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Gül E, Bakkeren E, Salazar G, Steiger Y, Abi Younes A, Clerc M, Christen P, Fattinger SA, Nguyen BD, Kiefer P, Slack E, Ackermann M, Vorholt JA, Sunagawa S, Diard M, Hardt WD. The microbiota conditions a gut milieu that selects for wild-type Salmonella Typhimurium virulence. PLoS Biol 2023; 21:e3002253. [PMID: 37651408 PMCID: PMC10499267 DOI: 10.1371/journal.pbio.3002253] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/13/2023] [Accepted: 07/13/2023] [Indexed: 09/02/2023] Open
Abstract
Salmonella Typhimurium elicits gut inflammation by the costly expression of HilD-controlled virulence factors. This inflammation alleviates colonization resistance (CR) mediated by the microbiota and thereby promotes pathogen blooms. However, the inflamed gut-milieu can also select for hilD mutants, which cannot elicit or maintain inflammation, therefore causing a loss of the pathogen's virulence. This raises the question of which conditions support the maintenance of virulence in S. Typhimurium. Indeed, it remains unclear why the wild-type hilD allele is dominant among natural isolates. Here, we show that microbiota transfer from uninfected or recovered hosts leads to rapid clearance of hilD mutants that feature attenuated virulence, and thereby contributes to the preservation of the virulent S. Typhimurium genotype. Using mouse models featuring a range of microbiota compositions and antibiotic- or inflammation-inflicted microbiota disruptions, we found that irreversible disruption of the microbiota leads to the accumulation of hilD mutants. In contrast, in models with a transient microbiota disruption, selection for hilD mutants was prevented by the regrowing microbiota community dominated by Lachnospirales and Oscillospirales. Strikingly, even after an irreversible microbiota disruption, microbiota transfer from uninfected donors prevented the rise of hilD mutants. Our results establish that robust S. Typhimurium gut colonization hinges on optimizing its manipulation of the host: A transient and tempered microbiota perturbation is favorable for the pathogen to both flourish in the inflamed gut and also minimize loss of virulence. Moreover, besides conferring CR, the microbiota may have the additional consequence of maintaining costly enteropathogen virulence mechanisms.
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Affiliation(s)
- Ersin Gül
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Erik Bakkeren
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Guillem Salazar
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Institute of Microbiology and Swiss Institute of Bioinformatics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Yves Steiger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Andrew Abi Younes
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Melanie Clerc
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Philipp Christen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Stefan A. Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Bidong D. Nguyen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Patrick Kiefer
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Emma Slack
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Institute for Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag, Duebendorf, Switzerland
| | - Julia A. Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Shinichi Sunagawa
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Institute of Microbiology and Swiss Institute of Bioinformatics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Médéric Diard
- Biozentrum, University of Basel, Basel, Switzerland
- Botnar Research Centre for Child Health, Basel, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
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Bakkeren E, Gül E, Huisman JS, Steiger Y, Rocker A, Hardt WD, Diard M. Impact of horizontal gene transfer on emergence and stability of cooperative virulence in Salmonella Typhimurium. Nat Commun 2022; 13:1939. [PMID: 35410999 PMCID: PMC9001671 DOI: 10.1038/s41467-022-29597-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 03/18/2022] [Indexed: 11/09/2022] Open
Abstract
Intestinal inflammation fuels the transmission of Salmonella Typhimurium (S.Tm). However, a substantial fitness cost is associated with virulence expression. Mutations inactivating transcriptional virulence regulators generate attenuated variants profiting from inflammation without enduring virulence cost. Such variants interfere with the transmission of fully virulent clones. Horizontal transfer of functional regulatory genes (HGT) into attenuated variants could nevertheless favor virulence evolution. To address this hypothesis, we cloned hilD, coding for the master regulator of virulence, into a conjugative plasmid that is highly transferrable during intestinal colonization. The resulting mobile hilD allele allows virulence to emerge from avirulent populations, and to be restored in attenuated mutants competing against virulent clones within-host. However, mutations inactivating the mobile hilD allele quickly arise. The stability of virulence mediated by HGT is strongly limited by its cost, which depends on the hilD expression level, and by the timing of transmission. We conclude that robust evolution of costly virulence expression requires additional selective forces such as narrow population bottlenecks during transmission. Salmonella Typhimurium virulence is costly and can be lost by mutation during infection. Bakkeren et al. show that virulence restoration via horizontal gene transfer is only transient while transmission bottlenecks promote long-term virulence stability.
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Sobota M, Rodilla Ramirez PN, Cambré A, Rocker A, Mortier J, Gervais T, Haas T, Cornillet D, Chauvin D, Hug I, Julou T, Aertsen A, Diard M. The expression of virulence genes increases membrane permeability and sensitivity to envelope stress in Salmonella Typhimurium. PLoS Biol 2022; 20:e3001608. [PMID: 35389980 PMCID: PMC9017878 DOI: 10.1371/journal.pbio.3001608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/19/2022] [Accepted: 03/17/2022] [Indexed: 11/19/2022] Open
Abstract
Virulence gene expression can represent a substantial fitness cost to pathogenic bacteria. In the model entero-pathogen Salmonella Typhimurium (S.Tm), such cost favors emergence of attenuated variants during infections that harbor mutations in transcriptional activators of virulence genes (e.g., hilD and hilC). Therefore, understanding the cost of virulence and how it relates to virulence regulation could allow the identification and modulation of ecological factors to drive the evolution of S.Tm toward attenuation. In this study, investigations of membrane status and stress resistance demonstrate that the wild-type (WT) expression level of virulence factors embedded in the envelope increases membrane permeability and sensitizes S.Tm to membrane stress. This is independent from a previously described growth defect associated with virulence gene expression in S.Tm. Pretreating the bacteria with sublethal stress inhibited virulence expression and increased stress resistance. This trade-off between virulence and stress resistance could explain the repression of virulence expression in response to harsh environments in S.Tm. Moreover, we show that virulence-associated stress sensitivity is a burden during infection in mice, contributing to the inherent instability of S.Tm virulence. As most bacterial pathogens critically rely on deploying virulence factors in their membrane, our findings could have a broad impact toward the development of antivirulence strategies.
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Affiliation(s)
| | | | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | | | - Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Théo Gervais
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | | | | | - Dany Chauvin
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Isabelle Hug
- Biozentrum, University of Basel, Basel, Switzerland
| | - Thomas Julou
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
- * E-mail: (AA); (MD)
| | - Médéric Diard
- Biozentrum, University of Basel, Basel, Switzerland
- * E-mail: (AA); (MD)
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Nguyen BD, Cuenca V M, Hartl J, Gül E, Bauer R, Meile S, Rüthi J, Margot C, Heeb L, Besser F, Escriva PP, Fetz C, Furter M, Laganenka L, Keller P, Fuchs L, Christen M, Porwollik S, McClelland M, Vorholt JA, Sauer U, Sunagawa S, Christen B, Hardt WD. Import of Aspartate and Malate by DcuABC Drives H 2/Fumarate Respiration to Promote Initial Salmonella Gut-Lumen Colonization in Mice. Cell Host Microbe 2020; 27:922-936.e6. [PMID: 32416061 PMCID: PMC7292772 DOI: 10.1016/j.chom.2020.04.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/16/2020] [Accepted: 04/14/2020] [Indexed: 12/13/2022]
Abstract
Initial enteropathogen growth in the microbiota-colonized gut is poorly understood. Salmonella Typhimurium is metabolically adaptable and can harvest energy by anaerobic respiration using microbiota-derived hydrogen (H2) as an electron donor and fumarate as an electron acceptor. As fumarate is scarce in the gut, the source of this electron acceptor is unclear. Here, transposon sequencing analysis along the colonization trajectory of S. Typhimurium implicates the C4-dicarboxylate antiporter DcuABC in early murine gut colonization. In competitive colonization assays, DcuABC and enzymes that convert the C4-dicarboxylates aspartate and malate into fumarate (AspA, FumABC), are required for fumarate/H2-dependent initial growth. Thus, S. Typhimurium obtains fumarate by DcuABC-mediated import and conversion of L-malate and L-aspartate. Fumarate reduction yields succinate, which is exported by DcuABC in exchange for L-aspartate and L-malate. This cycle allows S. Typhimurium to harvest energy by H2/fumarate respiration in the microbiota-colonized gut. This strategy may also be relevant for commensal E. coli diminishing the S. Typhimurium infection.
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Affiliation(s)
- Bidong D Nguyen
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | | | - Johannes Hartl
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Ersin Gül
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Rebekka Bauer
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Susanne Meile
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Joel Rüthi
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Céline Margot
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Laura Heeb
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Franziska Besser
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Pau Pérez Escriva
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Céline Fetz
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Markus Furter
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Leanid Laganenka
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Philipp Keller
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Lea Fuchs
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Matthias Christen
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Julia A Vorholt
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Uwe Sauer
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Shinichi Sunagawa
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland.
| | - Beat Christen
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland.
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