1
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Li Y, Zhang R, Fu C, Jiang Q, Zhang P, Zhang Y, Chen J, Tao K, Chen WH, Zeng X. Intratumoral microbiome promotes liver metastasis and dampens adjuvant imatinib treatment in gastrointestinal stromal tumor. Cancer Lett 2024:217149. [PMID: 39117066 DOI: 10.1016/j.canlet.2024.217149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 06/06/2024] [Accepted: 07/28/2024] [Indexed: 08/10/2024]
Abstract
Understanding the determinants of long-term liver metastasis (LM) outcomes in gastrointestinal stromal tumor (GIST) patients is crucial. We established the feature selection model of intratumoral microbiome at the surgery, achieving robust predictive accuracies of 0.953 and 0.897 AUCs in discovery (n = 74) and validation (n = 34) cohorts, respectively. Notably, despite the significant reduction in LM occurrence with adjuvant imatinib (AI) treatment, intratumoral microbiome exerted independently stronger effects on post-operative LM. Employing both 16S and full-length rRNA sequencing, we pinpoint intracellular Shewanella algae as a foremost LM risk factor in both AI- and non-AI-treated patients. Experimental validation confirmed S. algae's intratumoral presence in GIST, along with migration/invasion-promoting effects on GIST cells. Furthermore, S. algae promoted LM and impeded AI treatment in metastatic mouse models. Our findings advocate for incorporating intratumoral microbiome evaluation at surgery, and propose S. algae as a therapeutic target for LM suppression in GIST.
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Affiliation(s)
- Yanze Li
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Key Laboratory of Bioinformatics and Molecular-imaging, Center for Artificial Intelligence Biology, Department of Bioinformatics and Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China; Department of Computer Science, School of Science, Aalto University, Helsinki, Finland
| | - Ruizhi Zhang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chengbo Fu
- Department of Computer Science, School of Science, Aalto University, Helsinki, Finland
| | - Qi Jiang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Peng Zhang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yong Zhang
- Department of Radiation Oncology, Hubei Cancer Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingchao Chen
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Key Laboratory of Bioinformatics and Molecular-imaging, Center for Artificial Intelligence Biology, Department of Bioinformatics and Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Kaixiong Tao
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Wei-Hua Chen
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Key Laboratory of Bioinformatics and Molecular-imaging, Center for Artificial Intelligence Biology, Department of Bioinformatics and Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China; Institution of Medical Artificial Intelligence, Binzhou Medical University, Yantai 264003, China.
| | - Xiangyu Zeng
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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2
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Yammine J, Doulgeraki AI, O'Byrne CP, Gharsallaoui A, Chihib NE, Karam L. The impact of different acidic conditions and food substrates on Listeria monocytogenes biofilms development and removal using nanoencapsulated carvacrol. Int J Food Microbiol 2024; 416:110676. [PMID: 38507974 DOI: 10.1016/j.ijfoodmicro.2024.110676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 02/16/2024] [Accepted: 03/09/2024] [Indexed: 03/22/2024]
Abstract
Listeria monocytogenes biofilms present a significant challenge in the food industry. This study explores the impact of different acidic conditions of culture media and food matrices on the development and removal of biofilms developed on stainless steel surfaces by wild-type (WT) L. monocytogenes strains as well as in two mutant derivatives, ΔsigB and ΔagrA, that have defects in the general stress response and quorum sensing, respectively. Additionally, the study investigates the efficacy of nanoencapsulated carvacrol as an antimicrobial against L. monocytogenes biofilms developed in Tryptic Soy Broth (TSB) culture media acidified to different pH conditions (3.5, 4.5, 5.5, 6.5), and in food substrates (apple juice, strained yogurt, vegetable soup, semi-skimmed milk) having the same pH levels. No biofilm formation was observed for all L. monocytogenes strains at pH levels of 3.5 and 4.5 in both culture media and food substrates. However, at pH 5.5 and 6.5, increased biofilm levels were observed in both the culture media and food substrates, with the WT strain showing significantly higher biofilm formation (3.04-6.05 log CFU cm-2) than the mutant strains (2.30-5.48 log CFU cm-2). For both applications, the nanoencapsulated carvacrol demonstrated more potent antimicrobial activity against biofilms developed at pH 5.5 with 2.23 to 3.61 log reductions, compared to 1.58-2.95 log reductions at pH 6.5, with mutants being more vulnerable in acidic environments. In food substrates, nanoencapsulated carvacrol induced lower log reductions (1.58-2.90) than the ones in TSB (2.02-3.61). These findings provide valuable insights into the impact of different acidic conditions on the development of L. monocytogenes biofilms on stainless steel surfaces and the potential application of nanoencapsulated carvacrol as a biofilm control agent in food processing environments.
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Affiliation(s)
- Jina Yammine
- Univ Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, Lille, France
| | - Agapi I Doulgeraki
- Laboratory of Food Microbiology and Hygiene, Department of Food Science & Technology, Faculty of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Conor P O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Biological & Chemical Sciences, University of Galway, Galway H91 TK33, Ireland
| | - Adem Gharsallaoui
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, LAGEPP UMR 5007, Villeurbanne, France
| | - Nour-Eddine Chihib
- Univ Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, Lille, France
| | - Layal Karam
- Human Nutrition Department, College of Health Sciences, QU Health, Qatar University, Doha, Qatar.
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3
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Meireles D, Pombinho R, Cabanes D. Signals behind Listeria monocytogenes virulence mechanisms. Gut Microbes 2024; 16:2369564. [PMID: 38979800 PMCID: PMC11236296 DOI: 10.1080/19490976.2024.2369564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 06/13/2024] [Indexed: 07/10/2024] Open
Abstract
The tight and coordinated regulation of virulence gene expression is crucial to ensure the survival and persistence of bacterial pathogens in different contexts within their hosts. Considering this, bacteria do not express virulence factors homogenously in time and space, either due to their associated fitness cost or to their detrimental effect at specific infection stages. To efficiently infect and persist into their hosts, bacteria have thus to monitor environmental cues or chemical cell-to-cell signaling mechanisms that allow their transition from the external environment to the host, and therefore adjust gene expression levels, intrinsic biological activities, and appropriate behaviors. Listeria monocytogenes (Lm), a major Gram-positive facultative intracellular pathogen, stands out for its adaptability and capacity to thrive in a wide range of environments. Because of that, Lm presents itself as a significant concern in food safety and public health, that can lead to potentially life-threatening infections in humans. A deeper understanding of the intricate bacterial virulence mechanisms and the signals that control them provide valuable insights into the dynamic interplay between Lm and the host. Therefore, this review addresses the role of some crucial signals behind Lm pathogenic virulence mechanisms and explores how the ability to assimilate and interpret these signals is fundamental for pathogenesis, identifying potential targets for innovative antimicrobial strategies.
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Affiliation(s)
- Diana Meireles
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar – ICBAS, Porto, Portugal
| | - Rita Pombinho
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
| | - Didier Cabanes
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
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4
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Brantl S, Ul Haq I. Small proteins in Gram-positive bacteria. FEMS Microbiol Rev 2023; 47:fuad064. [PMID: 38052429 PMCID: PMC10730256 DOI: 10.1093/femsre/fuad064] [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: 10/25/2023] [Revised: 11/27/2023] [Accepted: 12/04/2023] [Indexed: 12/07/2023] Open
Abstract
Small proteins comprising less than 100 amino acids have been often ignored in bacterial genome annotations. About 10 years ago, focused efforts started to investigate whole peptidomes, which resulted in the discovery of a multitude of small proteins, but only a number of them have been characterized in detail. Generally, small proteins can be either membrane or cytosolic proteins. The latter interact with larger proteins, RNA or even metal ions. Here, we summarize our current knowledge on small proteins from Gram-positive bacteria with a special emphasis on the model organism Bacillus subtilis. Our examples include membrane-bound toxins of type I toxin-antitoxin systems, proteins that block the assembly of higher order structures, regulate sporulation or modulate the RNA degradosome. We do not consider antimicrobial peptides. Furthermore, we present methods for the identification and investigation of small proteins.
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Affiliation(s)
- Sabine Brantl
- AG Bakteriengenetik, Matthias-Schleiden-Institut, Friedrich-Schiller-Universität Jena, Philosophenweg 12, Jena D-07743, Germany
| | - Inam Ul Haq
- AG Bakteriengenetik, Matthias-Schleiden-Institut, Friedrich-Schiller-Universität Jena, Philosophenweg 12, Jena D-07743, Germany
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5
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Oliveira AH, Tiensuu T, Guerreiro D, Tükenmez H, Dessaux C, García-Del Portillo F, O'Byrne C, Johansson J. The Virulence and Infectivity of Listeria monocytogenes Are Not Substantially Altered by Elevated SigB Activity. Infect Immun 2023:e0057122. [PMID: 37125941 DOI: 10.1128/iai.00571-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Listeria monocytogenes is a bacterial pathogen capable of causing severe infections but also thriving outside the host. To respond to different stress conditions, L. monocytogenes mainly utilizes the general stress response regulon, which largely is controlled by the alternative sigma factor Sigma B (SigB). In addition, SigB is important for virulence gene expression and infectivity. Upon encountering stress, a large multicomponent protein complex known as the stressosome becomes activated, ultimately leading to SigB activation. RsbX is a protein needed to reset a "stressed" stressosome and prevent unnecessary SigB activation in nonstressed conditions. Consequently, absence of RsbX leads to constitutive activation of SigB even without prevailing stress stimulus. To further examine the involvement of SigB in the virulence of this pathogen, we investigated whether a strain with constitutively active SigB would be affected in virulence factor expression and/or infectivity in cultured cells and in a chicken embryo infection model. Our results suggest that increased SigB activity does not substantially alter virulence gene expression compared with the wild-type (WT) strain at transcript and protein levels. Bacteria lacking RsbX were taken up by phagocytic and nonphagocytic cells at a similar frequency to WT bacteria, both in stressed and nonstressed conditions. Finally, the absence of RsbX only marginally affected the ability of bacteria to infect chicken embryos. Our results suggest only a minor role of RsbX in controlling virulence factor expression and infectivity under these conditions.
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Affiliation(s)
- Ana H Oliveira
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre of Microbial Research, Umeå University, Umeå, Sweden
| | - Teresa Tiensuu
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre of Microbial Research, Umeå University, Umeå, Sweden
| | - Duarte Guerreiro
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre of Microbial Research, Umeå University, Umeå, Sweden
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Hasan Tükenmez
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre of Microbial Research, Umeå University, Umeå, Sweden
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Charlotte Dessaux
- Laboratory of Intracellular Bacterial Pathogens, National Center of Biotechnology, (CNB)-CSIC, Madrid, Spain
| | | | - Conor O'Byrne
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Jörgen Johansson
- Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Umeå Centre of Microbial Research, Umeå University, Umeå, Sweden
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6
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Tran BM, Linnik DS, Punter CM, Śmigiel WM, Mantovanelli L, Iyer A, O’Byrne C, Abee T, Johansson J, Poolman B. Super-resolving microscopy reveals the localizations and movement dynamics of stressosome proteins in Listeria monocytogenes. Commun Biol 2023; 6:51. [PMID: 36641529 PMCID: PMC9840623 DOI: 10.1038/s42003-023-04423-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023] Open
Abstract
The human pathogen Listeria monocytogenes can cope with severe environmental challenges, for which the high molecular weight stressosome complex acts as the sensing hub in a complicated signal transduction pathway. Here, we show the dynamics and functional roles of the stressosome protein RsbR1 and its paralogue, the blue-light receptor RsbL, using photo-activated localization microscopy combined with single-particle tracking and single-molecule displacement mapping and supported by physiological studies. In live cells, RsbR1 is present in multiple states: in protomers with RsbS, large clusters of stressosome complexes, and in connection with the plasma membrane via Prli42. RsbL diffuses freely in the cytoplasm but forms clusters upon exposure to light. The clustering of RsbL is independent of the presence of Prli42. Our work provides a comprehensive view of the spatial organization and intracellular dynamics of the stressosome proteins in L. monocytogenes, which paves the way towards uncovering the stress-sensing mechanism of this signal transduction pathway.
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Affiliation(s)
- Buu Minh Tran
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Dmitrii Sergeevich Linnik
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Christiaan Michiel Punter
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Wojciech Mikołaj Śmigiel
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Luca Mantovanelli
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Aditya Iyer
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Conor O’Byrne
- Microbiology, School of Biological & Chemical Sciences, Ryan Institute, University of Galway, Galway, Ireland
| | - Tjakko Abee
- grid.4818.50000 0001 0791 5666Laboratory of Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Jörgen Johansson
- grid.12650.300000 0001 1034 3451Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Bert Poolman
- grid.4830.f0000 0004 0407 1981Department of Biochemistry, University of Groningen, Groningen, the Netherlands
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7
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Cutugno L, Tamayo BKS, Lens PN, O'Byrne C, Pané-Farré J, Boyd A. In vivo characterisation of the Vibrio vulnificus stressosome: A complex involved in reshaping glucose metabolism and motility regulation, in nutrient- and iron-limited growth conditions. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 4:100186. [PMID: 36936406 PMCID: PMC10014275 DOI: 10.1016/j.crmicr.2023.100186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
Stressosomes are signal-sensing and integration hubs identified in many bacteria. At present, the role of the stressosome has only been investigated in Gram-positive bacteria. This work represents the first in vivo characterisation of the stressosome in a Gram-negative bacterium, Vibrio vulnificus. Previous in vitro characterisation of the complex has led to the hypothesis of a complex involved in iron metabolism and control of c-di-GMP levels. We demonstrate that the stressosome is probably involved in reshaping the glucose metabolism in Fe- and nutrient-limited conditions and mutations of the locus affect the activation of the glyoxylate shunt. Moreover, we show that the stressosome is needed for the transcription of fleQ and to promote motility, consistent with the hypothesis that the stressosome is involved in regulating c-di-GMP. This report highlights the potential role of the stressosome in a Gram-negative bacterium, with implications for the metabolism and motility of this pathogen.
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Affiliation(s)
- Laura Cutugno
- School of Natural Sciences, University of Galway, Ireland
| | | | - Piet N.L. Lens
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Conor O'Byrne
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Jan Pané-Farré
- Centre for synthetic Microbiology (SYNMIKRO) & Department of Chemistry, Philipps-University Marburg, Germany
| | - Aoife Boyd
- School of Natural Sciences, University of Galway, Ireland
- Corresponding author.
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8
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Wu J, NicAogáin K, McAuliffe O, Jordan K, O’Byrne C. Phylogenetic and Phenotypic Analyses of a Collection of Food and Clinical Listeria monocytogenes Isolates Reveal Loss of Function of Sigma B from Several Clonal Complexes. Appl Environ Microbiol 2022; 88:e0005122. [PMID: 35481758 PMCID: PMC9128516 DOI: 10.1128/aem.00051-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/17/2022] [Indexed: 12/14/2022] Open
Abstract
To understand the molecular mechanisms that contribute to the stress responses of the important foodborne pathogen Listeria monocytogenes, we collected 139 strains (meat, n = 25; dairy, n = 10; vegetable, n = 8; seafood, n = 14; mixed food, n = 4; and food processing environments, n = 78), mostly isolated in Ireland, and subjected them to whole-genome sequencing. These strains were compared to 25 Irish clinical isolates and 4 well-studied reference strains. Core genome and pan-genome analysis confirmed a highly clonal and deeply branched population structure. Multilocus sequence typing showed that this collection contained a diverse range of strains from L. monocytogenes lineages I and II. Several groups of isolates with highly similar genome content were traced to single or multiple food business operators, providing evidence of strain persistence or prevalence, respectively. Phenotypic screening assays for tolerance to salt stress and resistance to acid stress revealed variants within several clonal complexes that were phenotypically distinct. Five of these phenotypic outliers were found to carry mutations in the sigB operon, which encodes the stress-inducible sigma factor sigma B. Transcriptional analysis confirmed that three of the strains that carried mutations in sigB, rsbV, or rsbU had reduced SigB activity, as predicted. These strains exhibited increased tolerance to salt stress and displayed decreased resistance to low pH stress. Overall, this study shows that loss-of-function mutations in the sigB operon are comparatively common in field isolates, probably reflecting the cost of the general stress response to reproductive fitness in this pathogen. IMPORTANCE The bacterial foodborne pathogen Listeria monocytogenes frequently contaminates various categories of food products and is able to cause life-threatening infections when ingested by humans. Thus, it is important to control the growth of this bacterium in food by understanding the mechanisms that allow its proliferation under suboptimal conditions. In this study, intraspecies heterogeneity in stress response was observed across a collection consisting of mainly Irish L. monocytogenes isolates. Through comparisons of genome sequence and phenotypes observed, we identified three strains with impairment of the general stress response regulator SigB. Two of these strains are used widely in food challenge studies for evaluating the growth potential of L. monocytogenes. Given that loss of SigB function is associated with atypical phenotypic properties, the use of these strains in food challenge studies should be re-evaluated.
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Affiliation(s)
- Jialun Wu
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
| | - Kerrie NicAogáin
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
| | | | - Kieran Jordan
- Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
| | - Conor O’Byrne
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
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9
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Guerreiro DN, Pucciarelli MG, Tiensuu T, Gudynaite D, Boyd A, Johansson J, García-del Portillo F, O’Byrne CP. Acid stress signals are integrated into the σB-dependent general stress response pathway via the stressosome in the food-borne pathogen Listeria monocytogenes. PLoS Pathog 2022; 18:e1010213. [PMID: 35275969 PMCID: PMC8942246 DOI: 10.1371/journal.ppat.1010213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/23/2022] [Accepted: 02/28/2022] [Indexed: 12/17/2022] Open
Abstract
The general stress response (GSR) in Listeria monocytogenes plays a critical role in the survival of this pathogen in the host gastrointestinal tract. The GSR is regulated by the alternative sigma factor B (σB), whose role in protection against acid stress is well established. Here, we investigated the involvement of the stressosome, a sensory hub, in transducing low pH signals to induce the GSR. Mild acid shock (15 min at pH 5.0) activated σB and conferred protection against a subsequent lethal pH challenge. A mutant strain where the stressosome subunit RsbR1 was solely present retained the ability to induce σB activity at pH 5.0. The role of stressosome phosphorylation in signal transduction was investigated by mutating the putative phosphorylation sites in the core stressosome proteins RsbR1 (rsbR1-T175A, -T209A, -T241A) and RsbS (rsbS-S56A), or the stressosome kinase RsbT (rsbT-N49A). The rsbS S56A and rsbT N49A mutations abolished the response to low pH. The rsbR1-T209A and rsbR1-T241A mutants displayed constitutive σB activity. Mild acid shock upregulates invasion genes inlAB and stimulates epithelial cell invasion, effects that were abolished in mutants with an inactive or overactive stressosome. Overall, the results show that the stressosome is required for acid-induced activation of σB in L. monocytogenes. Furthermore, they show that RsbR1 can function independently of its paralogues and signal transduction requires RsbT-mediated phosphorylation of RsbS on S56 and RsbR1 on T209 but not T175. These insights shed light on the mechanisms of signal transduction that activate the GSR in L. monocytogenes in response to acidic environments, and highlight the role this sensory process in the early stages of the infectious cycle. The stress sensing hub known as the stressosome, found in many bacterial and archaeal lineages, plays a crucial role in both stress tolerance and virulence in the food-borne pathogen Listeria monocytogenes. However, the mechanisms that lead to its activation and the subsequent activation of the general stress response have remained elusive. In this study, we examined the signal transduction mechanisms that operate in the stressosome in response to acid stress. We found that only one of the five putative sensory proteins present in L. monocytogenes, RsbR1, was required for effective transduction of acid tress signals. We further found that phosphorylation of RsbS and RsbR1, mediated by the RsbT kinase, is essential for signal transduction. Failure to phosphorylate RsbS on Serine 56 completely abolished acid sensing by the stressosome, which prevented the development of adaptive acid tolerance. The acid-induced activation of internalin gene expression was also abolished in mutants with defective stressosome signalling, suggesting a role for the stressosome in the invasion of host cells. Together the data provide new insights into the mechanisms that activate the stressosome in response to acid stress and highlight the role this sensory hub plays in virulence.
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Affiliation(s)
- Duarte N. Guerreiro
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
| | - M. Graciela Pucciarelli
- Laboratory of Intracellular Bacterial Pathogens, National Centre for Biotechnology (CNB)-CSIC, Madrid, Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid, Centre of Molecular Biology ‘Severo Ochoa’ (CBMSO CSIC-UAM), Madrid, Spain
| | - Teresa Tiensuu
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre of Microbial Research, Umeå, Sweden
| | - Diana Gudynaite
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
| | - Aoife Boyd
- Pathogenic Mechanisms Research Group, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Jörgen Johansson
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre of Microbial Research, Umeå, Sweden
| | | | - Conor P. O’Byrne
- Bacterial Stress Response Group, Microbiology, School of Biological and Chemical Sciences, National University of Ireland, Galway, Ireland
- * E-mail:
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10
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Listeria monocytogenes requires the RsbX protein to prevent SigB-activation under non-stressed conditions. J Bacteriol 2021; 204:e0048621. [PMID: 34694900 PMCID: PMC8765406 DOI: 10.1128/jb.00486-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The survival of microbial cells under changing environmental conditions requires an efficient reprogramming of transcription, often mediated by alternative sigma factors. The Gram-positive human pathogen Listeria monocytogenes senses and responds to environmental stress mainly through the alternative sigma factor σB (SigB), which controls expression of the general stress response regulon. SigB activation is achieved through a complex series of phosphorylation/dephosphorylation events culminating in the release of SigB from its anti-sigma factor RsbW. At the top of the signal transduction pathway lies a large multiprotein complex known as the stressosome that is believed to act as a sensory hub for stresses. Following signal detection, stressosome proteins become phosphorylated. Resetting of the stressosome is hypothesized to be exerted by a putative phosphatase, RsbX, which presumably removes phosphate groups from stressosome proteins poststress. We addressed the role of the RsbX protein in modulating the activity of the stressosome and consequently regulating SigB activity in L. monocytogenes. We show that RsbX is required to reduce SigB activation levels under nonstress conditions and that it is required for appropriate SigB-mediated stress adaptation. A strain lacking RsbX displayed impaired motility and biofilm formation and also an increased survival at low pH. Our results could suggest that absence of RsbX alters the multiprotein composition of the stressosome without dramatically affecting its phosphorylation status. Overall, the data show that RsbX plays a critical role in modulating the signal transduction pathway by blocking SigB activation under nonstressed conditions. IMPORTANCE Pathogenic bacteria need to sense and respond to stresses to survive harsh environments and also to turn off the response when no longer facing stress. Activity of the stress sigma factor SigB in the human pathogen Listeria monocytogenes is controlled by a hierarchic system having a large stress-sensing multiprotein complex known as the stressosome at the top. Following stress exposure, proteins in the stressosome become phosphorylated, leading to SigB activation. We have studied the role of a putative phosphatase, RsbX, which is hypothesized to dephosphorylate stressosome proteins. RsbX is critical not only to switch off the stress response poststress but also to keep the activity of SigB low at nonstressed conditions to prevent unnecessary gene expression and save energy.
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