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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] [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 PMCID: PMC11072981 DOI: 10.1007/s00018-023-05002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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Gayán E, Wang Z, Salvador M, Gänzle MG, Aertsen A. Dynamics of high hydrostatic pressure resistance development in RpoS-deficient Escherichia coli. Food Res Int 2023; 164:112280. [PMID: 36737893 DOI: 10.1016/j.foodres.2022.112280] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/17/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
High hydrostatic pressure (HHP) treatment is one of the most widely accepted non-thermal food processing methods, but HHP-resistance development in pathogenic or spoilage bacteria might compromise the safety and stability of HHP-treated foods. Charting the possible routes and mechanisms of HHP resistance development in foodborne bacteria is therefore essential to anticipate or prevent the appearance of resistant variants. While upregulation of the RpoS-governed general stress response is a well-established route for increased HHP resistance in Escherichia coli, previous work revealed that mutations causing attenuated cAMP/CRP activity or aggregation-prone TnaA variants can evolve to overcome the HHP-hypersensitivity of an E. coli ΔrpoS mutant. In this study, further directed evolution and genetic analysis approaches allowed us to demonstrate that both kinds of mutants tend to co-emerge and compete with each other in E. coli ΔrpoS populations evolving towards HHP resistance, because of the higher HHP resistance of cAMP/CRP mutants and the faster growth rate of the TnaA mutants. Moreover, closer scrutiny of evolving populations revealed RpoS, cAMP/CRP and TnaA independent routes of HHP resistance development, based on downregulation of YegW or RppH activity.
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Affiliation(s)
- Elisa Gayán
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium
| | - Zhiying Wang
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Maika Salvador
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
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Van Riet S, Tadesse W, Mortier J, Schlegel S, Simoens K, Bernaerts K, Dal Co A, Aertsen A. Heterogeneity and Evolutionary Tunability of Escherichia coli Resistance against Extreme Acid Stress. Microbiol Spectr 2022; 10:e0375722. [PMID: 36453903 PMCID: PMC9769608 DOI: 10.1128/spectrum.03757-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 10/27/2022] [Indexed: 12/05/2022] Open
Abstract
Since acidic environments often serve as an important line of defense against bacterial pathogens, it is important to fully understand how the latter manage to mount and evolve acid resistance mechanisms. Escherichia coli, a species harboring many pathovars, is typically equipped with the acid fitness island (AFI), a genomic region encoding the GadE master regulator together with several GadE-controlled functions to counter acid stress. This study reveals that gadE and consequently AFI functions are heterogeneously expressed even in the absence of any prior acid stress, thereby preemptively creating acid-resistant subpopulations within a clonal E. coli population. Directed evolution efforts selecting for modulated gadE expression confirm that a gain-of-function mutation in the EvgS sensor kinase can constitutively upregulate gadE expression and concomitant acid resistance. However, we reveal that such upregulation of EvgS also causes cross-resistance to heat stress because of SafA-mediated cross-activation of the PhoPQ regulon. Surprisingly, loss of function of the serC gene (encoding phosphoserine/phosphohydroxythreonine aminotransferase) can also significantly upregulate gadE expression, acid resistance, and heat cross-resistance, although via a currently cryptic mechanism. As such, our data reveal a noisy expression of gadE in E. coli that is functional for the survival of sudden acid stress and that can readily be genetically tuned. IMPORTANCE Acidic environments constitute one of the most important stresses for enteric bacteria and can be encountered in both natural (e.g., host gastrointestinal tract) and manmade (e.g., food processing) environments. The enteric species Escherichia coli harbors many pathovars and is well known for its ability to cope with acid stress. In this study, we uncover that E. coli's acid fitness island (AFI), a genomic region that encodes important functions to deal with acid stress, is by default expressed in a heterogeneous manner. In fact, using microfluidics-based single-cell approaches, we further demonstrate that this heterogeneity preemptively creates a clonal subpopulation that is much better equipped to survive a sudden acid shock. In addition, we reveal that environments with recurring acid stress can readily select for mutants displaying a higher fraction of AFI-expressing cells. These new insights are important to properly understand and anticipate the survival characteristics of E. coli.
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Affiliation(s)
- Stefanie Van Riet
- Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
| | - Wubishet Tadesse
- Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
| | - Julien Mortier
- Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
| | - Susan Schlegel
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Kenneth Simoens
- Department of Chemical Engineering, KU Leuven, Leuven, Belgium
| | | | - Alma Dal Co
- Department of Environmental Microbiology, Eawag, Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Abram Aertsen
- Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
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Polymorphism of 16s rRNA Gene: Any Effect on the Biomolecular Quantitation of the Honey Bee (Apis mellifera L., 1758) Pathogen Nosema ceranae? APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12010422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The microsporidian Nosema ceranae is a severe threat to the western honey bee Apis mellifera, as it is responsible for nosemosis type C, which leads the colonies to dwindle and collapse. Infection quantification is essential to clinical and research aims. Assessment is made often with molecular assays based on rRNA genes, which are present in the N. ceranae genome as multiple and polymorphic copies. This study aims to compare two different methods of Real-Time PCR (qPCR), respectively relying on the 16S rRNA and Hsp70 genes, the first of which is described as a multiple and polymorphic gene. Young worker bees, hatched in the laboratory and artificially inoculated with N. ceranae spores, were incubated at 33 °C and subject to different treatment regimens. Samples were taken post-infection and analyzed with both qPCR methods. Compared to Hsp70, the 16S rRNA method systematically detected higher abundance. Straightforward conversion between the two methods is made impossible by erratic 16s rRNA/Hsp70 ratios. The 16s rRNA polymorphism showed an increase around the inoculated dose, where a higher prevalence of ungerminated spores was expected due to the treatment effects. The possible genetic background of that irregular distribution is discussed in detail. The polymorphic nature of 16S rRNA showed to be a limit in the infection quantification. More reliably, the N. ceranae abundance can be assessed in honey bee samples with methods based on the single-copy gene Hsp70.
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