor found in some extraintestinal pathogenic Escherichia coli (ExPEC) strains from the B2 phylogenetic group and particularly in newborn meningitic and avian pathogenic strains. It was shown to be involved in the invasion process of the newborn meningitic strain RS218. In a previous work, we showed that in the avian pathogenic E. coli (APEC) strain BEN2908, isolated from a colibacillosis case, ibeA was rather involved in adhesion to eukaryotic cells by modulating type 1 fimbria synthesis (M. A. Cortes et al., Infect. Immun. 76:4129-4136, 2008). In this study, we demonstrate a new role for ibeA in oxidative stress resistance. We showed that an ibeA mutant of E. coli BEN2908 was more sensitive than its wild-type counterpart to H(2)O(2) killing. This phenotype was also observed in a mutant deleted for the whole GimA genomic region carrying ibeA and might be linked to alterations in the expression of a subset of genes involved in the oxidative stress response. We also showed that RpoS expression was not altered by the ibeA deletion. Moreover, the transfer of an ibeA-expressing plasmid into an E. coli K-12 strain, expressing or not expressing type 1 fimbriae, rendered it more resistant to an H(2)O(2) challenge. Altogether, these results show that ibeA by itself is able to confer increased H(2)O(2) resistance to E. coli. This feature could partly explain the role played by ibeA in the virulence of pathogenic strains.
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Yu ACY, Worrall LJ, Strynadka NCJ. Structural insight into the bacterial mucinase StcE essential to adhesion and immune evasion during enterohemorrhagic E. coli infection. Structure 2012; 20:707-17. [PMID: 22483117 DOI: 10.1016/j.str.2012.02.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/11/2012] [Accepted: 02/16/2012] [Indexed: 01/19/2023]
Abstract
Mucin glycoproteins with large numbers of O-linked glycosylations comprise the mucosal barrier lining the mammalian gastrointestinal tract from mouth to gut. A critical biological function of mucins is to protect the underlying epithelium from infection. Enterohemorrhagic Escherichia coli (EHEC), the mediator of severe food- and water-borne disease, can breach this barrier and adhere to intestinal cells. StcE, a ∼100 kDa metalloprotease secreted by EHEC, plays a pivotal role in remodeling the mucosal lining during infection. To obtain mechanistic insight into its function, we have determined the structure of StcE. Our data reveal a dynamic, multidomain architecture featuring an unusually large substrate-binding cleft and a prominent polarized surface charge distribution highly suggestive of an electrostatic role in substrate targeting. The observation of key conserved motifs in the active site allows us to propose the structural basis for the specific recognition of α-O-glycan-containing substrates. Complementary biochemical analysis provides further insight into its distinct substrate specificity and binding stoichiometry.
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Affiliation(s)
- Angel C Y Yu
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, Life Sciences Center, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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Ruby T, McLaughlin L, Gopinath S, Monack D. Salmonella's long-term relationship with its host. FEMS Microbiol Rev 2012; 36:600-15. [PMID: 22335190 DOI: 10.1111/j.1574-6976.2012.00332.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 01/30/2012] [Accepted: 02/07/2012] [Indexed: 12/23/2022] Open
Abstract
Host-adapted strains of Salmonella enterica cause systemic infections and have the ability to persist systemically for long periods of time and pose significant public-health problems. Multidrug-resistant S. enterica serovar Typhi (S. Typhi) and nontyphoidal Salmonella (NTS) are on the increase and are often associated with HIV infection. Chronically infected hosts are often asymptomatic and transmit disease to naïve hosts via fecal shedding of bacteria, thereby serving as a critical reservoir for disease. Salmonella utilizes multiple ways to evade and modulate host innate and adaptive immune responses in order to persist in the presence of a robust immune response. Survival in macrophages and modulation of immune cells migration allow Salmonella to evade various immune responses. The ability of Salmonella to persist depends on a balance between immune responses that lead to the clearance of the pathogen and avoidance of damage to host tissues.
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Affiliation(s)
- Thomas Ruby
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA
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31
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Pilonieta MC, Nagy TA, Jorgensen DR, Detweiler CS. A glycine betaine importer limits Salmonella stress resistance and tissue colonization by reducing trehalose production. Mol Microbiol 2012; 84:296-309. [PMID: 22375627 DOI: 10.1111/j.1365-2958.2012.08022.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mechanisms by which Salmonella establish chronic infections are not well understood. Microbes respond to stress by importing or producing compatible solutes, small molecules that stabilize proteins and lipids. The Salmonella locus opuABCD (also called OpuC) encodes a predicted importer of the compatible solute glycine betaine. Under stress conditions, if glycine betaine cannot be imported, Salmonella enterica produce the disaccharide trehalose, a highly effective compatible solute. We demonstrate that strains lacking opuABCD accumulate more trehalose under stress conditions than wild-type strains. ΔopuABCD mutant strains are more resistant to high-salt, low-pH and -hydrogen peroxide, conditions that mimic aspects of innate immunity, in a trehalose-dependent manner. In addition, ΔopuABCD mutant strains require the trehalose production genes to out-compete wild-type strains in mice and macrophages. These data suggest that in the absence of opuABCD, trehalose accumulation increases bacterial resistance to stress in broth and mice. Thus, opuABCD reduces bacterial colonization via a mechanism that limits trehalose production. Mechanisms by which microbes limit disease may reveal novel pathways as therapeutic targets.
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Affiliation(s)
- M Carolina Pilonieta
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
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King D, Strynadka N. Crystal structure of New Delhi metallo-β-lactamase reveals molecular basis for antibiotic resistance. Protein Sci 2011; 20:1484-91. [PMID: 21774017 DOI: 10.1002/pro.697] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 07/08/2011] [Indexed: 11/11/2022]
Abstract
β-Lactams are the most commonly prescribed class of antibiotics and have had an enormous impact on human health. Thus, it is disquieting that an enzyme called New Delhi metallo-β-lactamase-1 (NDM-1) can confer Enterobacteriaceae with nearly complete resistance to all β-lactam antibiotics including the carbapenams. We have determined the crystal structure of Klebsiella pneumoniae apo-NDM-1 to 2.1-Å resolution. From the structure, we see that NDM-1 has an expansive active site with a unique electrostatic profile, which we propose leads to a broader substrate specificity. In addition, NDM-1 undergoes important conformational changes upon substrate binding. These changes have not been previously observed in metallo-β-lactamase enzymes and may have a direct influence on substrate recognition and catalysis.
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Affiliation(s)
- Dustin King
- Department of Biochemistry and Molecular Biology and Center for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
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McDermott JE, Yoon H, Nakayasu ES, Metz TO, Hyduke DR, Kidwai AS, Palsson BO, Adkins JN, Heffron F. Technologies and approaches to elucidate and model the virulence program of salmonella. Front Microbiol 2011; 2:121. [PMID: 21687430 PMCID: PMC3108385 DOI: 10.3389/fmicb.2011.00121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/15/2011] [Indexed: 11/13/2022] Open
Abstract
Salmonella is a primary cause of enteric diseases in a variety of animals. During its evolution into a pathogenic bacterium, Salmonella acquired an elaborate regulatory network that responds to multiple environmental stimuli within host animals and integrates them resulting in fine regulation of the virulence program. The coordinated action by this regulatory network involves numerous virulence regulators, necessitating genome-wide profiling analysis to assess and combine efforts from multiple regulons. In this review we discuss recent high-throughput analytic approaches used to understand the regulatory network of Salmonella that controls virulence processes. Application of high-throughput analyses have generated large amounts of data and necessitated the development of computational approaches for data integration. Therefore, we also cover computer-aided network analyses to infer regulatory networks, and demonstrate how genome-scale data can be used to construct regulatory and metabolic systems models of Salmonella pathogenesis. Genes that are coordinately controlled by multiple virulence regulators under infectious conditions are more likely to be important for pathogenesis. Thus, reconstructing the global regulatory network during infection or, at the very least, under conditions that mimic the host cellular environment not only provides a bird's eye view of Salmonella survival strategy in response to hostile host environments but also serves as an efficient means to identify novel virulence factors that are essential for Salmonella to accomplish systemic infection in the host.
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Affiliation(s)
- Jason E. McDermott
- Computational Biology and Bioinformatics Group, Pacific Northwest National LaboratoryRichland, WA, USA
| | - Hyunjin Yoon
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences UniversityPortland, OR, USA
| | - Ernesto S. Nakayasu
- Biological Separations and Mass Spectroscopy Group, Pacific Northwest National LaboratoryRichland WA, USA
| | - Thomas O. Metz
- Biological Separations and Mass Spectroscopy Group, Pacific Northwest National LaboratoryRichland WA, USA
| | - Daniel R. Hyduke
- Systems Biology, University of California San DiegoSan Diego, CA, USA
| | - Afshan S. Kidwai
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences UniversityPortland, OR, USA
| | | | - Joshua N. Adkins
- Biological Separations and Mass Spectroscopy Group, Pacific Northwest National LaboratoryRichland WA, USA
| | - Fred Heffron
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences UniversityPortland, OR, USA
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Gal-Mor O, Elhadad D, Deng W, Rahav G, Finlay BB. The Salmonella enterica PhoP directly activates the horizontally acquired SPI-2 gene sseL and is functionally different from a S. bongori ortholog. PLoS One 2011; 6:e20024. [PMID: 21625519 PMCID: PMC3098285 DOI: 10.1371/journal.pone.0020024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 04/09/2011] [Indexed: 11/22/2022] Open
Abstract
To establish a successful infection within the host, a pathogen must closely regulate multiple virulence traits to ensure their accurate temporal and spatial expression. As a highly adapted intracellular pathogen, Salmonella enterica has acquired during its evolution various virulence genes via numerous lateral transfer events, including the acquisition of the Salmonella Pathogenicity Island 2 (SPI-2) and its associated effectors. Beneficial use of horizontally acquired genes requires that their expression is effectively coordinated with the already existing virulence programs and the regulatory set-up in the bacterium. As an example for such a mechanism, we show here that the ancestral PhoPQ system of Salmonella enterica is able to regulate directly the SPI-2 effector gene sseL (encoding a secreted deubiquitinase) in an SsrB-independent manner and that PhoP plays a part in a feed-forward regulatory loop, which fine-tunes the cellular level of SseL. Additionally, we demonstrate the presence of conserved cis regulatory elements in the promoter region of sseL and show direct binding of purified PhoP to this region. Interestingly, in contrast to the S. enterica PhoP, an ortholog regulator from a S. bongori SARC 12 strain was found to be impaired in promoting transcription of sseL and other genes from the PhoP regulon. These findings have led to the identification of a previously uncharacterized residue in the DNA-binding domain of PhoP, which is required for the transcriptional activation of PhoP regulated genes in Salmonella spp. Collectively our data demonstrate an interesting interface between the acquired SsrB regulon and the ancestral PhoPQ regulatory circuit, provide novel insights into the function of PhoP, and highlight a mechanism of regulatory integration of horizontally acquired genes into the virulence network of Salmonella enterica.
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Affiliation(s)
- Ohad Gal-Mor
- Infectious Diseases Research Laboratory, Sheba Medical Center Tel-Hashomer, Tel-Hashomer, Israel.
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Discovery of Salmonella virulence factors translocated via outer membrane vesicles to murine macrophages. Infect Immun 2011; 79:2182-92. [PMID: 21464085 DOI: 10.1128/iai.01277-10] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhimurium, an intracellular pathogen and leading cause of food-borne illness, encodes a plethora of virulence effectors. Salmonella virulence factors are translocated into host cells and manipulate host cellular activities, providing a more hospitable environment for bacterial proliferation. In this study, we report a new set of virulence factors that is translocated into the host cytoplasm via bacterial outer membrane vesicles (OMV). PagK (or PagK1), PagJ, and STM2585A (or PagK2) are small proteins composed of ∼70 amino acids and have high sequence homology to each other (>85% identity). Salmonella lacking all three homologues was attenuated for virulence in a mouse infection model, suggesting at least partial functional redundancy among the homologues. While each homologue was translocated into the macrophage cytoplasm, their translocation was independent of all three Salmonella gene-encoded type III secretion systems (T3SSs)-Salmonella pathogenicity island 1 (SPI-1) T3SS, SPI-2 T3SS, and the flagellar system. Selected methods, including direct microscopy, demonstrated that the PagK-homologous proteins were secreted through OMV, which were enriched with lipopolysaccharide (LPS) and outer membrane proteins. Vesicles produced by intracellular bacteria also contained lysosome-associated membrane protein 1 (LAMP1), suggesting the possibility of OMV convergence with host cellular components during intracellular trafficking. This study identified novel Salmonella virulence factors secreted via OMV and demonstrated that OMV can function as a vehicle to transfer virulence determinants to the cytoplasm of the infected host cell.
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Tsai JC, Yen MR, Castillo R, Leyton DL, Henderson IR, Saier MH. The bacterial intimins and invasins: a large and novel family of secreted proteins. PLoS One 2010; 5:e14403. [PMID: 21203509 PMCID: PMC3008723 DOI: 10.1371/journal.pone.0014403] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 10/14/2010] [Indexed: 11/26/2022] Open
Abstract
Background Gram-negative bacteria have developed a limited repertoire of solutions for secreting proteins from the cytoplasmic compartment to the exterior of the cell. Amongst the spectrum of secreted proteins are the intimins and invasins (the Int/Inv family; TC# 1.B.54) which are characterized by an N-terminal β-barrel domain and a C-terminal surface localized passenger domain. Despite the important role played by members of this family in diseases mediated by several species of the Enterobacteriaceae, there has been little appreciation for the distribution and diversity of these proteins amongst Gram-negative bacteria. Furthermore, there is little understanding of the molecular events governing secretion of these proteins to the extracellular milieu. Principal Findings In silico approaches were used to analyze the domain organization and diversity of members of this secretion family. Proteins belonging to this family are predominantly associated with organisms from the γ-proteobacteria. Whilst proteins from the Chlamydia, γ-, β- and ε-proteobacteria possess β-barrel domains and passenger domains of various sizes, Int/Inv proteins from the α-proteobacteria, cyanobacteria and chlorobi possess only the predicted β-barrel domains. Phylogenetic analyses revealed that with few exceptions these proteins cluster according to organismal type, indicating that divergence occurred contemporaneously with speciation, and that horizontal transfer was limited. Clustering patterns of the β-barrel domains correlate well with those of the full-length proteins although the passenger domains do so with much less consistency. The modular subdomain design of the passenger domains suggests that subdomain duplication and deletion have occurred with high frequency over evolutionary time. However, all repeated subdomains are found in tandem, suggesting that subdomain shuffling occurred rarely if at all. Topological predictions for the β-barrel domains are presented. Conclusion Based on our in silico analyses we present a model for the biogenesis of these proteins. This study is the first of its kind to describe this unusual family of bacterial adhesins.
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Affiliation(s)
- Jennifer C. Tsai
- Department of Molecular Biology, University of California at San Diego, La Jolla, California, United States of America
| | - Ming-Ren Yen
- Department of Molecular Biology, University of California at San Diego, La Jolla, California, United States of America
| | - Rostislav Castillo
- Department of Molecular Biology, University of California at San Diego, La Jolla, California, United States of America
| | - Denisse L. Leyton
- The School of Immunity and Infection, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Ian R. Henderson
- The School of Immunity and Infection, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Milton H. Saier
- Department of Molecular Biology, University of California at San Diego, La Jolla, California, United States of America
- * E-mail:
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Abstract
Serratia marcescens has long been recognized as an important opportunistic pathogen, but the underlying pathogenesis mechanism is not completely clear. Here, we report a key pathogenesis pathway in S. marcescens comprising the RssAB two-component system and its downstream elements, FlhDC and the dominant virulence factor hemolysin ShlBA. Expression of shlBA is under the positive control of FlhDC, which is repressed by RssAB signaling. At 37°C, functional RssAB inhibits swarming, represses hemolysin production, and promotes S. marcescens biofilm formation. In comparison, when rssBA is deleted, S. marcescens displays aberrant multicellularity favoring motile swarming with unbridled hemolysin production. Cellular and animal infection models further demonstrate that loss of rssBA transforms this opportunistic pathogen into hypervirulent phenotypes, leading to extensive inflammatory responses coupled with destructive and systemic infection. Hemolysin production is essential in this context. Collectively, a major virulence regulatory pathway is identified in S. marcescens.
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38
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Reis RSD, Horn F. Enteropathogenic Escherichia coli, Samonella, Shigella and Yersinia: cellular aspects of host-bacteria interactions in enteric diseases. Gut Pathog 2010; 2:8. [PMID: 20649986 PMCID: PMC2921366 DOI: 10.1186/1757-4749-2-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 07/22/2010] [Indexed: 12/18/2022] Open
Abstract
A successful infection of the human intestine by enteropathogenic bacteria depends on the ability of bacteria to attach and colonize the intestinal epithelium and, in some cases, to invade the host cell, survive intracellularly and disseminate from cell to cell. To accomplish these processes bacteria have evolved an arsenal of molecules that are mostly secreted by dedicated type III secretion systems, and that interact with the host, subverting normal cellular functions. Here we overview the most important molecular strategies developed by enteropathogenic Escherichia coli, Salmonella enterica, Shigella flexneri, and Yersinia enterocolitica to cause enteric infections. Despite having evolved different effectors, these four microorganisms share common host cellular targets.
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Affiliation(s)
- Roberta Souza Dos Reis
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, P,O, Box 15005, 91501-970, Porto Alegre, Brazil.
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Stevens MP, Humphrey TJ, Maskell DJ. Molecular insights into farm animal and zoonotic Salmonella infections. Philos Trans R Soc Lond B Biol Sci 2009; 364:2709-23. [PMID: 19687040 PMCID: PMC2865095 DOI: 10.1098/rstb.2009.0094] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica is a facultative intracellular pathogen of worldwide importance. Infections may present in a variety of ways, from asymptomatic colonization to inflammatory diarrhoea or typhoid fever depending on serovar- and host-specific factors. Human diarrhoeal infections are frequently acquired via the food chain and farm environment by virtue of the ability of selected non-typhoidal serovars to colonize the intestines of food-producing animals and contaminate the avian reproductive tract and egg. Colonization of reservoir hosts often occurs in the absence of clinical symptoms; however, some S. enterica serovars threaten animal health owing to their ability to cause acute enteritis or translocate from the intestines to other organs causing fever, septicaemia and abortion. Despite the availability of complete genome sequences of isolates representing several serovars, the molecular mechanisms underlying Salmonella colonization, pathogenesis and transmission in reservoir hosts remain ill-defined. Here we review current knowledge of the bacterial factors influencing colonization of food-producing animals by Salmonella and the basis of host range, differential virulence and zoonotic potential.
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Affiliation(s)
- Mark P Stevens
- Division of Microbiology, Institute for Animal Health, Compton, Berkshire RG20 7NN, UK.
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40
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Eswarappa SM, Karnam G, Nagarajan AG, Chakraborty S, Chakravortty D. lac repressor is an antivirulence factor of Salmonella enterica: its role in the evolution of virulence in Salmonella. PLoS One 2009; 4:e5789. [PMID: 19495420 PMCID: PMC2686271 DOI: 10.1371/journal.pone.0005789] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Accepted: 04/22/2009] [Indexed: 12/04/2022] Open
Abstract
The genus Salmonella includes many pathogens of great medical and veterinary importance. Bacteria belonging to this genus are very closely related to those belonging to the genus Escherichia. lacZYA operon and lacI are present in Escherichia coli, but not in Salmonella enterica. It has been proposed that Salmonella has lost lacZYA operon and lacI during evolution. In this study, we have investigated the physiological and evolutionary significance of the absence of lacI in Salmonella enterica. Using murine model of typhoid fever, we show that the expression of LacI causes a remarkable reduction in the virulence of Salmonella enterica. LacI also suppresses the ability of Salmonella enterica to proliferate inside murine macrophages. Microarray analysis revealed that LacI interferes with the expression of virulence genes of Salmonella pathogenicity island 2. This effect was confirmed by RT-PCR and Western blot analysis. Interestingly, we found that SBG0326 of Salmonella bongori is homologous to lacI of Escherichia coli. Salmonella bongori is the only other species of the genus Salmonella and it lacks the virulence genes of Salmonella pathogenicity island 2. Overall, our results demonstrate that LacI is an antivirulence factor of Salmonella enterica and suggest that absence of lacI has facilitated the acquisition of virulence genes of Salmonella pathogenicity island 2 in Salmonella enterica making it a successful systemic pathogen.
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Affiliation(s)
- Sandeepa M. Eswarappa
- Centre for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Guruswamy Karnam
- Centre for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Arvindhan G. Nagarajan
- Centre for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sangeeta Chakraborty
- Centre for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Dipshikha Chakravortty
- Centre for Infectious Disease Research and Biosafety Laboratories, Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
- * E-mail:
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Samudrala R, Heffron F, McDermott JE. Accurate prediction of secreted substrates and identification of a conserved putative secretion signal for type III secretion systems. PLoS Pathog 2009; 5:e1000375. [PMID: 19390620 PMCID: PMC2668754 DOI: 10.1371/journal.ppat.1000375] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 03/11/2009] [Indexed: 11/18/2022] Open
Abstract
The type III secretion system is an essential component for virulence in many Gram-negative bacteria. Though components of the secretion system apparatus are conserved, its substrates--effector proteins--are not. We have used a novel computational approach to confidently identify new secreted effectors by integrating protein sequence-based features, including evolutionary measures such as the pattern of homologs in a range of other organisms, G+C content, amino acid composition, and the N-terminal 30 residues of the protein sequence. The method was trained on known effectors from the plant pathogen Pseudomonas syringae and validated on a set of effectors from the animal pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) after eliminating effectors with detectable sequence similarity. We show that this approach can predict known secreted effectors with high specificity and sensitivity. Furthermore, by considering a large set of effectors from multiple organisms, we computationally identify a common putative secretion signal in the N-terminal 20 residues of secreted effectors. This signal can be used to discriminate 46 out of 68 total known effectors from both organisms, suggesting that it is a real, shared signal applicable to many type III secreted effectors. We use the method to make novel predictions of secreted effectors in S. Typhimurium, some of which have been experimentally validated. We also apply the method to predict secreted effectors in the genetically intractable human pathogen Chlamydia trachomatis, identifying the majority of known secreted proteins in addition to providing a number of novel predictions. This approach provides a new way to identify secreted effectors in a broad range of pathogenic bacteria for further experimental characterization and provides insight into the nature of the type III secretion signal.
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Affiliation(s)
- Ram Samudrala
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Fred Heffron
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Jason E. McDermott
- Computational Biology and Bioinformatics, Pacific Northwest National Laboratory, Richland, Washington, United States of America
- * E-mail:
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42
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Saier MH, Ma CH, Rodgers L, Tamang DG, Yen MR. Protein secretion and membrane insertion systems in bacteria and eukaryotic organelles. ADVANCES IN APPLIED MICROBIOLOGY 2009; 65:141-97. [PMID: 19026865 DOI: 10.1016/s0065-2164(08)00606-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Milton H Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116, USA
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43
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McGhie EJ, Brawn LC, Hume PJ, Humphreys D, Koronakis V. Salmonella takes control: effector-driven manipulation of the host. Curr Opin Microbiol 2009; 12:117-24. [PMID: 19157959 PMCID: PMC2647982 DOI: 10.1016/j.mib.2008.12.001] [Citation(s) in RCA: 240] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 11/27/2008] [Accepted: 12/01/2008] [Indexed: 01/20/2023]
Abstract
Salmonella pathogenesis relies upon the delivery of over thirty specialised effector proteins into the host cell via two distinct type III secretion systems. These effectors act in concert to subvert the host cell cytoskeleton, signal transduction pathways, membrane trafficking and pro-inflammatory responses. This allows Salmonella to invade non-phagocytic epithelial cells, establish and maintain an intracellular replicative niche and, in some cases, disseminate to cause systemic disease. This review focuses on the actions of the effectors on their host cell targets during each stage of Salmonella infection.
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