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Ferreira MR, Queiroga V, Moreira LM. Genomic editing in Burkholderia multivorans by CRISPR/Cas9. Appl Environ Microbiol 2024; 90:e0225023. [PMID: 38299816 PMCID: PMC10880607 DOI: 10.1128/aem.02250-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/02/2024] [Indexed: 02/02/2024] Open
Abstract
Burkholderia cepacia complex bacteria have emerged as opportunistic pathogens in patients with cystic fibrosis and immunocompromised individuals, causing life-threatening infections. Because of the relevance of these microorganisms, genetic manipulation is crucial for explaining the genetic mechanisms leading to pathogenesis. Despite the availability of allelic exchange tools to obtain unmarked gene deletions in Burkholderia, these require a step of merodiploid formation and another of merodiploid resolution through two independent homologous recombination events, making the procedure long-lasting. The CRISPR/Cas9-based system could ease this constraint, as only one step is needed for allelic exchange. Here, we report the modification of a two-plasmid system (pCasPA and pACRISPR) for genome editing in Burkholderia multivorans. Several modifications were implemented, including selection marker replacement, the optimization of araB promoter induction for the expression of Cas9 and λ-Red system encoding genes, and the establishment of plasmid curing procedures based on the sacB gene or growth at a sub-optimal temperature of 18°C-20°C with serial passages. We have shown the efficiency of this CRISPR/Cas9 method in the precise and unmarked deletion of different genes (rpfR, bceF, cepR, and bcsB) from two strains of B. multivorans, as well as its usefulness in the targeted insertion of the gfp gene encoding the green fluorescence protein into a precise genome location. As pCasPA was successfully introduced in other Burkholderia cepacia complex species, this study opens up the possibility of using CRISPR/Cas9-based systems as efficient tools for genome editing in these species, allowing faster and more cost-effective genetic manipulation.IMPORTANCEBurkholderia encompasses different species of bacteria, some of them pathogenic to animals and plants, but others are beneficial by promoting plant growth through symbiosis or as biocontrol agents. Among these species, Burkholderia multivorans, a member of the Burkholderia cepacia complex, is one of the predominant species infecting the lungs of cystic fibrosis patients, often causing respiratory chronic infections that are very difficult to eradicate. Since the B. multivorans species is understudied, we have developed a genetic tool based on the CRISPR/Cas9 system to delete genes efficiently from the genomes of these strains. We could also insert foreign genes that can be precisely placed in a chosen genomic region. This method, faster than other conventional strategies based on allelic exchange, will have a major contribution to understanding the virulence mechanisms in B. multivorans, but it can likely be extended to other Burkholderia species.
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Affiliation(s)
- Mirela R. Ferreira
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Vasco Queiroga
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Leonilde M. Moreira
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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Butt AT, Banyard CD, Haldipurkar SS, Agnoli K, Mohsin M, Vitovski S, Paleja A, Tang Y, Lomax R, Ye F, Green J, Thomas M. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3709-3726. [PMID: 35234897 PMCID: PMC9023288 DOI: 10.1093/nar/gkac137] [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: 08/05/2021] [Revised: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 11/14/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that causes severe infections of the cystic fibrosis (CF) lung. To acquire iron, B. cenocepacia secretes the Fe(III)-binding compound, ornibactin. Genes for synthesis and utilisation of ornibactin are served by the iron starvation (IS) extracytoplasmic function (ECF) σ factor, OrbS. Transcription of orbS is regulated in response to the prevailing iron concentration by the ferric uptake regulator (Fur), such that orbS expression is repressed under iron-sufficient conditions. Here we show that, in addition to Fur-mediated regulation of orbS, the OrbS protein itself responds to intracellular iron availability. Substitution of cysteine residues in the C-terminal region of OrbS diminished the ability to respond to Fe(II) in vivo. Accordingly, whilst Fe(II) impaired transcription from and recognition of OrbS-dependent promoters in vitro by inhibiting the binding of OrbS to core RNA polymerase (RNAP), the cysteine-substituted OrbS variant was less responsive to Fe(II). Thus, the cysteine residues within the C-terminal region of OrbS contribute to an iron-sensing motif that serves as an on-board ‘anti-σ factor’ in the presence of Fe(II). A model to account for the presence two regulators (Fur and OrbS) that respond to the same intracellular Fe(II) signal to control ornibactin synthesis and utilisation is discussed.
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Affiliation(s)
- Aaron T Butt
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Christopher D Banyard
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Sayali S Haldipurkar
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Kirsty Agnoli
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Muslim I Mohsin
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Srdjan Vitovski
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Ameya Paleja
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Yingzhi Tang
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Rebecca Lomax
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield S10 2RX, UK
| | - Fuzhou Ye
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK
| | - Jeffrey Green
- Correspondence may also be addressed to Jeffrey Green. Tel: +44 114 222 4403; Fax: +44 114 222 2800;
| | - Mark S Thomas
- To whom correspondence should be addressed. Tel: +44 114 215 9557; Fax: +44 114 271 1863;
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Foxfire A, Buhrow AR, Orugunty RS, Smith L. Drug discovery through the isolation of natural products from Burkholderia. Expert Opin Drug Discov 2021; 16:807-822. [PMID: 33467922 PMCID: PMC9844120 DOI: 10.1080/17460441.2021.1877655] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Introduction: The increasing threat of antibiotic-resistant pathogens makes it imperative that new antibiotics to combat them are discovered. Burkholderia is a genus of Gram-negative, non-sporulating bacteria. While ubiquitous and capable of growing within plants and groundwater, they are primarily soil-dwelling organisms. These include the more virulent forms of Burkholderia such as Burkholderia mallei, Burkholderia pseudomallei, and the Burkholderia cepacia complex (Bcc).Areas covered: This review provides a synopsis of current research on the natural products isolated from the genus Burkholderia. The authors also cover the research on the drug discovery efforts that have been performed on the natural products derived from Burkholderia.Expert opinion: Though Burkholderia has a small number of pathogenic species, the majority of the genus is avirulent and almost all members of the genus are capable of producing useful antimicrobial products that could potentially lead to the development of novel therapeutics against infectious diseases. The need for discovery of new antibiotics is urgent due to the ever-increasing prevalence of antibiotic-resistant pathogens, coupled with the decline in the discovery of new antibiotics.
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Affiliation(s)
- Adam Foxfire
- Department of Biology, Texas A&M University, College Station, TX 77843
| | - Andrew Riley Buhrow
- Department of Biology, Texas A&M University, College Station, TX 77843,Antimicrobial Division, Sano Chemicals Inc., Bryan, TX 77803
| | | | - Leif Smith
- Department of Biology, Texas A&M University, College Station, TX 77843,Antimicrobial Division, Sano Chemicals Inc., Bryan, TX 77803,Address correspondence to Leif Smith,
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Hassan AA, Dos Santos SC, Cooper VS, Sá-Correia I. Comparative Evolutionary Patterns of Burkholderia cenocepacia and B. multivorans During Chronic Co-infection of a Cystic Fibrosis Patient Lung. Front Microbiol 2020; 11:574626. [PMID: 33101250 PMCID: PMC7545829 DOI: 10.3389/fmicb.2020.574626] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 08/31/2020] [Indexed: 12/26/2022] Open
Abstract
During chronic respiratory infections of cystic fibrosis (CF) patients, bacteria adaptively evolve in response to the nutritional and immune environment as well as influence other infecting microbes. The present study was designed to gain insights into the genetic mechanisms underlying adaptation and diversification by the two most prevalent pathogenic species of the Burkholderia cepacia complex (Bcc), B. cenocepacia and B. multivorans. Herein, we study the evolution of both of these species during coinfection of a CF patient for 4.4 years using genome sequences of 9 B. multivorans and 11 B. cenocepacia. This co-infection spanned at least 3 years following initial infection by B. multivorans and ultimately ended in the patient's death by cepacia syndrome. Both species acquired several mutations with accumulation rates of 2.08 (B. cenocepacia) and 2.27 (B. multivorans) SNPs/year. Many of the mutated genes are associated with oxidative stress response, transition metal metabolism, defense mechanisms against antibiotics, and other metabolic alterations consistent with the idea that positive selection might be driven by the action of the host immune system, antibiotic therapy and low oxygen and iron concentrations. Two orthologous genes shared by B. cenocepacia and B. multivorans were found to be under strong selection and accumulated mutations associated with lineage diversification. One gene encodes a nucleotide sugar dehydratase involved in lipopolysaccharide O-antigen (OAg) biosynthesis (wbiI). The other gene encodes a putative two-component regulatory sensor kinase protein required to sense and adapt to oxidative- and heavy metal- inducing stresses. This study contributes to understanding of shared and species-specific evolutionary patterns of B. cenocepacia and B. multivorans evolving in the same CF lung environment.
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Affiliation(s)
- A Amir Hassan
- iBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra C Dos Santos
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Vaughn S Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Isabel Sá-Correia
- iBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.,Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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Mügge C, Heine T, Baraibar AG, van Berkel WJH, Paul CE, Tischler D. Flavin-dependent N-hydroxylating enzymes: distribution and application. Appl Microbiol Biotechnol 2020; 104:6481-6499. [PMID: 32504128 PMCID: PMC7347517 DOI: 10.1007/s00253-020-10705-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/18/2020] [Accepted: 05/24/2020] [Indexed: 02/06/2023]
Abstract
Amino groups derived from naturally abundant amino acids or (di)amines can be used as "shuttles" in nature for oxygen transfer to provide intermediates or products comprising N-O functional groups such as N-hydroxy, oxazine, isoxazolidine, nitro, nitrone, oxime, C-, S-, or N-nitroso, and azoxy units. To this end, molecular oxygen is activated by flavin, heme, or metal cofactor-containing enzymes and transferred to initially obtain N-hydroxy compounds, which can be further functionalized. In this review, we focus on flavin-dependent N-hydroxylating enzymes, which play a major role in the production of secondary metabolites, such as siderophores or antimicrobial agents. Flavoprotein monooxygenases of higher organisms (among others, in humans) can interact with nitrogen-bearing secondary metabolites or are relevant with respect to detoxification metabolism and are thus of importance to understand potential medical applications. Many enzymes that catalyze N-hydroxylation reactions have specific substrate scopes and others are rather relaxed. The subsequent conversion towards various N-O or N-N comprising molecules is also described. Overall, flavin-dependent N-hydroxylating enzymes can accept amines, diamines, amino acids, amino sugars, and amino aromatic compounds and thus provide access to versatile families of compounds containing the N-O motif. Natural roles as well as synthetic applications are highlighted. Key points • N-O and N-N comprising natural and (semi)synthetic products are highlighted. • Flavin-based NMOs with respect to mechanism, structure, and phylogeny are reviewed. • Applications in natural product formation and synthetic approaches are provided. Graphical abstract .
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Affiliation(s)
- Carolin Mügge
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Thomas Heine
- Environmental Microbiology, Faculty of Chemistry and Physics, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Alvaro Gomez Baraibar
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
- Rottendorf Pharma GmbH, Ostenfelder Str. 51-61, 59320, Ennigerloh, Germany
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - Caroline E Paul
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, HZ 2629, Delft, The Netherlands
| | - Dirk Tischler
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
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McAvoy AC, Jaiyesimi O, Threatt PH, Seladi T, Goldberg JB, da Silva RR, Garg N. Differences in Cystic Fibrosis-Associated Burkholderia spp. Bacteria Metabolomes after Exposure to the Antibiotic Trimethoprim. ACS Infect Dis 2020; 6:1154-1168. [PMID: 32212725 DOI: 10.1021/acsinfecdis.9b00513] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Burkholderia cepacia complex is a group of closely related bacterial species with large genomes that infect immunocompromised individuals and those living with cystic fibrosis. Some of these species are found more frequently and cause more severe disease than others, yet metabolomic differences between these have not been described. Furthermore, our understanding of how these species respond to antibiotics is limited. We investigated the metabolomics differences between three most prevalent Burkholderia spp. associated with cystic fibrosis: B. cenocepacia, B. multivorans, and B. dolosa in the presence and absence of the antibiotic trimethoprim. Using a combination of supervised and unsupervised metabolomics data visualization and analysis tools, we describe the overall differences between strains of the same species and between species. Specifically, we report, for the first time, the role of the pyomelanin pathway in the metabolism of trimethoprim. We also report differences in the detection of known secondary metabolites such as fragin, ornibactin, and N-acylhomoserine lactones and their analogs in closely related strains. Furthermore, we highlight the potential for the discovery of new secondary metabolites in clinical strains of Burkholderia spp. The metabolomics differences described in this study highlight the personalized nature of closely related Burkholderia strains.
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Affiliation(s)
- Andrew C. McAvoy
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332-2000, United States
| | - Olakunle Jaiyesimi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332-2000, United States
| | - Paxton H. Threatt
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332-2000, United States
| | - Tyler Seladi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332-2000, United States
| | - Joanna B. Goldberg
- Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Emory University School of Medicine, 1510 Clifton Road NE, Suite 3009, Atlanta, Georgia 30322, United States
- Emory-Children’s Cystic Fibrosis Center, Atlanta, Georgia 30322, United States
| | - Ricardo R. da Silva
- School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Av. do Café - Vila Monte Alegre, Ribeirão Preto, São Paulo 14040-903, Brazil
| | - Neha Garg
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332-2000, United States
- Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Emory University School of Medicine, 1510 Clifton Road NE, Suite 3009, Atlanta, Georgia 30322, United States
- Center for Microbial Dynamics and Infection, School of Biological Sciences, Georgia Institute of Technology, 311 Ferst Drive, ES&T, Atlanta, Georgia 30332, United States
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 311 Ferst Drive, ES&T, Atlanta, Georgia 30322, United States
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Yang X, Chen X, Song Z, Zhang X, Zhang J, Mei S. Antifungal, plant growth-promoting, and mycotoxin detoxication activities of Burkholderia sp. strain XHY-12. 3 Biotech 2020; 10:158. [PMID: 32181120 PMCID: PMC7056774 DOI: 10.1007/s13205-020-2112-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 02/02/2020] [Indexed: 01/16/2023] Open
Abstract
A bacterial strain named XHY-12 was isolated from corn soil samples and identified as Burkholderia sp. based on 16S rDNA sequencing, it displayed high antagonistic activity against 12 fungal pathogens and the common fungal contaminant in grain Aspergillus flavus. Plate experiment showed that XHY-12 fermentation broth reduced the incidence of S. sclerotiorum on detached rape leaves (Brassica campestris L.) by 100%, and a greenhouse experiment showed that it could promote the growth of rape seedlings with significant increases in plant height, root length, and fresh weight. Furthermore, a novel funding was the reduction of aflatoxin B1 and B2 by over 85% in 60 h, and the decomposition enzymes should be extracellular. The results suggest that XHY-12 has a potential for commercial applications as biocontrol, mycotoxin detoxification agent or biofertilizer.
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Affiliation(s)
- Xiai Yang
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
| | - Xiaojun Chen
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
| | - Zhiqiang Song
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
| | - Xiaowei Zhang
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
| | - Jifang Zhang
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
| | - Shiyong Mei
- Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, 348# of West Road of Xianjia Lake, Changsha City, Hunan Province China
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Ferro P, Vaz-Moreira I, Manaia CM. Betaproteobacteria are predominant in drinking water: are there reasons for concern? Crit Rev Microbiol 2019; 45:649-667. [PMID: 31686572 DOI: 10.1080/1040841x.2019.1680602] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Betaproteobacteria include some of the most abundant and ubiquitous bacterial genera that can be found in drinking water, including mineral water. The combination of physiology and ecology traits place some Betaproteobacteria in the list of potential, yet sometimes neglected, opportunistic pathogens that can be transmitted by water or aqueous solutions. Indeed, some drinking water Betaproteobacteria with intrinsic and sometimes acquired antibiotic resistance, harbouring virulence factors and often found in biofilm structures, can persist after water disinfection and reach the consumer. This literature review summarises and discusses the current knowledge about the occurrence and implications of Betaproteobacteria in drinking water. Although the sparse knowledge on the ecology and physiology of Betaproteobacteria thriving in tap or bottled natural mineral/spring drinking water (DW) is an evidence of this review, it is demonstrated that DW holds a high diversity of Betaproteobacteria, whose presence may not be innocuous. Frequently belonging to genera also found in humans, DW Betaproteobacteria are ubiquitous in different habitats, have the potential to resist antibiotics either due to intrinsic or acquired mechanisms, and hold different virulence factors. The combination of these factors places DW Betaproteobacteria in the list of candidates of emerging opportunistic pathogens. Improved bacterial identification of clinical isolates associated with opportunistic infections and additional genomic and physiological studies may contribute to elucidate the potential impact of these bacteria.
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Affiliation(s)
- Pompeyo Ferro
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
| | - Ivone Vaz-Moreira
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
| | - Célia M Manaia
- Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal
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Sathe S, Mathew A, Agnoli K, Eberl L, Kümmerli R. Genetic architecture constrains exploitation of siderophore cooperation in the bacterium Burkholderia cenocepacia. Evol Lett 2019; 3:610-622. [PMID: 31844554 PMCID: PMC6906993 DOI: 10.1002/evl3.144] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Explaining how cooperation can persist in the presence of cheaters, exploiting the cooperative acts, is a challenge for evolutionary biology. Microbial systems have proved extremely useful to test evolutionary theory and identify mechanisms maintaining cooperation. One of the most widely studied system is the secretion and sharing of iron‐scavenging siderophores by Pseudomonas bacteria, with many insights gained from this system now being considered as hallmarks of bacterial cooperation. Here, we introduce siderophore secretion by the bacterium Burkholderia cenocepacia H111 as a novel parallel study system, and show that this system behaves differently. For ornibactin, the main siderophore of this species, we discovered a novel mechanism of how cheating can be prevented. Particularly, we found that secreted ornibactin cannot be exploited by ornibactin‐defective mutants because ornibactin receptor and synthesis genes are co‐expressed from the same operon, such that disruptive mutations in synthesis genes compromise receptor availability required for siderophore uptake and cheating. For pyochelin, the secondary siderophore of this species, we found that cheating was possible, but the relative success of cheaters was positive frequency dependent, thus diametrically opposite to the Pseudomonas and other microbial systems. Altogether, our results highlight that expanding our repertoire of microbial study systems leads to new discoveries and suggest that there is an enormous diversity of social interactions out there in nature, and we might have only looked at the tip of the iceberg so far.
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Affiliation(s)
- Santosh Sathe
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland.,Department of Quantitative Biomedicine, University of Zürich, Zürich, Switzerland
| | - Anugraha Mathew
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Kirsty Agnoli
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland.,Department of Quantitative Biomedicine, University of Zürich, Zürich, Switzerland
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Thapa SS, Grove A. Do Global Regulators Hold the Key to Production of Bacterial Secondary Metabolites? Antibiotics (Basel) 2019; 8:antibiotics8040160. [PMID: 31547528 PMCID: PMC6963729 DOI: 10.3390/antibiotics8040160] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 12/18/2022] Open
Abstract
The emergence of multiple antibiotic resistant bacteria has pushed the available pool of antibiotics to the brink. Bacterial secondary metabolites have long been a valuable resource in the development of antibiotics, and the genus Burkholderia has recently emerged as a source of novel compounds with antibacterial, antifungal, and anti-cancer activities. Genome mining has contributed to the identification of biosynthetic gene clusters, which encode enzymes that are responsible for synthesis of such secondary metabolites. Unfortunately, these large gene clusters generally remain silent or cryptic under normal laboratory settings, which creates a hurdle in identification and isolation of these compounds. Various strategies, such as changes in growth conditions and antibiotic stress, have been applied to elicit the expression of these cryptic gene clusters. Although a number of compounds have been isolated from different Burkholderia species, the mechanisms by which the corresponding gene clusters are regulated remain poorly understood. This review summarizes the activity of well characterized secondary metabolites from Burkholderia species and the role of local regulators in their synthesis, and it highlights recent evidence for the role of global regulators in controlling production of secondary metabolites. We suggest that targeting global regulators holds great promise for the awakening of cryptic gene clusters and for developing better strategies for discovery of novel antibiotics.
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Affiliation(s)
- Sudarshan Singh Thapa
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Anne Grove
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
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A screen of Crohn's disease-associated microbial metabolites identifies ascorbate as a novel metabolic inhibitor of activated human T cells. Mucosal Immunol 2019; 12:457-467. [PMID: 29695840 PMCID: PMC6202286 DOI: 10.1038/s41385-018-0022-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 01/17/2018] [Accepted: 02/27/2018] [Indexed: 02/06/2023]
Abstract
Microbial metabolites are an emerging class of mediators influencing CD4+ T-cell function. To advance the understanding of direct causal microbial factors contributing to Crohn's disease, we screened 139 predicted Crohn's disease-associated microbial metabolites for their bioactivity on human CD4+ T-cell functions induced by disease-associated T helper 17 (Th17) polarizing conditions. We observed 15 metabolites with CD4+ T-cell bioactivity, 3 previously reported, and 12 unprecedented. A deeper investigation of the microbe-derived metabolite, ascorbate, revealed its selective inhibition on activated human CD4+ effector T cells, including IL-17A-, IL-4-, and IFNγ-producing cells. Mechanistic assessment suggested the apoptosis of activated human CD4+ T cells associated with selective inhibition of energy metabolism. These findings suggest a substantial rate of relevant T-cell bioactivity among Crohn's disease-associated microbial metabolites, and evidence for novel modes of bioactivity, including targeting of T-cell energy metabolism.
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Esmaeel Q, Pupin M, Jacques P, Leclère V. Nonribosomal peptides and polyketides of Burkholderia: new compounds potentially implicated in biocontrol and pharmaceuticals. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:29794-29807. [PMID: 28547376 DOI: 10.1007/s11356-017-9166-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Bacteria belonging to the genus Burkholderia live in various ecological niches and present a significant role in the environments through the excretion of a wide variety of secondary metabolites including modular nonribosomal peptides (NRPs) and polyketides (PKs). These metabolites represent a widely distributed biomedically and biocontrol important class of natural products including antibiotics, siderophores, and anticancers as well as biopesticides that are considered as a novel source that can be used to defend ecological niche from competitors and to promote plant growth. The aim of this review is to present all NRPs produced or potentially produced by strains of Burkholderia, as NRPs represent a major source of active compounds implicated in biocontrol. The review is a compilation of results from a large screening we have performed on 48 complete sequenced genomes available in NCBI to identify NRPS gene clusters, and data found in the literature mainly because some interesting compounds are produced by strains not yet sequenced. In addition to NRPs, hybrids NRPs/PKs are also included. Specific features about biosynthetic gene clusters and structures of the modular enzymes responsible for the synthesis, the biological activities, and the potential uses in agriculture and pharmaceutical of NRPs and hybrids NRPs/PKs will also be discussed.
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Affiliation(s)
- Qassim Esmaeel
- University Lille, INRA, ISA, University Artois, University Littoral Côte d'Opale, EA 7394-ICV- Institut Charles Viollette, F-59000, Lille, France
- Laboratoire de Stress, Défenses et Reproduction des Plantes URVVC-EA 4707, UFR Sciences Exactes et Naturelles, University of Reims-Champagne-Ardenne, Reims, France
| | - Maude Pupin
- University Lille, CNRS, Centrale Lille, UMR 9189- CRIStAL- Centre de Recherche en Informatique Signal et Automatique de Lille, F-59000, Lille, France
- Inria-Lille Nord Europe, Bonsai team, F-59655, Villeneuve d'Ascq Cedex, France
| | - Philippe Jacques
- University Lille, INRA, ISA, University Artois, University Littoral Côte d'Opale, EA 7394-ICV- Institut Charles Viollette, F-59000, Lille, France
- TERRA Research Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech University of Liege, B-5030, Gembloux, Belgium
| | - Valérie Leclère
- University Lille, INRA, ISA, University Artois, University Littoral Côte d'Opale, EA 7394-ICV- Institut Charles Viollette, F-59000, Lille, France.
- University Lille, CNRS, Centrale Lille, UMR 9189- CRIStAL- Centre de Recherche en Informatique Signal et Automatique de Lille, F-59000, Lille, France.
- Inria-Lille Nord Europe, Bonsai team, F-59655, Villeneuve d'Ascq Cedex, France.
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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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14
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Roux D, Schaefers M, Clark BS, Weatherholt M, Renaud D, Scott D, LiPuma JJ, Priebe G, Gerard C, Yoder-Himes DR. A putative lateral flagella of the cystic fibrosis pathogen Burkholderia dolosa regulates swimming motility and host cytokine production. PLoS One 2018; 13:e0189810. [PMID: 29346379 PMCID: PMC5773237 DOI: 10.1371/journal.pone.0189810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 12/01/2017] [Indexed: 01/25/2023] Open
Abstract
Burkholderia dolosa caused an outbreak in the cystic fibrosis clinic at Boston Children's Hospital and was associated with high mortality in these patients. This species is part of a larger complex of opportunistic pathogens known as the Burkholderia cepacia complex (Bcc). Compared to other species in the Bcc, B. dolosa is highly transmissible; thus understanding its virulence mechanisms is important for preventing future outbreaks. The genome of one of the outbreak strains, AU0158, revealed a homolog of the lafA gene encoding a putative lateral flagellin, which, in other non-Bcc species, is used for movement on solid surfaces, attachment to host cells, or movement inside host cells. Here, we analyzed the conservation of the lafA gene and protein sequences, which are distinct from those of the polar flagella, and found lafA homologs to be present in numerous β-proteobacteria but notably absent from most other Bcc species. A lafA deletion mutant in B. dolosa showed a greater swimming motility than wild-type due to an increase in the number of polar flagella, but did not appear to contribute to biofilm formation, host cell invasion, or murine lung colonization or persistence over time. However, the lafA gene was important for cytokine production in human peripheral blood mononuclear cells, suggesting it may have a role in recognition by the human immune response.
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Affiliation(s)
- Damien Roux
- INSERM, IAME, UMR 1137, Paris, France
- Univ Paris Diderot, Sorbonne Paris Cité, Paris, France
- AP-HP, Louis Mourier Hospital, Intensive Care Unit, Colombes, France
| | - Matthew Schaefers
- Division of Critical Care Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- Department of Anesthesia, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Bradley S. Clark
- Department of Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Molly Weatherholt
- Department of Biology, University of Louisville, Louisville, Kentucky, United States of America
| | - Diane Renaud
- Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, Kentucky, United States of America
| | - David Scott
- Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, Kentucky, United States of America
| | - John J. LiPuma
- Division of Pediatrics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gregory Priebe
- Division of Critical Care Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- Department of Anesthesia, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Craig Gerard
- Division of Respiratory Diseases, Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Deborah R. Yoder-Himes
- Department of Biology, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail:
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15
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Butt AT, Thomas MS. Iron Acquisition Mechanisms and Their Role in the Virulence of Burkholderia Species. Front Cell Infect Microbiol 2017; 7:460. [PMID: 29164069 PMCID: PMC5681537 DOI: 10.3389/fcimb.2017.00460] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/18/2017] [Indexed: 11/19/2022] Open
Abstract
Burkholderia is a genus within the β-Proteobacteriaceae that contains at least 90 validly named species which can be found in a diverse range of environments. A number of pathogenic species occur within the genus. These include Burkholderia cenocepacia and Burkholderia multivorans, opportunistic pathogens that can infect the lungs of patients with cystic fibrosis, and are members of the Burkholderia cepacia complex (Bcc). Burkholderia pseudomallei is also an opportunistic pathogen, but in contrast to Bcc species it causes the tropical human disease melioidosis, while its close relative Burkholderia mallei is the causative agent of glanders in horses. For these pathogens to survive within a host and cause disease they must be able to acquire iron. This chemical element is essential for nearly all living organisms due to its important role in many enzymes and metabolic processes. In the mammalian host, the amount of accessible free iron is negligible due to the low solubility of the metal ion in its higher oxidation state and the tight binding of this element by host proteins such as ferritin and lactoferrin. As with other pathogenic bacteria, Burkholderia species have evolved an array of iron acquisition mechanisms with which to capture iron from the host environment. These mechanisms include the production and utilization of siderophores and the possession of a haem uptake system. Here, we summarize the known mechanisms of iron acquisition in pathogenic Burkholderia species and discuss the evidence for their importance in the context of virulence and the establishment of infection in the host. We have also carried out an extensive bioinformatic analysis to identify which siderophores are produced by each Burkholderia species that is pathogenic to humans.
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Affiliation(s)
- Aaron T Butt
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
| | - Mark S Thomas
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
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Regulator LdhR and d-Lactate Dehydrogenase LdhA of Burkholderia multivorans Play Roles in Carbon Overflow and in Planktonic Cellular Aggregate Formation. Appl Environ Microbiol 2017; 83:AEM.01343-17. [PMID: 28733286 DOI: 10.1128/aem.01343-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 07/17/2017] [Indexed: 11/20/2022] Open
Abstract
LysR-type transcriptional regulators (LTTRs) are the most commonly found regulators in Burkholderia cepacia complex, comprising opportunistic pathogens causing chronic respiratory infections in cystic fibrosis (CF) patients. Despite LTTRs being global regulators of pathogenicity in several types of bacteria, few have been characterized in Burkholderia Here, we show that gene ldhR of B. multivorans encoding an LTTR is cotranscribed with ldhA encoding a d-lactate dehydrogenase and evaluate their implication in virulence traits such as exopolysaccharide (EPS) synthesis and biofilm formation. A comparison of the wild type (WT) and its isogenic ΔldhR mutant grown in medium with 2% d-glucose revealed a negative impact on EPS biosynthesis and on cell viability in the presence of LdhR. The loss of viability in WT cells was caused by intracellular acidification as a consequence of the cumulative secretion of organic acids, including d-lactate, which was absent from the ΔldhR mutant supernatant. Furthermore, LdhR is implicated in the formation of planktonic cellular aggregates. WT cell aggregates reached 1,000 μm in size after 24 h in liquid cultures, in contrast to ΔldhR mutant aggregates that never grew more than 60 μm. The overexpression of d-lactate dehydrogenase LdhA in the ΔldhR mutant partially restored the formed aggregate size, suggesting a role for fermentation inside aggregates. Similar results were obtained for surface-attached biofilms, with WT cells producing more biofilm. A systematic evaluation of planktonic aggregates in Burkholderia CF clinical isolates showed aggregates in 40 of 74. As CF patients' lung environments are microaerophilic and bacteria are found as free aggregates/biofilms, LdhR and LdhA might have central roles in adapting to this environment.IMPORTANCE Cystic fibrosis patients often suffer from chronic respiratory infections caused by several types of microorganisms. Among them are the Burkholderia cepacia complex bacteria, which cause progressive deterioration of lung function that, in some patients, might develop into fatal necrotizing pneumoniae with bacteremia, known as "cepacia syndrome." Burkholderia pathogenesis is multifactorial as they express several virulence factors, form biofilms, and are highly resistant to antimicrobial compounds, making their eradication from the CF patients' airways very difficult. As Burkholderia is commonly found in CF lungs in the form of cell aggregates and biofilms, the need to investigate the mechanisms of cellular aggregation is obvious. In this study, we demonstrate the importance of a d-lactate dehydrogenase and a regulator in regulating carbon overflow, cellular aggregates, and surface-attached biofilm formation. This not only enhances our understanding of Burkholderia pathogenesis but can also lead to the development of drugs against these proteins to circumvent biofilm formation.
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17
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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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18
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A Broad-Host-Range Tailocin from Burkholderia cenocepacia. Appl Environ Microbiol 2017; 83:AEM.03414-16. [PMID: 28258146 PMCID: PMC5411513 DOI: 10.1128/aem.03414-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/07/2017] [Indexed: 02/07/2023] Open
Abstract
The Burkholderia cepacia complex (Bcc) consists of 20 closely related Gram-negative bacterial species that are significant pathogens for persons with cystic fibrosis (CF). Some Bcc strains are highly transmissible and resistant to multiple antibiotics, making infection difficult to treat. A tailocin (phage tail-like bacteriocin), designated BceTMilo, with a broad host range against members of the Bcc, was identified in B. cenocepacia strain BC0425. Sixty-eight percent of Bcc representing 10 species and 90% of non-Bcc Burkholderia strains tested were sensitive to BceTMilo. BceTMilo also showed killing activity against Pseudomonas aeruginosa PAO1 and derivatives. Liquid chromatography-mass spectrometry analysis of the major BceTMilo proteins was used to identify a 23-kb tailocin locus in a draft BC0425 genome. The BceTMilo locus was syntenic and highly similar to a 24.6-kb region on chromosome 1 of B. cenocepacia J2315 (BCAL0081 to BCAL0107). A close relationship and synteny were observed between BceTMilo and Burkholderia phage KL3 and, by extension, with paradigm temperate myophage P2. Deletion mutants in the gene cluster encoding enzymes for biosynthesis of lipopolysaccharide (LPS) in the indicator strain B. cenocepacia K56-2 conferred resistance to BceTMilo. Analysis of the defined mutants in LPS biosynthetic genes indicated that an α-d-glucose residue in the core oligosaccharide is the receptor for BceTMilo.IMPORTANCE BceTMilo, presented in this study, is a broad-host-range tailocin active against Burkholderia spp. As such, BceTMilo and related or modified tailocins have potential as bactericidal therapeutic agents against plant- and human-pathogenic Burkholderia.
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Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
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Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
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20
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The Siderophore Product Ornibactin Is Required for the Bactericidal Activity of Burkholderia contaminans MS14. Appl Environ Microbiol 2017; 83:AEM.00051-17. [PMID: 28188204 DOI: 10.1128/aem.00051-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 02/06/2017] [Indexed: 11/20/2022] Open
Abstract
Burkholderia contaminans MS14 was isolated from soil in Mississippi. When it is cultivated on nutrient broth-yeast extract agar, the colonies exhibit bactericidal activity against a wide range of plant-pathogenic bacteria. A bacteriostatic compound with siderophore activity was successfully purified and was determined by nuclear magnetic resonance spectroscopy to be ornibactin. Isolation of the bactericidal compound has not yet been achieved; therefore, the exact nature of the bactericidal compound is still unknown. During an attempt to isolate the bactericidal compound, an interesting relationship between the production of ornibactin and the bactericidal activity of MS14 was characterized. Transposon mutagenesis resulted in two strains that lost bactericidal activity, with insertional mutations in a nonribosomal peptide synthetase (NRPS) gene for ornibactin biosynthesis and a luxR family transcriptional regulatory gene. Coculture of these two mutant strains resulted in restoration of the bactericidal activity. Furthermore, the addition of ornibactin to the NRPS mutant restored the bactericidal phenotype. It has been demonstrated that, in MS14, ornibactin has an alternative function, aside from iron sequestration. Comparison of the ornibactin biosynthesis genes in Burkholderia species shows diversity among the regulatory elements, while the gene products for ornibactin synthesis are conserved. This is an interesting observation, given that ornibactin is thought to have the same defined function within Burkholderia species. Ornibactin is produced by most Burkholderia species, and its role in regulating the production of secondary metabolites should be investigated.IMPORTANCE Identification of the antibacterial product from strain MS14 is not the key feature of this study. We present a series of experiments that demonstrate that ornibactin is directly involved in the bactericidal phenotype of MS14. This observation provides evidence for an alternative function for ornibactin, aside from iron sequestration. Ornibactin should be further evaluated for its role in regulating the biosynthesis of secondary metabolites in other Burkholderia species.
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21
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Identification and characterization of a FAD-dependent putrescine N-hydroxylase (GorA) from Gordonia rubripertincta CWB2. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Discovery of new diketopiperazines inhibiting Burkholderia cenocepacia quorum sensing in vitro and in vivo. Sci Rep 2016; 6:32487. [PMID: 27580679 PMCID: PMC5007513 DOI: 10.1038/srep32487] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/08/2016] [Indexed: 02/08/2023] Open
Abstract
Burkholderia cenocepacia, an opportunistic respiratory pathogen particularly relevant for cystic fibrosis patients, is difficult to eradicate due to its high level of resistance to most clinically relevant antimicrobials. Consequently, the discovery of new antimicrobials as well as molecules capable of inhibiting its virulence is mandatory. In this regard quorum sensing (QS) represents a good target for anti-virulence therapies, as it has been linked to biofilm formation and is important for the production of several virulence factors, including proteases and siderophores. Here, we report the discovery of new diketopiperazine inhibitors of the B. cenocepacia acyl homoserine lactone synthase CepI, and report their anti-virulence properties. Out of ten different compounds assayed against recombinant CepI, four were effective inhibitors, with IC50 values in the micromolar range. The best compounds interfered with protease and siderophore production, as well as with biofilm formation, and showed good in vivo activity in a Caenorhabditis elegans infection model. These molecules were also tested in human cells and showed very low toxicity. Therefore, they could be considered for in vivo combined treatments with established or novel antimicrobials, to improve the current therapeutic strategies against B. cenocepacia.
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23
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Nunvar J, Kalferstova L, Bloodworth RAM, Kolar M, Degrossi J, Lubovich S, Cardona ST, Drevinek P. Understanding the Pathogenicity of Burkholderia contaminans, an Emerging Pathogen in Cystic Fibrosis. PLoS One 2016; 11:e0160975. [PMID: 27512997 PMCID: PMC4981469 DOI: 10.1371/journal.pone.0160975] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 07/27/2016] [Indexed: 12/22/2022] Open
Abstract
Several bacterial species from the Burkholderia cepacia complex (Bcc) are feared opportunistic pathogens that lead to debilitating lung infections with a high risk of developing fatal septicemia in cystic fibrosis (CF) patients. However, the pathogenic potential of other Bcc species is yet unknown. To elucidate clinical relevance of Burkholderia contaminans, a species frequently isolated from CF respiratory samples in Ibero-American countries, we aimed to identify its key virulence factors possibly linked with an unfavorable clinical outcome. We performed a genome-wide comparative analysis of two isolates of B. contaminans ST872 from sputum and blood culture of a female CF patient in Argentina. RNA-seq data showed significant changes in expression for quorum sensing-regulated virulence factors and motility and chemotaxis. Furthermore, we detected expression changes in a recently described low-oxygen-activated (lxa) locus which encodes stress-related proteins, and for two clusters responsible for the biosynthesis of antifungal and hemolytic compounds pyrrolnitrin and occidiofungin. Based on phenotypic assays that confirmed changes in motility and in proteolytic, hemolytic and antifungal activities, we were able to distinguish two phenotypes of B. contaminans that coexisted in the host and entered her bloodstream. Whole genome sequencing revealed that the sputum and bloodstream isolates (each representing a distinct phenotype) differed by over 1,400 mutations as a result of a mismatch repair-deficient hypermutable state of the sputum isolate. The inferred lack of purifying selection against nonsynonymous mutations and the high rate of pseudogenization in the derived isolate indicated limited evolutionary pressure during evolution in the nutrient-rich, stable CF sputum environment. The present study is the first to examine the genomic and transcriptomic differences between longitudinal isolates of B. contaminans. Detected activity of a number of putative virulence factors implies a genuine pathogenic nature of this novel Bcc species.
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Affiliation(s)
- Jaroslav Nunvar
- Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
| | - Lucie Kalferstova
- Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
| | - Ruhi A. M. Bloodworth
- Department of Medical Microbiology & Infectious Disease, University of Manitoba, Winnipeg, Canada
| | - Michal Kolar
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jose Degrossi
- School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
| | - Silvina Lubovich
- Centro Respiratorio Dr. A. Alvarez, Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Silvia T. Cardona
- Department of Medical Microbiology & Infectious Disease, University of Manitoba, Winnipeg, Canada
| | - Pavel Drevinek
- Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
- * E-mail:
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Abstract
In the 1990s several biocontrol agents on that contained Burkholderia strains were registered by the United States Environmental Protection Agency (EPA). After risk assessment these products were withdrawn from the market and a moratorium was placed on the registration of Burkholderia-containing products, as these strains may pose a risk to human health. However, over the past few years the number of novel Burkholderia species that exhibit plant-beneficial properties and are normally not isolated from infected patients has increased tremendously. In this commentary we wish to summarize recent efforts that aim at discerning pathogenic from beneficial Burkholderia strains.
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Affiliation(s)
- Leo Eberl
- Department of Plant and Microbial Biology, University Zürich, Zurich, CH-8008, Switzerland
| | - Peter Vandamme
- Laboratory of Microbiology, Ghent University, Ledeganckstraat 35, B-9000 Gent, Belgium
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25
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Genetic and Functional Analysis of the Biosynthesis of a Non-Ribosomal Peptide Siderophore in Burkholderia xenovorans LB400. PLoS One 2016; 11:e0151273. [PMID: 26963250 PMCID: PMC4786211 DOI: 10.1371/journal.pone.0151273] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 02/25/2016] [Indexed: 11/26/2022] Open
Abstract
B. xenovorans LB400 is a model bacterium for the study of the metabolism of aromatic compounds. The aim of this study was the genomic and functional characterization of a non-ribosomal peptide synthetase containing gene cluster that encodes a siderophore in B. xenovorans LB400. The mba gene cluster from strain LB400 encodes proteins involved in the biosynthesis and transport of a hydroxamate-type siderophore. Strain LB400 has a unique mba gene organization, although mba gene clusters have been observed in diverse Burkholderiales. Bioinformatic analysis revealed the presence of promoters in the mba gene cluster that strongly suggest regulation by the ferric uptake regulator protein (Fur) and by the alternative RNA polymerase extracytoplasmic function sigma factor MbaF. Reverse transcriptase PCR analyses showed the expression of iron-regulated transcriptional units mbaFGHIJKL, mbaN, mbaABCE, mbaO, mbaP and mbaD genes under iron limitation. Chrome azurol S (CAS) assay strongly suggests that strain LB400 synthesized a siderophore under iron limitation. Mass spectrometry ESI-MS and MALDI-TOF-MS analyses revealed that the siderophore is a non-ribosomal peptide, and forms an iron complex with a molecular mass of 676 Da. Based on bioinformatic prediction, CAS assay and MS analyses, we propose that the siderophore is L-Nδ-hydroxy-Nδ-formylOrn-D-β-hydroxyAsp-L-Ser-L-Nδ-hydroxy-Nδ-formylOrn-1,4-diaminobutane that is closely related to malleobactin-type siderophores reported in B. thailandensis.
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Zhao S, Wei H, Lin CY, Zeng Y, Tucker MP, Himmel ME, Ding SY. Burkholderia phytofirmans Inoculation-Induced Changes on the Shoot Cell Anatomy and Iron Accumulation Reveal Novel Components of Arabidopsis-Endophyte Interaction that Can Benefit Downstream Biomass Deconstruction. FRONTIERS IN PLANT SCIENCE 2016; 7:24. [PMID: 26858740 PMCID: PMC4731519 DOI: 10.3389/fpls.2016.00024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 01/08/2016] [Indexed: 06/05/2023]
Abstract
It is known that plant growth promoting bacteria (PGPB) elicit positive effects on plant growth and biomass yield. However, the actual mechanism behind the plant-PGPB interaction is poorly understood, and the literature is scarce regarding the thermochemical pretreatability and enzymatic degradability of biomass derived from PGPB-inoculated plants. Most recent transcriptional analyses of PGPB strain Burkholderia phytofirmans PsJN inoculating potato in literature and Arabidopsis in our present study have revealed the expression of genes for ferritin and the biosynthesis and transport of siderophores (i.e., the molecules with high affinity for iron), respectively. The expression of such genes in the shoots of PsJN-inoculated plants prompted us to propose that PsJN-inoculation can improve the host plant's iron uptake and accumulation, which facilitates the downstream plant biomass pretreatment and conversion to simple sugars. In this study, we employed B. phytofirmans PsJN to inoculate the Arabidopsis thaliana plants, and conducted the first investigation for its effects on the biomass yield, the anatomical organization of stems, the iron accumulation, and the pretreatment and enzymatic hydrolysis of harvested biomass. The results showed that the strain PsJN stimulated plant growth in the earlier period of plant development and enlarged the cell size of stem piths, and it also indeed enhanced the essential metals uptake and accumulation in host plants. Moreover, we found that the PsJN-inoculated plant biomass released more glucose and xylose after hot water pretreatment and subsequent co-saccharification, which provided a novel insight into development of lignocellulosic biofuels from renewable biomass resources.
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Affiliation(s)
- Shuai Zhao
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Hui Wei
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Chien-Yuan Lin
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Yining Zeng
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Melvin P Tucker
- National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Michael E Himmel
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Shi-You Ding
- Bioscience Center, National Renewable Energy Laboratory Golden, CO, USA
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Tyrrell J, Callaghan M. Iron acquisition in the cystic fibrosis lung and potential for novel therapeutic strategies. MICROBIOLOGY-SGM 2015; 162:191-205. [PMID: 26643057 DOI: 10.1099/mic.0.000220] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Iron acquisition is vital to microbial survival and is implicated in the virulence of many of the pathogens that reside in the cystic fibrosis (CF) lung. The multifaceted nature of iron acquisition by both bacterial and fungal pathogens encompasses a range of conserved and species-specific mechanisms, including secretion of iron-binding siderophores, utilization of siderophores from other species, release of iron from host iron-binding proteins and haemoproteins, and ferrous iron uptake. Pathogens adapt and deploy specific systems depending on iron availability, bioavailability of the iron pool, stage of infection and presence of competing pathogens. Understanding the dynamics of pathogen iron acquisition has the potential to unveil new avenues for therapeutic intervention to treat both acute and chronic CF infections. Here, we examine the range of strategies utilized by the primary CF pathogens to acquire iron and discuss the different approaches to targeting iron acquisition systems as an antimicrobial strategy.
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Affiliation(s)
- Jean Tyrrell
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin D24KT9, Ireland
| | - Máire Callaghan
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin D24KT9, Ireland
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Tyrrell J, Whelan N, Wright C, Sá-Correia I, McClean S, Thomas M, Callaghan M. Investigation of the multifaceted iron acquisition strategies of Burkholderia cenocepacia. Biometals 2015; 28:367-80. [DOI: 10.1007/s10534-015-9840-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/18/2015] [Indexed: 10/23/2022]
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Badieyan S, Bach RD, Sobrado P. Mechanism of N-Hydroxylation Catalyzed by Flavin-Dependent Monooxygenases. J Org Chem 2015; 80:2139-47. [DOI: 10.1021/jo502651v] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Somayesadat Badieyan
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Robert D. Bach
- Departments
of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Pablo Sobrado
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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Pribytkova T, Lightly TJ, Kumar B, Bernier SP, Sorensen JL, Surette MG, Cardona ST. The attenuated virulence of aBurkholderia cenocepacia paaABCDEmutant is due to inhibition of quorum sensing by release of phenylacetic acid. Mol Microbiol 2014; 94:522-36. [DOI: 10.1111/mmi.12771] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Tanya Pribytkova
- Department of Microbiology; University of Manitoba; Winnipeg Manitoba Canada
| | - Tasia Joy Lightly
- Department of Microbiology; University of Manitoba; Winnipeg Manitoba Canada
| | - Brijesh Kumar
- Department of Microbiology; University of Manitoba; Winnipeg Manitoba Canada
| | - Steve P. Bernier
- Department of Medicine; Farncombe Family Digestive Health Research Institute; McMaster University; Hamilton Ontario Canada
| | - John L. Sorensen
- Department of Chemistry; University of Manitoba; Winnipeg Manitoba Canada
| | - Michael G. Surette
- Department of Medicine; Farncombe Family Digestive Health Research Institute; McMaster University; Hamilton Ontario Canada
- Department of Biochemistry and Biological Sciences; McMaster University; Hamilton Ontario Canada
| | - Silvia T. Cardona
- Department of Microbiology; University of Manitoba; Winnipeg Manitoba Canada
- Department of Medical Microbiology & Infectious Disease; University of Manitoba; Winnipeg Manitoba Canada
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Mathew A, Eberl L, Carlier AL. A novel siderophore-independent strategy of iron uptake in the genusBurkholderia. Mol Microbiol 2014; 91:805-20. [DOI: 10.1111/mmi.12499] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Anugraha Mathew
- Institute of Plant Biology; University of Zurich; Zurich CH-8008 Switzerland
| | - Leo Eberl
- Institute of Plant Biology; University of Zurich; Zurich CH-8008 Switzerland
| | - Aurelien L. Carlier
- Institute of Plant Biology; University of Zurich; Zurich CH-8008 Switzerland
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Abstract
In recent years the zebrafish has gained enormous attention in infection biology, and many protocols have been developed to study interaction of both human and fish pathogens, including viruses, fungi, and bacteria, with the host. Especially the extraordinary possibilities for live imaging of disease processes in the transparent embryos using fluorescent bacteria and cell-specific reporter fish combined with gene knockdown, transcriptome, and genetic studies have dramatically advanced our understanding of disease mechanisms. The zebrafish embryo is amenable to study virulence of both extracellular and facultative intracellular pathogens introduced through the technique of microinjection. Several protocols have been published that address the different sites of injection, antisense strategies, imaging, and production of transgenic fish in detail. Here we describe a protocol to study the virulence profiles, ranging from acute fatal to persistent, of bacteria belonging to the Burkholderia cepacia complex. This standard operating protocol combines simple survival assays, analysis of bacterial kinetics, analysis of the early innate immune response with qRT-PCR, and the use of transgenic reporter fish to study interactions with host phagocytes, and is also applicable to other pathogens.
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Denman CC, Robinson MT, Sass AM, Mahenthiralingam E, Brown AR. Growth on mannitol-rich media elicits a genome-wide transcriptional response in Burkholderia multivorans that impacts on multiple virulence traits in an exopolysaccharide-independent manner. MICROBIOLOGY-SGM 2013; 160:187-197. [PMID: 24196427 DOI: 10.1099/mic.0.072975-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In common with other members of the Burkholderia cepacia complex (BCC), Burkholderia multivorans is capable of producing exopolysaccharide (EPS) when grown on certain mannitol-rich media. The significance of the resulting mucoid phenotype and the genome-wide response to mannitol has never been characterized despite its clinical relevance following the approval of a dried-powder preparation of mannitol as an inhaled osmolyte therapy for cystic fibrosis (CF) patients. In the present study we defined the transcriptional response of B. multivorans ATCC 17616, a model genome-sequenced strain of environmental origin, to growth on mannitol-rich yeast extract media (MYEM). EPS-dependent and -independent impact of MYEM on virulence-associated traits was assessed in both strain ATCC 17616 and the CF isolate B. multivorans C1576. Our studies revealed a significant transcriptional response to MYEM encompassing approximately 23 % of predicted genes within the genome. Strikingly, this transcriptional response identified that EPS induction occurs in ATCC 17616 without the upregulation of the bce-I and bce-II EPS gene clusters, despite their pivotal role in EPS biosynthesis. Of approximately 20 differentially expressed putative virulence factors, 16 exhibited upregulation including flagella, ornibactin, oxidative stress proteins and phospholipases. MYEM-grown B. multivorans also exhibited enhanced motility, biofilm formation and epithelial cell invasion. In contrast to these potential virulence enhancements, MYEM-grown B. multivorans C1576 showed attenuated virulence in the Galleria mellonella infection model. All of the observed phenotypic responses occurred independently of EPS production, highlighting the profound impact that mannitol-based growth has on the physiology and virulence of B. multivorans.
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Affiliation(s)
- Carmen C Denman
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Matthew T Robinson
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Andrea M Sass
- Organisms & Environment Division, Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - Eshwar Mahenthiralingam
- Organisms & Environment Division, Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - Alan R Brown
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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Subramoni S, Sokol PA. Quorum sensing systems influence Burkholderia cenocepacia virulence. Future Microbiol 2013; 7:1373-87. [PMID: 23231487 DOI: 10.2217/fmb.12.118] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Burkholderia cepacia complex strains communicate using N-acyl homoserine lactones and BDSF-dependent quorum sensing (QS) systems. Burkholderia cenocepacia QS systems include CepIR, CciIR, CepR2 and BDSF. Analysis of CepR, CciIR, CepR2 and RpfF (BDSF synthase) QS regulons revealed that these QS systems both independently regulate and coregulate many target genes, often in an opposing manner. The role of QS and several QS-regulated genes in virulence has been determined using vertebrate, invertebrate and plant infection models. Virulence phenotypes are strain and model dependent, suggesting that different QS-regulated genes are important depending on the strain and type of infection. QS inhibitors in combination with antibiotics can reduce biofilm formation and virulence in infection models.
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Affiliation(s)
- Sujatha Subramoni
- Department of Microbiology, Immunology & Infectious Diseases, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
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Comparative transcriptomic analysis of the Burkholderia cepacia tyrosine kinase bceF mutant reveals a role in tolerance to stress, biofilm formation, and virulence. Appl Environ Microbiol 2013; 79:3009-20. [PMID: 23435894 DOI: 10.1128/aem.00222-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The bacterial tyrosine-kinase (BY-kinase) family comprises the major group of bacterial enzymes endowed with tyrosine kinase activity. We previously showed that the BceF protein from Burkholderia cepacia IST408 belongs to this BY-kinase family and is involved in the biosynthesis of the exopolysaccharide cepacian. However, little is known about the extent of regulation of this protein kinase activity. In order to examine this regulation, we performed a comparative transcriptome profile between the bceF mutant and wild-type B. cepacia IST408. The analyses led to identification of 630 genes whose expression was significantly changed. Genes with decreased expression in the bceF mutant were related to stress response, motility, cell adhesion, and carbon and energy metabolism. Genes with increased expression were related to intracellular signaling and lipid metabolism. Mutation of bceF led to reduced survival under heat shock and UV light exposure, reduced swimming motility, and alteration in biofilm architecture when grown in vitro. Consistent with some of these phenotypes, the bceF mutant demonstrated elevated levels of cyclic-di-GMP. Furthermore, BceF contributed to the virulence of B. cepacia for larvae of the Greater wax moth, Galleria mellonella. Taken together, BceF appears to play a considerable role in many cellular processes, including biofilm formation and virulence. As homologues of BceF occur in a number of pathogenic and plant-associated Burkholderia strains, the modulation of bacterial behavior through tyrosine kinase activity is most likely a widely occurring phenomenon.
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Identification of Burkholderia cenocepacia strain H111 virulence factors using nonmammalian infection hosts. Infect Immun 2012; 81:143-53. [PMID: 23090963 DOI: 10.1128/iai.00768-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cenocepacia H111, a strain isolated from a cystic fibrosis patient, has been shown to effectively kill the nematode Caenorhabditis elegans. We used the C. elegans model of infection to screen a mini-Tn5 mutant library of B. cenocepacia H111 for attenuated virulence. Of the approximately 5,500 B. cenocepacia H111 random mini-Tn5 insertion mutants that were screened, 22 showed attenuated virulence in C. elegans. Except for the quorum-sensing regulator cepR, none of the mutated genes coded for the biosynthesis of classical virulence factors such as extracellular proteases or siderophores. Instead, the mutants contained insertions in metabolic and regulatory genes. Mutants attenuated in virulence in the C. elegans infection model were also tested in the Drosophila melanogaster pricking model, and those also attenuated in this model were further tested in Galleria mellonella. Six of the 22 mutants were attenuated in D. melanogaster, and five of these were less pathogenic in the G. mellonella model. We show that genes encoding enzymes of the purine, pyrimidine, and shikimate biosynthesis pathways are critical for virulence in multiple host models of infection.
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Extracellular glutathione decreases the ability of Burkholderia cenocepacia to penetrate into epithelial cells and to induce an inflammatory response. PLoS One 2012; 7:e47550. [PMID: 23094061 PMCID: PMC3477146 DOI: 10.1371/journal.pone.0047550] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 09/18/2012] [Indexed: 12/16/2022] Open
Abstract
Background The airway surface liquid (ASL) of Cystic Fibrosis (CF) patients contains a lower concentration of reduced glutathione (GSH) with respect to healthy people. It is not known whether this defect may favor lung colonization by opportunistic pathogens. Principal Findings We have analyzed the effects of extracellular GSH on the ability of Burkholderia cenocepacia to penetrate and multiply in epithelial respiratory cells. Extracellular GSH proved to be able to drastically reduce the pathogen ability to adhere and invade airway epithelial cells. This effect is correlated to a GSH-dependent increase in the number of free thiols on the surface of epithelial cells, suggestive of a change in the oxidoreductive status of membrane proteins involved in B. cenocepacia recognition. Moreover, treatments with GSH led to a consistent reduction of the expression of IL-8, TNF-α and IL-1β in response to B. cenocepacia infection. Conclusions and Significance Extracellular GSH modulates the interaction between B. cenocepacia and epithelial respiratory cells and inhibits the bacterial invasion into these cells. This suggests that therapies aimed at restoring normal levels of GSH in the ASL might be beneficial to control CF lung infections.
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Mil-Homens D, Fialho AM. A BCAM0223 mutant of Burkholderia cenocepacia is deficient in hemagglutination, serum resistance, adhesion to epithelial cells and virulence. PLoS One 2012; 7:e41747. [PMID: 22848588 PMCID: PMC3404963 DOI: 10.1371/journal.pone.0041747] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/25/2012] [Indexed: 11/19/2022] Open
Abstract
Burkholderia cepacia complex (Bcc) bacteria are a problematic group of microorganisms causing severe infections in patients with Cystic Fibrosis. In early stages of infection, Bcc bacteria must be able to adhere to and colonize the respiratory epithelium. Although this is not fully understood, this primary stage of infection is believed to be in part mediated by a specific type of adhesins, named trimeric autotransporter adhesins (TAAs). These homotrimeric proteins exist on the surface of many gram negative pathogens and often mediate a number of critical functions, including biofilm formation, serum resistance and adherence to an invasion of host cells. We have previously identified in the genome of the epidemic clinical isolate B. cenocepacia J2315, a novel cluster of genes putatively encoding three TAAs (BCAM0219, BCAM0223 and BCAM0224). In this study, the genomic organization of the TAA cluster has been determined. To further address the direct role of the putative TAA BCAM0223 in B. cenocepacia pathogenicity, an isogenic mutant was constructed via insertional inactivation. The BCAM0223::Tp mutant is deficient in hemagglutination, affected in adherence to vitronectin and in biofilm formation and showed attenuated virulence in the Galleria mellonella model of infection. Moreover, the BCAM0223::Tp mutant also showed a significant reduction in its resistance to human serum as well as in adherence, but not in invasion of, cultured human bronchial epithelial cells. Altogether these results demonstrate that the BCAM0223 protein is a multifunctional virulence factor that may contribute to the pathogenicity of B. cenocepacia.
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Affiliation(s)
- Dalila Mil-Homens
- IBB-Institute for Biotechnology and Bioengineering, Center for Biological and Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal
| | - Arsenio M. Fialho
- IBB-Institute for Biotechnology and Bioengineering, Center for Biological and Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal
- * E-mail:
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Burkholderia pseudomallei known siderophores and hemin uptake are dispensable for lethal murine melioidosis. PLoS Negl Trop Dis 2012; 6:e1715. [PMID: 22745846 PMCID: PMC3383733 DOI: 10.1371/journal.pntd.0001715] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 05/16/2012] [Indexed: 11/19/2022] Open
Abstract
Burkholderia pseudomallei is a mostly saprophytic bacterium, but can infect humans where it causes the difficult-to-manage disease melioidosis. Even with proper diagnosis and prompt therapeutic interventions mortality rates still range from >20% in Northern Australia to over 40% in Thailand. Surprisingly little is yet known about how B. pseudomallei infects, invades and survives within its hosts, and virtually nothing is known about the contribution of critical nutrients such as iron to the bacterium's pathogenesis. It was previously assumed that B. pseudomallei used iron-acquisition systems commonly found in other bacteria, for example siderophores. However, our previous discovery of a clinical isolate carrying a large chromosomal deletion missing the entire malleobactin gene cluster encoding the bacterium's major high-affinity siderophore while still being fully virulent in a murine melioidosis model suggested that other iron-acquisition systems might make contributions to virulence. Here, we deleted the major siderophore malleobactin (mba) and pyochelin (pch) gene clusters in strain 1710b and revealed a residual siderophore activity which was unrelated to other known Burkholderia siderophores such as cepabactin and cepaciachelin, and not due to increased secretion of chelators such as citrate. Deletion of the two hemin uptake loci, hmu and hem, showed that Hmu is required for utilization of hemin and hemoglobin and that Hem cannot complement a Hmu deficiency. Prolonged incubation of a hmu hem mutant in hemoglobin-containing minimal medium yielded variants able to utilize hemoglobin and hemin suggesting alternate pathways for utilization of these two host iron sources. Lactoferrin utilization was dependent on malleobactin, but not pyochelin synthesis and/or uptake. A mba pch hmu hem quadruple mutant could use ferritin as an iron source and upon intranasal infection was lethal in an acute murine melioidosis model. These data suggest that B. pseudomallei may employ a novel ferritin-iron acquisition pathway as a means to sustain in vivo growth. Burkholderia pseudomallei is the etiologic agent of melioidosis, a multifaceted deadly and difficult to treat disease of equatorial regions of the world. Disease manifestations range from acute infections to long term chronic infections. The factors by which this bacterium causes disease are not yet well understood. Studies thus far focused on elucidation of the roles of traditional virulence factors such as secreted proteins and exopolysaccharides, but virtually nothing is known about the roles of nutrient acquisition systems in B. pseudomallei's survival in its mammalian hosts. One nutrient that is essential for bacterial metabolism and pathogenicity is iron. As free iron is not readily available in nature, bacteria developed numerous mechanisms for iron acquisition from abiotic and biotic sources. These mechanisms include siderophores and hemin/hemoglobin utilization systems, and it is therefore not too surprising that mutants defective in these systems are often impaired in virulence. In this study we show that defined B. pseudomallei mutants defective in siderophore and hemin/hemoglobin utilization systems remain fully lethal in a murine melioidosis model and present evidence for in vitro ferritin-iron acquisition which may be one or perhaps the main means by which this pathogen sustains in vivo growth.
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Tolman JS, Valvano MA. Global changes in gene expression by the opportunistic pathogen Burkholderia cenocepacia in response to internalization by murine macrophages. BMC Genomics 2012; 13:63. [PMID: 22321740 PMCID: PMC3296584 DOI: 10.1186/1471-2164-13-63] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 02/09/2012] [Indexed: 12/18/2022] Open
Abstract
Background Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in patients with cystic fibrosis. The bacterium survives within macrophages by interfering with endocytic trafficking and delaying the maturation of the B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia undergoes changes in gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation. Results We examined gene expression by intracellular B. cenocepacia using selective capture of transcribed sequences (SCOTS) combined with microarray analysis. We identified 767 genes with significantly different levels of expression by intracellular bacteria, of which 330 showed increased expression and 437 showed decreased expression. Affected genes represented all aspects of cellular life including information storage and processing, cellular processes and signaling, and metabolism. In general, intracellular gene expression demonstrated a pattern of environmental sensing, bacterial response, and metabolic adaptation to the phagosomal environment. Deletion of various SCOTS-identified genes affected bacterial entry into macrophages and intracellular replication. We also show that intracellular B. cenocepacia is cytotoxic towards the macrophage host, and capable of spread to neighboring cells, a role dependent on SCOTS-identified genes. In particular, genes involved in bacterial motility, cobalamin biosynthesis, the type VI secretion system, and membrane modification contributed greatly to macrophage entry and subsequent intracellular behavior of B. cenocepacia. Conclusions B. cenocepacia enters macrophages, adapts to the phagosomal environment, replicates within a modified phagosome, and exhibits cytotoxicity towards the host cells. The analysis of the transcriptomic response of intracellular B. cenocepacia reveals that metabolic adaptation to a new niche plays a major role in the survival of B. cenocepacia in macrophages. This adaptive response does not require the expression of any specific virulence-associated factor, which is consistent with the opportunistic nature of this microorganism. Further investigation into the remaining SCOTS-identified genes will provide a more complete picture of the adaptive response of B. cenocepacia to the host cell environment.
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Affiliation(s)
- Jennifer S Tolman
- Infectious Diseases Research Group, Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, N6A 5C1, Canada
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O'Grady EP, Sokol PA. Burkholderia cenocepacia differential gene expression during host-pathogen interactions and adaptation to the host environment. Front Cell Infect Microbiol 2011; 1:15. [PMID: 22919581 PMCID: PMC3417382 DOI: 10.3389/fcimb.2011.00015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 11/20/2011] [Indexed: 01/08/2023] Open
Abstract
Members of the Burkholderia cepacia complex (Bcc) are important in medical, biotechnological, and agricultural disciplines. These bacteria naturally occur in soil and water environments and have adapted to survive in association with plants and animals including humans. All Bcc species are opportunistic pathogens including Burkholderia cenocepacia that causes infections in cystic fibrosis and chronic granulomatous disease patients. The adaptation of B. cenocepacia to the host environment was assessed in a rat chronic respiratory infection model and compared to that of high cell-density in vitro grown cultures using transcriptomics. The distribution of genes differentially expressed on chromosomes 1, 2, and 3 was relatively proportional to the size of each genomic element, whereas the proportion of plasmid-encoded genes differentially expressed was much higher relative to its size and most genes were induced in vivo. The majority of genes encoding known virulence factors, components of types II and III secretion systems and chromosome 2-encoded type IV secretion system were similarly expressed between in vitro and in vivo environments. Lower expression in vivo was detected for genes encoding N-acyl-homoserine lactone synthase CepI, orphan LuxR homolog CepR2, zinc metalloproteases ZmpA and ZmpB, LysR-type transcriptional regulator ShvR, nematocidal protein AidA, and genes associated with flagellar motility, Flp type pilus formation, and type VI secretion. Plasmid-encoded type IV secretion genes were markedly induced in vivo. Additional genes induced in vivo included genes predicted to be involved in osmotic stress adaptation or intracellular survival, metal ion, and nutrient transport, as well as those encoding outer membrane proteins. Genes identified in this study are potentially important for virulence during host–pathogen interactions and may be associated with survival and adaptation to the host environment during chronic lung infections.
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Affiliation(s)
- Eoin P O'Grady
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
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Olucha J, Lamb AL. Mechanistic and structural studies of the N-hydroxylating flavoprotein monooxygenases. Bioorg Chem 2011; 39:171-7. [PMID: 21871647 PMCID: PMC3188341 DOI: 10.1016/j.bioorg.2011.07.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/28/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
The N-hydroxylating flavoprotein monooxygenases are siderophore biosynthetic enzymes that catalyze the hydroxylation of the sidechain amino-group of ornithine or lysine or the primary amino-group of putrescine. This hydroxylated product is subsequently formylated or acylated and incorporated into the siderophore. Importantly, the modified amino-group is a hydroxamate and serves as an iron chelating moiety in the siderophore. This review describes recent work to characterize the ornithine hydroxylases from Pseudomonas aeruginosa (PvdA) and Aspergillus fumigatus (SidA) and the lysine hydroxylase from Escherichia coli (IucD). This includes summaries of steady and transient state kinetic data for all three enzymes and the X-ray crystallographic structure of PvdA.
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Affiliation(s)
- Jose Olucha
- Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, Kansas
| | - Audrey L. Lamb
- Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, Kansas
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Fang K, Zhao H, Sun C, Lam CMC, Chang S, Zhang K, Panda G, Godinho M, Martins dos Santos VAP, Wang J. Exploring the metabolic network of the epidemic pathogen Burkholderia cenocepacia J2315 via genome-scale reconstruction. BMC SYSTEMS BIOLOGY 2011; 5:83. [PMID: 21609491 PMCID: PMC3123600 DOI: 10.1186/1752-0509-5-83] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 05/25/2011] [Indexed: 11/10/2022]
Abstract
BACKGROUND Burkholderia cenocepacia is a threatening nosocomial epidemic pathogen in patients with cystic fibrosis (CF) or a compromised immune system. Its high level of antibiotic resistance is an increasing concern in treatments against its infection. Strain B. cenocepacia J2315 is the most infectious isolate from CF patients. There is a strong demand to reconstruct a genome-scale metabolic network of B. cenocepacia J2315 to systematically analyze its metabolic capabilities and its virulence traits, and to search for potential clinical therapy targets. RESULTS We reconstructed the genome-scale metabolic network of B. cenocepacia J2315. An iterative reconstruction process led to the establishment of a robust model, iKF1028, which accounts for 1,028 genes, 859 internal reactions, and 834 metabolites. The model iKF1028 captures important metabolic capabilities of B. cenocepacia J2315 with a particular focus on the biosyntheses of key metabolic virulence factors to assist in understanding the mechanism of disease infection and identifying potential drug targets. The model was tested through BIOLOG assays. Based on the model, the genome annotation of B. cenocepacia J2315 was refined and 24 genes were properly re-annotated. Gene and enzyme essentiality were analyzed to provide further insights into the genome function and architecture. A total of 45 essential enzymes were identified as potential therapeutic targets. CONCLUSIONS As the first genome-scale metabolic network of B. cenocepacia J2315, iKF1028 allows a systematic study of the metabolic properties of B. cenocepacia and its key metabolic virulence factors affecting the CF community. The model can be used as a discovery tool to design novel drugs against diseases caused by this notorious pathogen.
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Affiliation(s)
- Kechi Fang
- Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China
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Drevinek P, Mahenthiralingam E. Burkholderia cenocepacia in cystic fibrosis: epidemiology and molecular mechanisms of virulence. Clin Microbiol Infect 2011; 16:821-30. [PMID: 20880411 DOI: 10.1111/j.1469-0691.2010.03237.x] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Burkholderia cepacia complex (Bcc) bacteria have gained notoriety as pathogens in cystic fibrosis (CF) because they are difficult to identify and treat, and also have the ability to spread between CF individuals. Of the 17 formally named species within the complex, Burkholderia multivorans and Burkholderia cenocepacia dominate in CF. Multilocus sequence typing has proven to be a very useful tool for tracing the global epidemiology of Bcc bacteria and has shown that B. cenocepacia strains with high transmissibility, such as the ET-12 strain (ST-28) and the Czech strain (ST-32), have spread epidemically within CF populations in Canada and Europe. The majority of research on the molecular pathogenesis of Bcc bacteria has focused on the B. cenocepacia ET-12 epidemic lineage, with gene mutation, genome sequence analysis and, most recently, global gene expression studies shedding considerable light on the virulence and antimicrobial resistance of this pathogen. These studies demonstrate that the ability of B. cenocepacia to acquire foreign DNA (genomic islands, insertion sequences and other mobile elements), regulate gene expression via quorum sensing, compete for iron during infection, and mediate antimicrobial resistance and inflammation via its membrane and surface polysaccharides are key features that underpin the virulence of different strains. With the wealth of molecular knowledge acquired in the last decade on B. cenocepacia strains, we are now in a much better position to develop strategies for the treatment of pathogenic colonization with Bcc and to answer key questions on pathogenesis concerning, for example, the factors that trigger the rapid clinical decline in CF patients.
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Affiliation(s)
- P Drevinek
- Paediatric Department, 2nd Medical School, Charles University, Prague, Czech Republic.
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Asghar AH, Shastri S, Dave E, Wowk I, Agnoli K, Cook AM, Thomas MS. The pobA gene of Burkholderia cenocepacia encodes a Group I Sfp-type phosphopantetheinyltransferase required for biosynthesis of the siderophores ornibactin and pyochelin. Microbiology (Reading) 2011; 157:349-361. [DOI: 10.1099/mic.0.045559-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opportunistic pathogen Burkholderia cenocepacia produces the siderophores ornibactin and pyochelin under iron-restricted conditions. Biosynthesis of both siderophores requires the involvement of non-ribosomal peptide synthetases (NRPSs). Using a transposon containing the lacZ reporter gene, two B. cenocepacia mutants were isolated which were deficient in siderophore production. Mutant IW10 was shown to produce normal amounts of ornibactin but only trace amounts of pyochelin, whereas synthesis of both siderophores was abolished in AHA27. Growth of AHA27, but not IW10, was inhibited under iron-restricted conditions. In both mutants, the transposon had integrated into the pobA gene, which encodes a polypeptide exhibiting similarity to the Sfp-type phosphopantetheinyltransferases (PPTases). These enzymes are responsible for activation of NRPSs by the covalent attachment of the 4′-phosphopantetheine (P-pant) moiety of coenzyme A. Previously characterized PPTase genes from other bacteria were shown to efficiently complement both mutants for siderophore production when provided in trans. The B. cenocepacia pobA gene was also able to efficiently complement an Escherichia coli entD mutant for production of the siderophore enterobactin. Using mutant IW10, in which the lacZ gene carried by the transposon is inserted in the same orientation as pobA, it was shown that pobA is not appreciably iron-regulated. Finally, we confirmed that Sfp-type bacterial PPTases can be subdivided into two distinct groups, and we present the amino acid signature sequences which characterize each of these groups.
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Affiliation(s)
- Atif H. Asghar
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Sravanthi Shastri
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Emma Dave
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Irena Wowk
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Kirsty Agnoli
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Anne M. Cook
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Mark S. Thomas
- Department of Infection and Immunity, The Medical School, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
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Abstract
The Burkholderia cepacia complex (Bcc) is a group of genetically related environmental bacteria that can cause chronic opportunistic infections in patients with cystic fibrosis (CF) and other underlying diseases. These infections are difficult to treat due to the inherent resistance of the bacteria to antibiotics. Bacteria can spread between CF patients through social contact and sometimes cause cepacia syndrome, a fatal pneumonia accompanied by septicemia. Burkholderia cenocepacia has been the focus of attention because initially it was the most common Bcc species isolated from patients with CF in North America and Europe. Today, B. cenocepacia, along with Burkholderia multivorans, is the most prevalent Bcc species in patients with CF. Given the progress that has been made in our understanding of B. cenocepacia over the past decade, we thought that it was an appropriate time to review our knowledge of the pathogenesis of B. cenocepacia, paying particular attention to the characterization of virulence determinants and the new tools that have been developed to study them. A common theme emerging from these studies is that B. cenocepacia establishes chronic infections in immunocompromised patients, which depend more on determinants mediating host niche adaptation than those involved directly in host cells and tissue damage.
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Affiliation(s)
- Slade A. Loutet
- Centre for Human Immunology, Department of Microbiology and Immunology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Miguel A. Valvano
- Centre for Human Immunology, Department of Microbiology and Immunology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
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Chocklett SW, Sobrado P. Aspergillus fumigatus SidA is a highly specific ornithine hydroxylase with bound flavin cofactor. Biochemistry 2010; 49:6777-83. [PMID: 20614882 DOI: 10.1021/bi100291n] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N(5)-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed and purified as a soluble tetramer and is the first member of this class of flavin monooxygenases to be isolated with a bound flavin cofactor. The enzyme showed typical saturation kinetics with respect to l-ornithine while substrate inhibition was observed at high concentrations of NADPH and NADH. Increasing amounts of hydrogen peroxide were measured as a function of reduced nicotinamide coenzyme concentration, indicating that inhibition was caused by increased uncoupling. Af SidA is highly specific for its amino acid substrate, only hydroxylating l-ornithine. An 8-fold preference in the catalytic efficiency was determined for NADPH compared to NADH. In the absence of substrate, Af SidA can be reduced by NADPH, and a C4a-(hydro)peroxyflavin intermediate is observed. The decay of this intermediate is accelerated by l-ornithine binding. This intermediate was only stabilized by NADPH and not by NADH, suggesting a role for NADP(+) in the stabilization of intermediates in the reaction of Af SidA. NADP(+) is a competitive inhibitor with respect to NADPH, demonstrating that Af SidA forms a ternary complex with NADP(+) and l-ornithine during catalysis. The data suggest that Af SidA likely proceeds by a sequential kinetic mechanism.
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Affiliation(s)
- Samuel W Chocklett
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
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48
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Vergunst AC, Meijer AH, Renshaw SA, O'Callaghan D. Burkholderia cenocepacia creates an intramacrophage replication niche in zebrafish embryos, followed by bacterial dissemination and establishment of systemic infection. Infect Immun 2010; 78:1495-508. [PMID: 20086083 PMCID: PMC2849400 DOI: 10.1128/iai.00743-09] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/05/2009] [Accepted: 01/09/2010] [Indexed: 11/20/2022] Open
Abstract
Bacteria belonging to the "Burkholderia cepacia complex" (Bcc) often cause fatal pulmonary infections in cystic fibrosis patients, yet little is know about the underlying molecular mechanisms. These Gram-negative bacteria can adopt an intracellular lifestyle, although their ability to replicate intracellularly has been difficult to demonstrate. Here we show that Bcc bacteria survive and multiply in macrophages of zebrafish embryos. Local dissemination by nonlytic release from infected cells was followed by bacteremia and extracellular replication. Burkholderia cenocepacia isolates belonging to the epidemic electrophoretic type 12 (ET12) lineage were highly virulent for the embryos; intravenous injection of <10 bacteria of strain K56-2 killed embryos within 3 days. However, small but significant differences between the clonal ET12 isolates K56-2, J2315, and BC7 were evident. In addition, the innate immune response in young embryos was sufficiently developed to control infection with other less virulent Bcc strains, such as Burkholderia vietnamiensis FC441 and Burkholderia stabilis LMG14294. A K56-2 cepR quorum-sensing regulator mutant was highly attenuated, and its ability to replicate and spread to neighboring cells was greatly reduced. Our data indicate that the zebrafish embryo is an excellent vertebrate model to dissect the molecular basis of intracellular replication and the early innate immune responses in this intricate host-pathogen interaction.
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Affiliation(s)
- Annette C Vergunst
- INSERM, ESPRI 26, UFR Médecine, CS83021, Avenue Kennedy, 30908 Nimes, France.
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The Burkholderia cenocepacia K56-2 pleiotropic regulator Pbr, is required for stress resistance and virulence. Microb Pathog 2010; 48:168-77. [PMID: 20206249 DOI: 10.1016/j.micpath.2010.02.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 02/22/2010] [Accepted: 02/25/2010] [Indexed: 11/23/2022]
Abstract
Burkholderia cenocepacia is one of the most virulent species of the Burkholderia cepacia complex, a group of bacteria that emerged as important pathogens, especially to cystic fibrosis (CF) patients. In this study, we report the identification and characterization of a mutant strain derived form the CF isolate Burkholderia cenocepacia K56-2, carrying a plasposon insertion in a gene, located in a 3516 bp chromosomal region with an atypical G+C content, encoding a 80 amino acid putative regulatory protein named Pbr. Besides its inability to produce phenazines, the B. cenocepacia K56-2 pbr mutant exhibited a pleiotropic phenotype, including impaired survival to oxidative and osmotic stress, aromatic amino acid and prolonged nutrient starvation periods. In addition, the pbr mutant exhibited decreased virulence the nematode Caenorhabditis elegans. Altogether, our results demonstrate the involvement of Pbr on the regulation of phenazine biosynthesis, and an important role for this regulatory protein on several cellular processes related to stress resistance and virulence.
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50
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Experimental adaptation of Burkholderia cenocepacia to onion medium reduces host range. Appl Environ Microbiol 2010; 76:2387-96. [PMID: 20154121 DOI: 10.1128/aem.01930-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It is unclear whether adaptation to a new host typically broadens or compromises host range, yet the answer bears on the fate of emergent pathogens and symbionts. We investigated this dynamic using a soil isolate of Burkholderia cenocepacia, a species that normally inhabits the rhizosphere, is related to the onion pathogen B. cepacia, and can infect the lungs of cystic fibrosis patients. We hypothesized that adaptation of B. cenocepacia to a novel host would compromise fitness and virulence in alternative hosts. We modeled adaptation to a specific host by experimentally evolving 12 populations of B. cenocepacia in liquid medium composed of macerated onion tissue for 1,000 generations. The mean fitness of all populations increased by 78% relative to the ancestor, but significant variation among lines was observed. Populations also varied in several phenotypes related to host association, including motility, biofilm formation, and quorum-sensing function. Together, these results suggest that each population adapted by fixing different sets of adaptive mutations. However, this adaptation was consistently accompanied by a loss of pathogenicity to the nematode Caenorhabditis elegans; by 500 generations most populations became unable to kill nematodes. In conclusion, we observed a narrowing of host range as a consequence of prolonged adaptation to an environment simulating a specific host, and we suggest that emergent pathogens may face similar consequences if they become host-restricted.
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