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Choi B, Park WR, Kim YJ, Mun S, Park SJ, Jeong JH, Choi HS, Kim DK. Nuclear receptor estrogen-related receptor modulates antimicrobial peptide expression for host innate immunity in Tribolium castaneum. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 148:103816. [PMID: 35926689 DOI: 10.1016/j.ibmb.2022.103816] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/15/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Antimicrobial peptides (AMPs) are core components of innate immunity to protect insects against microbial infections. Nuclear receptors (NRs) are ligand-dependent transcription factors that can regulate the expression of genes critical for insect development including molting and metamorphosis. However, the role of NRs in host innate immune response to microbial infection remains poorly understood in Tribolium castaneum (T. castaneum). Here, we show that estrogen-related receptor (ERR), an insect ortholog of the mammalian ERR family of NRs, is a novel transcriptional regulator of AMP genes for innate immune response of T. castaneum. Tribolium ERR (TcERR) expression was induced by immune deficiency (IMD)-Relish signaling in response to infection by Escherichia coli (E. coli), a Gram-negative bacterium, as demonstrated in TcIMD-deficient beetles. Interestingly, genome-wide transcriptome analysis of TcERR-deficient old larvae using RNA-sequencing analysis showed that TcERR expression was positively correlated with gene transcription levels of AMPs including attacins, defensins, and coleoptericin. Moreover, chromatin immunoprecipitation analysis revealed that TcERR could directly bind to ERR-response elements on promoters of genes encoding defensin3 and coleoptericin, critical for innate immune response of T. castaneum. Finally, TcERR-deficient old larvae infected with E. coli displayed enhanced bacterial load and significantly less host survival. These findings suggest that TcERR can coordinate transcriptional regulation of AMPs and host innate immune response to bacterial infection.
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Affiliation(s)
- Byungyoon Choi
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Woo-Ram Park
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Yu-Ji Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Seulgi Mun
- Department of Applied Biology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Su-Jin Park
- Functional Biomaterial Research Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup, 56212, Republic of Korea.
| | - Jae-Ho Jeong
- Department of Microbiology, Chonnam National University Medical School, Gwangju, 61468, Republic of Korea.
| | - Hueng-Sik Choi
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Don-Kyu Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Republic of Korea.
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ScmR, a Global Regulator of Gene Expression, Quorum Sensing, pH Homeostasis, and Virulence in Burkholderia thailandensis. J Bacteriol 2020; 202:JB.00776-19. [PMID: 32312745 DOI: 10.1128/jb.00776-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 04/13/2020] [Indexed: 11/20/2022] Open
Abstract
The nonpathogenic soil saprophyte Burkholderia thailandensis is a member of the Burkholderia pseudomallei /B. thailandensis/B. mallei group, which also comprises the closely related human pathogens B. pseudomallei and Burkholderia mallei responsible for the melioidosis and glanders diseases, respectively. ScmR, a recently identified LysR-type transcriptional regulator in B. thailandensis, acts as a global transcriptional regulator throughout the stationary phase and modulates the production of a wide range of secondary metabolites, including N-acyl-l-homoserine lactones and 4-hydroxy-3-methyl-2-alkylquinolines and virulence in the Caenorhabditis elegans nematode worm host model, as well as several quorum sensing (QS)-dependent phenotypes. We have investigated the role of ScmR in B. thailandensis strain E264 during the exponential phase. We used RNA sequencing transcriptomic analyses to identify the ScmR regulon, which was compared to the QS-controlled regulon, showing a considerable overlap between the ScmR-regulated genes and those controlled by QS. We characterized several genes modulated by ScmR using quantitative reverse transcription-PCR or mini-CTX-lux transcriptional reporters, including the oxalate biosynthetic gene obc1 required for pH homeostasis, the orphan LuxR-type transcriptional regulator BtaR5-encoding gene, and the bsa (Burkholderia secretion apparatus) type III secretion system genes essential for both B. pseudomallei and B. mallei pathogenicity, as well as the scmR gene itself. We confirmed that the transcription of scmR is under QS control, presumably ensuring fine-tuned modulation of gene expression. Finally, we demonstrated that ScmR influences virulence using the fruit fly model host Drosophila melanogaster We conclude that ScmR represents a central component of the B. thailandensis QS regulatory network.IMPORTANCE Coordination of the expression of genes associated with bacterial virulence and environmental adaptation is often dependent on quorum sensing (QS). The QS circuitry of the nonpathogenic bacterium Burkholderia thailandensis, widely used as a model system for the study of the human pathogen Burkholderia pseudomallei, is complex. We found that the LysR-type transcriptional regulator, ScmR, which is highly conserved and involved in the control of virulence/survival factors in the Burkholderia genus, is a global regulator mediating gene expression through the multiple QS systems coexisting in B. thailandensis, as well as QS independently. We conclude that ScmR represents a key QS modulatory network element, ensuring tight regulation of the transcription of QS-controlled genes, particularly those required for acclimatization to the environment.
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Thiaminase I Provides a Growth Advantage by Salvaging Precursors from Environmental Thiamine and Its Analogs in Burkholderia thailandensis. Appl Environ Microbiol 2018. [PMID: 30006396 DOI: 10.1128/aem.01268-18)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thiamine is essential to life, as it serves as a cofactor for enzymes involved in critical carbon transformations. Many bacteria can synthesize thiamine, while thiamine auxotrophs must obtain it or its precursors from the environment. Thiaminases degrade thiamine by catalyzing the base-exchange substitution of thiazole with a nucleophile, and thiaminase I specifically has been implicated in thiamine deficiency syndromes in animals. The biological role of this secreted enzyme has been a long-standing mystery. We used the thiaminase I-producing soil bacterium Burkholderia thailandensis as a model to ascertain its function. First, we generated thiamine auxotrophs, which are still able to use exogenous precursors (thiazole and hydroxymethyl pyrimidine), to synthesize thiamine. We found that thiaminase I extended the survival of these strains, when grown in defined media where thiamine was serially diluted out, compared to isogenic strains that could not produce thiaminase I. Thiamine auxotrophs grew better on thiamine precursors than thiamine itself, suggesting thiaminase I functions to convert thiamine to useful precursors. Furthermore, our findings demonstrate that thiaminase I cleaves phosphorylated thiamine and toxic analogs, which releases precursors that can then be used for thiamine synthesis. This study establishes a biological role for this perplexing enzyme and provides additional insight into the complicated nature of thiamine metabolism and how individual bacteria may manipulate the availability of a vital nutrient in the environment.IMPORTANCE The function of thiaminase I has remained a long-standing, unsolved mystery. The enzyme is only known to be produced by a small subset of microorganisms, although thiaminase I activity has been associated with numerous plants and animals, and is implicated in thiamine deficiencies brought on by consumption of organisms containing this enzyme. Genomic and biochemical analyses have shed light on potential roles for the enzyme. Using the genetically amenable thiaminase I-producing soil bacterium Burkholderia thailandensis, we were able to demonstrate that thiaminase I helps salvage precursors from thiamine derivatives in the environment and degrades thiamine to its precursors, which are preferentially used by B. thailandensis auxotrophs. Our study establishes a biological role for this perplexing enzyme and provides insight into the complicated nature of thiamine metabolism. It also establishes B. thailandensis as a robust model system for studying thiamine metabolism.
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4
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Thiaminase I Provides a Growth Advantage by Salvaging Precursors from Environmental Thiamine and Its Analogs in Burkholderia thailandensis. Appl Environ Microbiol 2018; 84:AEM.01268-18. [PMID: 30006396 DOI: 10.1128/aem.01268-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/03/2018] [Indexed: 12/14/2022] Open
Abstract
Thiamine is essential to life, as it serves as a cofactor for enzymes involved in critical carbon transformations. Many bacteria can synthesize thiamine, while thiamine auxotrophs must obtain it or its precursors from the environment. Thiaminases degrade thiamine by catalyzing the base-exchange substitution of thiazole with a nucleophile, and thiaminase I specifically has been implicated in thiamine deficiency syndromes in animals. The biological role of this secreted enzyme has been a long-standing mystery. We used the thiaminase I-producing soil bacterium Burkholderia thailandensis as a model to ascertain its function. First, we generated thiamine auxotrophs, which are still able to use exogenous precursors (thiazole and hydroxymethyl pyrimidine), to synthesize thiamine. We found that thiaminase I extended the survival of these strains, when grown in defined media where thiamine was serially diluted out, compared to isogenic strains that could not produce thiaminase I. Thiamine auxotrophs grew better on thiamine precursors than thiamine itself, suggesting thiaminase I functions to convert thiamine to useful precursors. Furthermore, our findings demonstrate that thiaminase I cleaves phosphorylated thiamine and toxic analogs, which releases precursors that can then be used for thiamine synthesis. This study establishes a biological role for this perplexing enzyme and provides additional insight into the complicated nature of thiamine metabolism and how individual bacteria may manipulate the availability of a vital nutrient in the environment.IMPORTANCE The function of thiaminase I has remained a long-standing, unsolved mystery. The enzyme is only known to be produced by a small subset of microorganisms, although thiaminase I activity has been associated with numerous plants and animals, and is implicated in thiamine deficiencies brought on by consumption of organisms containing this enzyme. Genomic and biochemical analyses have shed light on potential roles for the enzyme. Using the genetically amenable thiaminase I-producing soil bacterium Burkholderia thailandensis, we were able to demonstrate that thiaminase I helps salvage precursors from thiamine derivatives in the environment and degrades thiamine to its precursors, which are preferentially used by B. thailandensis auxotrophs. Our study establishes a biological role for this perplexing enzyme and provides insight into the complicated nature of thiamine metabolism. It also establishes B. thailandensis as a robust model system for studying thiamine metabolism.
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5
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Kraft CE, Angert ER. Competition for vitamin B1 (thiamin) structures numerous ecological interactions. QUARTERLY REVIEW OF BIOLOGY 2018; 92:151-68. [PMID: 29562121 DOI: 10.1086/692168] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Thiamin (vitamin B1) is a cofactor required for essential biochemical reactions in all living organisms, yet free thiamin is scarce in the environment. The diversity of biochemical pathways involved in the acquisition, degradation, and synthesis of thiamin indicates that organisms have evolved numerous ecological strategies for meeting this nutritional requirement. In this review we synthesize information from multiple disciplines to show how the complex biochemistry of thiamin influences ecological outcomes of interactions between organisms in environments ranging from the open ocean and the Australian outback to the gastrointestinal tract of animals. We highlight population and ecosystem responses to the availability or absence of thiamin. These include widespread mortality of fishes, birds, and mammals, as well as the thiamin-dependent regulation of ocean productivity. Overall, we portray thiamin biochemistry as the foundation for molecularly mediated ecological interactions that influence survival and abundance of a vast array of organisms.
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Chua J, Fisher NA, Falcinelli SD, DeShazer D, Friedlander AM. The Madagascar Hissing Cockroach as an Alternative Non-mammalian Animal Model to Investigate Virulence, Pathogenesis, and Drug Efficacy. J Vis Exp 2017:56491. [PMID: 29286449 PMCID: PMC5755476 DOI: 10.3791/56491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Many aspects of innate immunity are conserved between mammals and insects. An insect, the Madagascar hissing cockroach from the genus Gromphadorhina, can be utilized as an alternative animal model for the study of virulence, host-pathogen interaction, innate immune response, and drug efficacy. Details for the rearing, care and breeding of the hissing cockroach are provided. We also illustrate how it can be infected with bacteria such as the intracellular pathogens Burkholderia mallei, B. pseudomallei, and B. thailandensis. Use of the hissing cockroach is inexpensive and overcomes regulatory issues dealing with the use of mammals in research. In addition, results found using the hissing cockroach model are reproducible and similar to those obtained using mammalian models. Thus, the Madagascar hissing cockroach represents an attractive surrogate host that should be explored when conducting animal studies.
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Affiliation(s)
- Jennifer Chua
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases;
| | | | - Shane D Falcinelli
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases
| | - Arthur M Friedlander
- Headquarters Division, United States Army Medical Research Institute of Infectious Diseases
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pH Alkalinization by Chloroquine Suppresses Pathogenic Burkholderia Type 6 Secretion System 1 and Multinucleated Giant Cells. Infect Immun 2016; 85:IAI.00586-16. [PMID: 27799332 DOI: 10.1128/iai.00586-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/23/2016] [Indexed: 01/14/2023] Open
Abstract
Burkholderia mallei and B. pseudomallei cause glanders and melioidosis, respectively, in humans and animals. A hallmark of pathogenesis is the formation of granulomas containing multinucleated giant cells (MNGCs) and cell death. These processes depend on type 6 secretion system 1 (T6SS-1), which is required for virulence in animals. We examined the cell biology of MNGC formation and cell death. We found that chloroquine diphosphate (CLQ), an antimalarial drug, inhibits Burkholderia growth, phagosomal escape, and subsequent MNGC formation. This depends on CLQ's ability to neutralize the acid pH because other alkalinizing compounds similarly inhibit escape and MNGC formation. CLQ inhibits bacterial virulence protein expression because T6SS-1 and some effectors of type 3 secretion system 3 (T3SS-3), which is also required for virulence, are expressed at acid pH. We show that acid pH upregulates the expression of Hcp1 of T6SS-1 and TssM, a protein coregulated with T6SS-1. Finally, we demonstrate that CLQ treatment of Burkholderia-infected Madagascar hissing cockroaches (HCs) increases their survival. This study highlights the multiple mechanisms by which CLQ inhibits growth and virulence and suggests that CLQ be further tested and considered, in conjunction with antibiotic use, for the treatment of diseases caused by Burkholderia.
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8
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Choe JE, Welch MD. Actin-based motility of bacterial pathogens: mechanistic diversity and its impact on virulence. Pathog Dis 2016; 74:ftw099. [PMID: 27655913 DOI: 10.1093/femspd/ftw099] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A diverse spectrum of intracellular bacterial pathogens that inhabit the cytosol have evolved the ability to polymerize actin on their surface to power intracellular actin-based motility (ABM). These include species of Listeria, Burkholderia and Rickettsia, as well as Shigella and Mycobacteria Here, we provide an overview of the roles of bacterial ABM in survival and virulence. Moreover, we survey the molecular mechanisms of actin polymerization in host cells and describe how bacterial pathogens mimic or harness the full diversity of these mechanisms for ABM. Finally, we present ABM through a new lens by comparing motility mechanisms between related species of Listeria, Burkholderia, and Rickettsia Through these comparisons, we hope to illuminate how exploitation of different actin polymerization mechanisms influences ABM as well as pathogenicity and virulence in humans and other animals.
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Affiliation(s)
- Julie E Choe
- Department of Molecular & Cell Biology, University of California, Berkeley CA 94720 USA
| | - Matthew D Welch
- Department of Molecular & Cell Biology, University of California, Berkeley CA 94720 USA
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9
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Choline Catabolism in Burkholderia thailandensis Is Regulated by Multiple Glutamine Amidotransferase 1-Containing AraC Family Transcriptional Regulators. J Bacteriol 2016; 198:2503-14. [PMID: 27381916 PMCID: PMC4999938 DOI: 10.1128/jb.00372-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 06/30/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Burkholderia thailandensis is a soil-dwelling bacterium that shares many metabolic pathways with the ecologically similar, but evolutionarily distant, Pseudomonas aeruginosa Among the diverse nutrients it can utilize is choline, metabolizable to the osmoprotectant glycine betaine and subsequently catabolized as a source of carbon and nitrogen, similar to P. aeruginosa Orthologs of genes in the choline catabolic pathway in these two bacteria showed distinct differences in gene arrangement as well as an additional orthologous transcriptional regulator in B. thailandensis In this study, we showed that multiple glutamine amidotransferase 1 (GATase 1)-containing AraC family transcription regulators (GATRs) are involved in regulation of the B. thailandensis choline catabolic pathway (gbdR1, gbdR2, and souR). Using genetic analyses and sequencing the transcriptome in the presence and absence of choline, we identified the likely regulons of gbdR1 (BTH_II1869) and gbdR2 (BTH_II0968). We also identified a functional ortholog for P. aeruginosa souR, a GATR that regulates the metabolism of sarcosine to glycine. GbdR1 is absolutely required for expression of the choline catabolic locus, similar to P. aeruginosa GbdR, while GbdR2 is important to increase expression of the catabolic locus. Additionally, the B. thailandensis SouR ortholog (BTH_II0994) is required for catabolism of choline and its metabolites as carbon sources, whereas in P. aeruginosa, SouR function can by bypassed by GbdR. The strategy employed by B. thailandensis represents a distinct regulatory solution to control choline catabolism and thus provides both an evolutionary counterpoint and an experimental system to analyze the acquisition and regulation of this pathway during environmental growth and infection. IMPORTANCE Many proteobacteria that occupy similar environmental niches have horizontally acquired orthologous genes for metabolism of compounds useful in their shared environment. The arrangement and differential regulation of these components can help us understand both the evolution of these systems and the potential roles these pathways have in the biology of each bacterium. Here, we describe the transcriptome response of Burkholderia thailandensis to the eukaryote-enriched molecule choline, identify the regulatory pathway governing choline catabolism, and compare the pathway to that previously described for Pseudomonas aeruginosa These data support a multitiered regulatory network in B. thailandensis, with conserved orthologs in the select agents Burkholderia pseudomallei and Burkholderia mallei, as well as the opportunistic lung pathogens in the Burkholderia cepacia clade.
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López Hernández Y, Yero D, Pinos-Rodríguez JM, Gibert I. Animals devoid of pulmonary system as infection models in the study of lung bacterial pathogens. Front Microbiol 2015; 6:38. [PMID: 25699030 PMCID: PMC4316775 DOI: 10.3389/fmicb.2015.00038] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/12/2015] [Indexed: 01/15/2023] Open
Abstract
Biological disease models can be difficult and costly to develop and use on a routine basis. Particularly, in vivo lung infection models performed to study lung pathologies use to be laborious, demand a great time and commonly are associated with ethical issues. When infections in experimental animals are used, they need to be refined, defined, and validated for their intended purpose. Therefore, alternative and easy to handle models of experimental infections are still needed to test the virulence of bacterial lung pathogens. Because non-mammalian models have less ethical and cost constraints as a subjects for experimentation, in some cases would be appropriated to include these models as valuable tools to explore host-pathogen interactions. Numerous scientific data have been argued to the more extensive use of several kinds of alternative models, such as, the vertebrate zebrafish (Danio rerio), and non-vertebrate insects and nematodes (e.g., Caenorhabditis elegans) in the study of diverse infectious agents that affect humans. Here, we review the use of these vertebrate and non-vertebrate models in the study of bacterial agents, which are considered the principal causes of lung injury. Curiously none of these animals have a respiratory system as in air-breathing vertebrates, where respiration takes place in lungs. Despite this fact, with the present review we sought to provide elements in favor of the use of these alternative animal models of infection to reveal the molecular signatures of host-pathogen interactions.
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Affiliation(s)
- Yamilé López Hernández
- Centro de Biociencias, Universidad Autónoma de San Luis Potosí San Luis de Potosí, Mexico
| | - Daniel Yero
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Juan M Pinos-Rodríguez
- Centro de Biociencias, Universidad Autónoma de San Luis Potosí San Luis de Potosí, Mexico
| | - Isidre Gibert
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
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11
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Fauvarque MO. Small flies to tackle big questions: assaying complex bacterial virulence mechanisms usingDrosophila melanogaster. Cell Microbiol 2014; 16:824-33. [DOI: 10.1111/cmi.12292] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 03/05/2014] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Marie-Odile Fauvarque
- Univ. Grenoble Alpes; iRTSV-BGE; F-38000 Grenoble France
- CEA; iRTSV-BGE; F-38000 Grenoble France
- INSERM; BGE; F-38000 Grenoble France
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12
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Peano C, Chiaramonte F, Motta S, Pietrelli A, Jaillon S, Rossi E, Consolandi C, Champion OL, Michell SL, Freddi L, Falciola L, Basilico F, Garlanda C, Mauri P, De Bellis G, Landini P. Gene and protein expression in response to different growth temperatures and oxygen availability in Burkholderia thailandensis. PLoS One 2014; 9:e93009. [PMID: 24671187 PMCID: PMC3966863 DOI: 10.1371/journal.pone.0093009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/27/2014] [Indexed: 12/25/2022] Open
Abstract
Burkholderia thailandensis, although normally avirulent for mammals, can infect macrophages in vitro and has occasionally been reported to cause pneumonia in humans. It is therefore used as a model organism for the human pathogen B. pseudomallei, to which it is closely related phylogenetically. We characterized the B. thailandensis clinical isolate CDC2721121 (BtCDC272) at the genome level and studied its response to environmental cues associated with human host colonization, namely, temperature and oxygen limitation. Effects of the different growth conditions on BtCDC272 were studied through whole genome transcription studies and analysis of proteins associated with the bacterial cell surface. We found that growth at 37°C, compared to 28°C, negatively affected cell motility and flagella production through a mechanism involving regulation of the flagellin-encoding fliC gene at the mRNA stability level. Growth in oxygen-limiting conditions, in contrast, stimulated various processes linked to virulence, such as lipopolysaccharide production and expression of genes encoding protein secretion systems. Consistent with these observations, BtCDC272 grown in oxygen limitation was more resistant to phagocytosis and strongly induced the production of inflammatory cytokines from murine macrophages. Our results suggest that, while temperature sensing is important for regulation of B. thailandensis cell motility, oxygen limitation has a deeper impact on its physiology and constitutes a crucial environmental signal for the production of virulence factors.
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Affiliation(s)
- Clelia Peano
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | | | - Sara Motta
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Alessandro Pietrelli
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Sebastien Jaillon
- Humanitas Clinical and Research Center Institute, Rozzano, Milan, Italy
| | - Elio Rossi
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Clarissa Consolandi
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Olivia L. Champion
- College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Stephen L. Michell
- College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Luca Freddi
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - Luigi Falciola
- Department of Chemistry, Università degli Studi di Milano, Milan, Italy
| | - Fabrizio Basilico
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Cecilia Garlanda
- Humanitas Clinical and Research Center Institute, Rozzano, Milan, Italy
| | - Pierluigi Mauri
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Gianluca De Bellis
- Institute of Biomedical Technologies, National Research Council, Segrate, Milan, Italy
| | - Paolo Landini
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
- * E-mail:
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13
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Global analysis of the Burkholderia thailandensis quorum sensing-controlled regulon. J Bacteriol 2014; 196:1412-24. [PMID: 24464461 DOI: 10.1128/jb.01405-13] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Burkholderia thailandensis contains three acyl-homoserine lactone quorum sensing circuits and has two additional LuxR homologs. To identify B. thailandensis quorum sensing-controlled genes, we carried out transcriptome sequencing (RNA-seq) analyses of quorum sensing mutants and their parent. The analyses were grounded in the fact that we identified genes coding for factors shown previously to be regulated by quorum sensing among a larger set of quorum-controlled genes. We also found that genes coding for contact-dependent inhibition were induced by quorum sensing and confirmed that specific quorum sensing mutants had a contact-dependent inhibition defect. Additional quorum-controlled genes included those for the production of numerous secondary metabolites, an uncharacterized exopolysaccharide, and a predicted chitin-binding protein. This study provides insights into the roles of the three quorum sensing circuits in the saprophytic lifestyle of B. thailandensis, and it provides a foundation on which to build an understanding of the roles of quorum sensing in the biology of B. thailandensis and the closely related pathogenic Burkholderia pseudomallei and Burkholderia mallei.
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14
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Panayidou S, Ioannidou E, Apidianakis Y. Human pathogenic bacteria, fungi, and viruses in Drosophila: disease modeling, lessons, and shortcomings. Virulence 2014; 5:253-69. [PMID: 24398387 DOI: 10.4161/viru.27524] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Drosophila has been the invertebrate model organism of choice for the study of innate immune responses during the past few decades. Many Drosophila-microbe interaction studies have helped to define innate immunity pathways, and significant effort has been made lately to decipher mechanisms of microbial pathogenesis. Here we catalog 68 bacterial, fungal, and viral species studied in flies, 43 of which are relevant to human health. We discuss studies of human pathogens in flies revealing not only the elicitation and avoidance of immune response but also mechanisms of tolerance, host tissue homeostasis, regeneration, and predisposition to cancer. Prominent among those is the emerging pattern of intestinal regeneration as a defense response induced by pathogenic and innocuous bacteria. Immunopathology mechanisms and many microbial virulence factors have been elucidated, but their relevance to human health conventionally necessitates validation in mammalian models of infection.
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Affiliation(s)
- Stavria Panayidou
- Department of Biological Sciences; University of Cyprus; Nicosia, Cyprus
| | - Eleni Ioannidou
- Department of Biological Sciences; University of Cyprus; Nicosia, Cyprus
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Abstract
We constructed a near-saturation transposon mutant library for Burkholderia thailandensis, a low-virulence surrogate for the causative agent of melioidosis (Burkholderia pseudomallei). A primary set of nearly 42,000 unique mutants (~7.5 mutants/gene) was generated using transposon Tn5 derivatives. The strains carry insertions in 87% of the predicted protein-coding genes of the organism, corresponding to nearly all of those nonessential for growth on nutrient agar. To achieve high genome coverage, we developed procedures for efficient sequence identification of insertions in extremely GC-rich regions of DNA. To facilitate strain distribution, we created a secondary library with two mutants per gene for which most transposon locations had been confirmed by resequencing. A map of mutations in the two-allele library and procedures for obtaining strains can be found at http://tools.nwrce.org/tn_mutants/ and http://www.gs.washington.edu/labs/manoil/. The library should facilitate comprehensive mutant screens and serve as a source of strains to test predicted genotype-phenotype associations. The Gram-negative bacterium Burkholderia pseudomallei is a biothreat agent due to its potential for aerosol delivery and intrinsic antibiotic resistance and because exposure produces pernicious infections. Large-scale studies of B. pseudomallei are limited by the fact that the organism must be manipulated under biological safety level 3 conditions. A close relative of B. pseudomallei called Burkholderia thailandensis, which can be studied under less restrictive conditions, has been validated as a low-virulence surrogate in studies of virulence, antibiotic resistance and other traits. To facilitate large-scale studies of B. thailandensis, we created a near-saturation, sequence-defined transposon mutant library of the organism. The library facilitates genetic studies that identify genotype-phenotype associations conserved in B. pseudomallei.
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