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Leclerc JM, Dozois CM, Daigle F. Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells. Microbiology (Reading) 2013; 159:591-602. [DOI: 10.1099/mic.0.064329-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jean-Mathieu Leclerc
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Charles M. Dozois
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC H7V 1B7, Canada
| | - France Daigle
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
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Selection of Salmonella enterica serovar Typhi genes involved during interaction with human macrophages by screening of a transposon mutant library. PLoS One 2012; 7:e36643. [PMID: 22574205 PMCID: PMC3344905 DOI: 10.1371/journal.pone.0036643] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 04/04/2012] [Indexed: 12/21/2022] Open
Abstract
The human-adapted Salmonella enterica serovar Typhi (S. Typhi) causes a systemic infection known as typhoid fever. This disease relies on the ability of the bacterium to survive within macrophages. In order to identify genes involved during interaction with macrophages, a pool of approximately 105 transposon mutants of S. Typhi was subjected to three serial passages of 24 hours through human macrophages. Mutants recovered from infected macrophages (output) were compared to the initial pool (input) and those significantly underrepresented resulted in the identification of 130 genes encoding for cell membrane components, fimbriae, flagella, regulatory processes, pathogenesis, and many genes of unknown function. Defined deletions in 28 genes or gene clusters were created and mutants were evaluated in competitive and individual infection assays for uptake and intracellular survival during interaction with human macrophages. Overall, 26 mutants had defects in the competitive assay and 14 mutants had defects in the individual assay. Twelve mutants had defects in both assays, including acrA, exbDB, flhCD, fliC, gppA, mlc, pgtE, typA, waaQGP, SPI-4, STY1867-68, and STY2346. The complementation of several mutants by expression of plasmid-borne wild-type genes or gene clusters reversed defects, confirming that the phenotypic impairments within macrophages were gene-specific. In this study, 35 novel phenotypes of either uptake or intracellular survival in macrophages were associated with Salmonella genes. Moreover, these results reveal several genes encoding molecular mechanisms not previously known to be involved in systemic infection by human-adapted typhoidal Salmonella that will need to be elucidated.
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Forest CG, Ferraro E, Sabbagh SC, Daigle F. Intracellular survival of Salmonella enterica serovar Typhi in human macrophages is independent of Salmonella pathogenicity island (SPI)-2. MICROBIOLOGY-SGM 2010; 156:3689-3698. [PMID: 20817644 DOI: 10.1099/mic.0.041624-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
For successful infection, Salmonella enterica secretes and injects effector proteins into host cells by two distinct type three secretion systems (T3SSs) located on Salmonella pathogenicity islands (SPIs)-1 and -2. The SPI-2 T3SS is involved in intracellular survival of S. enterica serovar Typhimurium and systemic disease. As little is known regarding the function of the SPI-2 T3SS from S. enterica serovar Typhi, the aetiological agent of typhoid fever, we investigated its role for survival in human macrophages. Mutations in the translocon (sseB), basal secretion apparatus (ssaR) and regulator (ssrB) did not result in any reduction in survival under many of the conditions tested. Similar results were obtained with another S. Typhi strain or by using human primary cells. Results were corroborated based on complete deletion of the SPI-2 T3SS. Surprisingly, the data suggest that the SPI-2 T3SS of S. Typhi is not required for survival in human macrophages.
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Affiliation(s)
- Chantal G Forest
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Elyse Ferraro
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Sébastien C Sabbagh
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - France Daigle
- Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
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Faucher SP, Forest C, Béland M, Daigle F. A novel PhoP-regulated locus encoding the cytolysin ClyA and the secreted invasin TaiA of Salmonella enterica serovar Typhi is involved in virulence. Microbiology (Reading) 2009; 155:477-488. [DOI: 10.1099/mic.0.022988-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Salmonella enterica serovar Typhi causes a human-restricted systemic infection called typhoid fever. We have identified a Typhi genomic region encoding two ORFs, STY1498 and STY1499, that are expressed during infection of human macrophages and organized in an operon. STY1498 corresponds to clyA, which encodes a pore-forming cytolysin, and STY1499 encodes a 27 kDa protein, without any attributed function, which we have named TaiA (Typhi-associated invasin A). In order to evaluate the roles of these genes in Typhi pathogenesis, isogenic Typhi strains harbouring a non-polar mutation of either clyA or taiA were constructed. In macrophages, taiA was involved in increasing phagocytosis, as taiA deletion reduced bacterial uptake, whereas clyA reduced or controlled bacterial growth, as clyA deletion enhanced Typhi survival within macrophages without affecting cytotoxicity. In epithelial cells, deletion of taiA had no effect on invasion, whereas deletion of clyA enhanced the Typhi invasion rate, and reduced cytotoxicity. Overexpression of taiA in Typhi or in Escherichia coli resulted in a higher invasion rate of epithelial cells. We have demonstrated that TaiA is secreted independently of both the Salmonella pathogenicity island (SPI)-1 and the SPI-2 type three secretion systems. We have shown that this operon is regulated by the virulence-associated regulator PhoP. Moreover, our results revealed that products of this operon might be involved in promoting the use of macrophages as a sheltered reservoir for Typhi and allowing long-term persistence inside the host.
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Affiliation(s)
- Sébastien P. Faucher
- Department of Microbiology and Immunology, University of Montreal, CP 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
| | - Chantal Forest
- Department of Microbiology and Immunology, University of Montreal, CP 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
| | - Maxime Béland
- Department of Microbiology and Immunology, University of Montreal, CP 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
| | - France Daigle
- Department of Microbiology and Immunology, University of Montreal, CP 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
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Finnegan S, Gadda G. Substitution of an active site valine uncovers a kinetically slow equilibrium between competent and incompetent forms of choline oxidase. Biochemistry 2009; 47:13850-61. [PMID: 19053262 DOI: 10.1021/bi801424p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The enzymatic oxidation of choline to glycine betaine is of interest because organisms accumulate glycine betaine intracellularly in response to stress conditions. This is relevant for the genetic engineering of crops with economic interest that do not naturally possess efficient pathways for the synthesis of glycine betaine and for the potential development of drugs that target the glycine betaine biosynthetic pathway in human pathogens. To date, the best characterized choline-oxidizing enzyme is the flavin-dependent choline oxidase from Arthrobacter globiformis, for which structural, mechanistic, and biochemical data are available. Here, we have replaced a hydrophobic residue (Val464) lining the active site cavity close to the N(5) atom of the flavin with threonine or alanine to investigate its role in the reaction of choline oxidation catalyzed by choline oxidase. The reductive half-reactions of the enzyme variants containing Thr464 or Ala464 were investigated using substrate and solvent kinetic isotope effects, solvent viscosity effects, and proton inventories. Replacement of Val464 with threonine or alanine uncovered a kinetically slow equilibrium between a catalytically incompetent form of enzyme and an active species that can efficiently oxidize choline. In both variants, the active form of enzyme shows a decreased rate of hydroxyl proton abstraction from the alcohol substrate, with minimal changes in the subsequent rate of hydride ion transfer to the flavin. This study therefore establishes that a hydrophobic residue not directly participating in catalysis plays important roles in the reaction of choline oxidation catalyzed by choline oxidase.
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Affiliation(s)
- Steffan Finnegan
- Departments of Chemistry and Biology, The Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, USA
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Klumpp J, Fuchs TM. Identification of novel genes in genomic islands that contribute to Salmonella typhimurium replication in macrophages. MICROBIOLOGY-SGM 2007; 153:1207-1220. [PMID: 17379730 DOI: 10.1099/mic.0.2006/004747-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmonella enterica serovar Typhimurium (S. typhimurium) survives and proliferates within macrophage cells. A mutant library of strain ATCC 14028 based on gene disruption by homologous recombination was screened in order to identify genes that are required for wild-type-like intracellular replication. Randomly generated chromosomal fragments from the genome of S. typhimurium were cloned into a temperature-sensitive vector, and approximately 8000 individual mutant clones were obtained by insertional-duplication mutagenesis (IDM) upon selection at non-permissive temperature. Large-scale screening for replication defects in mouse macrophages, but not during growth in rich or minimal medium, revealed a set of attenuated mutants that were further characterized by PCR amplification and sequencing of the mutagenic fragments. Following analysis of a Salmonella genome map with the annotated positions of vector insertions, an accumulation of 33 attenuating insertions within genes of ten non-collinear regions was found. Insertions in virK, gipA and five SPI-2 genes as well as seven non-polar deletions validated the screen. No invasion deficiencies of the mutants were observed. The cob-cbi-pdu cluster containing the genes for cobalamin synthesis and 1,2-propanediol degradation was shown to be required for Salmonella replication within macrophages. These data gave rise to a model of eukaryotic glycoconjugates and phospholipids as alternative carbon, nitrogen and energy sources for intracellularly replicating bacteria. The contribution of as yet unknown components of SPI-6 and the Gifsy-1 and Gifsy-2 prophage islands to intracellular replication is reported, as well as the fivefold reduced intracellular growth rate of a mutant with a deletion of STM1677, which probably encodes a LysR-like transcriptional regulator. The intracellular replication rate of three double mutants, each lacking two gene products of the cob-cbi-pdu cluster or the Gifsy-1 prophage, was shown to be lower than that of the respective single mutants, suggesting that additive effects of subtle intracellular advantages contribute to Salmonella fitness in vivo.
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Affiliation(s)
- Jochen Klumpp
- Institute of Food Science and Nutrition, ETH Zürich, Schmelzbergstr. 7, 8092 Zürich, Switzerland
- Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL), Abteilung Mikrobiologie, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Thilo M Fuchs
- Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL), Abteilung Mikrobiologie, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
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Bucarey SA, Villagra NA, Martinic MP, Trombert AN, Santiviago CA, Maulén NP, Youderian P, Mora GC. The Salmonella enterica serovar Typhi tsx gene, encoding a nucleoside-specific porin, is essential for prototrophic growth in the absence of nucleosides. Infect Immun 2005; 73:6210-9. [PMID: 16177292 PMCID: PMC1230887 DOI: 10.1128/iai.73.10.6210-6219.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Salmonella enterica serovar Typhi tsx gene encodes a porin that facilitates the import of nucleosides. When serovar Typhi is grown under anaerobic conditions, Tsx is among the outer membrane proteins whose expression increases dramatically. This increase in expression is due, at least in part, to increased transcription and is dependent on Fnr but not on ArcA. A mutant derivative of serovar Typhi strain STH2370 with a deletion of the tsx gene is an auxotroph that requires either adenosine or thymidine for growth on minimal medium. In contrast, an otherwise isogenic nupG nupC double mutant, defective in the inner membrane nucleoside permeases, is a prototroph. Because anaerobic growth enhances the virulence of serovar Typhi in vitro, we assessed the role that the tsx gene plays in pathogenicity and found that the serovar Typhi STH2370 Deltatsx mutant is defective in survival within human macrophage-like U937 cells. To understand why the Deltatsx mutant is an auxotroph, we selected for insertions of minitransposon T-POP in the Deltatsx genetic background that restored prototrophy. One T-POP insertion that suppressed the Deltatsx mutation in the presence of the inducer tetracycline was located upstream of the pyrD gene. The results of reverse transcription-PCR analysis showed that addition of the inducer decreased the rate of pyrD transcription. These results suggest that the Tsx porin and the balance of products of the tsx and pyrD genes play critical roles in membrane assembly and integrity and thus in the virulence of serovar Typhi.
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Affiliation(s)
- Sergio A Bucarey
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile
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Apoptotic cell death of macrophages by iron-stressed Salmonella enterica serovar Typhimurium. World J Microbiol Biotechnol 2004. [DOI: 10.1007/s11274-004-3044-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Daily JP, Le Roch KG, Sarr O, Fang X, Zhou Y, Ndir O, Mboup S, Sultan A, Winzeler EA, Wirth DF. In vivo transcriptional profiling of Plasmodium falciparum. Malar J 2004; 3:30. [PMID: 15296511 PMCID: PMC514566 DOI: 10.1186/1475-2875-3-30] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Accepted: 08/05/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Both host and pathogen factors contribute to disease outcome in Plasmodium falciparum infection. The feasibility of studying the P. falciparum in vivo transcriptome to understand parasite transcriptional response while it resides in the human host is presented. METHODS A custom made oligonucleotide array with probes based on the P. falciparum 3D7 laboratory strain chromosome 2 sequence was used to detect in vivo P. falciparum transcripts. This study analyzed transcripts from total RNA derived from small blood samples of P. falciparum infected patients and compared the in vivo expression profile to the in vitro cultivated 3D7 strain transcriptome. RESULTS The data demonstrated that in vivo transcription can be studied from a small blood sample, despite the abundance of human RNA. The in vivo transcriptome is similar to the 3D7 ring stage transcriptome, but there are significant differences in genes encoding a sexual stage antigen and surface proteins. CONCLUSIONS Whole genome transcription analysis of P. falciparum can be carried out successfully and further studies in selected patient cohorts may provide insight into parasite in vivo biology and defense against host immunity.
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Affiliation(s)
- Johanna P Daily
- Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, Massachusetts 02115, USA
| | - Karine G Le Roch
- Genomics Institute of the Novartis Research Foundation, San Diego California, 92121, USA
| | - Ousmane Sarr
- Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, Dakar, Senegal
| | - Xuemin Fang
- Department of Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts 02115, USA
| | - Yingyao Zhou
- Genomics Institute of the Novartis Research Foundation, San Diego California, 92121, USA
| | - Omar Ndir
- Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, Dakar, Senegal
| | - Soulyemane Mboup
- Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, Dakar, Senegal
| | - Ali Sultan
- Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, Massachusetts 02115, USA
| | - Elizabeth A Winzeler
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
- Genomics Institute of the Novartis Research Foundation, San Diego California, 92121, USA
| | - Dyann F Wirth
- Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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