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Ebenberger SP, Cakar F, Chen Y, Pressler K, Eberl L, Schild S. The activity of the quorum sensing regulator HapR is modulated by the bacterial extracellular vesicle (BEV)-associated protein ObfA of Vibrio cholerae. J Extracell Vesicles 2024; 13:e12507. [PMID: 39252550 PMCID: PMC11386269 DOI: 10.1002/jev2.12507] [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: 04/03/2024] [Revised: 08/05/2024] [Accepted: 08/22/2024] [Indexed: 09/11/2024] Open
Abstract
Vibrio cholerae, a facultative human pathogen and causative agent of the severe diarrheal disease cholera, transits between the human intestinal tract and aquatic reservoirs. Like other bacterial species, V. cholerae continuously releases bacterial extracellular vesicles (BEVs) from its surface, which have been recently characterised for their role during in vivo colonisation. However, between epidemic outbreaks, V. cholerae persists in the biofilm mode for extended periods in aquatic reservoirs, which enhances environmental fitness and host transition. In this study, we investigated the effect of V. cholerae BEVs on biofilm formation, a critical feature for ex vivo survival. In contrast to BEVs from planktonic cultures, our results show that physiological concentrations of BEVs from dynamic biofilm cultures facilitate V. cholerae biofilm formation, which could be linked to a proteinaceous factor. Comparative proteomic analyses of planktonic- and biofilm-derived BEVs identified a previously uncharacterised outer membrane protein as an abundant component of dynamic biofilm-derived BEVs, which was found to be responsible for the BEV-dependent enhancement of biofilm production. Consequently, this protein was named outer membrane-associated biofilm facilitating protein A (ObfA). Comprehensive molecular studies unravelled ObfA as a negative modulator of HapR activity. HapR is a key transcriptional regulator of the V. cholerae quorum sensing (QS) cascade acting as a potent repressor of biofilm formation and virulence. Consistently, obfA mutants not only exhibited reduced biofilm production but also reduced colonisation fitness. Surprisingly, our results demonstrate that ObfA does not affect HapR through the canonical QS system but via the Csr-cascade altering the expression of the small regulatory RNAs CsrC and CsrD. In summary, this study elucidates a novel intraspecies BEV-based communication in V. cholerae that influences biofilm formation and colonisation fitness via a new regulatory pathway involving HapR, Csr-cascade and the BEV-associated protein ObfA.
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Affiliation(s)
| | - Fatih Cakar
- Institute of Molecular BiosciencesUniversity of GrazGrazAustria
| | - Yi‐Chi Chen
- Department of Plant and Microbial BiologyUniversity of ZurichZurichSwitzerland
| | | | - Leo Eberl
- Department of Plant and Microbial BiologyUniversity of ZurichZurichSwitzerland
| | - Stefan Schild
- Institute of Molecular BiosciencesUniversity of GrazGrazAustria
- BioTechMed‐GrazGrazAustria
- Field of Excellence BiohealthUniversity of GrazGrazAustria
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2
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ToxT Regulon Is Nonessential for Vibrio cholerae Colonization in Adult Mice. Appl Environ Microbiol 2022; 88:e0007222. [PMID: 35384706 DOI: 10.1128/aem.00072-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae is the causative agent of cholera, a life-threatening diarrheal disease in humans. The ability of V. cholerae to colonize the intestine of different animals is a key factor for its fitness and transmissibility between hosts. Many virulence factors, including the ToxT regulon, have been identified to be the major components allowing V. cholerae to colonize the small intestine of suckling mice; however, the mechanism of V. cholerae colonization in the adult mammalian intestine is unclear. In this study, using the streptomycin-treated adult mouse animal model, we characterized the role of the ToxT regulon in V. cholerae colonization in adult mammalian intestine. We first found that the activity of TcpP regulating ToxT regulon expression was attenuated by intestinal reactive oxygen species (ROS). We then found that V. cholerae containing a deletion of the ToxT regulon showed a competition advantage in colonizing adult mice; however, a mutant containing a constitutively active ToxT regulon showed a significant defect in colonizing adult mice. Constitutively producing the virulence factors in the ToxT regulon causes a V. cholerae competition defect in nutrient-limiting conditions. The results of this study demonstrate that modulating the activity of the ToxT regulon through ROS sensed by TcpP is critical for V. cholerae to enhance its colonization in the intestine of adult mice. IMPORTANCE Vibrio cholerae can inhabit both marine and freshwater ecosystems and can also enter and proliferate in the intestine of different animals which consume contaminated food or water. To successfully colonize the intestines of different hosts, V. cholerae coordinates its gene expression in response to different environments. Here, we describe how V. cholerae modulates the activity of the ToxT regulon by TcpP sensing ROS signals in the intestine of adult mice to better survive in this environment. We found that the constitutively active ToxT regulon causes V. cholerae growth retardation and colonization defect in adult mice. Our work highlights the distinctive role that regulating the activity of the ToxT regulon plays for V. cholerae to achieve full survival fitness in the adult mammalian intestine.
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Wölflingseder M, Tutz S, Fengler VH, Schild S, Reidl J. Regulatory Interplay of RpoS and RssB Controls Motility and Colonization in Vibrio cholerae. Int J Med Microbiol 2022; 312:151555. [DOI: 10.1016/j.ijmm.2022.151555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 03/27/2022] [Accepted: 04/12/2022] [Indexed: 11/28/2022] Open
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Karpov DS, Goncharenko AV, Usachev EV, Vasina DV, Divisenko EV, Chalenko YM, Pochtovyi AA, Ovchinnikov RS, Makarov VV, Yudin SM, Tkachuk AP, Gushchin VA. A Strategy for the Rapid Development of a Safe Vibrio cholerae Candidate Vaccine Strain. Int J Mol Sci 2021; 22:ijms222111657. [PMID: 34769085 PMCID: PMC8583953 DOI: 10.3390/ijms222111657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/01/2022] Open
Abstract
Approximately 1/6 of humanity is at high risk of experiencing cholera epidemics. The development of effective and safe vaccines against Vibrio cholerae, the primary cause of cholera, is part of the public health measures to prevent cholera epidemics. Natural nontoxigenic V. cholerae isolates represent a source of new genetically improved and relatively safe vaccine strains. However, the genomic engineering of wild-type V. cholerae strains is difficult, and these strains are genetically unstable due to their high homologous recombination activity. We comprehensively characterized two V. cholerae isolates using genome sequencing, bioinformatic analysis, and microscopic, physiological, and biochemical tests. Genetic constructs were Gibson assembled and electrotransformed into V. cholerae. Bacterial colonies were assessed using standard microbiological and immunological techniques. As a result, we created a synthetic chromoprotein-expressing reporter operon. This operon was used to improve the V. cholerae genome engineering approach and monitor the stability of the genetic constructs. Finally, we created a stable candidate V. cholerae vaccine strain bearing a recA deletion and expressing the β-subunit of cholera toxin. Thus, we developed a strategy for the rapid creation of genetically stable and relatively safe candidate vaccine strains. This strategy can be applied not only to V. cholerae but also to other important human bacterial pathogens.
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Affiliation(s)
- Dmitry S. Karpov
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str., 32, 119991 Moscow, Russia
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
- Correspondence: ; Tel.: +7-(499)-135-98-01
| | - Anna V. Goncharenko
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
| | - Evgenii V. Usachev
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Daria V. Vasina
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Elizaveta V. Divisenko
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Yaroslava M. Chalenko
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Andrei A. Pochtovyi
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
- Department of Virology, Biological Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Roman S. Ovchinnikov
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Valentin V. Makarov
- Centre for Strategic Planning of FMBA of Russia, 119121 Moscow, Russia; (V.V.M.); (S.M.Y.)
| | - Sergei M. Yudin
- Centre for Strategic Planning of FMBA of Russia, 119121 Moscow, Russia; (V.V.M.); (S.M.Y.)
| | - Artem P. Tkachuk
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
| | - Vladimir A. Gushchin
- Bach Institute of Biochemistry, Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences, 119071 Moscow, Russia; (A.V.G.); (E.V.U.); (D.V.V.); (A.P.T.); (V.A.G.)
- N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Gamaleya str., 18, 123098 Moscow, Russia; (E.V.D.); (Y.M.C.); (A.A.P.); (R.S.O.)
- Department of Virology, Biological Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia
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5
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Vaure C, Grégoire-Barou V, Courtois V, Chautard E, Dégletagne C, Liu Y. Göttingen Minipigs as a Model to Evaluate Longevity, Functionality, and Memory of Immune Response Induced by Pertussis Vaccines. Front Immunol 2021; 12:613810. [PMID: 33815369 PMCID: PMC8009978 DOI: 10.3389/fimmu.2021.613810] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Evaluation of the short-term and long-term immunological responses in a preclinical model that simulates the targeted age population with a relevant vaccination schedule is essential for human vaccine development. A Göttingen minipig model was assessed, using pertussis vaccines, to demonstrate that vaccine antigen-specific humoral and cellular responses, including IgG titers, functional antibodies, Th polarization and memory B cells can be assessed in a longitudinal study. A vaccination schedule of priming with a whole cell (DTwP) or an acellular (DTaP) pertussis vaccine was applied in neonatal and infant minipigs followed by boosting with a Tdap acellular vaccine. Single cell RNAsequencing was used to explore the long-term maintenance of immune memory cells and their functionality for the first time in this animal model. DTaP but not DTwP vaccination induced pertussis toxin (PT) neutralizing antibodies. The cellular immune response was also characterized by a distinct Th polarization, with a Th-2-biased response for DTaP and a Th-1/Th-17-biased response for DTwP. No difference in the maintenance of pertussis-specific memory B cells was observed in DTaP- or DTwP-primed animals 6 months post Tdap boost. However, an increase in pertussis-specific T cells was still observed in DTaP primed minipigs, together with up-regulation of genes involved in antigen presentation and interferon pathways. Overall, the minipig model reproduced the humoral and cellular immune responses induced in humans by DTwP vs. DTaP priming, followed by Tdap boosting. Our data suggest that the Göttingen minipig is an attractive preclinical model to predict the long-term immunogenicity of human vaccines against Bordetella pertussis and potentially also vaccines against other pathogens.
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Affiliation(s)
- Céline Vaure
- Research and External Innovation, Sanofi Pasteur, Marcy l'Etoile, France
| | | | - Virginie Courtois
- Research and External Innovation, Sanofi Pasteur, Marcy l'Etoile, France
| | - Emilie Chautard
- Research and External Innovation, Sanofi Pasteur, Marcy l'Etoile, France
| | - Cyril Dégletagne
- Research and External Innovation, Sanofi Pasteur, Marcy l'Etoile, France
| | - Yuanqing Liu
- Research and External Innovation, Sanofi Pasteur, Marcy l'Etoile, France
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6
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Kandari D, Joshi H, Bhatnagar R. Zur: Zinc-Sensing Transcriptional Regulator in a Diverse Set of Bacterial Species. Pathogens 2021; 10:344. [PMID: 33804265 PMCID: PMC8000910 DOI: 10.3390/pathogens10030344] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 12/18/2022] Open
Abstract
Zinc (Zn) is the quintessential d block metal, needed for survival in all living organisms. While Zn is an essential element, its excess is deleterious, therefore, maintenance of its intracellular concentrations is needed for survival. The living organisms, during the course of evolution, developed proteins that can track the limitation or excess of necessary metal ions, thus providing survival benefits under variable environmental conditions. Zinc uptake regulator (Zur) is a regulatory transcriptional factor of the FUR superfamily of proteins, abundant among the bacterial species and known for its intracellular Zn sensing ability. In this study, we highlight the roles played by Zur in maintaining the Zn levels in various bacterial species as well as the fact that in recent years Zur has emerged not only as a Zn homeostatic regulator but also as a protein involved directly or indirectly in virulence of some pathogens. This functional aspect of Zur could be exploited in the ventures for the identification of newer antimicrobial targets. Despite extensive research on Zur, the insights into its overall regulon and its moonlighting functions in various pathogens yet remain to be explored. Here in this review, we aim to summarise the disparate functional aspects of Zur proteins present in various bacterial species.
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Affiliation(s)
- Divya Kandari
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India; (D.K.); (H.J.)
| | - Hemant Joshi
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India; (D.K.); (H.J.)
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India; (D.K.); (H.J.)
- Banaras Hindu University, Banaras 221005, India
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7
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Zingl FG, Kohl P, Cakar F, Leitner DR, Mitterer F, Bonnington KE, Rechberger GN, Kuehn MJ, Guan Z, Reidl J, Schild S. Outer Membrane Vesiculation Facilitates Surface Exchange and In Vivo Adaptation of Vibrio cholerae. Cell Host Microbe 2019; 27:225-237.e8. [PMID: 31901519 DOI: 10.1016/j.chom.2019.12.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/25/2019] [Accepted: 12/05/2019] [Indexed: 10/25/2022]
Abstract
Gram-negative bacteria release outer membrane vesicles into the external milieu to deliver effector molecules that alter the host and facilitate virulence. Vesicle formation is driven by phospholipid accumulation in the outer membrane and regulated by the phospholipid transporter VacJ/Yrb. We use the facultative human pathogen Vibrio cholerae to show that VacJ/Yrb is silenced early during mammalian infection, which stimulates vesiculation that expedites bacterial surface exchange and adaptation to the host environment. Hypervesiculating strains rapidly alter their bacterial membrane composition and exhibit enhanced intestinal colonization fitness. This adaptation is exemplified by faster accumulation of glycine-modified lipopolysaccharide (LPS) and depletion of outer membrane porin OmpT, which confers resistance to host-derived antimicrobial peptides and bile, respectively. The competitive advantage of hypervesiculation is lost upon pre-adaptation to bile and antimicrobial peptides, indicating the importance of these adaptive processes. Thus, bacteria use outer membrane vesiculation to exchange cell surface components, thereby increasing survival during mammalian infection.
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Affiliation(s)
- Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Paul Kohl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Fatih Cakar
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Deborah R Leitner
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Fabian Mitterer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | | | - Gerald N Rechberger
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; Center for Explorative Lipidomics, BioTechMed Graz, 8010 Graz, Austria
| | - Meta J Kuehn
- Duke University Medical Center, Durham, NC 27710, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Joachim Reidl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria.
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8
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Gardette M, Le Hello S, Mariani-Kurkdjian P, Fabre L, Gravey F, Garrivier A, Loukiadis E, Jubelin G. Identification and prevalence of in vivo-induced genes in enterohaemorrhagic Escherichia coli. Virulence 2019; 10:180-193. [PMID: 30806162 PMCID: PMC6550539 DOI: 10.1080/21505594.2019.1582976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/25/2019] [Accepted: 02/06/2019] [Indexed: 12/14/2022] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) are food-borne pathogens responsible for bloody diarrhoea and renal failure in humans. While Shiga toxin (Stx) is the cardinal virulence factor of EHEC, its production by E. coli is not sufficient to cause disease and many Shiga-toxin producing E. coli (STEC) strains have never been implicated in human infection. So far, the pathophysiology of EHEC infection is not fully understood and more knowledge is needed to characterize the "auxiliary" factors that enable a STEC strain to cause disease in humans. In this study, we applied a recombinase-based in vivo expression technology (RIVET) to the EHEC reference strain EDL933 in order to identify genes specifically induced during the infectious process, using mouse as an infection model. We identified 31 in vivo-induced (ivi) genes having functions related to metabolism, stress adaptive response and bacterial virulence or fitness. Eight of the 31 ivi genes were found to be heterogeneously distributed in EHEC strains circulating in France these last years. In addition, they are more prevalent in strains from the TOP seven priority serotypes and particularly strains carrying significant virulence determinants such as Stx2 and intimin adhesin. This work sheds further light on bacterial determinants over-expressed in vivo during infection that may contribute to the potential of STEC strains to cause disease in humans.
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Affiliation(s)
- Marion Gardette
- UCA, INRA, UMR454 MEDIS, Clermont-Ferrand, France
- Laboratoire d’écologie microbienne de Lyon, Université de Lyon, CNRS, INRA, UCBL, VetAgro Sup, Marcy l’Etoile, France
| | - Simon Le Hello
- Centre de Référence National des Escherichia coli, Shigella et Salmonella, Institut Pasteur, Paris, France
- Université de Normandie, EA 2656 GRAM 2.0, UNICAEN, Caen, France
| | - Patricia Mariani-Kurkdjian
- Service de Microbiologie, Centre National de Référence associé Escherichia coli, Hôpital Robert-Debré, AP-HP, Paris, France
| | - Laetitia Fabre
- Centre de Référence National des Escherichia coli, Shigella et Salmonella, Institut Pasteur, Paris, France
| | - François Gravey
- Centre de Référence National des Escherichia coli, Shigella et Salmonella, Institut Pasteur, Paris, France
- Université de Normandie, EA 2656 GRAM 2.0, UNICAEN, Caen, France
| | | | - Estelle Loukiadis
- Laboratoire d’écologie microbienne de Lyon, Université de Lyon, CNRS, INRA, UCBL, VetAgro Sup, Marcy l’Etoile, France
- Laboratoire national de référence des E. coli, Université de Lyon, VetAgro Sup, Marcy l’Etoile, France
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9
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Herzog R, Peschek N, Fröhlich KS, Schumacher K, Papenfort K. Three autoinducer molecules act in concert to control virulence gene expression in Vibrio cholerae. Nucleic Acids Res 2019; 47:3171-3183. [PMID: 30649554 PMCID: PMC6451090 DOI: 10.1093/nar/gky1320] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/21/2018] [Accepted: 12/28/2018] [Indexed: 12/24/2022] Open
Abstract
Bacteria use quorum sensing to monitor cell density and coordinate group behaviours. In Vibrio cholerae, the causative agent of the diarrheal disease cholera, quorum sensing is connected to virulence gene expression via the two autoinducer molecules, AI-2 and CAI-1. Both autoinducers share one signal transduction pathway to control the production of AphA, a key transcriptional activator of biofilm formation and virulence genes. In this study, we demonstrate that the recently identified autoinducer, DPO, also controls AphA production in V. cholerae. DPO, functioning through the transcription factor VqmA and the VqmR small RNA, reduces AphA levels at the post-transcriptional level and consequently inhibits virulence gene expression. VqmR-mediated repression of AphA provides an important link between the AI-2/CAI-1 and DPO-dependent quorum sensing pathways in V. cholerae. Transcriptome analyses comparing the effect of single autoinducers versus autoinducer combinations show that quorum sensing controls the expression of ∼400 genes in V. cholerae and that all three autoinducers are required for a full quorum sensing response. Together, our data provide a global view on autoinducer interplay in V. cholerae and highlight the importance of RNA-based gene control for collective functions in this major human pathogen.
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Affiliation(s)
- Roman Herzog
- Faculty of Biology I, Department of Microbiology, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Nikolai Peschek
- Faculty of Biology I, Department of Microbiology, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany.,Munich Center for Integrated Protein Science (CIPSM), Germany
| | - Kathrin S Fröhlich
- Faculty of Biology I, Department of Microbiology, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Kilian Schumacher
- Faculty of Biology I, Department of Microbiology, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Kai Papenfort
- Faculty of Biology I, Department of Microbiology, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany.,Munich Center for Integrated Protein Science (CIPSM), Germany
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10
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Tanno-Nakanishi M, Kikuchi Y, Kokubu E, Yamada S, Ishihara K. Treponema denticola transcriptional profiles in serum-restricted conditions. FEMS Microbiol Lett 2019; 365:5049473. [PMID: 29982599 DOI: 10.1093/femsle/fny171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 07/04/2018] [Indexed: 12/13/2022] Open
Abstract
Treponema denticola is a major pathogen in periodontal disease and is frequently isolated from the lesions of patients with chronic periodontitis. Treponema denticola utilizes serum components as nutrient sources so as to colonize and proliferate in the gingival crevice. However, the mechanisms of serum utilization remain unclear. Therefore, the aim of the present study was to identify T. denticola serum utilization genes. Precultured T. denticola cells were suspended in a tryptone-yeast extract-gelatin-volatile fatty acids medium containing 0, 1% and 10% serum, respectively, and incubated anaerobically for 17 h. Total RNA was isolated, and T. denticola gene expression was compared by microarray and reverse transcription-polymerase chain reaction. In serum-depleted conditions, the expression levels of a potential hydroxylamine reductase, several ABC transporters, and phosphoenolpyruvate synthase were increased, while those of genes encoding methyl-accepting chemotaxis proteins and a transcriptional regulator were decreased. These results suggest that T. denticola may uptake serum components mainly through the action of ABC transporters. In particular, the decrease in the dmcA expression level with decreasing serum concentration suggests its involvement in chemotaxis toward serum-rich environments.
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Affiliation(s)
- Mariko Tanno-Nakanishi
- Department of Periodontology, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan
| | - Yuichiro Kikuchi
- Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan.,Oral Health Science Center, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan
| | - Eitoyo Kokubu
- Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan.,Oral Health Science Center, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan
| | - Satoru Yamada
- Department of Periodontology, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan
| | - Kazuyuki Ishihara
- Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan.,Oral Health Science Center, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan
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11
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Naydich AD, Nangle SN, Bues JJ, Trivedi D, Nissar N, Inniss MC, Niederhuber MJ, Way JC, Silver PA, Riglar DT. Synthetic Gene Circuits Enable Systems-Level Biosensor Trigger Discovery at the Host-Microbe Interface. mSystems 2019; 4:e00125-19. [PMID: 31186335 PMCID: PMC6561318 DOI: 10.1128/msystems.00125-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/18/2019] [Indexed: 01/22/2023] Open
Abstract
Engineering synthetic circuits into intestinal bacteria to sense, record, and respond to in vivo signals is a promising new approach for the diagnosis, treatment, and prevention of disease. However, because the design of disease-responsive circuits is limited by a relatively small pool of known biosensors, there is a need for expanding the capacity of engineered bacteria to sense and respond to the host environment. Here, we apply a robust genetic memory circuit in Escherichia coli to identify new bacterial biosensor triggers responding in the healthy and diseased mammalian gut, which may be used to construct diagnostic or therapeutic circuits. We developed a pipeline for rapid systems-level library construction and screening, using next-generation sequencing and computational analysis, which demonstrates remarkably reliable identification of responsive biosensor triggers from pooled libraries. By testing libraries of potential triggers-each consisting of a promoter and ribosome binding site (RBS)-and using RBS variation to augment the range of trigger sensitivity, we identify and validate triggers that selectively activate our synthetic memory circuit during transit through the gut. We further identify biosensor triggers with increased response in the inflamed gut through comparative screening of one of our libraries in healthy mice and those with intestinal inflammation. Our results demonstrate the power of systems-level screening for the identification of novel biosensor triggers in the gut and provide a platform for disease-specific screening that is capable of contributing to both the understanding and clinical management of intestinal illness.IMPORTANCE The gut is a largely obscure and inaccessible environment. The use of live, engineered probiotics to detect and respond to disease signals in vivo represents a new frontier in the management of gut diseases. Engineered probiotics have also shown promise as a novel mechanism for drug delivery. However, the design and construction of effective strains that respond to the in vivo environment is hindered by our limited understanding of bacterial behavior in the gut. Our work expands the pool of environmentally responsive synthetic circuits for the healthy and diseased gut, providing insight into host-microbe interactions and enabling future development of increasingly complex biosensors. This method also provides a framework for rapid prototyping of engineered systems and for application across bacterial strains and disease models, representing a practical step toward the construction of clinically useful synthetic tools.
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Affiliation(s)
- Alexander D Naydich
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts, USA
| | - Shannon N Nangle
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts, USA
| | - Johannes J Bues
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Disha Trivedi
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Nabeel Nissar
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Mara C Inniss
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Jeffrey C Way
- Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts, USA
| | - Pamela A Silver
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts, USA
| | - David T Riglar
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts, USA
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12
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Echazarreta MA, Klose KE. Vibrio Flagellar Synthesis. Front Cell Infect Microbiol 2019; 9:131. [PMID: 31119103 PMCID: PMC6504787 DOI: 10.3389/fcimb.2019.00131] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 04/12/2019] [Indexed: 12/31/2022] Open
Abstract
Vibrio spp. are highly motile Gram-negative bacteria, ubiquitously found in aquatic environments. Some Vibrios are responsible for disease and morbidity of marine invertebrates and humans, while others are studied for their symbiotic interactions. Vibrio spp. are motile due to synthesis of flagella that rotate and propel the bacteria. Many Vibrio spp. synthesize monotrichous polar flagella (e.g., V. cholerae, V. alginolyticus); however, some synthesize peritrichous or lophotrichous flagella. Flagellar-mediated motility is intimately connected to biological and cellular processes such as chemotaxis, biofilm formation, colonization, and virulence of Vibrio spp. This review focuses on the polar flagellum and its regulation in regard to Vibrio virulence and environmental persistence.
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Affiliation(s)
- Mylea A Echazarreta
- Department of Biology, South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Karl E Klose
- Department of Biology, South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, United States
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13
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Abstract
Cholera is an epidemic diarrheal disease caused by Vibrio cholerae that continues to cause significant morbidity and mortality in many parts of the world. Several different animal models have been used by scientists over the years to study the pathogenesis of cholera. However, the most commonly used is the infant (suckling) mouse model, which has been found to replicate important aspects of human intestinal colonization. Here we present a detailed protocol for using the infant mouse model to assess the colonization of V. cholerae strains using a competition assay.
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Affiliation(s)
- Jyl S Matson
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA.
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14
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Ghosh P, Sinha R, Samanta P, Saha DR, Koley H, Dutta S, Okamoto K, Ghosh A, Ramamurthy T, Mukhopadhyay AK. Haitian Variant Vibrio cholerae O1 Strains Manifest Higher Virulence in Animal Models. Front Microbiol 2019; 10:111. [PMID: 30804907 PMCID: PMC6370728 DOI: 10.3389/fmicb.2019.00111] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/18/2019] [Indexed: 11/13/2022] Open
Abstract
Vibrio cholerae causes fatal diarrheal disease cholera in humans due to consumption of contaminated water and food. To instigate the disease, the bacterium must evade the host intestinal innate immune system; penetrate the mucus layer of the small intestine, adhere and multiply on the surface of microvilli and produce toxin(s) through the action of virulence associated genes. V. cholerae O1 that has caused a major cholera outbreak in Haiti contained several unique genetic signatures. These novel traits are used to differentiate them from the canonical El Tor strains. Several studies reported the spread of these Haitian variant strains in different parts of the world including Asia and Africa, but there is a paucity of information on the clinical consequence of these genetic changes. To understand the impact of these changes, we undertook a study involving mice and rabbit models to evaluate the pathogenesis. The colonization ability of Haitian variant strain in comparison to canonical El Tor strain was found to be significantly more in both suckling mice and rabbit model. Adult mice also displayed the same results. Besides that, infection patterns of Haitian variant strains showed a completely different picture. Increased mucosal damaging, colonization, and inflammatory changes were observed through hematoxylin-eosin staining and transmission electron microscopy. Fluid accumulation ability was also significantly higher in rabbit model. Our study indicated that these virulence features of the Haitian variant strain may have some association with the severe clinical outcome of the cholera patients in different parts of the world.
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Affiliation(s)
- Priyanka Ghosh
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Ritam Sinha
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Prosenjit Samanta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Dhira Rani Saha
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Hemanta Koley
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shanta Dutta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Keinosuke Okamoto
- Collaborative Research Center of Okayama University for Infectious Diseases in India, Kolkata, India
| | - Amit Ghosh
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - T. Ramamurthy
- Center for Human Microbial Ecology, Translational Health Science and Technology Institute, Faridabad, India
| | - Asish K. Mukhopadhyay
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
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15
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Abstract
Measuring biological data across time and space is critical for understanding complex biological processes and for various biosurveillance applications. However, such data are often inaccessible or difficult to directly obtain. Less invasive, more robust and higher-throughput biological recording tools are needed to profile cells and their environments. DNA-based cellular recording is an emerging and powerful framework for tracking intracellular and extracellular biological events over time across living cells and populations. Here, we review and assess DNA recorders that utilize CRISPR nucleases, integrases and base-editing strategies, as well as recombinase and polymerase-based methods. Quantitative characterization, modelling and evaluation of these DNA-recording modalities can guide their design and implementation for specific application areas.
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Affiliation(s)
- Ravi U Sheth
- Department of Systems Biology, Columbia University Medical Center, New York, NY, USA
- Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University, New York, NY, USA
| | - Harris H Wang
- Department of Systems Biology, Columbia University Medical Center, New York, NY, USA.
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
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16
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Shane JL, Grogan CL, Cwalina C, Lampe DJ. Blood meal-induced inhibition of vector-borne disease by transgenic microbiota. Nat Commun 2018; 9:4127. [PMID: 30297781 PMCID: PMC6175951 DOI: 10.1038/s41467-018-06580-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 09/12/2018] [Indexed: 01/26/2023] Open
Abstract
Vector-borne diseases are a substantial portion of the global disease burden; one of the deadliest of these is malaria. Vector control strategies have been hindered by mosquito and pathogen resistances, and population alteration approaches using transgenic mosquitos still have many hurdles to overcome before they can be implemented in the field. Here we report a paratransgenic control strategy in which the microbiota of Anopheles stephensi was engineered to produce an antiplasmodial effector causing the mosquito to become refractory to Plasmodium berghei. The midgut symbiont Asaia was used to conditionally express the antiplasmodial protein scorpine only when a blood meal was present. These blood meal inducible Asaia strains significantly inhibit pathogen infection, and display improved fitness compared to strains that constitutively express the antiplasmodial effector. This strategy may allow the antiplasmodial bacterial strains to survive and be transmitted through mosquito populations, creating an easily implemented and enduring vector control strategy.
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Affiliation(s)
- Jackie L Shane
- Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Christina L Grogan
- Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Caroline Cwalina
- Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - David J Lampe
- Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA.
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17
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In vivo repressed genes of Vibrio cholerae reveal inverse requirements of an H +/Cl - transporter along the gastrointestinal passage. Proc Natl Acad Sci U S A 2018; 115:E2376-E2385. [PMID: 29463743 PMCID: PMC5877934 DOI: 10.1073/pnas.1716973115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The facultative human pathogen Vibrio cholerae changes its transcriptional profile upon oral ingestion by the host to facilitate survival and colonization fitness. Here, we used a modified version of recombination-based in vivo expression technology to investigate gene silencing during the in vivo passage, which has been understudied. Using a murine model of cholera, we screened a V. cholerae transposon library composed of 10,000 randomly generated reporter fusions and identified 101 in vivo repressed (ivr) genes. Our data indicate that constitutive expression of ivr genes reduces colonization fitness, highlighting the necessity to down-regulate these genes in vivo. For example, the ivr gene clcA, encoding an H+/Cl- transporter, could be linked to the acid tolerance response against hydrochloric acid. In a chloride-dependent manner, ClcA facilitates survival under low pH (e.g., the stomach), but its presence becomes detrimental under alkaline conditions (e.g., lower gastrointestinal tract). This pH-dependent clcA expression is controlled by the LysR-type activator AphB, which acts in concert with AphA to initiate the virulence cascade in V. cholerae after oral ingestion. Thus, transcriptional networks dictating induction of virulence factors and the repression of ivr genes overlap to regulate in vivo colonization dynamics. Overall, the results presented herein highlight the impact of spatiotemporal gene silencing in vivo. The molecular characterization of the underlying mechanisms can provide important insights into in vivo physiology and virulence network regulation.
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18
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Folliard T, Steel H, Prescott TP, Wadhams G, Rothschild LJ, Papachristodoulou A. A Synthetic Recombinase-Based Feedback Loop Results in Robust Expression. ACS Synth Biol 2017; 6:1663-1671. [PMID: 28602075 DOI: 10.1021/acssynbio.7b00131] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Accurate control of a biological process is essential for many critical functions in biology, from the cell cycle to proteome regulation. To achieve this, negative feedback is frequently employed to provide a highly robust and reliable output. Feedback is found throughout biology and technology, but due to challenges posed by its implementation, it is yet to be widely adopted in synthetic biology. In this paper we design a synthetic feedback network using a class of recombinase proteins called integrases, which can be re-engineered to flip the orientation of DNA segments in a digital manner. This system is highly orthogonal, and demonstrates a strong capability for regulating and reducing the expression variability of genes being transcribed under its control. An excisionase protein provides the negative feedback signal to close the loop in this system, by flipping DNA segments in the reverse direction. Our integrase/excisionase negative feedback system thus provides a modular architecture that can be tuned to suit applications throughout synthetic biology and biomanufacturing that require a highly robust and orthogonally controlled output.
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Affiliation(s)
- Thomas Folliard
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, U.K
| | - Harrison Steel
- Department
of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, U.K
| | - Thomas P. Prescott
- Department
of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, U.K
| | - George Wadhams
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, U.K
| | - Lynn J. Rothschild
- National
Aeronautics
and Space Administration Ames Research Center, Moffett Field, California 94035, United States
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19
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Identification of a two-component Class IIb bacteriocin in Streptococcus pyogenes by recombinase-based in vivo expression technology. Sci Rep 2016; 6:36233. [PMID: 27808235 PMCID: PMC5093712 DOI: 10.1038/srep36233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 10/10/2016] [Indexed: 12/30/2022] Open
Abstract
Streptococcus pyogenes is a globally prominent bacterial pathogen that exhibits strict tropism for the human host, yet bacterial factors responsible for the ability of S. pyogenes to compete within this limited biological niche are not well understood. Using an engineered recombinase-based in vivo expression technology (RIVET) system, we identified an in vivo-induced promoter region upstream of a predicted Class IIb bacteriocin system in the M18 serotype S. pyogenes strain MGAS8232. This promoter element was not active under in vitro laboratory conditions, but was highly induced within the mouse nasopharynx. Recombinant expression of the predicted mature S. pyogenes bacteriocin peptides (designated SpbM and SpbN) revealed that both peptides were required for antimicrobial activity. Using a gain of function experiment in Lactococcus lactis, we further demonstrated S. pyogenes immunity function is encoded downstream of spbN. These data highlight the importance of bacterial gene regulation within appropriate environments to help understand mechanisms of niche adaptation by bacterial pathogens.
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20
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Pressler K, Vorkapic D, Lichtenegger S, Malli G, Barilich BP, Cakar F, Zingl FG, Reidl J, Schild S. AAA+ proteases and their role in distinct stages along the Vibrio cholerae lifecycle. Int J Med Microbiol 2016; 306:452-62. [PMID: 27345492 DOI: 10.1016/j.ijmm.2016.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/09/2016] [Accepted: 05/24/2016] [Indexed: 12/29/2022] Open
Abstract
The facultative human pathogen Vibrio cholerae has to adapt to different environmental conditions along its lifecycle by means of transcriptional, translational and post-translational regulation. This study provides a first comprehensive analysis regarding the contribution of the cytoplasmic AAA+ proteases Lon, ClpP and HslV to distinct features of V. cholerae behaviour, including biofilm formation, motility, cholera toxin expression and colonization fitness in the mouse model. While absence of HslV did not yield to any altered phenotype compared to wildtype, absence of Lon or ClpP resulted in significantly reduced colonization in vivo. In addition, a Δlon deletion mutant showed altered biofilm formation and increased motility, which could be correlated with higher expression of V. cholerae flagella gene class IV. Concordantly, we could show by immunoblot analysis, that Lon is the main protease responsible for proteolytic control of FliA, which is required for class IV flagella gene transcription, but also downregulates virulence gene expression. FliA becomes highly sensitive to proteolytic degradation in absence of its anti-sigma factor FlgM, a scenario reported to occur during mucosal penetration due to FlgM secretion through the broken flagellum. Our results confirm that the high stability of FliA in the absence of Lon results in less cholera toxin and toxin corgulated pilus production under virulence gene inducing conditions and in the presence of a damaged flagellum. Thus, the data presented herein provide a molecular explanation on how V. cholerae can achieve full expression of virulence genes during early stages of colonization, despite FliA getting liberated from the anti-sigma factor FlgM.
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Affiliation(s)
- Katharina Pressler
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Dina Vorkapic
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Sabine Lichtenegger
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Gerald Malli
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Benjamin P Barilich
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Fatih Cakar
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Joachim Reidl
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, A-8010 Graz, Austria.
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21
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Abstract
Vibrio cholerae can switch between motile and biofilm lifestyles. The last decades have been marked by a remarkable increase in our knowledge of the structure, regulation, and function of biofilms formed under laboratory conditions. Evidence has grown suggesting that V. cholerae can form biofilm-like aggregates during infection that could play a critical role in pathogenesis and disease transmission. However, the structure and regulation of biofilms formed during infection, as well as their role in intestinal colonization and virulence, remains poorly understood. Here, we review (i) the evidence for biofilm formation during infection, (ii) the coordinate regulation of biofilm and virulence gene expression, and (iii) the host signals that favor V. cholerae transitions between alternative lifestyles during intestinal colonization, and (iv) we discuss a model for the role of V. cholerae biofilms in pathogenicity.
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22
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Gumpenberger T, Vorkapic D, Zingl FG, Pressler K, Lackner S, Seper A, Reidl J, Schild S. Nucleoside uptake in Vibrio cholerae and its role in the transition fitness from host to environment. Mol Microbiol 2015. [PMID: 26202476 DOI: 10.1111/mmi.13143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
As it became evident recently, extracellular DNA could be a versatile nutrient source of the facultative pathogen Vibrio cholerae along the different stages of its life cycle. By the use of two extracellular nucleases and periplasmic phosphatases, V. cholerae degrades extracellular DNA to nucleosides. In this study, we investigated the nucleoside uptake via identification and characterization of VCA0179, VC1953 and VC2352 representing the three nucleoside transport systems in V. cholerae. Based on our results VC2352 seems to be the dominant nucleoside transporter. Nevertheless, all three transporters are functional and can contribute to the utilization of nucleosides as a sole source of carbon or nitrogen. We found that the transcriptional activity of these three distal genes is equally promoted or antagonized by CRP or CytR respectively. Finally, mutants impaired for nucleoside uptake exhibit decreased transition fitness from the host into low carbon environments along the life cycle of V. cholerae.
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Affiliation(s)
- Tanja Gumpenberger
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Dina Vorkapic
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Katharina Pressler
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Stefanie Lackner
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Andrea Seper
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Joachim Reidl
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
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23
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Kariisa AT, Grube A, Tamayo R. Two nucleotide second messengers regulate the production of the Vibrio cholerae colonization factor GbpA. BMC Microbiol 2015; 15:166. [PMID: 26286031 PMCID: PMC4545359 DOI: 10.1186/s12866-015-0506-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 08/12/2015] [Indexed: 11/30/2022] Open
Abstract
Background The nucleotide second messengers cAMP and c-di-GMP allow many bacteria, including the human intestinal pathogen Vibrio cholerae, to respond to environmental stimuli with appropriate physiological adaptations. In response to limitation of specific carbohydrates, cAMP and its receptor CRP control the transcription of genes important for nutrient acquisition and utilization; c-di-GMP controls the transition between motile and sessile lifestyles often, but not exclusively, through transcriptional mechanisms. In this study, we investigated the convergence of cAMP and c-di-GMP signaling pathways in regulating the expression of gbpA. GbpA is a colonization factor that participates in the attachment of V. cholerae to N-acetylglucosamine-containing surfaces in its native aquatic environment and the host intestinal tract. Results We show that c-di-GMP inhibits gbpA activation in a fashion independent of the known transcription factors that directly sense c-di-GMP. Interestingly, inhibition of gbpA activation by c-di-GMP only occurs during growth on non-PTS dependent nutrient sources. Consistent with this result, we show that CRP binds to the gbpA promoter in a cAMP-dependent manner in vitro and drives transcription of gbpA in vivo. The interplay between cAMP and c-di-GMP does not broadly impact the CRP-cAMP regulon, but occurs more specifically at the gbpA promoter. Conclusions These findings suggest that c-di-GMP directly interferes with the interaction of CRP-cAMP and the gbpA promoter via an unidentified regulator. The use of two distinct second messenger signaling mechanisms to regulate gbpA transcription may allow V. cholerae to finely modulate GbpA production, and therefore colonization of aquatic and host surfaces, in response to discrete environmental stimuli. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0506-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ankunda T Kariisa
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, 125 Mason Farm Rd, 6th Floor, Chapel Hill, NC, 27599, USA.
| | - Alyssa Grube
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, 125 Mason Farm Rd, 6th Floor, Chapel Hill, NC, 27599, USA. .,Biology Department, Juniata College, Huntingdon, PA, USA.
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, 125 Mason Farm Rd, 6th Floor, Chapel Hill, NC, 27599, USA.
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24
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Identification of genes induced in Vibrio cholerae in a dynamic biofilm system. Int J Med Microbiol 2014; 304:749-63. [PMID: 24962154 PMCID: PMC4101255 DOI: 10.1016/j.ijmm.2014.05.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/23/2014] [Accepted: 05/25/2014] [Indexed: 12/13/2022] Open
Abstract
The facultative human pathogen Vibrio cholerae, the causative agent of the severe secretory diarrheal disease cholera, persists in its aquatic reservoirs in biofilms during interepidemic periods. Biofilm is a likely form in which clinically relevant V. cholerae is taken up by humans, providing an infective dose. Thus, a better understanding of biofilm formation of V. cholerae is relevant for the ecology and epidemiology of cholera as well as a target to control the disease. Most previous studies have investigated static biofilms of V. cholerae and elucidated structural prerequisites like flagella, pili and a biofilm matrix including extracellular DNA, numerous matrix proteins and exopolysaccharide, as well as the involvement of regulatory pathways like two-component systems, quorum sensing and c-di-GMP signaling. However, aquatic environments are more likely to reflect an open, dynamic system. Hence, we used a biofilm system with constant medium flow and a temporal controlled reporter-system of transcription to identify genes induced during dynamic biofilm formation. We identified genes known or predicted to be involved in c-di-GMP signaling, motility and chemotaxis, metabolism, and transport. Subsequent phenotypic characterization of mutants with independent mutations in candidate dynamic biofilm-induced genes revealed novel insights into the physiology of static and dynamic biofilm conditions. The results of this study also reinforce the hypotheses that distinct differences in regulatory mechanisms governing biofilm development are present under dynamic conditions compared to static conditions.
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25
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McDonough E, Lazinski DW, Camilli A. Identification of in vivo regulators of the Vibrio cholerae xds gene using a high-throughput genetic selection. Mol Microbiol 2014; 92:302-15. [PMID: 24673931 DOI: 10.1111/mmi.12557] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2014] [Indexed: 01/20/2023]
Abstract
Vibrio cholerae, the causative agent of cholera, remains a threat to public health in areas with inadequate sanitation. As a waterborne pathogen, V. cholerae moves between two dissimilar environments, aquatic reservoirs and the intestinal tract of humans. Accordingly, this pathogen undergoes adaptive shifts in gene expression throughout the different stages of its lifecycle. One particular gene, xds, encodes a secreted exonuclease that was previously identified as being induced during infection. Here we sought to identify regulators responsible for the in vivo-specific induction of xds. A transcriptional fusion of xds to two consecutive antibiotic resistance genes was used to select transposon mutants that had inserted within or adjacent to regulatory genes and thereby caused increased expression of the xds fusion under non-inducing conditions. Large pools of selected insertion sites were sequenced in a high throughput manner using Tn-seq to identify potential mechanisms of xds regulation. Our selection identified the two-component system PhoB/R as the dominant activator of xds expression. In vitro validation confirmed that PhoB, a protein which is only active during phosphate limitation, was responsible for xds activation. Using xds expression as a biosensor of the extracellular phosphate level, we observed that the mouse small intestine is a phosphate-limited environment.
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Affiliation(s)
- Emilykate McDonough
- Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
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Abstract
There is a real crisis in healthcare with the emergence of bacterial pathogens resistant to multiple drugs. The drug discovery industry is faced with the challenge of developing new classes of antibiotics that are effective against resistant organisms. Targeting bacterial virulence is one approach that has yet to be fully exploited, and the last decade or so has seen the development of reagents, screens and approaches that could make this possible. Several processes utilized by bacteria to cause infection are employed in a wide range of pathogens and as such may make attractive targets. Inhibitors of such targets would be unlikely to affect host cells, be cross-resistant to existing therapies and induce resistance themselves.
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Affiliation(s)
- Andrea Marra
- Pfizer Global Research and Development, Antibacterials Discovery, MS8118W-249 Eastern Point Road Groton, CT 06340, USA.
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LaRocque RC, Harris JB, Ryan ET, Qadri F, Calderwood SB. Postgenomic approaches to cholera vaccine development. Expert Rev Vaccines 2014; 5:337-46. [PMID: 16827618 DOI: 10.1586/14760584.5.3.337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cholera remains an important public health threat. A cholera vaccine that provides durable protection at the mucosal surface, especially among children in endemic settings, is urgently needed. The availability of the complete genome sequence of a clinical isolate of Vibrio cholerae O1 El Tor has allowed for comparative and functional genomic approaches in the study of cholera. This work holds promise for the identification of bacterial targets of protective human immune responses and may contribute to the development of a new generation of cholera vaccines.
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Affiliation(s)
- Regina C LaRocque
- Division of Infectious Diseases, Massachusetts General Hospital, GRJ 504, 55 Fruit Street, Boston, MA 02114, USA.
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Lozano MJ, Salas ME, Giusti MDLA, Martini MC, López JL, Salto I, Del Papa MF, Pistorio M, Lagares A. Novel tnpR-based transposable promoter traps suitable for RIVET studies in different gram-negative bacteria. J Microbiol Methods 2013; 93:9-11. [PMID: 23384825 DOI: 10.1016/j.mimet.2013.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 11/26/2022]
Abstract
The preparation of plasmid-borne RIVET libraries can be troublesome when high genomic coverages are needed. We present here the construction and functional validation of a new set of miniTn5 promoter traps to generate tnpR-based RIVET libraries. The ability to generate tnpR transcriptional fusions by transposition will significantly facilitate the setup of RIVET studies in those bacteria where Tn5 transposition is operative.
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Affiliation(s)
- Mauricio J Lozano
- IBBM-Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata,Calles 47 y 115 (1900), La Plata, Argentina
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Varivarn K, Champa LA, Silby MW, Robleto EA. Colonization strategies of Pseudomonas fluorescens Pf0-1: activation of soil-specific genes important for diverse and specific environments. BMC Microbiol 2013; 13:92. [PMID: 23622502 PMCID: PMC3646685 DOI: 10.1186/1471-2180-13-92] [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: 12/13/2012] [Accepted: 04/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pseudomonas fluorescens is a common inhabitant of soil and the rhizosphere environment. In addition to potential applications in biocontrol and bioremediation, P. fluorescens is of interest as a model for studying bacterial survival and fitness in soil. A previous study using in vivo expression technology (IVET) identified 22 genes in P. fluorescens Pf0-1 which are up-regulated during growth in Massachusetts loam soil, a subset of which are important for fitness in soil. Despite this and other information on adaptation to soil, downstream applications such as biocontrol or bioremediation in diverse soils remain underdeveloped. We undertook an IVET screen to identify Pf0-1 genes induced during growth in arid Nevada desert soil, to expand our understanding of growth in soil environments, and examine whether Pf0-1 uses general or soil type-specific mechanisms for success in soil environments. RESULTS Twenty six genes were identified. Consistent with previous studies, these genes cluster in metabolism, information storage/processing, regulation, and 'hypothetical', but there was no overlap with Pf0-1 genes induced during growth in loam soil. Mutation of both a putative glutamine synthetase gene (Pfl01_2143) and a gene predicted to specify a component of a type VI secretion system (Pfl01_5595) resulted in a decline in arid soil persistence. When examined in sterile loam soil, mutation of Pfl01_5595 had no discernible impact. In contrast, the Pfl01_2143 mutant was not impaired in persistence in sterile soil, but showed a significant reduction in competitive fitness. CONCLUSIONS These data support the conclusion that numerous genes are specifically important for survival and fitness in natural environments, and will only be identified using in vivo approaches. Furthermore, we suggest that a subset of soil-induced genes is generally important in different soils, while others may contribute to success in specific types of soil. The importance of glutamine synthetase highlights a critical role for nitrogen metabolism in soil fitness. The implication of Type 6 secretion underscores the importance of microbial interactions in natural environments. Understanding the general and soil-specific genes will greatly improve the persistence of designed biocontrol and bioremediation strains within the target environment.
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Affiliation(s)
- Katila Varivarn
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
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Kroupitski Y, Brandl MT, Pinto R, Belausov E, Tamir-Ariel D, Burdman S, Sela Saldinger S. Identification of Salmonella enterica genes with a role in persistence on lettuce leaves during cold storage by recombinase-based in vivo expression technology. PHYTOPATHOLOGY 2013; 103:362-72. [PMID: 23506363 DOI: 10.1094/phyto-10-12-0254-fi] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recurrent outbreaks of enteric illness linked to lettuce and a lack of efficacious strategies to decontaminate produce underscores the need for a better understanding of the molecular interactions of foodborne pathogens with plants. This study aimed at identifying Salmonella enterica genes involved in the persistence of this organism on post-harvest lettuce during cold storage using recombinase-based in vivo expression technology (RIVET). In total, 37 potentially induced loci were identified in four distinct screenings. Knockout mutations in eight upregulated genes revealed that four of them have a role in persistence of the pathogen in this system. These genes included stfC, bcsA, misL, and yidR, encoding a fimbrial outer membrane usher, a cellulose synthase catalytic subunit, an adhesin of the autotransporter family expressed from the Salmonella pathogenicity island-3, and a putative ATP/GTP-binding protein, respectively. bcsA, misL, and yidR but not stfC mutants were impaired also in attachment and biofilm formation, suggesting that these functions are required for survival of S. enterica on post-harvest lettuce. This is the first report that MisL, which has a role in Salmonella binding to fibronectin in animal hosts, is involved also in adhesion to plant tissue. Hence, our study uncovered a new plant attachment factor in Salmonella and demonstrates that RIVET is an effective approach for investigating human pathogen-plant interactions in a post-harvest leafy vegetable.
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Affiliation(s)
- Y Kroupitski
- Department of Food Quality & safety, Institute for Postharvest and Food Sciences, Israel
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Klumpp J, Fouts DE, Sozhamannan S. Bacteriophage functional genomics and its role in bacterial pathogen detection. Brief Funct Genomics 2013; 12:354-65. [DOI: 10.1093/bfgp/elt009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Webb JS, Nikolakakis KC, Willett JLE, Aoki SK, Hayes CS, Low DA. Delivery of CdiA nuclease toxins into target cells during contact-dependent growth inhibition. PLoS One 2013; 8:e57609. [PMID: 23469034 PMCID: PMC3585180 DOI: 10.1371/journal.pone.0057609] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/23/2013] [Indexed: 12/26/2022] Open
Abstract
Bacterial contact-dependent growth inhibition (CDI) is mediated by the CdiB/CdiA family of two-partner secretion proteins. CDI systems deploy a variety of distinct toxins, which are contained within the polymorphic C-terminal region (CdiA-CT) of CdiA proteins. Several CdiA-CTs are nucleases, suggesting that the toxins are transported into the target cell cytoplasm to interact with their substrates. To analyze CdiA transfer to target bacteria, we used the CDI system of uropathogenic Escherichia coli 536 (UPEC536) as a model. Antibodies recognizing the amino- and carboxyl-termini of CdiAUPEC536 were used to visualize transfer of CdiA from CDIUPEC536+ inhibitor cells to target cells using fluorescence microscopy. The results indicate that the entire CdiAUPEC536 protein is deposited onto the surface of target bacteria. CdiAUPEC536 transfer to bamA101 mutants is reduced, consistent with low expression of the CDI receptor BamA on these cells. Notably, our results indicate that the C-terminal CdiA-CT toxin region of CdiAUPEC536 is translocated into target cells, but the N-terminal region remains at the cell surface based on protease sensitivity. These results suggest that the CdiA-CT toxin domain is cleaved from CdiAUPEC536 prior to translocation. Delivery of a heterologous Dickeya dadantii CdiA-CT toxin, which has DNase activity, was also visualized. Following incubation with CDI+ inhibitor cells targets became anucleate, showing that the D.dadantii CdiA-CT was delivered intracellularly. Together, these results demonstrate that diverse CDI toxins are efficiently translocated across target cell envelopes.
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Affiliation(s)
- Julia S. Webb
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Kiel C. Nikolakakis
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Julia L. E. Willett
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Stephanie K. Aoki
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Christopher S. Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - David A. Low
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California, United States of America
- * E-mail:
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Characterizing the hexose-6-phosphate transport system of Vibrio cholerae, a utilization system for carbon and phosphate sources. J Bacteriol 2013; 195:1800-8. [PMID: 23417487 DOI: 10.1128/jb.01952-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The facultative human pathogen Vibrio cholerae transits between the gastrointestinal tract of its host and aquatic reservoirs. V. cholerae adapts to different situations by the timely coordinated expression of genes during its life cycle. We recently identified a subclass of genes that are induced at late stages of infection. Initial characterization demonstrated that some of these genes facilitate the transition of V. cholerae from host to environmental conditions. Among these genes are uptake systems lacking detailed characterization or correct annotation. In this study, we comprehensively investigated the function of the VCA0682-to-VCA0687 gene cluster, which was previously identified as in vivo induced. The results presented here demonstrate that the operon encompassing open reading frames VCA0685 to VCA0687 encodes an ABC transport system for hexose-6-phosphates with Km values ranging from 0.275 to 1.273 μM for glucose-6P and fructose-6P, respectively. Expression of the operon is induced by the presence of hexose-6P controlled by the transcriptional activator VCA0682, representing a UhpA homolog. Finally, we provide evidence that the operon is essential for the utilization of hexose-6P as a C and P source. Thereby, a physiological role can be assigned to hexose-6P uptake, which correlates with increased fitness of V. cholerae after a transition from the host into phosphate-limiting environments.
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Singh A, Hodgson N, Yan M, Joo J, Gu L, Sang H, Gregory-Bryson E, Wood WG, Ni Y, Smith K, Jackson SH, Coleman WG. Screening Helicobacter pylori genes induced during infection of mouse stomachs. World J Gastroenterol 2012; 18:4323-34. [PMID: 22969195 PMCID: PMC3436047 DOI: 10.3748/wjg.v18.i32.4323] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 07/30/2012] [Accepted: 08/03/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of in vivo environment on gene expression in Helicobacter pylori (H. pylori) as it relates to its survival in the host.
METHODS: In vivo expression technology (IVET) systems are used to identify microbial virulence genes. We modified the IVET-transcriptional fusion vector, pIVET8, which uses antibiotic resistance as the basis for selection of candidate genes in host tissues to develop two unique IVET-promoter-screening vectors, pIVET11 and pIVET12. Our novel IVET systems were developed by the fusion of random Sau3A DNA fragments of H. pylori and a tandem-reporter system of chloramphenicol acetyltransferase and beta-galactosidase. Additionally, each vector contains a kanamycin resistance gene. We used a mouse macrophage cell line, RAW 264.7 and mice, as selective media to identify specific genes that H. pylori expresses in vivo. Gene expression studies were conducted by infecting RAW 264.7 cells with H. pylori. This was followed by real time polymerase chain reaction (PCR) analysis to determine the relative expression levels of in vivo induced genes.
RESULTS: In this study, we have identified 31 in vivo induced (ivi) genes in the initial screens. These 31 genes belong to several functional gene families, including several well-known virulence factors that are expressed by the bacterium in infected mouse stomachs. Virulence factors, vacA and cagA, were found in this screen and are known to play important roles in H. pylori infection, colonization and pathogenesis. Their detection validates the efficacy of these screening systems. Some of the identified ivi genes have already been implicated to play an important role in the pathogenesis of H. pylori and other bacterial pathogens such as Escherichia coli and Vibrio cholerae. Transcription profiles of all ivi genes were confirmed by real time PCR analysis of H. pylori RNA isolated from H. pylori infected RAW 264.7 macrophages. We compared the expression profile of H. pylori and RAW 264.7 coculture with that of H. pylori only. Some genes such as cagA, vacA, lpxC, murI, tlpC, trxB, sodB, tnpB, pgi, rbfA and infB showed a 2-20 fold upregulation. Statistically significant upregulation was obtained for all the above mentioned genes (P < 0.05). tlpC, cagA, vacA, sodB, rbfA, infB, tnpB, lpxC and murI were also significantly upregulated (P < 0.01). These data suggest a strong correlation between results obtained in vitro in the macrophage cell line and in the intact animal.
CONCLUSION: The positive identification of these genes demonstrates that our IVET systems are powerful tools for studying H. pylori gene expression in the host environment.
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Gao M, Coggin A, Yagnik K, Teplitski M. Role of specific quorum-sensing signals in the regulation of exopolysaccharide II production within Sinorhizobium meliloti spreading colonies. PLoS One 2012; 7:e42611. [PMID: 22912712 PMCID: PMC3418255 DOI: 10.1371/journal.pone.0042611] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 07/10/2012] [Indexed: 01/21/2023] Open
Abstract
Background Quorum sensing (QS) in Sinorhizobium meliloti involves at least half a dozen different N-acyl homoserine lactone (AHL) signals. These signals are produced by SinI, the sole AHL synthase in S. meliloti Rm8530. The sinI gene is regulated by two LuxR-type transcriptional regulators, SinR and ExpR. Mutations in sinI, sinR and expR abolish the production of exopolysaccharide II (EPS II). Methodology/Principal Findings This study investigated a new type of coordinated surface spreading of Rm8530 that can be categorized as swarming. Motility assays on semi-solid surfaces revealed that both flagella and EPS II are required for this type of motility. The production of EPS II depends on AHLs produced by SinI. Of these AHLs, only C16:1- and 3-oxo-C16:1-homoserine lactones (HSLs) stimulated swarming in an ExpR-dependent manner. These two AHLs induced the strongest response in the wggR reporter fusions. WggR is a positive regulator of the EPS II biosynthesis gene expression. The levels of the wggR activation correlated with the extent of swarming. Furthermore, swarming of S. meliloti required the presence of the high molecular weight (HMW) fraction of EPS II. Within swarming colonies, a recombinase-based RIVET reporter in the wggR gene was resolved in 30% of the cells, indicating an enhanced regulation of EPS II production in the subpopulation of cells, which was sufficient to support swarming of the entire colony. Conclusions/Significance Swarming behavior of S. meliloti Rm8530 on semi-solid surfaces is found to be dependent on the functional QS regulatory cascades. Even though multiple AHL signals are produced by the bacterium, only two AHLs species, C16:1- and 3-oxo-C16:1-HSLs, affected swarming by up-regulating the expression of wggR. While EPS II is produced by Rm8530 as high and low molecular weight fractions, only the HMW EPS II facilitated initial stages of swarming, thus, suggesting a function for this polymer.
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Affiliation(s)
- Mengsheng Gao
- Soil and Water Science Department, University of Florida/Institute of Food and Agricultural Sciences, Gainesville, Florida, United States of America
- * E-mail:
| | | | - Kruti Yagnik
- Soil and Water Science Department, University of Florida/Institute of Food and Agricultural Sciences, Gainesville, Florida, United States of America
| | - Max Teplitski
- Soil and Water Science Department, University of Florida/Institute of Food and Agricultural Sciences, Gainesville, Florida, United States of America
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Tamir-Ariel D, Rosenberg T, Navon N, Burdman S. A secreted lipolytic enzyme from Xanthomonas campestris pv. vesicatoria is expressed in planta and contributes to its virulence. MOLECULAR PLANT PATHOLOGY 2012; 13:556-67. [PMID: 22176521 PMCID: PMC6638646 DOI: 10.1111/j.1364-3703.2011.00771.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A recombinase-based in vivo expression technology (RIVET) approach with Xanthomonas campestris pv. vesicatoria (Xcv) revealed that lipA, annotated as putative secreted lipase, is expressed during the interaction between this pathogen and tomato. Here, the tnpR and uidA reporter genes were used to show that lipA is strongly induced in XVM2 minimal medium and during the early stages of tomato infection by Xcv. A mutant strain impaired in lipA was generated by insertional mutagenesis. This mutant grew in a similar manner to the wild-type in rich medium, but its growth was significantly compromised in a medium containing olive oil as a single carbon source. The lipolytic activity of the extracellular fraction of the lipA mutant was reduced significantly relative to that of the wild-type strain, thus confirming that lipA indeed encodes a functional secreted enzyme with lipolytic activity. A plasmid carrying a wild-type copy of lipA complemented the lipA mutant for extracellular lipolytic activity. Dip inoculation experiments with tomato lines Hawaii 7998 (H7998) and Micro Tom showed that the lipA mutant grew to a lesser extent than the wild-type in tomato leaves. Following leaf syringe infiltrations, the mutant strain induced disease symptoms that were less severe than those induced by the wild-type strain, supporting a significant role of lipA in the pathogenicity of Xcv.
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Affiliation(s)
- Dafna Tamir-Ariel
- Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel
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The Helicobacter pylori autotransporter ImaA (HP0289) modulates the immune response and contributes to host colonization. Infect Immun 2012; 80:2286-96. [PMID: 22566509 DOI: 10.1128/iai.00312-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The human pathogen Helicobacter pylori employs a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced gene HP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenic H. pylori mutant that lacks HP0289 and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-type H. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that the HP0289 promoter is upregulated in the mouse stomach, and here we demonstrate that HP0289 expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that the HP0289 mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-type H. pylori. On the basis of this phenotype, we renamed HP0289 ImaA for immunomodulatory autotransporter protein. Our work has revealed that genes induced in vivo play an important role in H. pylori pathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allow H. pylori to fine tune the host immune response based on ImaA expression.
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Development of a single-gene, signature-tag-based approach in combination with alanine mutagenesis to identify listeriolysin O residues critical for the in vivo survival of Listeria monocytogenes. Infect Immun 2012; 80:2221-30. [PMID: 22451517 DOI: 10.1128/iai.06196-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Listeriolysin O (LLO) is a pore-forming toxin of the cholesterol-dependent cytolysin (CDC) family and a primary virulence factor of the intracellular pathogen Listeria monocytogenes. LLO mediates rupture of phagosomal membranes, thereby releasing bacteria into the growth-permissive host cell cytosol. Several unique features of LLO allow its activity to be precisely regulated in order to facilitate phagosomal escape, intracellular growth, and cell-to-cell spread. To improve our understanding of the multifaceted contribution of LLO to the pathogenesis of L. monocytogenes, we developed a screen that combined saturation mutagenesis and signature tags, termed in vivo analysis by saturation mutagenesis and signature tags (IVASS). We generated a library of LLO mutant strains, each harboring a single amino acid substitution and a signature tag, by using the previously described pPL2 integration vector. The signature tags acted as molecular barcodes, enabling high-throughput, parallel analysis of 40 mutants in a single animal and identification of attenuated mutants by negative selection. Using the IVASS technique we were able to screen over 90% of the 505 amino acids present in LLO and identified 60 attenuated mutants. Of these, 39 LLO residues were previously uncharacterized and potentially revealed novel functions of the toxin during infection. The mutants that were subsequently analyzed in vivo each conferred a 2- to 4-orders of magnitude loss in virulence compared to wild type, thereby validating the screening methods. Phenotypic analysis of the LLO mutant library using common in vitro techniques suggested that the functional contributions of some residues could only have been revealed through in vivo analysis.
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Functional genomics studies shed light on the nutrition and gene expression of non-typhoidal Salmonella and enterovirulent E. coli in produce. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.06.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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40
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Identification of Avian pathogenic Escherichia coli genes that are induced in vivo during infection in chickens. Appl Environ Microbiol 2012; 78:3343-51. [PMID: 22344666 DOI: 10.1128/aem.07677-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) is associated with extraintestinal infections in poultry causing a variety of diseases collectively known as colibacillosis. The host and bacterial factors influencing and/or responsible for carriage and systemic translocation of APEC inside the host are poorly understood. Identification of such factors could help in the understanding of its pathogenesis and in the subsequent development of control strategies. Recombination-based in vivo expression technology (RIVET) was used to identify APEC genes specifically expressed during infection in chickens. A total of 21 clones with in vivo-induced promoters were isolated from chicken livers and spleens, indicative of systemic infection. DNA sequencing of the cloned fragments revealed that 12 of the genes were conserved E. coli genes (metH, lysA, pntA, purL, serS, ybjE, ycdK [rutC], wcaJ, gspL, sdsR, ylbE, and yjiY), 6 of the genes were phage related/associated, and 3 genes were pathogen specific (tkt1, irp2, and eitD). These genes are involved in various cellular functions, such as metabolism, cell envelope and integrity, transport systems, and virulence. Others were phage related or have yet-unknown functions.
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Frank KL, Barnes AMT, Grindle SM, Manias DA, Schlievert PM, Dunny GM. Use of recombinase-based in vivo expression technology to characterize Enterococcus faecalis gene expression during infection identifies in vivo-expressed antisense RNAs and implicates the protease Eep in pathogenesis. Infect Immun 2012; 80:539-49. [PMID: 22144481 PMCID: PMC3264308 DOI: 10.1128/iai.05964-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 11/19/2011] [Indexed: 12/28/2022] Open
Abstract
Enterococcus faecalis is a member of the mammalian gastrointestinal microflora that has become a leading cause of nosocomial infections over the past several decades. E. faecalis must be able to adapt its physiology based on its surroundings in order to thrive in a mammalian host as both a commensal and a pathogen. We employed recombinase-based in vivo expression technology (RIVET) to identify promoters on the E. faecalis OG1RF chromosome that were specifically activated during the course of infection in a rabbit subdermal abscess model. The RIVET screen identified 249 putative in vivo-activated loci, over one-third of which are predicted to generate antisense transcripts. Three predicted antisense transcripts were detected in in vitro- and in vivo-grown cells, providing the first evidence of in vivo-expressed antisense RNAs in E. faecalis. Deletions in the in vivo-activated genes that encode glutamate 5-kinase (proB [EF0038]), the transcriptional regulator EbrA (ebrA [EF1809]), and the membrane metalloprotease Eep (eep [EF2380]) did not hinder biofilm formation in in vitro assays. In a rabbit model of endocarditis, the ΔebrA strain was fully virulent, the ΔproB strain was slightly attenuated, and the Δeep strain was severely attenuated. The Δeep virulence defect could be complemented by the expression of the wild-type gene in trans. Microscopic analysis of early Δeep biofilms revealed an abundance of small cellular aggregates that were not observed in wild-type biofilms. This work illustrates the use of a RIVET screen to provide information about the temporal activation of genes during infection, resulting in the identification and confirmation of a new virulence determinant in an important pathogen.
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Affiliation(s)
- Kristi L Frank
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
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Development of new positive-selection RIVET tools: Detection of induced promoters by the excision-based transcriptional activation of an aacCI (GmR)–gfp fusion. J Biotechnol 2011; 155:147-55. [DOI: 10.1016/j.jbiotec.2011.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 05/05/2011] [Accepted: 06/17/2011] [Indexed: 11/30/2022]
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Frans I, Michiels CW, Bossier P, Willems KA, Lievens B, Rediers H. Vibrio anguillarum as a fish pathogen: virulence factors, diagnosis and prevention. JOURNAL OF FISH DISEASES 2011; 34:643-661. [PMID: 21838709 DOI: 10.1111/j.1365-2761.2011.01279.x] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Vibrio anguillarum, also known as Listonella anguillarum, is the causative agent of vibriosis, a deadly haemorrhagic septicaemic disease affecting various marine and fresh/brackish water fish, bivalves and crustaceans. In both aquaculture and larviculture, this disease is responsible for severe economic losses worldwide. Because of its high morbidity and mortality rates, substantial research has been carried out to elucidate the virulence mechanisms of this pathogen and to develop rapid detection techniques and effective disease-prevention strategies. This review summarizes the current state of knowledge pertaining to V. anguillarum, focusing on pathogenesis, known virulence factors, diagnosis, prevention and treatment.
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Affiliation(s)
- I Frans
- Laboratory for Process Microbial Ecology and Bioinspirational Management, Consortium for Industrial Microbiology and Biotechnology, Department of Microbial and Molecular Systems, K.U. Leuven Association, Lessius Mechelen, Sint-Katelijne-Waver, Belgium
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44
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Bradley ES, Bodi K, Ismail AM, Camilli A. A genome-wide approach to discovery of small RNAs involved in regulation of virulence in Vibrio cholerae. PLoS Pathog 2011; 7:e1002126. [PMID: 21779167 PMCID: PMC3136459 DOI: 10.1371/journal.ppat.1002126] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Accepted: 05/02/2011] [Indexed: 11/18/2022] Open
Abstract
Small RNAs (sRNAs) are becoming increasingly recognized as important regulators in bacteria. To investigate the contribution of sRNA mediated regulation to virulence in Vibrio cholerae, we performed high throughput sequencing of cDNA generated from sRNA transcripts isolated from a strain ectopically expressing ToxT, the major transcriptional regulator within the virulence gene regulon. We compared this data set with ToxT binding sites determined by pulldown and deep sequencing to identify sRNA promoters directly controlled by ToxT. Analysis of the resulting transcripts with ToxT binding sites in cis revealed two sRNAs within the Vibrio Pathogenicity Island. When deletions of these sRNAs were made and the resulting strains were competed against the parental strain in the infant mouse model of V. cholerae colonization, one, TarB, displayed a variable colonization phenotype dependent on its physiological state at the time of inoculation. We identified a target of TarB as the mRNA for the secreted colonization factor, TcpF. We verified negative regulation of TcpF expression by TarB and, using point mutations that disrupted interaction between TarB and tpcF mRNA, showed that loss of this negative regulation was primarily responsible for the colonization phenotype observed in the TarB deletion mutant.
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Affiliation(s)
- Evan S. Bradley
- Howard Hughes Medical Institute and the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Kip Bodi
- Howard Hughes Medical Institute and the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Ayman M. Ismail
- Howard Hughes Medical Institute and the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Andrew Camilli
- Howard Hughes Medical Institute and the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Bagnoli F, Baudner B, Mishra RPN, Bartolini E, Fiaschi L, Mariotti P, Nardi-Dei V, Boucher P, Rappuoli R. Designing the next generation of vaccines for global public health. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2011; 15:545-66. [PMID: 21682594 DOI: 10.1089/omi.2010.0127] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Vaccine research and development are experiencing a renaissance of interest from the global scientific community. There are four major reasons for this: (1) the lack of efficacious treatment for many devastating infections; (2) the emergence of multidrug resistant bacteria; (3) the need for improving the safety of the more traditional licensed vaccines; and finally, (4) the great promise for innovative vaccine design and research with convergence of omics sciences, such as genomics, proteomics, immunomics, and vaccinology. Our first project based on omics was initiated in 2000 and was termed reverse vaccinology. At that time, antigen identification was mainly based on bioinformatic analysis of a singular genome. Since then, omics-guided approaches have been applied to its full potential in several proof-of-concept studies in the industry, with the first reverse vaccinology-derived vaccine now in late stage clinical trials and several vaccines developed by omics in preclinical studies. In the meantime, vaccine discovery and development has been further improved with the support of proteomics, functional genomics, comparative genomics, structural biology, and most recently vaccinomics. We illustrate in this review how omics biotechnologies and integrative biology are expected to accelerate the identification of vaccine candidates against difficult pathogens for which traditional vaccine development has thus far been failing, and how research will provide safer vaccines and improved formulations for immunocompromised patients in the near future. Finally, we present a discussion to situate omics-guided rational vaccine design in the broader context of global public health and how it can benefit citizens in both developed and developing countries.
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Xu G, Jia H, Li Y, Liu X, Li M, Wang Y. Hemolytic phospholipase Rv0183 of Mycobacterium tuberculosis induces inflammatory response and apoptosis in alveolar macrophage RAW264.7 cells. Can J Microbiol 2011; 56:916-24. [PMID: 21076482 DOI: 10.1139/w10-079] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The metabolic pathway of phospholipids is one of the most important physiologic pathways in Mycobacterium tuberculosis, a typical intracellular bacterium. The hemolytic phospholipase lip gene (Rv0183) is one of 24 phospholipase genes that have been demonstrated to play critical roles in the metabolism of phospholipids in M. tuberculosis. Quantitative RT-PCR and flow cytometry were used to elucidate the immunological and pathogenic implications of the Rv0183 gene on the inflammatory response following persistent expression of Rv0183 in mouse alveolar macrophage RAW264.7 cells. Our results demonstrate that a time-course-dependent ectopic expression of Rv0183 significantly elevated the expression of IL-6, NF-κB, TLR-2, TLR-6, TNFα, and MyD88 in these alveolar macrophage cells. Furthermore, the persistent expression of Rv0183 induced RAW264.7 cell apoptosis in vitro. These findings demonstrate that the expression of Rv0183 induces an inflammatory response and cell apoptosis in the host cells, suggesting that Rv0183 may play an important role in the virulence and pathogenesis of M. tuberculosis infection.
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Affiliation(s)
- Guangxian Xu
- College of Life Science, Ningxia University, Yinchuan, Ningxia 750021, China
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Ahmer BMM, Gunn JS. Interaction of Salmonella spp. with the Intestinal Microbiota. Front Microbiol 2011; 2:101. [PMID: 21772831 PMCID: PMC3131049 DOI: 10.3389/fmicb.2011.00101] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 04/25/2011] [Indexed: 12/20/2022] Open
Abstract
Salmonella spp. are major cause of human morbidity and mortality worldwide. Upon entry into the human host, Salmonella spp. must overcome the resistance to colonization mediated by the gut microbiota and the innate immune system. They successfully accomplish this by inducing inflammation and mechanisms of innate immune defense. Many models have been developed to study Salmonella spp. interaction with the microbiota that have helped to identify factors necessary to overcome colonization resistance and to mediate disease. Here we review the current state of studies into this important pathogen/microbiota/host interaction in the mammalian gastrointestinal tract.
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Affiliation(s)
- Brian M M Ahmer
- The Department of Microbiology, The Ohio State University Columbus, OH, USA
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Tamir-Ariel D, Rosenberg T, Burdman S. The Xanthomonas campestris pv. vesicatoria citH gene is expressed early in the infection process of tomato and is positively regulated by the TctDE two-component regulatory system. MOLECULAR PLANT PATHOLOGY 2011; 12:57-71. [PMID: 21118349 PMCID: PMC6640381 DOI: 10.1111/j.1364-3703.2010.00652.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Xanthomonas campestris pv. vesicatoria (Xcv) is the causal agent of bacterial spot disease of tomato and pepper. Previously, we have reported the adaptation of a recombinase- or resolvase-based in vivo expression technology (RIVET) approach to identify Xcv genes that are specifically induced during its interaction with tomato. Analysis of some of these genes revealed that a citH (citrate transporter) homologous gene contributes to Xcv virulence on tomato. Here, we demonstrate that the citH product indeed facilitates citrate uptake by showing the following: citH is specifically needed for Xcv growth in citrate, but not in other carbon sources; the citH promoter is specifically induced by citrate; and the concentration of citrate from tomato leaf apoplast is considerably reduced following growth of the wild-type and a citH-complemented strain, but not the citH mutant. We also show that, in the Xcv-tomato interaction, the promoter activity of the citH gene is induced as early as 2.5h after Xcv is syringe infiltrated into tomato leaves, and continues to be active for at least 96h after inoculation. We identified an operon containing a two-component regulatory system homologous to tctD/tctE influencing citH expression in Xcv, as well as its heterologous expression in Escherichia coli. The expression of hrp genes does not seem to be affected in the citH mutant, and this mutant cannot be complemented for growth in planta when co-inoculated with the wild-type strain, indicating that citrate uptake in the apoplast is important for the virulence of Xcv.
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Affiliation(s)
- Dafna Tamir-Ariel
- Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Guerrero-Ferreira RC, Nishiguchi MK. Differential gene expression in bacterial symbionts from loliginid squids demonstrates variation between mutualistic and environmental niches. ENVIRONMENTAL MICROBIOLOGY REPORTS 2010; 2:514-523. [PMID: 20680094 PMCID: PMC2911791 DOI: 10.1111/j.1758-2229.2009.00077.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Luminescent bacteria (gamma-Proteobacteria: Vibrionaceae) are found in complex bilobed light organs of both sepiolid and loliginid squids (Mollusca: Cephalopoda). Despite the existence of multiple strain colonization between Vibrio bacteria and loliginid squids, specificity at the genus level still exists and may influence interactions between symbiotic and free-living stages of the symbiont. The environmentally transmitted behaviour of Vibrio symbionts bestows a certain degree of recognition that exists prior and subsequent to the colonization process. Therefore, we identified bacterial genes required for successful colonization of loliginid light organs by examining transcripts solely expressed in either the light organ or free-living stages. Selective capture of transcribed sequences (SCOTS) was used to differentiate genes expressed by the same bacterium when thriving in two different environments (i.e. loliginid light organs and seawater). Genes specific for squid light organs included vulnibactin synthetase, outer membrane protein W and dihydroxy dehydratase, which have been associated with the maintenance of bacterial host associations in other systems. In contrast, genes that were solely expressed in the free-living condition consisted of transcripts recognized as important factors for bacterial survival in the environment. These transcripts included genes for methyl accepting chemotaxis proteins, arginine decarboxylase and chitinase. These results provide valuable information regarding mechanisms determining specificity, establishment, and maintenance of bacteria-squid associations.
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Hanin A, Sava I, Bao Y, Huebner J, Hartke A, Auffray Y, Sauvageot N. Screening of in vivo activated genes in Enterococcus faecalis during insect and mouse infections and growth in urine. PLoS One 2010; 5:e11879. [PMID: 20686694 PMCID: PMC2912369 DOI: 10.1371/journal.pone.0011879] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Accepted: 07/05/2010] [Indexed: 12/15/2022] Open
Abstract
Enterococcus faecalis is part of the commensal microbiota of humans and its main habitat is the gastrointestinal tract. Although harmless in healthy individuals, E. faecalis has emerged as a major cause of nosocomial infections. In order to better understand the transformation of a harmless commensal into a life-threatening pathogen, we developed a Recombination-based In VivoExpression Technology for E. faecalis. Two R-IVET systems with different levels of sensitivity have been constructed in a E. faecalis V583 derivative strain and tested in the insect model Galleria mellonella, during growth in urine, in a mouse bacteremia and in a mouse peritonitis model. Our combined results led to the identification of 81 in vivo activated genes. Among them, the ef_3196/7 operon was shown to be strongly induced in the insect host model. Deletion of this operonic structure demonstrated that this two-component system was essential to the E. faecalis pathogenic potential in Galleria. Gene ef_0377, induced in insect and mammalian models, has also been further analyzed and it has been demonstrated that this ankyrin-encoding gene was also involved in E. faecalis virulence. Thus these R-IVET screenings led to the identification of new E. faecalis factors implied in in vivo persistence and pathogenic potential of this opportunistic pathogen.
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Affiliation(s)
- Aurelie Hanin
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Irina Sava
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - YinYin Bao
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - Johannes Huebner
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - Axel Hartke
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Yanick Auffray
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Nicolas Sauvageot
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
- * E-mail:
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