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Chapartegui-González I, Stockton JL, Bowser S, Badten AJ, Torres AG. Unraveling the role of toxin-antitoxin systems in Burkholderia pseudomallei: exploring bacterial pathogenesis and interactions within the HigBA families. Microbiol Spectr 2024; 12:e0074824. [PMID: 38916327 PMCID: PMC11302019 DOI: 10.1128/spectrum.00748-24] [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: 03/21/2024] [Accepted: 05/28/2024] [Indexed: 06/26/2024] Open
Abstract
Burkholderia pseudomallei (Bpm) is a Gram-negative intracellular pathogen that causes melioidosis in humans, a neglected, underreported, and lethal disease that can reach a fatal outcome in over 50% of the cases. It can produce both acute and chronic infections, the latter being particularly challenging to eliminate because of the intracellular life cycle of the bacteria and its ability to generate a "persister" dormant state. The molecular mechanism that allows the switch between growing and persister phenotypes is not well understood but it is hypothesized to be due at least in part to the participation of toxin-antitoxin (TA) systems. We have previously studied the link between one of those systems (defined as HigBA) with specific expression patterns associated with levofloxacin antibiotic exposure. Through in silico methods, we predicted the presence of another three pairs of genes encoding for additional putative HigBA systems. Therefore, our main goal was to establish which mechanisms are conserved as well as which pathways are specific among different Bpm TA systems from the same family. We hypothesize that the high prevalence, and sometimes even redundancy of these systems in the Bpm chromosomes indicates that they can interact with each other and not function as only individual systems, as it was traditionally thought, and might be playing an undefined role in Bpm lifecycle. Here, we show that both the toxin and the antitoxin of the different systems contribute to bacterial survival and that toxins from the same family can have a cumulative effect under environmental stressful conditions. IMPORTANCE Toxin-antitoxin (TA) systems play a significant role in bacterial persistence, a phenomenon where bacterial cells enter a dormant or slow-growing state to survive adverse conditions such as nutrient deprivation, antibiotic exposure, or host immune responses. By studying TA systems in Burkholderia pseudomallei, we can gain insights into how this pathogen survives and persists in the host environment, contributing to its virulence and ability to cause melioidosis chronic infections.
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Affiliation(s)
| | - Jacob L. Stockton
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Sarah Bowser
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alexander J. Badten
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Asai M, Li Y, Newton SM, Robertson BD, Langford PR. Galleria mellonella-intracellular bacteria pathogen infection models: the ins and outs. FEMS Microbiol Rev 2023; 47:fuad011. [PMID: 36906279 PMCID: PMC10045907 DOI: 10.1093/femsre/fuad011] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/13/2023] Open
Abstract
Galleria mellonella (greater wax moth) larvae are used widely as surrogate infectious disease models, due to ease of use and the presence of an innate immune system functionally similar to that of vertebrates. Here, we review G. mellonella-human intracellular bacteria pathogen infection models from the genera Burkholderia, Coxiella, Francisella, Listeria, and Mycobacterium. For all genera, G. mellonella use has increased understanding of host-bacterial interactive biology, particularly through studies comparing the virulence of closely related species and/or wild-type versus mutant pairs. In many cases, virulence in G. mellonella mirrors that found in mammalian infection models, although it is unclear whether the pathogenic mechanisms are the same. The use of G. mellonella larvae has speeded up in vivo efficacy and toxicity testing of novel antimicrobials to treat infections caused by intracellular bacteria: an area that will expand since the FDA no longer requires animal testing for licensure. Further use of G. mellonella-intracellular bacteria infection models will be driven by advances in G. mellonella genetics, imaging, metabolomics, proteomics, and transcriptomic methodologies, alongside the development and accessibility of reagents to quantify immune markers, all of which will be underpinned by a fully annotated genome.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Yanwen Li
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Sandra M Newton
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Brian D Robertson
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, South Kensington campus, Imperial College London, London SW7 2AZ, United Kingdom
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
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Evaluating the Contribution of the Predicted Toxin-Antitoxin System HigBA to Persistence, Biofilm Formation, and Virulence in Burkholderia pseudomallei. Infect Immun 2022; 90:e0003522. [PMID: 35695502 PMCID: PMC9302164 DOI: 10.1128/iai.00035-22] [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: 12/15/2022] Open
Abstract
Melioidosis is an underreported human disease caused by the Gram-negative intracellular pathogen Burkholderia pseudomallei (Bpm). Both the treatment and the clearance of the pathogen are challenging, with high relapse rates leading to latent infections. This has been linked to the bacterial persistence phenomenon, a growth arrest strategy that allows bacteria to survive under stressful conditions, as in the case of antibiotic treatment, within a susceptible clonal population. At a molecular level, this phenomenon has been associated with the presence of toxin-antitoxin (TA) systems. We annotated the Bpm K96243 genome and selected 11 pairs of genes encoding for these TA systems, and their expression was evaluated under different conditions (supralethal antibiotic conditions; intracellular survival bacteria). The predicted HigB toxin (BPSL3343) and its predicted antitoxin HigA (BPS_RS18025) were further studied using mutant construction. The phenotypes of two mutants (ΔhigB and ΔhigB ΔhigA) were evaluated under different conditions compared to the wild-type (WT) strain. The ΔhigB toxin mutant showed a defect in intracellular survival on macrophages, a phenotype that was eliminated after levofloxacin treatment. We found that the absence of the toxin provides an advantage over the WT strain, in both in vitro and in vivo models, during persister conditions induced by levofloxacin. The lack of the antitoxin also resulted in differential responses to the conditions evaluated, and under some conditions, it restored the WT phenotype, overall suggesting that both toxin and antitoxin components play a role in the persister-induced phenotype in Bpm.
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Chewapreecha C, Pensar J, Chattagul S, Pesonen M, Sangphukieo A, Boonklang P, Potisap C, Koosakulnirand S, Feil EJ, Dunachie S, Chantratita N, Limmathurotsakul D, Peacock SJ, Day NPJ, Parkhill J, Thomson NR, Sermswan RW, Corander J. Co-evolutionary Signals Identify Burkholderia pseudomallei Survival Strategies in a Hostile Environment. Mol Biol Evol 2022; 39:6400259. [PMID: 34662416 PMCID: PMC8760936 DOI: 10.1093/molbev/msab306] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The soil bacterium Burkholderia pseudomallei is the causative agent of melioidosis and a significant cause of human morbidity and mortality in many tropical and subtropical countries. The species notoriously survives harsh environmental conditions but the genetic architecture for these adaptations remains unclear. Here we employed a powerful combination of genome-wide epistasis and co-selection studies (2,011 genomes), condition-wide transcriptome analyses (82 diverse conditions), and a gene knockout assay to uncover signals of "co-selection"-that is a combination of genetic markers that have been repeatedly selected together through B. pseudomallei evolution. These enabled us to identify 13,061 mutation pairs under co-selection in distinct genes and noncoding RNA. Genes under co-selection displayed marked expression correlation when B. pseudomallei was subjected to physical stress conditions, highlighting the conditions as one of the major evolutionary driving forces for this bacterium. We identified a putative adhesin (BPSL1661) as a hub of co-selection signals, experimentally confirmed a BPSL1661 role under nutrient deprivation, and explored the functional basis of co-selection gene network surrounding BPSL1661 in facilitating the bacterial survival under nutrient depletion. Our findings suggest that nutrient-limited conditions have been the common selection pressure acting on this species, and allelic variation of BPSL1661 may have promoted B. pseudomallei survival during harsh environmental conditions by facilitating bacterial adherence to different surfaces, cells, or living hosts.
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Affiliation(s)
- Claire Chewapreecha
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Parasites and Microbes Programme, Wellcome Sanger Insitute, Hinxton, United Kingdom
- Bioinformatics & Systems Biology Program, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand
- Corresponding authors: E-mails: ; ;
| | - Johan Pensar
- Department of Mathematics, University of Oslo, Oslo, Norway
- Department of Mathematics and Statistics, Helsinki Institute of Information Technology, University of Helsinki, Helsinki, Finland
| | - Supaksorn Chattagul
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Maiju Pesonen
- Oslo Centre for Biostatistics and Epidemiology, Oslo University Hospital, Oslo, Norway
| | - Apiwat Sangphukieo
- Bioinformatics & Systems Biology Program, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand
| | - Phumrapee Boonklang
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chotima Potisap
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
| | - Sirikamon Koosakulnirand
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Edward J Feil
- Department of Biology and Biochemistry, The Milner Centre for Evolution, University of Bath, Bath, United Kingdom
| | - Susanna Dunachie
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Narisara Chantratita
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Direk Limmathurotsakul
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Sharon J Peacock
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Nick P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Julian Parkhill
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Nicholas R Thomson
- Parasites and Microbes Programme, Wellcome Sanger Insitute, Hinxton, United Kingdom
| | - Rasana W Sermswan
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Corresponding authors: E-mails: ; ;
| | - Jukka Corander
- Parasites and Microbes Programme, Wellcome Sanger Insitute, Hinxton, United Kingdom
- Department of Mathematics and Statistics, Helsinki Institute of Information Technology, University of Helsinki, Helsinki, Finland
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Corresponding authors: E-mails: ; ;
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