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Berdejo D, Mortier J, Cambré A, Sobota M, Van Eyken R, Kim TD, Vanoirbeek K, García Gonzalo D, Pagán R, Diard M, Aertsen A. Evolutionary trade-off between heat shock resistance, growth at high temperature, and virulence expression in Salmonella Typhimurium. mBio 2024; 15:e0310523. [PMID: 38349183 PMCID: PMC10936172 DOI: 10.1128/mbio.03105-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/12/2024] [Indexed: 03/14/2024] Open
Abstract
Understanding the evolutionary dynamics of foodborne pathogens throughout our food production chain is of utmost importance. In this study, we reveal that Salmonella Typhimurium can readily and reproducibly acquire vastly increased heat shock resistance upon repeated exposure to heat shock. Counterintuitively, this boost in heat shock resistance was invariantly acquired through loss-of-function mutations in the dnaJ gene, encoding a heat shock protein that acts as a molecular co-chaperone of DnaK and enables its role in protein folding and disaggregation. As a trade-off, however, the acquisition of heat shock resistance inevitably led to attenuated growth at 37°C and higher temperatures. Interestingly, loss of DnaJ also downregulated the activity of the master virulence regulator HilD, thereby lowering the fraction of virulence-expressing cells within the population and attenuating virulence in mice. By connecting heat shock resistance evolution to attenuation of HilD activity, our results confirm the complex interplay between stress resistance and virulence in Salmonella Typhimurium. IMPORTANCE Bacterial pathogens such as Salmonella Typhimurium are equipped with both stress response and virulence features in order to navigate across a variety of complex inhospitable environments that range from food-processing plants up to the gastrointestinal tract of its animal host. In this context, however, it remains obscure whether and how adaptation to one environment would obstruct fitness in another. In this study, we reveal that severe heat stress counterintuitively, but invariantly, led to the selection of S. Typhimurium mutants that are compromised in the activity of the DnaJ heat shock protein. While these mutants obtained massively increased heat resistance, their virulence became greatly attenuated. Our observations, therefore, reveal a delicate balance between optimal tuning of stress response and virulence features in bacterial pathogens.
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Affiliation(s)
- Daniel Berdejo
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2, Universidad de Zaragoza-CITA, Zaragoza, Spain
| | - Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | | | - Ronald Van Eyken
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Tom Dongmin Kim
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Kristof Vanoirbeek
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Diego García Gonzalo
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2, Universidad de Zaragoza-CITA, Zaragoza, Spain
| | - Rafael Pagán
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2, Universidad de Zaragoza-CITA, Zaragoza, Spain
| | | | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
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Mortier J, Govers SK, Cambré A, Van Eyken R, Verheul J, den Blaauwen T, Aertsen A. Protein aggregates act as a deterministic disruptor during bacterial cell size homeostasis. Cell Mol Life Sci 2023; 80:360. [PMID: 37971522 DOI: 10.1007/s00018-023-05002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/13/2023] [Accepted: 10/15/2023] [Indexed: 11/19/2023]
Abstract
Mechanisms underlying deviant cell size fluctuations among clonal bacterial siblings are generally considered to be cryptic and stochastic in nature. However, by scrutinizing heat-stressed populations of the model bacterium Escherichia coli, we uncovered the existence of a deterministic asymmetry in cell division that is caused by the presence of intracellular protein aggregates (PAs). While these structures typically locate at the cell pole and segregate asymmetrically among daughter cells, we now show that the presence of a polar PA consistently causes a more distal off-center positioning of the FtsZ division septum. The resulting increased length of PA-inheriting siblings persists over multiple generations and could be observed in both E. coli and Bacillus subtilis populations. Closer investigation suggests that a PA can physically perturb the nucleoid structure, which subsequently leads to asymmetric septation.
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Affiliation(s)
- Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Sander K Govers
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
- Department of Biology, KU Leuven, Leuven, Belgium
| | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Ronald Van Eyken
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Jolanda Verheul
- Swammerdam Institute for Life Sciences, Bacterial Cell Biology and Physiology, University of Amsterdam, Amsterdam, The Netherlands
| | - Tanneke den Blaauwen
- Swammerdam Institute for Life Sciences, Bacterial Cell Biology and Physiology, University of Amsterdam, Amsterdam, The Netherlands
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium.
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Mortier J, Cambré A, Schack S, Christie G, Aertsen A. Impact of Protein Aggregates on Sporulation and Germination of Bacillus subtilis. Microorganisms 2023; 11:2365. [PMID: 37764209 PMCID: PMC10536567 DOI: 10.3390/microorganisms11092365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
In order to improve our general understanding of protein aggregate (PA) management and impact in bacteria, different model systems and processes need to be investigated. As such, we developed an inducible synthetic PA model system to investigate PA dynamics in the Gram-positive model organism Bacillus subtilis. This confirmed previous observations that PA segregation in this organism seems to follow the Escherichia coli paradigm of nucleoid occlusion governing polar localization and asymmetric segregation during vegetative growth. However, our findings also revealed that PAs can readily persist throughout the entire sporulation process after encapsulation in the forespore during sporulation. Moreover, no deleterious effects of PA presence on sporulation, germination and spore survival against heat or UV stress could be observed. Our findings therefore indicate that the sporulation process is remarkably robust against perturbations by PAs and misfolded proteins.
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Affiliation(s)
- Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
| | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
| | - Sina Schack
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK; (S.S.); (G.C.)
| | - Graham Christie
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK; (S.S.); (G.C.)
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
The rise in fluorescence-based imaging techniques over the past 3 decades has improved the ability of researchers to scrutinize live cell biology at increased spatial and temporal resolution. In microbiology, these real-time vivisections structurally changed the view on the bacterial cell away from the "watery bag of enzymes" paradigm toward the perspective that these organisms are as complex as their eukaryotic counterparts. Capitalizing on the enormous potential of (time-lapse) fluorescence microscopy and the ever-extending pallet of corresponding probes, initial breakthroughs were made in unraveling the localization of proteins and monitoring real-time gene expression. However, later it became clear that the potential of this technique extends much further, paving the way for a focus-shift from observing single events within bacterial cells or populations to obtaining a more global picture at the intra- and intercellular level. In this review, we outline the current state of the art in fluorescence-based vivisection of bacteria and provide an overview of important case studies to exemplify how to use or combine different strategies to gain detailed information on the cell's physiology. The manuscript therefore consists of two separate (but interconnected) parts that can be read and consulted individually. The first part focuses on the fluorescent probe pallet and provides a perspective on modern methodologies for microscopy using these tools. The second section of the review takes the reader on a tour through the bacterial cell from cytoplasm to outer shell, describing strategies and methods to highlight architectural features and overall dynamics within cells.
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Affiliation(s)
- Alexander Cambré
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
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Staes I, Passaris I, Cambré A, Aertsen A. Population heterogeneity tactics as driving force in Salmonella virulence and survival. Food Res Int 2019; 125:108560. [DOI: 10.1016/j.foodres.2019.108560] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 01/28/2023]
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Abstract
The well-studied spv operon of Salmonellatyphimurium is important for causing full virulence in mice and both the regulation and function of the Spv proteins have been characterized extensively over the past several decades. Using quantitative single-cell fluorescence microscopy, we demonstrate the spv regulon to display a bimodal expression pattern that originates in the bimodal expression of the SpvR activator. The spv expression pattern is influenced by growth conditions and the specific Styphimurium strain used, but does not require Salmonella-specific virulence regulators. By monitoring real-time promoter kinetics, we reveal that SpvA has the ability to impart negative feedback on spvABCD expression without affecting spvR expression. Together, our data suggest that the SpvA protein counteracts the positive feedback loop imposed by SpvR, and could thus be responsible for dampening spvABCD expression and coordinating virulence protein production in time. The results presented here yield new insights in the intriguing regulation of the spv operon and adds this operon to the growing list of virulence factors exhibiting marked expression heterogeneity in Styphimurium.
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Affiliation(s)
- Ioannis Passaris
- Department of Microbial and Molecular Systems (MS), Katholieke Universiteit Leuven, 3001 Leuven, Belgium
| | - Alexander Cambré
- Department of Microbial and Molecular Systems (MS), Katholieke Universiteit Leuven, 3001 Leuven, Belgium
| | - Sander K Govers
- Department of Microbial and Molecular Systems (MS), Katholieke Universiteit Leuven, 3001 Leuven, Belgium
| | - Abram Aertsen
- Department of Microbial and Molecular Systems (MS), Katholieke Universiteit Leuven, 3001 Leuven, Belgium
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Gayán E, Cambré A, Michiels CW, Aertsen A. RpoS-independent evolution reveals the importance of attenuated cAMP/CRP regulation in high hydrostatic pressure resistance acquisition in E. coli. Sci Rep 2017; 7:8600. [PMID: 28819154 PMCID: PMC5561100 DOI: 10.1038/s41598-017-08958-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 07/20/2017] [Indexed: 11/09/2022] Open
Abstract
High hydrostatic pressure (HHP) processing is an attractive non-thermal alternative to food pasteurization. Nevertheless, the large inter- and intra-species variations in HHP resistance among foodborne pathogens and the ease by which they can acquire extreme resistance are an issue of increasing concern. Since RpoS activity has been considered as a central determinant in the HHP resistance of E. coli and its pathovars, this study probed for the potential of an E. coli MG1655 ΔrpoS mutant to acquire HHP resistance by directed evolution. Despite the higher initial HHP sensitivity of the ΔrpoS mutant compared to the wild-type strain, evolved lineages of the former readily managed to restore or even succeed wild-type levels of resistance. A number of these ΔrpoS derivatives were affected in cAMP/CRP regulation, and this could be causally related to their HHP resistance. Subsequent inspection revealed that some of previously isolated HHP-resistant mutants derived from the wild-type strain also incurred a causal decrease in cAMP/CRP regulation. cAMP/CRP attenuated HHP-resistant mutants also exhibited higher resistance to fosfomycin, a preferred treatment for STEC infections. As such, this study reveals attenuation of cAMP/CRP regulation as a relevant and RpoS-independent evolutionary route towards HHP resistance in E. coli that coincides with fosfomycin resistance.
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Affiliation(s)
- Elisa Gayán
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Alexander Cambré
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Chris W Michiels
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium.
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Cambré A, Zimmermann M, Sauer U, Vivijs B, Cenens W, Michiels CW, Aertsen A, Loessner MJ, Noben JP, Ayala JA, Lavigne R, Briers Y. Metabolite profiling and peptidoglycan analysis of transient cell wall-deficient bacteria in a new Escherichia coli model system. Environ Microbiol 2014; 17:1586-99. [PMID: 25142185 DOI: 10.1111/1462-2920.12594] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/11/2014] [Indexed: 12/01/2022]
Abstract
Many bacteria are able to assume a transient cell wall-deficient (or L-form) state under favourable osmotic conditions. Cell wall stress such as exposure to β-lactam antibiotics can enforce the transition to and maintenance of this state. L-forms actively proliferate and can return to the walled state upon removal of the inducing agent. We have adopted Escherichia coli as a model system for the controlled transition to and reversion from the L-form state, and have studied these dynamics with genetics, cell biology and 'omics' technologies. As such, a transposon mutagenesis screen underscored the requirement for the Rcs phosphorelay and colanic acid synthesis, while proteomics show only little differences between rods and L-forms. In contrast, metabolome comparison reveals the high abundance of lysophospholipids and phospholipids with unsaturated or cyclopropanized fatty acids in E. coli L-forms. This increase of membrane lipids associated with increased membrane fluidity may facilitate proliferation through bud formation. Visualization of the residual peptidoglycan with a fluorescently labelled peptidoglycan binding protein indicates de novo cell wall synthesis and a role for septal peptidoglycan synthesis during bud constriction. The DD-carboxypeptidases PBP5 and PBP6 are threefold and fourfold upregulated in L-forms, indicating a specific role for regulation of crosslinking during L-form proliferation.
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Affiliation(s)
- Alexander Cambré
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, B-3001, Heverlee, Belgium; Laboratory of Food Microbiology, Department of Microbial and Molecular Systems, KU Leuven, B-3001, Heverlee, Belgium
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Abstract
Carpal tunnel syndrome (CTS) is the most common of the compression neuropathies. Several studies have demonstrated the efficacy of wrist splinting in relieving the symptoms of CTS; however, the chosen angle of immobilization has varied. Wick catheter measurements of carpal tunnel pressures suggest that the neural position has less pressure and, therefore, greater potential to provide relief from symptoms. This study is a prospectively gathered, blind trial comparing the symptom relief experienced by wearers of splints immobilized at 20 degrees extension and at neutral. The results indicate that the neutral angle provided superior symptom relief, and that the relief did not often improve between 2 weeks and 2 months of wear. Relief of symptoms was not related to the length of time that the patient had experienced of CTS symptoms. The results also indicate that the results of the electromyography/nerve conduction study (EMG/NCS) do not provide information about the subjects' likely response to splinting.
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Affiliation(s)
- D T Burke
- Department of Medicine, Louisiana State University Medical Center, New Orleans 70112
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