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Sanchez-Villamil JI, Tapia D, Khakhum N, Widen SG, Torres AG. Dual RNA-seq reveals a type 6 secretion system-dependent blockage of TNF-α signaling and BicA as a Burkholderia pseudomallei virulence factor important during gastrointestinal infection. Gut Microbes 2022; 14:2111950. [PMID: 35984745 PMCID: PMC9397134 DOI: 10.1080/19490976.2022.2111950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/03/2022] [Indexed: 02/04/2023] Open
Abstract
Melioidosis is a disease caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm), commonly found in soil and water of endemic areas. Naturally acquired human melioidosis infections can result from either exposure through percutaneous inoculation, inhalation, or ingestion of soil-contaminated food or water. Our prior studies recognized Bpm as an effective enteric pathogen, capable of establishing acute or chronic gastrointestinal infections following oral inoculation. However, the specific mechanisms and virulence factors involved in the pathogenesis of Bpm during intestinal infection are unknown. In our current study, we standardized an in vitro intestinal infection model using primary intestinal epithelial cells (IECs) and demonstrated that Bpm requires a functional T6SS for full virulence. Further, we performed dual RNA-seq analysis on Bpm-infected IECs to evaluate differentially expressed host and bacterial genes in the presence or absence of a T6SS. Our results showed a dysregulation in the TNF-α signaling via NF-κB pathway in the absence of the T6SS, with some of the genes involved in inflammatory processes and cell death also affected. Analysis of the bacterial transcriptome identified virulence factors and regulatory proteins playing a role during infection, with association to the T6SS. By using a Bpm transposon mutant library and isogenic mutants, we showed that deletion of the bicA gene, encoding a putative T3SS/T6SS regulator, ablated intracellular survival and plaque formation by Bpm and impacted survival and virulence when using murine models of acute and chronic gastrointestinal infection. Overall, these results highlight the importance of the type 6 secretion system in the gastrointestinal pathogenesis of Bpm.
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Affiliation(s)
| | - Daniel Tapia
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nittaya Khakhum
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Steven G. Widen
- Department of Biochemistry and Molecular Biology, 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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Tan KY, Dutta A, Tan TK, Hari R, Othman RY, Choo SW. Comprehensive genome analysis of a pangolin-associated Paraburkholderia fungorum provides new insights into its secretion systems and virulence. PeerJ 2020; 8:e9733. [PMID: 32953261 PMCID: PMC7474880 DOI: 10.7717/peerj.9733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/25/2020] [Indexed: 12/26/2022] Open
Abstract
Background Paraburkholderia fungorum (P. fungorum) is a Gram-negative environmental species that has been commonly used as a beneficial microorganism in agriculture as an agent for biocontrol and bioremediation. Its use in agriculture is controversial as many people believe that it could harm human health; however, there is no clear evidence to support. Methodology The pangolin P. fungorum (pangolin Pf) genome has a genomic size of approximately 7.7 Mbps with N50 of 69,666 bps. Our study showed that pangolin Pf is a Paraburkholderia fungorum supported by evidence from the core genome SNP-based phylogenetic analysis and the ANI analysis. Functional analysis has shown that the presence of a considerably large number of genes related to stress response, virulence, disease, and defence. Interestingly, we identified different types of secretion systems in the genome of pangolin Pf, which are highly specialized and responsible for a bacterium’s response to its environment and in physiological processes such as survival, adhesion, and adaptation. The pangolin Pf also shared some common virulence genes with the known pathogenic member of the Burkholderiales. These genes play important roles in adhesion, motility, and invasion. Conclusion This study may provide better insights into the functions, secretion systems and virulence of this pangolin-associated bacterial strain. The addition of this genome sequence is also important for future comparative analysis and functional work of P. fungorum.
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Affiliation(s)
- Ka Yun Tan
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Avirup Dutta
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: The Novo Nordisk Foundation Center for Basic Metabolic Research, Human Genomics and Metagenomics in Metabolism, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tze King Tan
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Ranjeev Hari
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Rofina Y Othman
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Centre for Research in Biotechnology for Agriculture (CEBAR), Level 3, Research Management & Innovation Complex, Universiti Malaya, Copenhagen, Kuala Lumpur, Malaysia
| | - Siew Woh Choo
- College of Science and Technology, Wenzhou-Kean University, Wenzhou, Zhejiang Province, China
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Duangurai T, Indrawattana N, Pumirat P. Burkholderia pseudomallei Adaptation for Survival in Stressful Conditions. BIOMED RESEARCH INTERNATIONAL 2018; 2018:3039106. [PMID: 29992136 PMCID: PMC5994319 DOI: 10.1155/2018/3039106] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/09/2018] [Accepted: 04/05/2018] [Indexed: 12/19/2022]
Abstract
Burkholderia pseudomallei is a Gram-negative bacterium that causes melioidosis, which can be fatal in humans. Melioidosis is prevalent in the tropical regions of Southeast Asia and Northern Australia. Ecological data have shown that this bacterium can survive as a free-living organism in environmental niches, such as soil and water, as well as a parasite living in host organisms, such as ameba, plants, fungi, and animals. This review provides an overview of the survival and adaptation of B. pseudomallei to stressful conditions induced by hostile environmental factors, such as salinity, oxidation, and iron levels. The adaptation of B. pseudomallei in host cells is also reviewed. The adaptive survival mechanisms of this pathogen mainly involve modulation of gene and protein expression, which could cause alterations in the bacteria's cell membrane, metabolism, and virulence. Understanding the adaptations of this organism to environmental factors provides important insights into the survival and pathogenesis of B. pseudomallei, which may lead to the development of novel strategies for the control, prevention, and treatment of melioidosis in the future.
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Affiliation(s)
- Taksaon Duangurai
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand
| | - Nitaya Indrawattana
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Pornpan Pumirat
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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Abstract
Burkholderia pseudomallei is a Gram-negative environmental bacterium and the aetiological agent of melioidosis, a life-threatening infection that is estimated to account for ∼89,000 deaths per year worldwide. Diabetes mellitus is a major risk factor for melioidosis, and the global diabetes pandemic could increase the number of fatalities caused by melioidosis. Melioidosis is endemic across tropical areas, especially in southeast Asia and northern Australia. Disease manifestations can range from acute septicaemia to chronic infection, as the facultative intracellular lifestyle and virulence factors of B. pseudomallei promote survival and persistence of the pathogen within a broad range of cells, and the bacteria can manipulate the host's immune responses and signalling pathways to escape surveillance. The majority of patients present with sepsis, but specific clinical presentations and their severity vary depending on the route of bacterial entry (skin penetration, inhalation or ingestion), host immune function and bacterial strain and load. Diagnosis is based on clinical and epidemiological features as well as bacterial culture. Treatment requires long-term intravenous and oral antibiotic courses. Delays in treatment due to difficulties in clinical recognition and laboratory diagnosis often lead to poor outcomes and mortality can exceed 40% in some regions. Research into B. pseudomallei is increasing, owing to the biothreat potential of this pathogen and increasing awareness of the disease and its burden; however, better diagnostic tests are needed to improve early confirmation of diagnosis, which would enable better therapeutic efficacy and survival.
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Affiliation(s)
- W Joost Wiersinga
- Department of Medicine, Division of Infectious Diseases, Academic Medical Center, Meibergdreef 9, Rm. G2-132, 1105 AZ Amsterdam, The Netherlands
- Centre for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Harjeet S Virk
- Centre for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Alfredo G Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Bart J Currie
- Menzies School of Health Research, Charles Darwin University and Royal Darwin Hospital, Darwin, Australia
| | - Sharon J Peacock
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - David A B Dance
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Direk Limmathurotsakul
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
- Department of Tropical Hygiene and Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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Vander Broek CW, Stevens JM. Type III Secretion in the Melioidosis Pathogen Burkholderia pseudomallei. Front Cell Infect Microbiol 2017; 7:255. [PMID: 28664152 PMCID: PMC5471309 DOI: 10.3389/fcimb.2017.00255] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/31/2017] [Indexed: 02/03/2023] Open
Abstract
Burkholderia pseudomallei is a Gram-negative intracellular pathogen and the causative agent of melioidosis, a severe disease of both humans and animals. Melioidosis is an emerging disease which is predicted to be vastly under-reported. Type III Secretion Systems (T3SSs) are critical virulence factors in Gram negative pathogens of plants and animals. The genome of B. pseudomallei encodes three T3SSs. T3SS-1 and -2, of which little is known, are homologous to Hrp2 secretion systems of the plant pathogens Ralstonia and Xanthomonas. T3SS-3 is better characterized and is homologous to the Inv/Mxi-Spa secretion systems of Salmonella spp. and Shigella flexneri, respectively. Upon entry into the host cell, B. pseudomallei requires T3SS-3 for efficient escape from the endosome. T3SS-3 is also required for full virulence in both hamster and murine models of infection. The regulatory cascade which controls T3SS-3 expression and the secretome of T3SS-3 have been described, as well as the effect of mutations of some of the structural proteins. Yet only a few effector proteins have been functionally characterized to date and very little work has been carried out to understand the hierarchy of assembly, secretion and temporal regulation of T3SS-3. This review aims to frame current knowledge of B. pseudomallei T3SSs in the context of other well characterized model T3SSs, particularly those of Salmonella and Shigella.
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Affiliation(s)
- Charles W Vander Broek
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of EdinburghMidlothian, United Kingdom
| | - Joanne M Stevens
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of EdinburghMidlothian, United Kingdom
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Immune Recognition of the Epidemic Cystic Fibrosis Pathogen Burkholderia dolosa. Infect Immun 2017; 85:IAI.00765-16. [PMID: 28348057 DOI: 10.1128/iai.00765-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 03/20/2017] [Indexed: 12/31/2022] Open
Abstract
Burkholderia dolosa caused an outbreak in the cystic fibrosis (CF) clinic at Boston Children's Hospital from 1998 to 2005 and led to the infection of over 40 patients, many of whom died due to complications from infection by this organism. To assess whether B. dolosa significantly contributes to disease or is recognized by the host immune response, mice were infected with a sequenced outbreak B. dolosa strain, AU0158, and responses were compared to those to the well-studied CF pathogen Pseudomonas aeruginosa In parallel, mice were also infected with a polar flagellin mutant of B. dolosa to examine the role of flagella in B. dolosa lung colonization. The results showed a higher persistence in the host by B. dolosa strains, and yet, neutrophil recruitment and cytokine production were lower than those with P. aeruginosa The ability of host immune cells to recognize B. dolosa was then assessed, B. dolosa induced a robust cytokine response in cultured cells, and this effect was dependent on the flagella only when bacteria were dead. Together, these results suggest that B. dolosa can be recognized by host cells in vitro but may avoid or suppress the host immune response in vivo through unknown mechanisms. B. dolosa was then compared to other Burkholderia species and found to induce similar levels of cytokine production despite being internalized by macrophages more than Burkholderia cenocepacia strains. These data suggest that B. dolosa AU0158 may act differently with host cells and is recognized differently by immune systems than are other Burkholderia strains or species.
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Abstract
Human mitochondria produce ATP and metabolites to support development and maintain cellular homeostasis. Mitochondria harbor multiple copies of a maternally inherited, non-nuclear genome (mtDNA) that encodes for 13 subunit proteins of the respiratory chain. Mutations in mtDNA occur mainly in the 24 non-coding genes, with specific mutations implicated in early death, neuromuscular and neurodegenerative diseases, cancer, and diabetes. A significant barrier to new insights in mitochondrial biology and clinical applications for mtDNA disorders is our general inability to manipulate the mtDNA sequence. Microinjection, cytoplasmic fusion, nucleic acid import strategies, targeted endonucleases, and newer approaches, which include the transfer of genomic DNA, somatic cell reprogramming, and a photothermal nanoblade, attempt to change the mtDNA sequence in target cells with varying efficiencies and limitations. Here, we discuss the current state of manipulating mammalian mtDNA and provide an outlook for mitochondrial reverse genetics, which could further enable mitochondrial research and therapies for mtDNA diseases.
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Affiliation(s)
- Alexander N Patananan
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | | | - Pei-Yu Chiou
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Michael A Teitell
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Willcocks SJ, Denman CC, Atkins HS, Wren BW. Intracellular replication of the well-armed pathogen Burkholderia pseudomallei. Curr Opin Microbiol 2016; 29:94-103. [DOI: 10.1016/j.mib.2015.11.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/27/2015] [Accepted: 11/30/2015] [Indexed: 12/31/2022]
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Wong J, Chen Y, Gan YH. Host Cytosolic Glutathione Sensing by a Membrane Histidine Kinase Activates the Type VI Secretion System in an Intracellular Bacterium. Cell Host Microbe 2015; 18:38-48. [PMID: 26094804 DOI: 10.1016/j.chom.2015.06.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/26/2015] [Accepted: 06/02/2015] [Indexed: 12/17/2022]
Abstract
Type VI secretion systems (T6SSs) are major virulence mechanisms in many Gram-negative bacteria, but the physiological signals that activate them are not well understood. The T6SS1 of Burkholderia pseudomallei is essential for pathogenesis in mammalian hosts and is only expressed when the bacterium is intracellular. We found that signals for T6SS1 activation reside in the host cytosol. Through site-directed mutagenesis and biochemical studies, we identified low molecular weight thiols, particularly glutathione, as the signal sensed by a periplasmic cysteine residue (C62) on the histidine kinase sensor VirA. Upon glutathione exposure, dimeric VirA is converted to monomers via reduction at C62. When glutathione in the host was depleted, T6SS1 expression was abrogated, and bacteria could no longer induce multinucleate giant cell formation, the hallmark of T6SS1 function. Therefore, intracellular bacteria exploit the abundance of glutathione in host cytosol as a signal for expression of virulence at the appropriate time and place.
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Affiliation(s)
- Jocelyn Wong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore
| | - Yahua Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore. MD7, 8 Medical Drive, Singapore 117597, Singapore.
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Chen Y, Schröder I, French CT, Jaroszewicz A, Yee XJ, Teh BE, Toesca IJ, Miller JF, Gan YH. Characterization and analysis of the Burkholderia pseudomallei BsaN virulence regulon. BMC Microbiol 2014; 14:206. [PMID: 25085508 PMCID: PMC4236580 DOI: 10.1186/s12866-014-0206-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/18/2014] [Indexed: 01/06/2023] Open
Abstract
Background Burkholderia pseudomallei is a facultative intracellular pathogen and the causative agent of melioidosis. A conserved type III secretion system (T3SS3) and type VI secretion system (T6SS1) are critical for intracellular survival and growth. The T3SS3 and T6SS1 genes are coordinately and hierarchically regulated by a TetR-type regulator, BspR. A central transcriptional regulator of the BspR regulatory cascade, BsaN, activates a subset of T3SS3 and T6SS1 loci. Results To elucidate the scope of the BsaN regulon, we used RNAseq analysis to compare the transcriptomes of wild-type B. pseudomallei KHW and a bsaN deletion mutant. The 60 genes positively-regulated by BsaN include those that we had previously identified in addition to a polyketide biosynthesis locus and genes involved in amino acid biosynthesis. BsaN was also found to repress the transcription of 51 genes including flagellar motility loci and those encoding components of the T3SS3 apparatus. Using a promoter-lacZ fusion assay in E. coli, we show that BsaN together with the chaperone BicA directly control the expression of the T3SS3 translocon, effector and associated regulatory genes that are organized into at least five operons (BPSS1516-BPSS1552). Using a mutagenesis approach, a consensus regulatory motif in the promoter regions of BsaN-regulated genes was shown to be essential for transcriptional activation. Conclusions BsaN/BicA functions as a central regulator of key virulence clusters in B. pseudomallei within a more extensive network of genetic regulation. We propose that BsaN/BicA controls a gene expression program that facilitates the adaption and intracellular survival of the pathogen within eukaryotic hosts.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
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