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Yap ZL, Rahman ASMZ, Hogan AM, Levin DB, Cardona ST. A CRISPR-Cas-associated transposon system for genome editing in Burkholderia cepacia complex species. Appl Environ Microbiol 2024; 90:e0069924. [PMID: 38869300 PMCID: PMC11267881 DOI: 10.1128/aem.00699-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 05/20/2024] [Indexed: 06/14/2024] Open
Abstract
Genome editing in non-model bacteria is important to understand gene-to-function links that may differ from those of model microorganisms. Although species of the Burkholderia cepacia complex (Bcc) have great biotechnological capacities, the limited genetic tools available to understand and mitigate their pathogenic potential hamper their utilization in industrial applications. To broaden the genetic tools available for Bcc species, we developed RhaCAST, a targeted DNA insertion platform based on a CRISPR-associated transposase driven by a rhamnose-inducible promoter. We demonstrated the utility of the system for targeted insertional mutagenesis in the Bcc strains B. cenocepacia K56-2 and Burkholderia multivorans ATCC17616. We showed that the RhaCAST system can be used for loss- and gain-of-function applications. Importantly, the selection marker could be excised and reused to allow iterative genetic manipulation. The RhaCAST system is faster, easier, and more adaptable than previous insertional mutagenesis tools available for Bcc species and may be used to disrupt pathogenicity elements and insert relevant genetic modules, enabling Bcc biotechnological applications. IMPORTANCE Species of the Burkholderia cepacia complex (Bcc) have great biotechnological potential but are also opportunistic pathogens. Genetic manipulation of Bcc species is necessary to understand gene-to-function links. However, limited genetic tools are available to manipulate Bcc, hindering our understanding of their pathogenic traits and their potential in biotechnological applications. We developed a genetic tool based on CRISPR-associated transposase to increase the genetic tools available for Bcc species. The genetic tool we developed in this study can be used for loss and gain of function in Bcc species. The significance of our work is in expanding currently available tools to manipulate Bcc.
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Affiliation(s)
- Zhong Ling Yap
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Andrew M. Hogan
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David B. Levin
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Silvia T. Cardona
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
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Proteolytic Activity of DegP Is Required for the Burkholderia Symbiont To Persist in Its Host Bean Bug. Microbiol Spectr 2023; 11:e0433022. [PMID: 36511662 PMCID: PMC9927360 DOI: 10.1128/spectrum.04330-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Symbiosis requires the adaptation of symbiotic bacteria to the host environment. Symbiotic factors for bacterial adaptation have been studied in various experimental models, including the Burkholderia-bean bug symbiosis model. Previously identified symbiotic factors of Burkholderia symbionts of bean bugs provided insight into the host environment being stressful to the symbionts. Because DegP, which functions as both a protease and a chaperone, supports bacterial growth under various stressful conditions, we hypothesized that DegP might be a novel symbiotic factor of Burkholderia symbionts in the symbiotic association with bean bugs. The expression level of degP was highly elevated in symbiotic Burkholderia cells in comparison with cultured cells. When the degP-deficient strain competed for symbiotic association against the wild-type strain, the ΔdegP strain showed no symbiotic competitiveness. In vivo monoinfection with the ΔdegP strain revealed a lower symbiont titer in the symbiotic organ than that of the wild-type strain, indicating that the ΔdegP strain failed to persist in the host. In in vitro assays, the ΔdegP strain showed susceptibility to heat and high-salt stressors and a decreased level of biofilm formation. To further determine the role of the proteolytic activity of DegP in symbiosis, we generated missense mutant DegPS248A exhibiting a defect in protease activity only. The ΔdegP strain complemented with degPS248A showed in vitro characteristics similar to those of the ΔdegP strain and failed to persist in the symbiotic organ. Together, the results of our study demonstrated that the proteolytic activity of DegP, which is involved in the stress resistance and biofilm formation of the Burkholderia symbiont, plays an essential role in symbiotic persistence in the host bean bug. IMPORTANCE Bacterial DegP has dual functions as a protease and a chaperone and supports bacterial growth under stressful conditions. In symbioses involving bacteria, bacterial symbionts encounter various stressors and may need functional DegP for symbiotic association with the host. Using the Burkholderia-bean bug symbiosis model, which is a useful model for identifying bacterial symbiotic factors, we demonstrated that DegP is indeed a symbiotic factor of Burkholderia persistence in its host bean bug. In vitro experiments to understand the symbiotic mechanisms of degP revealed that degP confers resistance to heat and high-salt stresses. In addition, degP supports biofilm formation, which is a previously identified persistence factor of the Burkholderia symbiont. Furthermore, using a missense mutation in a protease catalytic site of degP, we specifically elucidated that the proteolytic activity of degP plays essential roles in stress resistance, biofilm formation, and, thus, symbiotic persistence in the host bean bug.
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Mekasha S, Linke D. Secretion Systems in Gram-Negative Bacterial Fish Pathogens. Front Microbiol 2022; 12:782673. [PMID: 34975803 PMCID: PMC8714846 DOI: 10.3389/fmicb.2021.782673] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/24/2021] [Indexed: 12/17/2022] Open
Abstract
Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here.
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Affiliation(s)
- Sophanit Mekasha
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
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Urmi AS, Inaba H, Nomura R, Yoshida S, Ohara N, Asai F, Nakano K, Matsumoto-Nakano M. Roles of Porphyromonas gulae proteases in bacterial and host cell biology. Cell Microbiol 2021; 23:e13312. [PMID: 33486854 DOI: 10.1111/cmi.13312] [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] [Received: 05/26/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 01/19/2023]
Abstract
Porphyromonas gulae, an animal-derived periodontal pathogen, expresses several virulence factors, including fimbria, lipopolysaccharide (LPS) and proteases. We previously reported that its invasive efficiency was dependent on fimbriae types. In addition, P. gulae LPS increased inflammatory responses via toll-like receptors. The present study was conducted to investigate the involvement of P. gulae proteases in bacterial and host cell biology. Porphyromonas gulae strains showed an ability to agglutinate mouse erythrocytes and also demonstrated co-aggregation with Actinomyces viscosus, while the protease inhibitors antipain, PMSF, TLCK and leupeptin diminished P. gulae proteolytic activity, resulting in inhibition of haemagglutination and co-aggregation with A. viscosus. In addition, specific proteinase inhibitors were found to reduce bacterial cell growth. Porphyromonas gulae inhibited Ca9-22 cell proliferation in a multiplicity of infection- and time-dependent manner. Additionally, P. gulae-induced decreases in cell contact and adhesion-related proteins were accompanied by a marked change in cell morphology from well spread to rounded. In contrast, inhibition of protease activity prevented degradation of proteins, such as E-cadherin, β-catenin and focal adhesion kinase, and also blocked inhibition of cell proliferation. Together, these results indicate suppression of the amount of human proteins, such as γ-globulin, fibrinogen and fibronectin, by P. gulae proteases, suggesting that a novel protease complex contributes to bacterial virulence.
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Affiliation(s)
- Alam Saki Urmi
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hiroaki Inaba
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Ryota Nomura
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan
| | - Sho Yoshida
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Naoya Ohara
- Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and the Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan
| | - Fumitoshi Asai
- Department of Pharmacology, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Kazuhiko Nakano
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan
| | - Michiyo Matsumoto-Nakano
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Jones C, Webster G, Mullins AJ, Jenner M, Bull MJ, Dashti Y, Spilker T, Parkhill J, Connor TR, LiPuma JJ, Challis GL, Mahenthiralingam E. Kill and cure: genomic phylogeny and bioactivity of Burkholderia gladioli bacteria capable of pathogenic and beneficial lifestyles. Microb Genom 2021; 7:mgen000515. [PMID: 33459584 PMCID: PMC8115902 DOI: 10.1099/mgen.0.000515] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/22/2020] [Indexed: 01/22/2023] Open
Abstract
Burkholderia gladioli is a bacterium with a broad ecology spanning disease in humans, animals and plants, but also encompassing multiple beneficial interactions. It is a plant pathogen, a toxin-producing food-poisoning agent, and causes lung infections in people with cystic fibrosis (CF). Contrasting beneficial traits include antifungal production exploited by insects to protect their eggs, plant protective abilities and antibiotic biosynthesis. We explored the genomic diversity and specialized metabolic potential of 206 B. gladioli strains, phylogenomically defining 5 clades. Historical disease pathovars (pv.) B. gladioli pv. allicola and B. gladioli pv. cocovenenans were distinct, while B. gladioli pv. gladioli and B. gladioli pv. agaricicola were indistinguishable; soft-rot disease and CF infection were conserved across all pathovars. Biosynthetic gene clusters (BGCs) for toxoflavin, caryoynencin and enacyloxin were dispersed across B. gladioli, but bongkrekic acid and gladiolin production were clade-specific. Strikingly, 13 % of CF infection strains characterized were bongkrekic acid-positive, uniquely linking this food-poisoning toxin to this aspect of B. gladioli disease. Mapping the population biology and metabolite production of B. gladioli has shed light on its diverse ecology, and by demonstrating that the antibiotic trimethoprim suppresses bongkrekic acid production, a potential therapeutic strategy to minimize poisoning risk in CF has been identified.
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Affiliation(s)
- Cerith Jones
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
- Present address: School of Applied Sciences, Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, CF37 4BD, UK
| | - Gordon Webster
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Alex J. Mullins
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Matthew Jenner
- Department of Chemistry and Warwick Integrative Synthetic Biology Centre, University of Warwick, CV4 7AL, UK
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Matthew J. Bull
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
- Present address: Pathogen Genomics Unit, Public Health Wales Microbiology Cardiff, University Hospital of Wales, Cardiff, CF14 4XW, UK
| | - Yousef Dashti
- Department of Chemistry and Warwick Integrative Synthetic Biology Centre, University of Warwick, CV4 7AL, UK
- Present address: The Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK
| | - Theodore Spilker
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Present address: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Thomas R. Connor
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - John J. LiPuma
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Gregory L. Challis
- Department of Chemistry and Warwick Integrative Synthetic Biology Centre, University of Warwick, CV4 7AL, UK
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry CV4 7AL, UK
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Eshwar Mahenthiralingam
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
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In Silico Structural and Functional Characterization of HtrA Proteins of Leptospira spp.: Possible Implications in Pathogenesis. Trop Med Infect Dis 2020; 5:tropicalmed5040179. [PMID: 33260771 PMCID: PMC7709667 DOI: 10.3390/tropicalmed5040179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 12/14/2022] Open
Abstract
Leptospirosis is a zoonosis caused by the pathogenic bacteria of the genus Leptospira. The identification of conserved outer membrane proteins among pathogenic strains is a major research target in elucidating mechanisms of pathogenicity. Surface-exposed proteins are most probably the ones involved in the interaction of leptospires with the environment. Some spirochetes use outer membrane proteases as a way to penetrate host tissues. HtrA is a family of proteins found in various cell types, from prokaryotes to primates. They are a set of proteases usually composed of a serine protease and PDZ domains, and they are generally transported to the periplasm. Here, we identified four genes—annotated as HtrA, LIC11111, LIC20143, LIC20144 and LIC11037—and another one annotated as a serine protease, LIC11112. It is believed that the last forms a functional heterodimer with LIC11111, since they are organized in one operon. Our analyses showed that these proteins are highly conserved among pathogenic strains. LIC11112, LIC20143, and LIC11037 have the serine protease domain with the conserved catalytic triad His-Asp-Ser. This is the first bioinformatics analysis of HtrA proteins from Leptospira that suggests their proteolytic activity potential. Experimental studies are warranted to elucidate this possibility.
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Leandro MR, Vespoli LDS, Andrade LF, Soares FS, Boechat AL, Pimentel VR, Moreira JR, Passamani LZ, Silveira V, de Souza Filho GA. DegP protease is essential for tolerance to salt stress in the plant growth-promoting bacterium Gluconacetobacter diazotrophicus PAL5. Microbiol Res 2020; 243:126654. [PMID: 33285429 DOI: 10.1016/j.micres.2020.126654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 11/19/2022]
Abstract
The use of plant growth-promoting bacteria represents an alternative to the massive use of mineral fertilizers in agriculture. However, some abiotic stresses commonly found in the environment, like salinity, can affect the efficiency of this approach. Here, we investigated the key mechanisms involved in the response of the plant growth-promoting bacterium Gluconacetobacter diazotrophicus to salt stress by using morphological and cell viability analyses, comparative proteomics, and reverse genetics. Our results revealed that the bacteria produce filamentous cells in response to salt at 100 mM and 150 mM NaCl. However, such a response was not observed at higher concentrations, where cell viability was severely affected. Proteomic analysis showed that salt stress modulates proteins involved in several pathways, including iron uptake, outer membrane efflux, osmotic adjustment, cell division and elongation, and protein transport and quality control. Proteomic data also revealed the repression of several extracytoplasmic proteins, especially those located at periplasm and outer membrane. The role of such pathways in the tolerance to salt stress was analyzed by the use of mutant defectives for Δtbdr (iron uptake), ΔmtlK and ΔotsA (compatible solutes synthesis), and ΔdegP (quality control of nascent extracytoplasmic proteins). ΔdegP presented the highest sensitivity to salt stress, Δtbdr, andΔmtlK also showed increased sensitivity, but ΔotsA was not affected. This is the first demonstration that DegP protein, a protease with minor chaperone activity, is essential for tolerance to salt stress in G. diazotrophicus. Our data contribute to a better understanding of the molecular bases that control the bacterial response/tolerance to salt stress, shedding light on quality control of nascent extracytoplasmic proteins.
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Affiliation(s)
- Mariana Ramos Leandro
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Luciano de Souza Vespoli
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Leandro Fernandes Andrade
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Fabiano Silva Soares
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Ana Laura Boechat
- Instituto de Química (Departamento de Bioquímica), Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, São Paulo, SP, Brazil
| | - Vivian Ribeiro Pimentel
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Julia Rosa Moreira
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Lucas Zanchetta Passamani
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Vanildo Silveira
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - Gonçalo Apolinário de Souza Filho
- Laboratório de Biotecnologia (Setor de Biologia Integrativa), Universidade Estadual do Norte, Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, Rio de Janeiro, Brazil.
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Tan KY, Dutta A, Tan TK, Hari R, Othman RY, Choo SW. Comprehensive genome analysis of a pangolin-associated Paraburkholderia fungorum provides new insights into its secretion systems and virulence. PeerJ 2020; 8:e9733. [PMID: 32953261 PMCID: PMC7474880 DOI: 10.7717/peerj.9733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/25/2020] [Indexed: 12/26/2022] Open
Abstract
Background Paraburkholderia fungorum (P. fungorum) is a Gram-negative environmental species that has been commonly used as a beneficial microorganism in agriculture as an agent for biocontrol and bioremediation. Its use in agriculture is controversial as many people believe that it could harm human health; however, there is no clear evidence to support. Methodology The pangolin P. fungorum (pangolin Pf) genome has a genomic size of approximately 7.7 Mbps with N50 of 69,666 bps. Our study showed that pangolin Pf is a Paraburkholderia fungorum supported by evidence from the core genome SNP-based phylogenetic analysis and the ANI analysis. Functional analysis has shown that the presence of a considerably large number of genes related to stress response, virulence, disease, and defence. Interestingly, we identified different types of secretion systems in the genome of pangolin Pf, which are highly specialized and responsible for a bacterium’s response to its environment and in physiological processes such as survival, adhesion, and adaptation. The pangolin Pf also shared some common virulence genes with the known pathogenic member of the Burkholderiales. These genes play important roles in adhesion, motility, and invasion. Conclusion This study may provide better insights into the functions, secretion systems and virulence of this pangolin-associated bacterial strain. The addition of this genome sequence is also important for future comparative analysis and functional work of P. fungorum.
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Affiliation(s)
- Ka Yun Tan
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Avirup Dutta
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: The Novo Nordisk Foundation Center for Basic Metabolic Research, Human Genomics and Metagenomics in Metabolism, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tze King Tan
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia.,Current affiliation: Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Ranjeev Hari
- Genome Informatics Research Laboratory, Centre for Research in Biotechnology for Agriculture (CEBAR), High Impact Research Building, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Rofina Y Othman
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia.,Centre for Research in Biotechnology for Agriculture (CEBAR), Level 3, Research Management & Innovation Complex, Universiti Malaya, Copenhagen, Kuala Lumpur, Malaysia
| | - Siew Woh Choo
- College of Science and Technology, Wenzhou-Kean University, Wenzhou, Zhejiang Province, China
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Abstract
The regulation and timely expression of bacterial genes during infection is critical for a pathogen to cause an infection. Bacteria have multiple mechanisms to regulate gene expression in response to their environment, one of which is two-component systems (TCS). TCS have two components. One component is a sensory histidine kinase (HK) that autophosphorylates when activated by a signal. The activated sensory histidine kinase then transfers the phosphoryl group to the second component, the response regulator, which activates transcription of target genes. The genus Burkholderia contains members that cause human disease and are often extensively resistant to many antibiotics. The Burkholderia cepacia complex (BCC) can cause severe lung infections in patients with cystic fibrosis (CF) or chronic granulomatous disease (CGD). BCC members have also recently been associated with several outbreaks of bacteremia from contaminated pharmaceutical products. Separate from the BCC is Burkholderia pseudomallei, which is the causative agent of melioidosis, a serious disease that occurs in the tropics, and a potential bioterrorism weapon. Bioinformatic analysis of sequenced Burkholderia isolates predicts that most strains have at least 40 TCS. The vast majority of these TCS are uncharacterized both in terms of the signals that activate them and the genes that are regulated by them. This review will highlight TCS that have been described to play a role in virulence in either the BCC or B. pseudomallei Since many of these TCS are involved in virulence, TCS are potential novel therapeutic targets, and elucidating their function is critical for understanding Burkholderia pathogenesis.
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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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Hogan AM, Rahman ASMZ, Lightly TJ, Cardona ST. A Broad-Host-Range CRISPRi Toolkit for Silencing Gene Expression in Burkholderia. ACS Synth Biol 2019; 8:2372-2384. [PMID: 31491085 DOI: 10.1021/acssynbio.9b00232] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Genetic tools are critical to dissecting the mechanisms governing cellular processes, from fundamental physiology to pathogenesis. Members of the genus Burkholderia have potential for biotechnological applications but can also cause disease in humans with a debilitated immune system. The lack of suitable genetic tools to edit Burkholderia GC-rich genomes has hampered the exploration of useful capacities and the understanding of pathogenic features. To address this, we have developed CRISPR interference (CRISPRi) technology for gene silencing in Burkholderia, testing it in B. cenocepacia, B. multivorans, and B. thailandensis. Tunable expression was provided by placing a codon-optimized dcas9 from Streptococcus pyogenes under control of a rhamnose-inducible promoter. As a proof of concept, the paaABCDE operon controlling genes necessary for phenylacetic acid degradation was targeted by plasmid-borne gRNAs, resulting in near complete inhibition of growth on phenylacetic acid as the sole carbon source. This was supported by reductions in paaA mRNA expression. The utility of CRISPRi to probe other functions at the single cell level was demonstrated by knocking down phbC and fliF, which dramatically reduces polyhydroxybutyrate granule accumulation and motility, respectively. As a hallmark of the mini-CTX system is the broad host-range of integration, we putatively identified 67 genera of Proteobacteria that might be amenable to modification with our CRISPRi toolkit. Our CRISPRi toolkit provides a simple and rapid way to silence gene expression to produce an observable phenotype. Linking genes to functions with CRISPRi will facilitate genome editing with the goal of enhancing biotechnological capabilities while reducing Burkholderia's pathogenic arsenal.
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Affiliation(s)
- Andrew M Hogan
- Department of Microbiology , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
| | - A S M Zisanur Rahman
- Department of Microbiology , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
| | - Tasia J Lightly
- Department of Microbiology , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
| | - Silvia T Cardona
- Department of Microbiology , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
- Department of Medical Microbiology & Infectious Diseases , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada
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12
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Mullins AJ, Murray JAH, Bull MJ, Jenner M, Jones C, Webster G, Green AE, Neill DR, Connor TR, Parkhill J, Challis GL, Mahenthiralingam E. Genome mining identifies cepacin as a plant-protective metabolite of the biopesticidal bacterium Burkholderia ambifaria. Nat Microbiol 2019; 4:996-1005. [PMID: 30833726 PMCID: PMC6544543 DOI: 10.1038/s41564-019-0383-z] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 01/22/2019] [Indexed: 11/09/2022]
Abstract
Beneficial microorganisms are widely used in agriculture for control of plant pathogens, but a lack of efficacy and safety information has limited the exploitation of multiple promising biopesticides. We applied phylogeny-led genome mining, metabolite analyses and biological control assays to define the efficacy of Burkholderia ambifaria, a naturally beneficial bacterium with proven biocontrol properties but potential pathogenic risk. A panel of 64 B. ambifaria strains demonstrated significant antimicrobial activity against priority plant pathogens. Genome sequencing, specialized metabolite biosynthetic gene cluster mining and metabolite analysis revealed an armoury of known and unknown pathways within B. ambifaria. The biosynthetic gene cluster responsible for the production of the metabolite cepacin was identified and directly shown to mediate protection of germinating crops against Pythium damping-off disease. B. ambifaria maintained biopesticidal protection and overall fitness in the soil after deletion of its third replicon, a non-essential plasmid associated with virulence in Burkholderia cepacia complex bacteria. Removal of the third replicon reduced B. ambifaria persistence in a murine respiratory infection model. Here, we show that by using interdisciplinary phylogenomic, metabolomic and functional approaches, the mode of action of natural biological control agents related to pathogens can be systematically established to facilitate their future exploitation.
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Affiliation(s)
- Alex J Mullins
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK.
| | - James A H Murray
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK
| | - Matthew J Bull
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK
| | - Matthew Jenner
- Department of Chemistry and Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, UK
| | - Cerith Jones
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK
- Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, UK
| | - Gordon Webster
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK
| | - Angharad E Green
- Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - Daniel R Neill
- Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - Thomas R Connor
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK
| | - Julian Parkhill
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
| | - Gregory L Challis
- Department of Chemistry and Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, UK
- Department of Biochemistry and Molecular Biology,Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Eshwar Mahenthiralingam
- Microbiomes, Microbes and Informatics Group, Organisms and Environment Division, School of Biosciences, Cardiff University, Cardiff, UK.
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13
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Zeidler S, Müller V. Coping with low water activities and osmotic stress in Acinetobacter baumannii: significance, current status and perspectives. Environ Microbiol 2019; 21:2212-2230. [PMID: 30773801 DOI: 10.1111/1462-2920.14565] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 01/26/2023]
Abstract
Multidrug resistant (MDR) pathogens are one of the most pressing challenges of contemporary health care. Acinetobacter baumannii takes a predominant position, emphasized in 2017 by the World Health Organization. The increasing emergence of MDR strains strengthens the demand for new antimicrobials. Possible targets for such compounds might be proteins involved in resistance against low water activity environments, since A. baumannii is known for its pronounced resistance against desiccation stress. Despite the importance of desiccation resistance for persistence of this pathogen in hospitals, comparable studies and precise data on this topic are rare and the mechanisms involved are largely unknown. This review aims to give an overview of the studies performed so far and the current knowledge on genes and proteins important for desiccation survival. 'Osmotic stress' is not identical to 'desiccation stress', but the two share the response of bacteria to low water activities. Osmotic stress resistance is in general studied much better, and in recent years it turned out that accumulation of compatible solutes in A. baumannii comprises some special features such as the bifunctional enzyme MtlD synthesizing the unusual solute mannitol. Furthermore, the regulatory pathways, as understood today, will be discussed.
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Affiliation(s)
- Sabine Zeidler
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
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14
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Kumar B, Sorensen JL, Cardona ST. A c-di-GMP-Modulating Protein Regulates Swimming Motility of Burkholderia cenocepacia in Response to Arginine and Glutamate. Front Cell Infect Microbiol 2018. [PMID: 29541628 PMCID: PMC5835511 DOI: 10.3389/fcimb.2018.00056] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic bacterium that can thrive in different environments, including the amino acid-rich mucus of the cystic fibrosis (CF) lung. B. cenocepacia responds to the nutritional conditions that mimic the CF sputum by increasing flagellin expression and swimming motility. Individual amino acids also induce swimming but not flagellin expression. Here, we show that modulation of the second messenger cyclic dimeric guanosine monophosphate (c-di-GMP) levels by the PAS-containing c-di-GMP phosphodiesterase, BCAL1069 (CdpA), regulates the swimming motility of B. cenocepacia K56-2 in response to CF sputum nutritional conditions. Heterologous expression of WspR, a diguanylate cyclase, in B. cenocepacia K56-2 caused an increase in c-di-GMP levels and reduced swimming motility but did not affect flagellin expression or flagellar biosynthesis. After insertional mutagenesis of 12 putative genes encoding c-di-GMP metabolizing enzymes, one mutant of the locus BCAL1069 (cdpA), exhibited decreased swimming motility independent of flagellin expression in CF sputum nutritional conditions and an increase in intracellular c-di-GMP levels. The reduced swimming motility phenotype of the BCAL1069 mutant was observed in the presence of arginine and glutamate, but not of histidine, phenylalanine, or proline. The B. cenocepacia CdpA was also found to be involved in regulation of protease activity but not in biofilm formation. Altogether, these results highlight a role of B. cenocepacia BCAL1069 (CdpA) in sensing the nutritional conditions of the CF sputum and eliciting a pathogenic response that includes swimming motility toward amino acids and an increase in protease activity.
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Affiliation(s)
- Brijesh Kumar
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, MB, Canada
| | - John L Sorensen
- Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, MB, Canada
| | - Silvia T Cardona
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, MB, Canada.,Department of Medical Microbiology & Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB, Canada
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15
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Bhate R, Pansare N, Chaudhari SP, Barbuddhe SB, Choudhary VK, Kurkure NV, Kolte SW. Prevalence and Phylogenetic Analysis of Orientia tsutsugamushi in Rodents and Mites from Central India. Vector Borne Zoonotic Dis 2017; 17:749-754. [PMID: 28934071 DOI: 10.1089/vbz.2017.2159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Orientia tsutsugamushi, the causative agent of scrub typhus in humans, is an obligate intracytosolic bacterium transmitted among animals and to humans by some species of larval trombiculid mites (chiggers) and is hosted mainly by rodents. In this study, we attempted detection of O. tsutsugamushi from blood and tissue samples of rodents trapped from different locations in Central India using PCR targeting the 56 kDa outer membrane protein gene and the 47 kDa high temperature transmembrane protein gene. A total of 59 rodent samples comprising 38 of blood collected from domestic and public surroundings and 21 of tissue from agricultural farm were included in this study. The 56 kDa outer membrane protein gene was detected from 10 of 59 samples by PCR, and the 47 kDa protein gene was detected from 4 of 59 samples by nested-PCR. Mites collected from the rodents were identified as Ornithonyssus bacoti, and one of five pooled samples was found to be positive for O. tsutsugamushi using PCR targeting 56 kDa outer membrane protein gene. Thus, perpetuation of O. tsutsugamushi among rodents and mites was detected constituting a potential public health concern.
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Affiliation(s)
- Ruchi Bhate
- 1 Centre for Zoonoses, Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra Animal and Fishery Sciences University , Nagpur, India
| | - Nilesh Pansare
- 1 Centre for Zoonoses, Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra Animal and Fishery Sciences University , Nagpur, India
| | - Sandeep P Chaudhari
- 1 Centre for Zoonoses, Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra Animal and Fishery Sciences University , Nagpur, India
| | | | - Vijay K Choudhary
- 2 ICAR-National Institute of Biotic Stress Management , Raipur, India
| | - Nitin V Kurkure
- 1 Centre for Zoonoses, Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra Animal and Fishery Sciences University , Nagpur, India
| | - Sunil W Kolte
- 1 Centre for Zoonoses, Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra Animal and Fishery Sciences University , Nagpur, India
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16
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Harrer A, Boehm M, Backert S, Tegtmeyer N. Overexpression of serine protease HtrA enhances disruption of adherens junctions, paracellular transmigration and type IV secretion of CagA by Helicobacter pylori. Gut Pathog 2017; 9:40. [PMID: 28770008 PMCID: PMC5526239 DOI: 10.1186/s13099-017-0189-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 07/11/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The serine protease HtrA is an important factor for regulating stress responses and protein quality control in bacteria. In recent studies, we have demonstrated that the gastric pathogen Helicobacter pylori can secrete HtrA into the extracellular environment, where it cleaves-off the ectodomain of the tumor suppressor and adherens junction protein E-cadherin on gastric epithelial cells. RESULTS E-cadherin cleavage opens cell-to-cell junctions, allowing paracellular transmigration of the bacteria across polarized monolayers of MKN-28 and Caco-2 epithelial cells. However, rapid research progress on HtrA function is mainly hampered by the lack of ΔhtrA knockout mutants, suggesting that htrA may represent an essential gene in H. pylori. To circumvent this major handicap and to investigate the role of HtrA further, we overexpressed HtrA by introducing a second functional htrA gene copy in the chromosome and studied various virulence properties of the bacteria. The resulting data demonstrate that overexpression of HtrA in H. pylori gives rise to elevated rates of HtrA secretion, cleavage of E-cadherin, bacterial transmigration and delivery of the type IV secretion system (T4SS) effector protein CagA into polarized epithelial cells, but did not affect IL-8 chemokine production or the secretion of vacuolating cytotoxin VacA and γ-glutamyl-transpeptidase GGT. CONCLUSIONS These data provide for the first time genetic evidence in H. pylori that HtrA is a novel major virulence factor controlling multiple pathogenic activities of this important microbe.
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Affiliation(s)
- Aileen Harrer
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Manja Boehm
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Steffen Backert
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Nicole Tegtmeyer
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
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17
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Song L, Jenner M, Masschelein J, Jones C, Bull MJ, Harris SR, Hartkoorn RC, Vocat A, Romero-Canelon I, Coupland P, Webster G, Dunn M, Weiser R, Paisey C, Cole ST, Parkhill J, Mahenthiralingam E, Challis GL. Discovery and Biosynthesis of Gladiolin: A Burkholderia gladioli Antibiotic with Promising Activity against Mycobacterium tuberculosis. J Am Chem Soc 2017; 139:7974-7981. [DOI: 10.1021/jacs.7b03382] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lijiang Song
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Matthew Jenner
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Joleen Masschelein
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Cerith Jones
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Matthew J. Bull
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Simon R. Harris
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Ruben C. Hartkoorn
- Global
Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland
| | - Anthony Vocat
- Global
Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland
| | | | - Paul Coupland
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Gordon Webster
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Matthew Dunn
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Rebecca Weiser
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Christopher Paisey
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Stewart T. Cole
- Global
Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Eshwar Mahenthiralingam
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Gregory L. Challis
- Organisms
and Environment Research Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, United Kingdom
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18
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Burkholderia cepacia Complex Regulation of Virulence Gene Expression: A Review. Genes (Basel) 2017; 8:genes8010043. [PMID: 28106859 PMCID: PMC5295037 DOI: 10.3390/genes8010043] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/11/2017] [Accepted: 01/12/2017] [Indexed: 12/31/2022] Open
Abstract
Burkholderia cepacia complex (Bcc) bacteria emerged as opportunistic pathogens in cystic fibrosis and immunocompromised patients. Their eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. Bcc bacteria have large and complex genomes, composed of two to four replicons, with variable numbers of insertion sequences. The complexity of Bcc genomes confers a high genomic plasticity to these bacteria, allowing their adaptation and survival to diverse habitats, including the human host. In this work, we review results from recent studies using omics approaches to elucidate in vivo adaptive strategies and virulence gene regulation expression of Bcc bacteria when infecting the human host or subject to conditions mimicking the stressful environment of the cystic fibrosis lung.
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19
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Wessler S, Schneider G, Backert S. Bacterial serine protease HtrA as a promising new target for antimicrobial therapy? Cell Commun Signal 2017; 15:4. [PMID: 28069057 PMCID: PMC5223389 DOI: 10.1186/s12964-017-0162-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022] Open
Abstract
Recent studies have demonstrated that the bacterial chaperone and serine protease high temperature requirement A (HtrA) is closely associated with the establishment and progression of several infectious diseases. HtrA activity enhances bacterial survival under stress conditions, but also has direct effects on functions of the cell adhesion protein E-cadherin and extracellular matrix proteins, including fibronectin and proteoglycans. Although HtrA cannot be considered as a pathogenic factor per se, it exhibits favorable characteristics making HtrA a potentially attractive drug target to combat various bacterial infections.
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Affiliation(s)
- Silja Wessler
- Department of Molecular Biology, Division of Microbiology, Paris-Lodron University of Salzburg, Billroth Str. 11, A-5020, Salzburg, Austria.
| | - Gisbert Schneider
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Vladimir-Prelog-Weg 4, CH-8093, Zürich, Switzerland
| | - Steffen Backert
- Division of Microbiology, University of Erlangen-Nuremberg, Staudtstr. 5, D-91058, Erlangen, Germany
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20
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Shastri S, Spiewak HL, Sofoluwe A, Eidsvaag VA, Asghar AH, Pereira T, Bull EH, Butt AT, Thomas MS. An efficient system for the generation of marked genetic mutants in members of the genus Burkholderia. Plasmid 2016; 89:49-56. [PMID: 27825973 PMCID: PMC5312678 DOI: 10.1016/j.plasmid.2016.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/24/2016] [Accepted: 11/04/2016] [Indexed: 12/22/2022]
Abstract
To elucidate the function of a gene in bacteria it is vital that targeted gene inactivation (allelic replacement) can be achieved. Allelic replacement is often carried out by disruption of the gene of interest by insertion of an antibiotic-resistance marker followed by subsequent transfer of the mutant allele to the genome of the host organism in place of the wild-type gene. However, due to their intrinsic resistance to many antibiotics only selected antibiotic-resistance markers can be used in members of the genus Burkholderia, including the Burkholderia cepacia complex (Bcc). Here we describe the construction of improved antibiotic-resistance cassettes that specify resistance to kanamycin, chloramphenicol or trimethoprim effectively in the Bcc and related species. These were then used in combination with and/or to construct a series enhanced suicide vectors, pSHAFT2, pSHAFT3 and pSHAFT-GFP to facilitate effective allelic replacement in the Bcc. Validation of these improved suicide vectors was demonstrated by the genetic inactivation of selected genes in the Bcc species Burkholderia cenocepacia and B. lata, and in the non-Bcc species, B. thailandensis. We have constructed antibiotic-resistance cassettes and suicide vectors for use in Burkholderia and related species. These vectors facilitate construction of mutants by gene disruption with antibiotic-resistance markers. We have validated the utility of the vectors for marked genetic inactivation in members of the genus Burkholderia.
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Affiliation(s)
- Sravanthi Shastri
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Helena L Spiewak
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Aderonke Sofoluwe
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Vigdis A Eidsvaag
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Atif H Asghar
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Tyrone Pereira
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Edward H Bull
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Aaron T Butt
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
| | - Mark S Thomas
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK,.
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21
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Custódio R, McLean CJ, Scott AE, Lowther J, Kennedy A, Clarke DJ, Campopiano DJ, Sarkar-Tyson M, Brown AR. Characterization of secreted sphingosine-1-phosphate lyases required for virulence and intracellular survival of Burkholderia pseudomallei. Mol Microbiol 2016; 102:1004-1019. [PMID: 27632710 DOI: 10.1111/mmi.13531] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2016] [Indexed: 01/09/2023]
Abstract
Sphingosine-1-phosphate (S1P), a bioactive sphingolipid metabolite, plays a critical role in the orchestration of immune responses. S1P levels within the mammalian host are tightly regulated, in part through the activity of S1P lyase (S1PL) which catalyses its irreversible degradation. Herein, we describe the identification and characterization of secreted S1PL orthologues encoded by the facultative intracellular bacteria Burkholderia pseudomallei and Burkholderia thailandensis. These bacterial orthologues exhibited S1PL enzymatic activity, functionally complemented an S1PL-deficient yeast strain and conferred resistance to the antimicrobial sphingolipid D-erythro-sphingosine. We report that secretion of these bacterial S1PLs is pH-dependent, and is observed during intracellular infection. S1PL-deficient mutants displayed impaired intracellular replication in murine macrophages (associated with an inability to evade the maturing phagosome) and were significantly attenuated in murine and larval infection models. Furthermore, treatment of Burkholderia-infected macrophages with either S1P or a selective agonist of S1P receptor 1 enhanced bacterial colocalisation with LAMP-1 and reduced their intracellular survival. In summary, our studies confirm bacterial-encoded S1PL as a critical virulence determinant of B. pseudomallei and B. thailandensis, further highlighting the pivotal role of S1P in host-pathogen interactions. In addition, our data suggest that S1P pathway modulators have potential for the treatment of intracellular infection.
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Affiliation(s)
- Rafael Custódio
- Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
| | | | - Andrew E Scott
- Microbiology, Defence Science and Technology Laboratory, Porton Down, UK
| | | | | | | | | | - Mitali Sarkar-Tyson
- Microbiology, Defence Science and Technology Laboratory, Porton Down, UK.,Marshall Centre for Infectious Diseases and Training, School of Pathology and Laboratory Medicine, University of Western Australia, WA 6009, Australia
| | - Alan R Brown
- Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
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22
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HtrA Is Important for Stress Resistance and Virulence in Haemophilus parasuis. Infect Immun 2016; 84:2209-2219. [PMID: 27217419 PMCID: PMC4962635 DOI: 10.1128/iai.00147-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/12/2016] [Indexed: 02/06/2023] Open
Abstract
Haemophilus parasuis is an opportunistic pathogen that causes Glässer's disease in swine, with polyserositis, meningitis, and arthritis. The high-temperature requirement A (HtrA)-like protease, which is involved in protein quality control, has been reported to be a virulence factor in many pathogens. In this study, we showed that HtrA of H. parasuis (HpHtrA) exhibited both chaperone and protease activities. Finally, nickel import ATP-binding protein (NikE), periplasmic dipeptide transport protein (DppA), and outer membrane protein A (OmpA) were identified as proteolytic substrates for HpHtrA. The protease activity reached its maximum at 40°C in a time-dependent manner. Disruption of the htrA gene from strain SC1401 affected tolerance to temperature stress and resistance to complement-mediated killing. Furthermore, increased autoagglutination and biofilm formation were detected in the htrA mutant. In addition, the htrA mutant was significantly attenuated in virulence in the murine model of infection. Together, these data demonstrate that HpHtrA plays an important role in the virulence of H. parasuis.
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23
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Zhang S, He L, Yang Y, Yang B, Liao Y, Xu X, Li J, Yang X, Li J. Effective in situ repair and bacteriostatic material of tooth enamel based on salivary acquired pellicle inspired oligomeric procyanidins. Polym Chem 2016. [DOI: 10.1039/c6py01362g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Remineralization and reduction of cariogenic bacteria at the tooth surface are effective ways to treat dental caries.
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Affiliation(s)
- Shuhui Zhang
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Libang He
- State Key Laboratory of Oral Diseases
- West China Hospital of Stomatology
- Sichuan University
- Chengdu
- China
| | - Yinxin Yang
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Bo Yang
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Yixue Liao
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Xinyuan Xu
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Jiyao Li
- State Key Laboratory of Oral Diseases
- West China Hospital of Stomatology
- Sichuan University
- Chengdu
- China
| | - Xiao Yang
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
| | - Jianshu Li
- College of Polymer Science and Engineering
- State Key Laboratory of Polymer Materials Engineering
- Sichuan University
- Chengdu
- China
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24
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Tegtmeyer N, Moodley Y, Yamaoka Y, Pernitzsch SR, Schmidt V, Traverso FR, Schmidt TP, Rad R, Yeoh KG, Bow H, Torres J, Gerhard M, Schneider G, Wessler S, Backert S. Characterisation of worldwide Helicobacter pylori strains reveals genetic conservation and essentiality of serine protease HtrA. Mol Microbiol 2015; 99:925-44. [PMID: 26568477 PMCID: PMC4832355 DOI: 10.1111/mmi.13276] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2015] [Indexed: 12/11/2022]
Abstract
HtrA proteases and chaperones exhibit important roles in periplasmic protein quality control and stress responses. The genetic inactivation of htrA has been described for many bacterial pathogens. However, in some cases such as the gastric pathogen Helicobacter pylori, HtrA is secreted where it cleaves the tumour‐suppressor E‐cadherin interfering with gastric disease development, but the generation of htrA mutants is still lacking. Here, we show that the htrA gene locus is highly conserved in worldwide strains. HtrA presence was confirmed in 992 H. pylori isolates in gastric biopsy material from infected patients. Differential RNA‐sequencing (dRNA‐seq) indicated that htrA is encoded in an operon with two subsequent genes, HP1020 and HP1021. Genetic mutagenesis and complementation studies revealed that HP1020 and HP1021, but not htrA, can be mutated. In addition, we demonstrate that suppression of HtrA proteolytic activity with a newly developed inhibitor is sufficient to effectively kill H. pylori, but not other bacteria. We show that Helicobacter
htrA is an essential bifunctional gene with crucial intracellular and extracellular functions. Thus, we describe here the first microbe in which htrA is an indispensable gene, a situation unique in the bacterial kingdom. HtrA can therefore be considered a promising new target for anti‐bacterial therapy.
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Affiliation(s)
- Nicole Tegtmeyer
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058, Erlangen, Germany.,Institut für Medizinische Mikrobiologie, Otto-von-Guericke Universität Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany
| | - Yoshan Moodley
- Department of Zoology, University of Venda, Private Bag X5050, Thohoyandou, 0950, South Africa.,Konrad-Lorenz-Institut für Vergleichende Verhaltensforschung, Department für Integrative Biologie und Evolution, Veterinärmedizinische Universität Wien, Savoyenstr. 1a, A-1160, Wien, Austria
| | - Yoshio Yamaoka
- Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, Dept. Medicine-Gastroenterology, Houston, TX, USA.,Oita University Faculty of Medicine, Dept. Environmental and Preventive Medicine, Yufu, Japan
| | - Sandy Ramona Pernitzsch
- Research Center for Infectious Diseases (ZINF), University of Würzburg, Josef-Schneider-Str. 2/Bau D15, D-97080, Würzburg, Germany
| | - Vanessa Schmidt
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058, Erlangen, Germany
| | - Francisco Rivas Traverso
- Institut für Medizinische Mikrobiologie, Otto-von-Guericke Universität Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany
| | - Thomas P Schmidt
- Department of Molecular Biology, Division of Microbiology, Paris-Lodron University of Salzburg, Billroth Str. 11, A-5020, Salzburg, Austria
| | - Roland Rad
- II Medical Department, Klinikum Rechts der Isar, Technical University Munich, Munich, Germany.,German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Khay Guan Yeoh
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ho Bow
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Javier Torres
- Unidad de Investigacion en Enfermedades Infecciosas, UMAE Pediatria, IMSS, Mexico City, Mexico
| | - Markus Gerhard
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich, 81675, Germany
| | - Gisbert Schneider
- ETH Zürich, Institut für Pharmazeutische Wissenschaften, Vladimir-Prelog-Weg 4, CH-8093, Zürich, Switzerland
| | - Silja Wessler
- Department of Molecular Biology, Division of Microbiology, Paris-Lodron University of Salzburg, Billroth Str. 11, A-5020, Salzburg, Austria
| | - Steffen Backert
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058, Erlangen, Germany.,Institut für Medizinische Mikrobiologie, Otto-von-Guericke Universität Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany
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25
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Bloodworth RAM, Zlitni S, Brown ED, Cardona ST. An electron transfer flavoprotein is essential for viability and its depletion causes a rod-to-sphere change in Burkholderia cenocepacia. MICROBIOLOGY-SGM 2015; 161:1909-1920. [PMID: 26253539 DOI: 10.1099/mic.0.000156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Essential gene studies often reveal novel essential functions for genes with dispensable homologues in other species. This is the case with the widespread family of electron transfer flavoproteins (ETFs), which are required for the metabolism of specific substrates or for symbiotic nitrogen fixation in some bacteria. Despite these non-essential functions high-throughput screens have identified ETFs as putatively essential in several species. In this study, we constructed a conditional expression mutant of one of the ETFs in Burkholderia cenocepacia, and demonstrated that its expression is essential for growth on both complex media and a variety of single-carbon sources. We further demonstrated that the two subunits EtfA and EtfB interact with each other, and that cells depleted of ETF are non-viable and lack redox potential. These cells also transition from the short rods characteristic of Burkholderia cenocepacia to small spheres independently of MreB. The putative membrane partner ETF dehydrogenase also induced the same rod-to-sphere change. We propose that the ETF of Burkholderia cenocepacia is a novel antibacterial target.
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Affiliation(s)
| | - Soumaya Zlitni
- Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Eric D Brown
- Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Silvia T Cardona
- Department of Microbiology, University of Manitoba, Winnipeg, Canada.,Department of Medical Microbiology & Infectious Disease, University of Manitoba, Winnipeg, Canada
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26
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Graminho ER, Takaya N, Nakamura A, Hoshino T. Purification, biochemical characterization, and genetic cloning of the phytase produced by Burkholderia sp. strain a13. J GEN APPL MICROBIOL 2015; 61:15-23. [DOI: 10.2323/jgam.61.15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Naoki Takaya
- Faculty of Life and Environmental Sciences, University of Tsukuba
| | - Akira Nakamura
- Faculty of Life and Environmental Sciences, University of Tsukuba
| | - Takayuki Hoshino
- Faculty of Life and Environmental Sciences, University of Tsukuba
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27
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Hanuszkiewicz A, Pittock P, Humphries F, Moll H, Rosales AR, Molinaro A, Moynagh PN, Lajoie GA, Valvano MA. Identification of the flagellin glycosylation system in Burkholderia cenocepacia and the contribution of glycosylated flagellin to evasion of human innate immune responses. J Biol Chem 2014; 289:19231-44. [PMID: 24841205 DOI: 10.1074/jbc.m114.562603] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen threatening patients with cystic fibrosis. Flagella are required for biofilm formation, as well as adhesion to and invasion of epithelial cells. Recognition of flagellin via the Toll-like receptor 5 (TLR5) contributes to exacerbate B. cenocepacia-induced lung epithelial inflammatory responses. In this study, we report that B. cenocepacia flagellin is glycosylated on at least 10 different sites with a single sugar, 4,6-dideoxy-4-(3-hydroxybutanoylamino)-D-glucose. We have identified key genes that are required for flagellin glycosylation, including a predicted glycosyltransferase gene that is linked to the flagellin biosynthesis cluster and a putative acetyltransferase gene located within the O-antigen lipopolysaccharide cluster. Another O-antigen cluster gene, rmlB, which is required for flagellin glycan and O-antigen biosynthesis, was essential for bacterial viability, uncovering a novel target against Burkholderia infections. Using glycosylated and nonglycosylated purified flagellin and a cell reporter system to assess TLR5-mediated responses, we also show that the presence of glycan in flagellin significantly impairs the inflammatory response of epithelial cells. We therefore suggest that flagellin glycosylation reduces recognition of flagellin by host TLR5, providing an evasive strategy to infecting bacteria.
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Affiliation(s)
- Anna Hanuszkiewicz
- From the Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast BT9 7AE, Ireland, United Kingdom
| | - Paula Pittock
- the Don Rix Protein Identification Facility, Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Fiachra Humphries
- the Institute of Immunology, Department of Biology, National University of Ireland at Maynooth, Maynooth, County Kildare, Ireland
| | - Hermann Moll
- the Bioanalytical Chemistry, Research Centre Borstel, 23845 Borstel, Germany
| | - Amanda Roa Rosales
- the Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada, and
| | - Antonio Molinaro
- the Dipartimento di Scienze Chimiche, Università di Napoli, Federico II, 80134 Naples, Italy
| | - Paul N Moynagh
- From the Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast BT9 7AE, Ireland, United Kingdom, the Institute of Immunology, Department of Biology, National University of Ireland at Maynooth, Maynooth, County Kildare, Ireland
| | - Gilles A Lajoie
- the Don Rix Protein Identification Facility, Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Miguel A Valvano
- From the Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast BT9 7AE, Ireland, United Kingdom, the Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada, and
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28
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Deng CY, Deng AH, Sun ST, Wang L, Wu J, Wu Y, Chen XY, Fang RX, Wen TY, Qian W. The periplasmic PDZ domain-containing protein Prc modulates full virulence, envelops stress responses, and directly interacts with dipeptidyl peptidase of Xanthomonas oryzae pv. oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:101-112. [PMID: 24200074 DOI: 10.1094/mpmi-08-13-0234-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PDZ domain-containing proteases, also known as HtrA family proteases, play important roles in bacterial cells by modulating disease pathogenesis and cell-envelope stress responses. These proteases have diverse functions through proteolysis- and nonproteolysis-dependent modes. Here, we report that the genome of the causative agent of rice bacterial blight, Xanthomonas oryzae pv. oryzae, encodes seven PDZ domain-containing proteins. Systematic inactivation of their encoding genes revealed that PXO_01122 and PXO_04290 (prc) are involved in virulence. prc encodes a putative HtrA family protease that localizes in the bacterial periplasm. Mutation of prc also resulted in susceptibility to multiple environmental stresses, including H2O2, sodium dodecylsulfate, and osmolarity stresses. Comparative subproteomic analyses showed that the amounts of 34 periplasmic proteins were lower in the prc mutant than in wild-type. These proteins were associated with proteolysis, biosynthesis of macromolecules, carbohydrate or energy metabolism, signal transduction, and protein translocation or folding. We provide in vivo and in vitro evidence demonstrating that Prc stabilizes and directly binds to one of these proteins, DppP, a dipeptidyl peptidase contributing to full virulence. Taken together, our results suggest that Prc contributes to bacterial virulence by acting as a periplasmic modulator of cell-envelope stress responses.
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29
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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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30
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Hansen G, Hilgenfeld R. Architecture and regulation of HtrA-family proteins involved in protein quality control and stress response. Cell Mol Life Sci 2013; 70:761-75. [PMID: 22806565 PMCID: PMC11113883 DOI: 10.1007/s00018-012-1076-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/24/2012] [Accepted: 06/26/2012] [Indexed: 12/22/2022]
Abstract
Protein quality control is vital for all living cells and sophisticated molecular mechanisms have evolved to prevent the excessive accumulation of unfolded proteins. High-temperature requirement A (HtrA) proteases have been identified as important ATP-independent quality-control factors in most species. HtrA proteins harbor a serine-protease domain and at least one peptide-binding PDZ domain to ensure efficient removal of misfolded or damaged proteins. One distinctive property of HtrAs is their ability to assemble into complex oligomers. Whereas all examined HtrAs are capable of forming pyramidal 3-mers, higher-order complexes consisting of up to 24 molecules have been reported. Tight control of chaperone and protease function is of pivotal importance in preventing deleterious HtrA-protease activity. In recent years, structural biology provided detailed insights into the molecular basis of the regulatory mechanisms, which include unique intramolecular allosteric signaling cascades and the dynamic switching of oligomeric states of HtrA proteins. Based on these results, functional models for many family members have been developed. The HtrA protein family represents a remarkable example of how structural and functional diversity is attained from the assembly of simple molecular building blocks.
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Affiliation(s)
- Guido Hansen
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, 23538, Lübeck, Germany.
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31
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Bloodworth RAM, Gislason AS, Cardona ST. Burkholderia cenocepacia conditional growth mutant library created by random promoter replacement of essential genes. Microbiologyopen 2013; 2:243-58. [PMID: 23389959 PMCID: PMC3633349 DOI: 10.1002/mbo3.71] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/24/2012] [Accepted: 01/08/2013] [Indexed: 01/05/2023] Open
Abstract
Identification of essential genes by construction of conditional knockouts with inducible promoters allows the identification of essential genes and creation of conditional growth (CG) mutants that are then available as genetic tools for further studies. We used large-scale transposon delivery of the rhamnose-inducible promoter, PrhaB followed by robotic screening of rhamnose-dependent growth to construct a genomic library of 106 Burkholderia cenocepacia CG mutants. Transposon insertions were found where PrhaB was in the same orientation of widely conserved, well-characterized essential genes as well as genes with no previous records of essentiality in other microorganisms. Using previously reported global gene-expression analyses, we demonstrate that PrhaB can achieve the wide dynamic range of expression levels required for essential genes when the promoter is delivered randomly and mutants with rhamnose-dependent growth are selected. We also show specific detection of the target of an antibiotic, novobiocin, by enhanced sensitivity of the corresponding CG mutant (PrhaB controlling gyrB expression) within the library. Modulation of gene expression to achieve 30-60% of wild-type growth created conditions for specific hypersensitivity demonstrating the value of the CG mutant library for chemogenomic experiments. In summary, CG mutants can be obtained on a large scale by random delivery of a tightly regulated inducible promoter into the bacterial chromosome followed by a simple screening for the CG phenotype, without previous information on gene essentiality.
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Affiliation(s)
- Ruhi A M Bloodworth
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
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32
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Denman CC, Brown AR. Mannitol promotes adherence of an outbreak strain of Burkholderia multivorans via an exopolysaccharide-independent mechanism that is associated with upregulation of newly identified fimbrial and afimbrial adhesins. MICROBIOLOGY-SGM 2013; 159:771-781. [PMID: 23378576 DOI: 10.1099/mic.0.064832-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia multivorans, a member of the Burkholderia cepacia complex (Bcc), is an important pathogen of the cystic fibrosis (CF) lung. Mannitol, approved as an inhaled osmolyte therapy for use in CF patients, promotes exopolysaccharide (EPS) production by the Bcc. In the present study, we investigated the role of mannitol-induced EPS in the adherence of B. multivorans. We report that mannitol promoted adherence of two representative B. multivorans strains. However, whilst this enhanced adherence was largely EPS-dependent in an environmental isolate, it was EPS-independent within a CF outbreak strain, suggesting strain-to-strain variation in adhesins. Genome sequencing of the outbreak strain enabled the identification of two distinct loci encoding putative fimbrial and afimbrial adhesins. The putative fimbriae-encoding locus was found to be widely distributed amongst clinical and environmental B. multivorans. In contrast, the locus encoding the putative afimbrial adhesin (of the filamentous haemagglutinin family, FHA) was restricted to clinical isolates. Both loci contributed to biofilm formation and mucin adherence. Furthermore, we report that mannitol promoted expression of both loci, and that the locus encoding the putative FHA-family adhesin is a key determinant of the enhanced adherence observed following growth in mannitol. Our studies provide the first characterization, to our knowledge, of B. multivorans adhesins, and in so doing highlight the strain-dependent role of EPS in the Bcc and the difficulties in assigning phenotypic traits to Bcc EPS due to the wider response to mannitol. Our observations also highlight the need to monitor the microbiological effects of inhaled mannitol therapy in Bcc-infected CF patients.
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Affiliation(s)
- Carmen C Denman
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Alan R Brown
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
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33
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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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34
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Yudistira H, McClarty L, Bloodworth RAM, Hammond SA, Butcher H, Mark BL, Cardona ST. Phenylalanine induces Burkholderia cenocepacia phenylacetic acid catabolism through degradation to phenylacetyl-CoA in synthetic cystic fibrosis sputum medium. Microb Pathog 2011; 51:186-93. [PMID: 21511027 DOI: 10.1016/j.micpath.2011.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 03/23/2011] [Accepted: 04/05/2011] [Indexed: 11/15/2022]
Abstract
Synthetic cystic fibrosis sputum medium (SCFM) is rich in amino acids and supports robust growth of Burkholderia cenocepacia, a member of the Burkholderia cepacia complex (Bcc). Previous work demonstrated that B. cenocepacia phenylacetic acid (PA) catabolic genes are up-regulated during growth in SCFM and are required for full virulence in a Caenorhabditis elegans host model. In this work, we investigated the role of phenylalanine, one of the aromatic amino acids present in SCFM, as an inducer of the PA catabolic pathway. Phenylalanine degradation intermediates were used as sole carbon sources for growth and gene reporter experiments. In addition to phenylalanine and PA, phenylethylamine, phenylpyruvate, and 2-phenylacetamide were usable as sole carbon sources by wild type B. cenocepacia K56-2, but not by a PA catabolism-defective mutant. EMSA analysis showed that the binding of PaaR, the negative regulator protein of B. cenocepacia PA catabolism, to PA regulatory DNA could only be relieved by phenylacetyl-Coenzyme A (PA-CoA), but not by any of the putative phenylalanine degradation intermediates. Taken together, our results show that in B. cenocepacia, phenylalanine is catabolized to PA and induces PA catabolism through PA activation to PA-CoA. Thus, PaaR shares the same inducer with PaaX, the regulator of PA catabolism in Escherichia coli, despite belonging to a different protein family.
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Affiliation(s)
- Harry Yudistira
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
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35
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Loutet SA, Mussen LE, Flannagan RS, Valvano MA. A two-tier model of polymyxin B resistance in Burkholderia cenocepacia. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:278-285. [PMID: 23761261 DOI: 10.1111/j.1758-2229.2010.00222.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Burkholderia cenocepacia is an environmental bacterium causing serious human opportunistic infections and is extremely resistant to multiple antibiotics including antimicrobial peptides, such as polymyxin B (PmB). Extreme antibiotic resistance is attributed to outer membrane impermeability ('intrinsic' resistance). Previous work showed that production of full-length lipopolysaccharide (LPS) prevents surface binding of PmB. We hypothesized that two tiers of resistance mechanisms rendering different thresholds of PmB resistance exist in B. cenocepacia. To test this notion, candidate genes were mutated in two isogenic strains expressing full-length LPS or truncated LPS devoid of heptose ('heptoseless LPS') respectively. We uncovered various proteins required for PmB resistance only in the strain with heptoseless LPS. These proteins are not involved in preventing PmB binding to whole cells or permeabilization of the outer membrane. Our results support a two-tier model of PmB resistance in B. cenocepacia. One tier sets a very high threshold mediated by the LPS and the outer membrane permeability barrier. The second tier sets a lower threshold that may play a role in PmB resistance only when outer membrane permeability is compromised. This model may be of general applicability to understanding the high antimicrobial peptide resistance of environmental opportunistic pathogens.
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Affiliation(s)
- Slade A Loutet
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada N6A 5C1 Department of Medicine, University of Western Ontario, London, ON, Canada N6A 5C1
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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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Costello A, Herbert G, Fabunmi L, Schaffer K, Kavanagh KA, Caraher EM, Callaghan M, McClean S. Virulence of an emerging respiratory pathogen, genus Pandoraea, in vivo and its interactions with lung epithelial cells. J Med Microbiol 2010; 60:289-299. [PMID: 21127160 DOI: 10.1099/jmm.0.022657-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pandoraea species have emerged as opportunistic pathogens among cystic fibrosis (CF) and non-CF patients. Pandoraea pulmonicola is the predominant Pandoraea species among Irish CF patients. The objective of this study was to investigate the pathogenicity and potential mechanisms of virulence of Irish P. pulmonicola isolates and strains from other Pandoraea species. Three patients from whom the P. pulmonicola isolates were isolated have since died. The in vivo virulence of these and other Pandoraea strains was examined by determining the ability to kill Galleria mellonella larvae. The P. pulmonicola strains generally were the most virulent of the species tested, with three showing a comparable or greater level of virulence in vivo relative to another CF pathogen, Burkholderia cenocepacia, whilst strains from two other species, Pandoraea apista and Pandoraea pnomenusa, were considerably less virulent. For all Pandoraea species, whole cells were required for larval killing, as cell-free supernatants had little effect on larval survival. Overall, invasive Pandoraea strains showed comparable invasion of two independent lung epithelial cell lines, irrespective of whether they had a CF phenotype. Pandoraea strains were also capable of translocation across polarized lung epithelial cell monolayers. Although protease secretion was a common characteristic across the genus, it is unlikely to be involved in pathogenesis. In conclusion, whilst multiple mechanisms of pathogenicity may exist across the genus Pandoraea, it appears that lung cell invasion and translocation contribute to the virulence of P. pulmonicola strains.
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Affiliation(s)
- Anne Costello
- Centre of Applied Science for Health, ITT Dublin, Tallaght, Dublin 24, Ireland.,Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
| | - Gillian Herbert
- Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
| | - Lydia Fabunmi
- Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
| | - Kirsten Schaffer
- Department of Microbiology, St Vincent's University Hospital, Elm Park, Dublin, Ireland
| | - Kevin A Kavanagh
- Department of Biology, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Emma M Caraher
- Centre of Applied Science for Health, ITT Dublin, Tallaght, Dublin 24, Ireland.,Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
| | - Máire Callaghan
- Centre of Applied Science for Health, ITT Dublin, Tallaght, Dublin 24, Ireland.,Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
| | - Siobhán McClean
- Centre of Applied Science for Health, ITT Dublin, Tallaght, Dublin 24, Ireland.,Centre of Microbial Host Interactions, ITT Dublin, Tallaght, Dublin 24, Ireland
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Different contributions of HtrA protease and chaperone activities to Campylobacter jejuni stress tolerance and physiology. Appl Environ Microbiol 2010; 77:57-66. [PMID: 21075890 DOI: 10.1128/aem.01603-10] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The microaerophilic bacterium Campylobacter jejuni is the most common cause of bacterial food-borne infections in the developed world. Tolerance to environmental stress relies on proteases and chaperones in the cell envelope, such as HtrA and SurA. HtrA displays both chaperone and protease activities, but little is known about how each of these activities contributes to stress tolerance in bacteria. In vitro experiments showed temperature-dependent protease and chaperone activities of C. jejuni HtrA. A C. jejuni mutant lacking only the protease activity of HtrA was used to show that the HtrA chaperone activity is sufficient for growth at high temperature or under oxidative stress, whereas the HtrA protease activity is essential only under conditions close to the growth limit for C. jejuni. However, the protease activity was required to prevent induction of the cytoplasmic heat shock response even under optimal growth conditions. Interestingly, the requirement of HtrA at high temperatures was found to depend on the oxygen level, and our data suggest that HtrA may protect oxidatively damaged proteins. Finally, protease activity stimulates HtrA production and oligomer formation, suggesting that a regulatory role depends on the protease activity of HtrA. Studying a microaerophilic organism encoding only two known periplasmic chaperones (HtrA and SurA) revealed an efficient HtrA chaperone activity and proposed multiple roles of the protease activity, increasing our understanding of HtrA in bacterial physiology.
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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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Burkholderia cepacia Complex: Emerging Multihost Pathogens Equipped with a Wide Range of Virulence Factors and Determinants. Int J Microbiol 2010; 2011. [PMID: 20811541 PMCID: PMC2929507 DOI: 10.1155/2011/607575] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 06/02/2010] [Indexed: 12/04/2022] Open
Abstract
The Burkholderia cepacia complex (Bcc) comprises at least 17 closely-related species of the β-proteobacteria subdivision, widely distributed in natural and man-made inhabitats. Bcc bacteria are endowed with an extraordinary metabolic diversity and emerged in the 1980s as life-threatening and difficult-to-treat pathogens among patients suffering from cystic fibrosis. More recently, these bacteria became recognized as a threat to hospitalized patients suffering from other diseases, in particular oncological patients. In the present paper, we review these and other traits of Bcc bacteria, as well as some of the strategies used to identify and validate the virulence factors and determinants used by these bacteria. The identification and characterization of these virulence factors is expected to lead to the design of novel therapeutic strategies to fight the infections caused by these emergent multidrug resistant human pathogens.
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Castonguay-Vanier J, Vial L, Tremblay J, Déziel E. Drosophila melanogaster as a model host for the Burkholderia cepacia complex. PLoS One 2010; 5:e11467. [PMID: 20635002 PMCID: PMC2902503 DOI: 10.1371/journal.pone.0011467] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 05/19/2010] [Indexed: 02/06/2023] Open
Abstract
Background Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis. In order to investigate the virulence of the Bcc, several alternative infection models have been developed. To this end, the fruit fly is increasingly used as surrogate host, and its validity to enhance our understanding of host-pathogen relationships has been demonstrated with a variety of microorganisms. Moreover, its relevance as a suitable alternative to mammalian hosts has been confirmed with vertebrate organisms. Methodology/Principal Findings The aim of this study was to establish Drosophila melanogaster as a surrogate host for species from the Bcc. While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations. Results obtained with the fruit fly model are comparable with results obtained using mammalian infection models. Furthermore, validity of the Drosophila infection model was confirmed with B. cenocepacia K56-2 mutants known to be less virulent in murine hosts or in other alternative models. Competitive index (CI) analyses were also performed using the fruit fly as host. Results of CI experiments agree with those obtained with mammalian models. Conclusions/Significance We conclude that Drosophila is a useful alternative infection model for Bcc and that fly pricking assays and competition indices are two complementary methods for virulence testing. Moreover, CI results indicate that this method is more sensitive than mortality tests.
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Affiliation(s)
- Josée Castonguay-Vanier
- Institut National de la Recherche Scientifique (INRS)-Institut Armand Frappier, Laval, Canada
| | - Ludovic Vial
- Institut National de la Recherche Scientifique (INRS)-Institut Armand Frappier, Laval, Canada
| | - Julien Tremblay
- Institut National de la Recherche Scientifique (INRS)-Institut Armand Frappier, Laval, Canada
| | - Eric Déziel
- Institut National de la Recherche Scientifique (INRS)-Institut Armand Frappier, Laval, Canada
- * E-mail:
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Ribeiro-Guimarães ML, Marengo EB, Tempone AJ, Amaral JJ, Klitzke CF, Silveira EKXD, Portaro FCV, Pessolani MCV. Cloning, expression and characterisation of an HtrA-like serine protease produced in vivo by Mycobacterium leprae. Mem Inst Oswaldo Cruz 2010; 104:1132-8. [PMID: 20140374 DOI: 10.1590/s0074-02762009000800010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Accepted: 11/30/2009] [Indexed: 11/22/2022] Open
Abstract
Members of the high temperature requirement A (HtrA) family of chaperone proteases have been shown to play a role in bacterial pathogenesis. In a recent report, we demonstrated that the gene ML0176, which codes for a predicted HtrA-like protease, a gene conserved in other species of mycobacteria, is transcribed by Mycobacterium leprae in human leprosy lesions. In the present study, the recombinant ML0176 protein was produced and its enzymatic properties investigated. M. lepraerecombinant ML0176 was able to hydrolyse a variety of synthetic and natural peptides. Similar to other HtrA proteins, this enzyme displayed maximum proteolytic activity at temperatures above 40 degrees C and was completely inactivated by aprotinin, a protease inhibitor with high selectivity for serine proteases. Finally, analysis of M. leprae ML0176 specificity suggested a broader cleavage preference than that of previously described HtrAs homologues. In summary, we have identified an HtrA-like protease in M. lepraethat may constitute a potential new target for the development of novel prophylactic and/or therapeutic strategies against mycobacterial infections.
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Clarke DJ, Ortega XP, Mackay CL, Valvano MA, Govan JRW, Campopiano DJ, Langridge-Smith P, Brown AR. Subdivision of the bacterioferritin comigratory protein family of bacterial peroxiredoxins based on catalytic activity. Biochemistry 2010; 49:1319-30. [PMID: 20078128 DOI: 10.1021/bi901703m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, thus conferring resistance to oxidative stress. Using high-resolution mass spectrometry, we recently reclassified one such peroxiredoxin, bacterioferritin comigratory protein (BCP) of Escherichia coli, as an atypical 2-Cys peroxiredoxin that functions through the formation of an intramolecular disulfide bond between the active and resolving cysteine. An engineered E. coli BCP, which lacked the resolving cysteine, retained enzyme activity through a novel catalytic pathway. Unlike the active cysteine, the resolving cysteine of BCP peroxiredoxins is not conserved across all members of the family. To clarify the catalytic mechanism of native BCP enzymes that lack the resolving cysteine, we have investigated the BCP homologue of Burkholderia cenocepacia. We demonstrate that the B. cenocepacia BCP (BcBCP) homologue functions through a 1-Cys catalytic pathway. During catalysis, BcBCP can utilize thioredoxin as a reductant for the sulfenic acid intermediate. However, significantly higher peroxidase activity is observed utilizing glutathione as a resolving cysteine and glutaredoxin as a redox partner. Introduction of a resolving cysteine into BcBCP changes the activity from a 1-Cys pathway to an atypical 2-Cys pathway, analogous to the E. coli enzyme. In contrast to the native B. cenocepacia enzyme, thioredoxin is the preferred redox partner for this atypical 2-Cys variant. BCP-deficient B. cenocepacia exhibit a growth-phase-dependent hypersensitivity to oxidative killing. On the basis of sequence alignments, we believe that BcBCP described herein is representative of the major class of bacterial BCP peroxiredoxins. To our knowledge, this is the first detailed characterization of their catalytic activity. These studies support the subdivision of the BCP family of peroxiredoxins into two classes based on their catalytic activity.
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Affiliation(s)
- David J Clarke
- SIRCAMS, School of Chemistry, University of Edinburgh, Edinburgh, UK
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Jiao XD, Zhang M, Cheng S, Sun L. Analysis of Edwardsiella tarda DegP, a serine protease and a protective immunogen. FISH & SHELLFISH IMMUNOLOGY 2010; 28:672-677. [PMID: 20060910 DOI: 10.1016/j.fsi.2010.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 12/23/2009] [Accepted: 01/03/2010] [Indexed: 05/28/2023]
Abstract
Edwardsiella tarda is a severe aquaculture pathogen with a broad host range that includes humans, animal, and fish. A gene (degP(Et)) encoding a DegP homologue was cloned from TX01, a pathogenic E. tarda strain isolated from diseased fish. DegP(Et) shares high sequence identities with the DegP proteins of several bacterial species. Functional analyses showed that degP(Et) could complement the temperature-sensitive phenotype of an Escherichia coli degP null mutant. Expression of degP(Et) in TX01 was modulated by growth phase and temperature, the latter possibly through the action of the sigma(E)-like factor. Overexpression of degP(Et) (i) enhanced the ability of TX01 to disseminate in fish blood at the advanced stage of infection, (ii) heightened the activity of type 2 autoinducer, and (iii) increased the expression of luxS and the genes encoding components of the virulence-associated type III secretion system. Recombinant DegP(Et) purified from E. coli was a serine protease that exhibited maximum activity at 40 degrees C and pH8.0. The proteolytic activity of recombinant DegP(Et) depended on the catalytic triad and the PDZ domains. Immunoprotective analyses showed that purified recombinant DegP(Et) was a protective immunogen that could induce the production of specific serum antibodies and elicit strong protective immunity in fish vaccinated with DegP(Et).
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Affiliation(s)
- Xu-dong Jiao
- Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, PR China; Graduate University of the Chinese Academy of Sciences, Beijing 100049, PR China
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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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PepD participates in the mycobacterial stress response mediated through MprAB and SigE. J Bacteriol 2010; 192:1498-510. [PMID: 20061478 DOI: 10.1128/jb.01167-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Currently, one-third of the world's population is believed to be latently infected with Mycobacterium tuberculosis. The mechanisms by which M. tuberculosis establishes latent infection remain largely undefined. mprAB encodes a two-component signal transduction system required by M. tuberculosis for aspects of persistent infection. MprAB regulates a large and diverse group of genetic determinants in response to membrane stress, including the extracytoplasmic function (ECF) sigma factor sigE and the HtrA-like serine protease pepD. Recent studies have demonstrated that PepD functions as both a protease and chaperone in vitro. In addition, inactivation of pepD alters the virulence of M. tuberculosis in a mouse model system of infection. Here, we demonstrate that PepD plays an important role in the stress response network of Mycobacterium mediated through MprAB and SigE. In particular, we demonstrate that the protease activity of PepD requires the PDZ domain, in addition to the catalytic serine at position 317. pepD expression initiates from at least three promoters in M. tuberculosis, including one that is regulated by SigE and is located upstream of the mprA coding sequence. Deletion of pepD or mprAB in Mycobacterium smegmatis and M. tuberculosis alters the stress response phenotypes of these strains, including increasing sensitivity to SDS and cell wall antibiotics and upregulating the expression of stress-responsive determinants, including sigE. Taking these data together, we hypothesize that PepD utilizes its PDZ domain to recognize and process misfolded proteins at the cell membrane, leading to activation of the MprAB and SigE signaling pathways and subsequent establishment of a positive feedback loop that facilitates bacterial adaptation.
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Jiao XD, Dang W, Hu YH, Sun L. Identification and immunoprotective analysis of an in vivo-induced Edwardsiella tarda antigen. FISH & SHELLFISH IMMUNOLOGY 2009; 27:633-638. [PMID: 19706328 DOI: 10.1016/j.fsi.2009.08.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2009] [Revised: 08/10/2009] [Accepted: 08/10/2009] [Indexed: 05/28/2023]
Abstract
Edwardsiella tarda is a severe aquaculture pathogen that can infect many important fish species cultured worldwide. The aim of this study was to evaluate the vaccine potential of an E. tarda antigen, Eta21, which was identified from a pathogenic E. tarda strain via the method of in vivo-induced antigen technology (IVIAT). Eta21 is 510-amino acid in length and shares approximately 58% sequence identity with a putative peptidase of several bacterial species. eta21 was subcloned into Escherichia coli, and recombinant Eta21 was purified as a histidine-tagged protein. When used as a subunit vaccine, purified recombinant Eta21 was effective against lethal E. tarda challenge in a Japanese flounder model. In order to improve the immunoprotective efficacy of Eta21, the chimera AgaV-Eta21 was constructed, which consists of Eta21 fused in-frame to the secretion domain of AgaV, an extracellular beta-agarase. E. coli DH5alpha harboring plasmid pTAET21, which constitutively expresses agaV-eta21, was able to produce and secret AgaV-Eta21 into the extracellular milieu. Vaccination of Japanese flounder with live DH5alpha/pTAET21 elicited immunoprotection that is significantly higher in level than that induced by vaccination with purified recombinant Eta21. Vaccination with DH5alpha/pTAET21 and recombinant Eta21 both induced the production of specific serum antibodies at four to eight weeks post-vaccination. Taken together, these results demonstrate that Eta21, especially that delivered by DH5alpha/pTAET21, is an effective vaccine candidate against E. tarda infection.
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Affiliation(s)
- Xu-dong Jiao
- Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, PR China
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Hamlin JNR, Bloodworth RAM, Cardona ST. Regulation of phenylacetic acid degradation genes of Burkholderia cenocepacia K56-2. BMC Microbiol 2009; 9:222. [PMID: 19835630 PMCID: PMC2770484 DOI: 10.1186/1471-2180-9-222] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 10/18/2009] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Metabolically versatile soil bacteria Burkholderia cepacia complex (Bcc) have emerged as opportunistic pathogens, especially of cystic fibrosis (CF). Previously, we initiated the characterization of the phenylacetic acid (PA) degradation pathway in B. cenocepacia, a member of the Bcc, and demonstrated the necessity of a functional PA catabolic pathway for full virulence in Caenorhabditis elegans. In this study, we aimed to characterize regulatory elements and nutritional requirements that control the PA catabolic genes in B. cenocepacia K56-2. RESULTS Translational fusions of the PA degradation gene promoters with eGFP were constructed and introduced in B. cenocepacia K56-2. eGFP expression was observed when the reporter strains were grown in minimal media containing glycerol and PA or other compounds expected to proceed through the PA pathway, and in synthetic CF medium (SCFM). Addition of succinate or glucose to the PA containing medium repressed eGFP expression. To show that BCAL0210, a putative TetR-type regulator gene encodes a regulator for the PA genes in B. cenocepacia, we developed a BCAL0210 insertional mutant reporter strain. Results show that these strains exhibit fluorescence regardless of the presence of PA in the culture. CONCLUSION The PA catabolic genes of B. cenocepacia K56-2 are induced by PA and other related compounds, are negatively regulated by PaaR (named herein), a TetR-type regulator, and are subjected to catabolic repression by glucose and succinate. As the PA catabolic pathway of B. cenocepacia appears to be induced during growth in synthetic cystic fibrosis medium (SCFM), further research is necessary to determine the relevance of this pathway in CF-like conditions and in other host-pathogen interactions.
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Affiliation(s)
- Jason N R Hamlin
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
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Saldías MS, Ortega X, Valvano MA. Burkholderia cenocepacia O antigen lipopolysaccharide prevents phagocytosis by macrophages and adhesion to epithelial cells. J Med Microbiol 2009; 58:1542-1548. [PMID: 19713359 DOI: 10.1099/jmm.0.013235-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chronic respiratory infections by the Burkholderia cepacia complex (Bcc) are of great concern to patients with cystic fibrosis. Bcc isolates may survive intracellularly within amoebae, respiratory epithelial cells and macrophages. The molecular mechanisms facilitating colonization and pathogenesis remain unclear. Given the importance of bacterial adhesion to host surfaces in microbial pathogenesis, we investigated the role of the O antigen LPS in the interaction of Burkholderia cenocepacia, a member of the Bcc, with macrophages and epithelial cells. Our results demonstrated that the O antigen modulates phagocytosis but does not affect intracellular survival of B. cenocepacia. Internalization of strains that lack O antigen was significantly increased compared to that of their isogenic smooth counterparts. However, no differences between rough and smooth strains were found in their ability to delay phagosomal maturation. We also found that the O antigen interfered with the ability of B. cenocepacia to adhere to bronchial epithelial cells, suggesting that this polysaccharide may mask one or more bacterial surface adhesins.
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Affiliation(s)
- M Soledad Saldías
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ximena Ortega
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Miguel A Valvano
- Department of Medicine, University of Western Ontario, London, Ontario N6A 5C1, Canada.,Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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Abstract
Bacteria infect the respiratory tract early in the course of cystic fibrosis disease, often fail to be eradicated, and together with an aggressive host inflammatory response, are thought to be key players in the irreversible airway damage from which most patients ultimately die. Although incompletely understood, certain aspects of the cystic fibrosis airway itself appear to favor the development of chronic modes of survival, in particular biofilm formation; this and the development of antibiotic resistance following exposure to multiple antibiotic courses lead to chronic, persistent infection. In addition to the common cystic fibrosis pathogens, such as Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa, several newer species are becoming more common. Furthermore, new molecular techniques have led to the identification of multiple different organisms within respiratory secretions, many of which are not cultured with conventional tools. Future work should aim to develop clinically applicable methods to identify these and to determine which have the potential to impact pulmonary health. We outline the basic tenets of infection control and treatment.
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Affiliation(s)
- Jane C Davies
- Department of Gene Therapy, Imperial College, Emmanuel Kaye Building, Manresa Road, London SW3 6NP, United Kingdom.
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