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Dr. Mireille Ansaldi
CNRS - French National Center for Scientific Research

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0 Biosensors
0 Microbiology
0 bacteriophage genetics hostvirus interactions
0 Bacteriophages
0 transcriptome and genome studies

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Journal article
Published: 21 April 2021 in Viruses
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Xylella fastidiosa (Xf) is a plant pathogen causing significant losses in agriculture worldwide. Originating from America, this bacterium caused recent epidemics in southern Europe and is thus considered an emerging pathogen. As the European regulations do not authorize antibiotic treatment in plants, alternative treatments are urgently needed to control the spread of the pathogen and eventually to cure infected crops. One such alternative is the use of phage therapy, developed more than 100 years ago to cure human dysentery and nowadays adapted to agriculture. The first step towards phage therapy is the isolation of the appropriate bacteriophages. With this goal, we searched for phages able to infect Xf strains that are endemic in the Mediterranean area. However, as Xf is truly a fastidious organism, we chose the phylogenetically closest and relatively fast-growing organism X. albineans as a surrogate host for the isolation step. Our results showed the isolation from various sources and preliminary characterization of several phages active on different Xf strains, namely, from the fastidiosa (Xff), multiplex (Xfm), and pauca (Xfp) subspecies, as well as on X. albilineans. We sequenced their genomes, described their genomic features, and provided a phylogeny analysis that allowed us to propose new taxonomic elements. Among the 14 genomes sequenced, we could identify two new phage species, belonging to two new genera of the Caudoviricetes order, namely, Usmevirus (Podoviridae family) and Subavirus (Siphoviridae family). Interestingly, no specific phages could be isolated from infected plant samples, whereas one was isolated from vector insects captured in a contaminated area, and several from surface and sewage waters from the Marseille area.

ACS Style

Fernando Clavijo-Coppens; Nicolas Ginet; Sophie Cesbron; Martial Briand; Marie-Agnès Jacques; Mireille Ansaldi. Novel Virulent Bacteriophages Infecting Mediterranean Isolates of the Plant Pest Xylella fastidiosa and Xanthomonas albilineans. Viruses 2021, 13, 725 .

AMA Style

Fernando Clavijo-Coppens, Nicolas Ginet, Sophie Cesbron, Martial Briand, Marie-Agnès Jacques, Mireille Ansaldi. Novel Virulent Bacteriophages Infecting Mediterranean Isolates of the Plant Pest Xylella fastidiosa and Xanthomonas albilineans. Viruses. 2021; 13 (5):725.

Chicago/Turabian Style

Fernando Clavijo-Coppens; Nicolas Ginet; Sophie Cesbron; Martial Briand; Marie-Agnès Jacques; Mireille Ansaldi. 2021. "Novel Virulent Bacteriophages Infecting Mediterranean Isolates of the Plant Pest Xylella fastidiosa and Xanthomonas albilineans." Viruses 13, no. 5: 725.

Research article
Published: 03 May 2020 in Environmental Microbiology
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Summary Environmental monitoring of bacteria using phage‐based biosensors has been widely developed for many different species. However, there are only a few available methods to detect specific bacteriophages in raw environmental samples. In this work, we developed a simple and efficient assay to rapidly monitor the phage content of a given sample. The assay is based on the bistable expression of the Salmonella enterica opvAB operon. Under regular growth conditions, opvAB is only expressed by a small fraction of the bacterial subpopulation. In the OpvABON subpopulation, synthesis of the OpvA and OpvB products shortens the O‐antigen and confers resistance to phages that use LPS as a receptor. As a consequence, the OpvABON subpopulation is selected in the presence of such phages. Using an opvAB::gfp fusion, we could monitor LPS‐binding phages in various media, including raw water samples. To enlarge our phage‐biosensor panoply, we also developed biosensors able to detect LPS‐ as well as protein‐binding coliphages. Moreover, the combination of these tools allowed to identify the bacterial receptor triggering phage infection. The epigenetic opvAB::gfp biosensor thus comes in different flavours to detect a wide range of bacteriophages and identify the type of receptor they recognize. This article is protected by copyright. All rights reserved.

ACS Style

David R. Olivenza; Josep Casadesús; Mireille Ansaldi. Epigenetic biosensors for bacteriophage detection and phage receptor discrimination. Environmental Microbiology 2020, 22, 3126 -3142.

AMA Style

David R. Olivenza, Josep Casadesús, Mireille Ansaldi. Epigenetic biosensors for bacteriophage detection and phage receptor discrimination. Environmental Microbiology. 2020; 22 (8):3126-3142.

Chicago/Turabian Style

David R. Olivenza; Josep Casadesús; Mireille Ansaldi. 2020. "Epigenetic biosensors for bacteriophage detection and phage receptor discrimination." Environmental Microbiology 22, no. 8: 3126-3142.

Preprint
Published: 24 November 2019
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Environmental monitoring of bacteria using phage-based biosensors has been widely developed for many different species. However, there are only a few available methods to detect specific bacteriophages in raw environmental samples. In this work, we developed a simple and efficient assay to rapidly monitor the phage content of a given sample. The assay is based on the bistable expression of theSalmonella enterica opvABoperon. Under regular growth conditions,opvABis only expressed by a small fraction of the bacterial subpopulation. In the OpvABONsubpopulation, synthesis of the OpvA and OpvB products shortens the O-antigen in the lipopolysaccharide and confers resistance to phages that use LPS as a receptor. As a consequence, the OpvABONsubpopulation is selected in the presence of such phages. Using anopvAB::gfpfusion, we could monitor LPS-binding phages in various media, including raw water samples. To enlarge our phage-biosensor panoply, we also developed several coliphage biosensors that proved efficient to detect LPS- as well as protein-binding coliphages. Moreover, the combination of these tools allows to identify what is the bacterial receptor triggering phage infection. TheopvAB::gfpbiosensor thus comes in different flavours to efficiently detect a wide range of bacteriophages and identify the type of receptor they recognize. Importance Detection and accurate counting of bacteriophages, the viruses that specifically infect bacteria, from environmental samples still constitutes a challenge for those interested in isolating and characterizing bacteriophages for ecological or biotechnological purposes. This work provides a simple and accurate method based on the bi-stable expression of genes that confer resistance to certain classes of bacteriophages in different bacterial models. It paves the way for future development of highly efficient phage biosensors that can discriminate among several receptor-binding phages and that could be declined in many more versions. In a context where phage ecology, research, and therapy are flourishing again, it becomes essential to possess simple and efficient tools for phage detection.

ACS Style

David R. Olivenza; Josep Casadesús; Mireille Ansaldi. Phase variation-based biosensors for bacteriophage detection and phage receptor discrimination. 2019, 851808 .

AMA Style

David R. Olivenza, Josep Casadesús, Mireille Ansaldi. Phase variation-based biosensors for bacteriophage detection and phage receptor discrimination. . 2019; ():851808.

Chicago/Turabian Style

David R. Olivenza; Josep Casadesús; Mireille Ansaldi. 2019. "Phase variation-based biosensors for bacteriophage detection and phage receptor discrimination." , no. : 851808.

Microreview
Published: 22 November 2018 in Molecular Microbiology
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Thanks to the exponentially increasing number of publicly available bacterial genome sequences, one can now estimate the important contribution of integrated viral sequences to the diversity of bacterial genomes. Indeed, temperate bacteriophages are able to stably integrate the genome of their host through site‐specific recombination and transmit vertically to the host siblings. Lysogenic conversion has been long acknowledged to provide additional functions to the host, and particularly to bacterial pathogen genomes where prophages contribute important virulence factors. This review aims particularly at highlighting the current knowledge and questions about lysogeny in Salmonella genomes where functional prophages are abundant, and where genetic interactions between host and prophages are of particular importance for human health considerations. This article is protected by copyright. All rights reserved.

ACS Style

Astrid Wahl; Aurélia Battesti; Mireille Ansaldi. Prophages in Salmonella enterica : a driving force in reshaping the genome and physiology of their bacterial host? Molecular Microbiology 2018, 111, 303 -316.

AMA Style

Astrid Wahl, Aurélia Battesti, Mireille Ansaldi. Prophages in Salmonella enterica : a driving force in reshaping the genome and physiology of their bacterial host? Molecular Microbiology. 2018; 111 (2):303-316.

Chicago/Turabian Style

Astrid Wahl; Aurélia Battesti; Mireille Ansaldi. 2018. "Prophages in Salmonella enterica : a driving force in reshaping the genome and physiology of their bacterial host?" Molecular Microbiology 111, no. 2: 303-316.

Conference report
Published: 10 March 2018 in Viruses
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In its third year of existence, the French Phage Network (Phages.fr) is pursuing its expansion. With more than 25 groups, mostly based in France, working on the various aspects of phage research, the network has increased its visibility, interactivity, and activity. The third meeting of the Phages.fr network, held on November 2017 at the Gif-sur-Yvette Centre National de la Recherche Scientifique (CNRS) campus, was a great opportunity for many young scientists to present their work and interact with more senior scientists, amongst which several were invited from abroad. Here we provide a summary of the work presented at this occasion during the oral presentations and poster sessions.

ACS Style

Mireille Ansaldi; Laurent Debarbieux; Sylvain Gandon; Marie-Agnès Petit; Paulo Tavares; Pascale Boulanger. “French Phage Network”—Third Meeting Report. Viruses 2018, 10, 123 .

AMA Style

Mireille Ansaldi, Laurent Debarbieux, Sylvain Gandon, Marie-Agnès Petit, Paulo Tavares, Pascale Boulanger. “French Phage Network”—Third Meeting Report. Viruses. 2018; 10 (3):123.

Chicago/Turabian Style

Mireille Ansaldi; Laurent Debarbieux; Sylvain Gandon; Marie-Agnès Petit; Paulo Tavares; Pascale Boulanger. 2018. "“French Phage Network”—Third Meeting Report." Viruses 10, no. 3: 123.

Journal article
Published: 01 February 2018 in Virologie
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In the 1917 article in which Félix d'Hérelle describes his first observations and proposes the name of bacteriophage, he also reports the first use of these viruses to treat bacterial infections, thus giving birth to phage therapy. Soon after antibiotics supplanted bacteriophages. Today, bacteria resistant to multiple antibiotics become a growing public health issue worldwide. This situation has revived research aiming at developing the antibacterial activity of bacteriophages to treat patients as well as diseases in animals and plants. In fact, the areas of applications of bacteriophages as antibacterial are widening as current solutions of chemical nature are questioned. This review summarizes the basic principles of therapeutic applications of bacteriophages and presents recent data in areas where commercial exploitation is occurring or about to emerge.

ACS Style

Mireille Ansaldi; Pascale Boulanger; Charlotte Brives; Laurent Debarbieux; Nicolas Dufour; Rémy Froissart; Sylvain Gandon; Claire Le Hénaff; Marie-Agnès Petit; Eduardo Rocha; Clara Torres-Barceló. Antibacterial applications of bacteriophages. Virologie 2018, 24, 23 -36.

AMA Style

Mireille Ansaldi, Pascale Boulanger, Charlotte Brives, Laurent Debarbieux, Nicolas Dufour, Rémy Froissart, Sylvain Gandon, Claire Le Hénaff, Marie-Agnès Petit, Eduardo Rocha, Clara Torres-Barceló. Antibacterial applications of bacteriophages. Virologie. 2018; 24 (1):23-36.

Chicago/Turabian Style

Mireille Ansaldi; Pascale Boulanger; Charlotte Brives; Laurent Debarbieux; Nicolas Dufour; Rémy Froissart; Sylvain Gandon; Claire Le Hénaff; Marie-Agnès Petit; Eduardo Rocha; Clara Torres-Barceló. 2018. "Antibacterial applications of bacteriophages." Virologie 24, no. 1: 23-36.

Journal article
Published: 01 February 2018 in Virologie
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Bacteriophages have a prominent place in the living world. They participate to our understanding of the living world through three main aspects : (i) the dissection of the most intimist aspects of viral infection molecular mechanisms (molecular biology), (ii) the description and functioning mechanisms of ecosystems (ecology), and (iii) the adaptive dynamics of integrated viral and host-cell populations (evolution). This review looks back at the genesis of these fundamental findings and draws a picture of the most active fields of current research.

ACS Style

Mireille Ansaldi; Pascale Boulanger; Charlotte Brives; Laurent Debarbieux; Nicolas Dufour; Rémy Froissart; Sylvain Gandon; Claire Le Hénaff; Marie-Agnès Petit; Eduardo Rocha; Clara Torres-Barceló. A century of research on bacteriophages. Virologie 2018, 24, 9 -22.

AMA Style

Mireille Ansaldi, Pascale Boulanger, Charlotte Brives, Laurent Debarbieux, Nicolas Dufour, Rémy Froissart, Sylvain Gandon, Claire Le Hénaff, Marie-Agnès Petit, Eduardo Rocha, Clara Torres-Barceló. A century of research on bacteriophages. Virologie. 2018; 24 (1):9-22.

Chicago/Turabian Style

Mireille Ansaldi; Pascale Boulanger; Charlotte Brives; Laurent Debarbieux; Nicolas Dufour; Rémy Froissart; Sylvain Gandon; Claire Le Hénaff; Marie-Agnès Petit; Eduardo Rocha; Clara Torres-Barceló. 2018. "A century of research on bacteriophages." Virologie 24, no. 1: 9-22.

Conference report
Published: 21 April 2017 in Viruses
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The study of bacteriophages (viruses of bacteria) includes a variety of approaches, such as structural biology, genetics, ecology, and evolution, with increasingly important implications for therapeutic and industrial uses. Researchers working with phages in France have recently established a network to facilitate the exchange on complementary approaches, but also to engage new collaborations. Here, we provide a summary of the topics presented during the second meeting of the French Phage Network that took place in Marseille in November 2016.

ACS Style

Clara Torres-Barceló; Oliver Kaltz; Rémy Froissart; Sylvain Gandon; Nicolas Ginet; Mireille Ansaldi. “French Phage Network”—Second Meeting Report. Viruses 2017, 9, 87 .

AMA Style

Clara Torres-Barceló, Oliver Kaltz, Rémy Froissart, Sylvain Gandon, Nicolas Ginet, Mireille Ansaldi. “French Phage Network”—Second Meeting Report. Viruses. 2017; 9 (4):87.

Chicago/Turabian Style

Clara Torres-Barceló; Oliver Kaltz; Rémy Froissart; Sylvain Gandon; Nicolas Ginet; Mireille Ansaldi. 2017. "“French Phage Network”—Second Meeting Report." Viruses 9, no. 4: 87.

In line multiplexed biosensing
Published: 12 November 2016 in Environmental Science and Pollution Research
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The use of biosensors as sensitive and rapid alert systems is a promising perspective to monitor accidental or intentional environmental pollution, but their implementation in the field is limited by the lack of adapted inline water monitoring devices. We describe here the design and initial qualification of an analyzer prototype able to accommodate three types of biosensors based on entirely different methodologies (immunological, whole-cell, and bacteriophage biosensors), but whose responses rely on the emission of light. We developed a custom light detector and a reaction chamber compatible with the specificities of the three systems and resulting in statutory detection limits. The water analyzer prototype resulting from the COMBITOX project can be situated at level 4 on the Technology Readiness Level (TRL) scale and this technical advance paves the way to the use of biosensors on-site.

ACS Style

Elodie C.T. Descamps; Damien Meunier; Catherine Brutesco; Sandra Prévéral; Nathalie Franche; Ingrid Bazin; Bertrand Miclot; Philippe LaRosa; Camille Escoffier; Jean-Raphael Fantino; Daniel Garcia; Mireille Ansaldi; Agnès Rodrigue; David Pignol; Pierre Cholat; Nicolas Ginet. Semi-autonomous inline water analyzer: design of a common light detector for bacterial, phage, and immunological biosensors. Environmental Science and Pollution Research 2016, 24, 66 -72.

AMA Style

Elodie C.T. Descamps, Damien Meunier, Catherine Brutesco, Sandra Prévéral, Nathalie Franche, Ingrid Bazin, Bertrand Miclot, Philippe LaRosa, Camille Escoffier, Jean-Raphael Fantino, Daniel Garcia, Mireille Ansaldi, Agnès Rodrigue, David Pignol, Pierre Cholat, Nicolas Ginet. Semi-autonomous inline water analyzer: design of a common light detector for bacterial, phage, and immunological biosensors. Environmental Science and Pollution Research. 2016; 24 (1):66-72.

Chicago/Turabian Style

Elodie C.T. Descamps; Damien Meunier; Catherine Brutesco; Sandra Prévéral; Nathalie Franche; Ingrid Bazin; Bertrand Miclot; Philippe LaRosa; Camille Escoffier; Jean-Raphael Fantino; Daniel Garcia; Mireille Ansaldi; Agnès Rodrigue; David Pignol; Pierre Cholat; Nicolas Ginet. 2016. "Semi-autonomous inline water analyzer: design of a common light detector for bacterial, phage, and immunological biosensors." Environmental Science and Pollution Research 24, no. 1: 66-72.

Journal article
Published: 23 February 2016 in Environmental Science and Pollution Research
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Water quality is a major safety consideration in environments that are impacted by human activity. The key challenge of the COMBITOX project is to develop a unique instrument that can accommodate several biodetector systems (see the accompanying COMBITOX papers) able to detect different pollutants such as bacteria, toxins, and heavy metals. The output signal chosen by our consortium is based on luminescence detection. Our group recently developed phage-based biosensors using gfp as a reporter gene to detect enteric bacteria in complex environments such as sea water, and the main challenge we faced was to adapt our biodetector to a luminescent signal that could fit the COMBITOX project requirements. Another key point was to use a substrate-independent reporter system in order to avoid substrate addition in the detection prototype. This paper describes the development of a phage-based biodetector using a luminescent and substrate-independent output to detect some enteric bacteria, such as Escherichia coli, in water samples. We have successfully engineered various prototypes using the HK620 and HK97 bacteriophages that use different packaging systems, and both proved functional for the integration of the full luxCDABE operon controlled by two different bacterial promoters. We show that the luxCDABE operon controlled by the PrplU bacterial promoter is the most efficient in terms of signal emission. The emission of luminescence is specific and allows the detection of 104 bacteria per milliliter in 1.5 h post-infection with neither a concentration nor enrichment step.

ACS Style

Nathalie Franche; Manon Vinay; Mireille Ansaldi. Substrate-independent luminescent phage-based biosensor to specifically detect enteric bacteria such as E. coli. Environmental Science and Pollution Research 2016, 24, 42 -51.

AMA Style

Nathalie Franche, Manon Vinay, Mireille Ansaldi. Substrate-independent luminescent phage-based biosensor to specifically detect enteric bacteria such as E. coli. Environmental Science and Pollution Research. 2016; 24 (1):42-51.

Chicago/Turabian Style

Nathalie Franche; Manon Vinay; Mireille Ansaldi. 2016. "Substrate-independent luminescent phage-based biosensor to specifically detect enteric bacteria such as E. coli." Environmental Science and Pollution Research 24, no. 1: 42-51.

Editorial
Published: 21 October 2015 in Environmental Science and Pollution Research
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International audienceno abstrac

ACS Style

Mireille Ansaldi; Ingrid Bazin; Pierre Cholat; Agnès Rodrigue; David Pignol. Toward inline multiplex biodetection of metals, bacteria, and toxins in water networks: the COMBITOX project. Environmental Science and Pollution Research 2015, 24, 1 -3.

AMA Style

Mireille Ansaldi, Ingrid Bazin, Pierre Cholat, Agnès Rodrigue, David Pignol. Toward inline multiplex biodetection of metals, bacteria, and toxins in water networks: the COMBITOX project. Environmental Science and Pollution Research. 2015; 24 (1):1-3.

Chicago/Turabian Style

Mireille Ansaldi; Ingrid Bazin; Pierre Cholat; Agnès Rodrigue; David Pignol. 2015. "Toward inline multiplex biodetection of metals, bacteria, and toxins in water networks: the COMBITOX project." Environmental Science and Pollution Research 24, no. 1: 1-3.

Research article
Published: 17 July 2015 in PLOS ONE
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Water safety is a major concern for public health and for natural environment preservation. We propose to use bacteriophages to develop biosensor tools able to detect human and animal pathogens present in water. For this purpose, we take advantage of the highly discriminating properties of the bacteriophages, which specifically infect their bacterial hosts. The challenge is to use a fluorescent reporter protein that will be synthesized, and thus detected, only once the specific recognition step between a genetically modified temperate bacteriophage and its bacterial host has occurred. To ensure the accuracy and the execution speed of our system, we developed a test that does not require bacterial growth, since a simple 1-hour infection step is required. To ensure a high sensitivity of our tool and in order to detect up to a single bacterium, fluorescence is measured using a portable flow cytometer, also allowing on-site detection. In this study, we have constructed and characterized several "phagosensor" prototypes using the HK620 bacteriophage and its host Escherichia coli TD2158 and we successfully adapted this method to Salmonella detection. We show that the method is fast, robust and sensitive, allowing the detection of as few as 10 bacteria per ml with no concentration nor enrichment step. Moreover, the test is functional in sea water and allows the detection of alive bacteria. Further development will aim to develop phagosensors adapted on demand to the detection of any human or animal pathogen that may be present in water.

ACS Style

Manon Vinay; Nathalie Franche; Gérald Grégori; Jean-Raphaël Fantino; Flavie Pouillot; Mireille Ansaldi. Phage-Based Fluorescent Biosensor Prototypes to Specifically Detect Enteric Bacteria Such as E. coli and Salmonella enterica Typhimurium. PLOS ONE 2015, 10, e0131466 .

AMA Style

Manon Vinay, Nathalie Franche, Gérald Grégori, Jean-Raphaël Fantino, Flavie Pouillot, Mireille Ansaldi. Phage-Based Fluorescent Biosensor Prototypes to Specifically Detect Enteric Bacteria Such as E. coli and Salmonella enterica Typhimurium. PLOS ONE. 2015; 10 (7):e0131466.

Chicago/Turabian Style

Manon Vinay; Nathalie Franche; Gérald Grégori; Jean-Raphaël Fantino; Flavie Pouillot; Mireille Ansaldi. 2015. "Phage-Based Fluorescent Biosensor Prototypes to Specifically Detect Enteric Bacteria Such as E. coli and Salmonella enterica Typhimurium." PLOS ONE 10, no. 7: e0131466.

Journal article
Published: 26 June 2015 in Frontiers in Microbiology
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The ability to respire sulfate linked to lactate oxidation is a key metabolic signature of the Desulfovibrio genus. Lactate oxidation by these incomplete oxidizers generates reductants through lactate dehydrogenase (LDH) and pyruvate-ferredoxin oxidoreductase (PFOR), with the latter catalyzing pyruvate conversion into acetyl-CoA. Acetyl-CoA is the source of substrate-level phosphorylation through the production of ATP. Here, we show that these crucial steps are performed by enzymes encoded by a nonacistronic transcriptional unit named now as operon luo (for lactate utilization operon). Using a combination of genetic and biochemical techniques, we assigned a physiological role to the operon genes DVU3027-28 and DVU3032-33. The growth of mutant Δ26-28 was highly disrupted on D-lactate, whereas the growth of mutant Δ32-33 was slower on L-lactate, which could be related to a decrease in the activity of D-lactate or L-lactate oxidase in the corresponding mutants. The DVU3027-28 and DVU3032-33 genes thus encode functional D-LDH and L-LDH enzymes, respectively. Scanning of the genome for lactate utilization revealed several lactate permease and dehydrogenase homologs. However, transcriptional compensation was not observed in any of the mutants except for lactate permease. Although there is a high degree of redundancy for lactate oxidase, it is not functionally efficient in LDH mutants. This result could be related to the identification of several operon enzymes, including LDHs, in the PFOR activity bands, suggesting the occurrence of a lactate-oxidizing supermolecular structure that can optimize the performance of lactate utilization in Desulfovibrio species.

ACS Style

Nicolas Vita; Odile Valette; Gaël Brasseur; Sabrina Lignon; Yann Denis; Mireille Ansaldi; Alain Dolla; Laetitia Pieulle. The primary pathway for lactate oxidation in Desulfovibrio vulgaris. Frontiers in Microbiology 2015, 6, 606 .

AMA Style

Nicolas Vita, Odile Valette, Gaël Brasseur, Sabrina Lignon, Yann Denis, Mireille Ansaldi, Alain Dolla, Laetitia Pieulle. The primary pathway for lactate oxidation in Desulfovibrio vulgaris. Frontiers in Microbiology. 2015; 6 ():606.

Chicago/Turabian Style

Nicolas Vita; Odile Valette; Gaël Brasseur; Sabrina Lignon; Yann Denis; Mireille Ansaldi; Alain Dolla; Laetitia Pieulle. 2015. "The primary pathway for lactate oxidation in Desulfovibrio vulgaris." Frontiers in Microbiology 6, no. : 606.

Review
Published: 01 January 2015 in FEMS Microbiology Letters
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Bacteriophages co-exist and co-evolve with their hosts in natural environments. Virulent phages lyse infected cells through lytic cycles, whereas temperate phages often remain dormant and can undergo lysogenic or lytic cycles. In their lysogenic state, prophages are actually part of the host genome and replicate passively in rhythm with host division. However, prophages are far from being passive residents: they can modify or bring new properties to their host. In this review, we focus on two important phage-encoded recombination mechanisms, i.e. site-specific recombination and homologous recombination, and how they remodel bacterial genomes.

ACS Style

Rachid Menouni; Geoffrey Hutinet; Marie-Agnès Petit; Mireille Ansaldi. Bacterial genome remodeling through bacteriophage recombination. FEMS Microbiology Letters 2015, 362, 1 -10.

AMA Style

Rachid Menouni, Geoffrey Hutinet, Marie-Agnès Petit, Mireille Ansaldi. Bacterial genome remodeling through bacteriophage recombination. FEMS Microbiology Letters. 2015; 362 (1):1-10.

Chicago/Turabian Style

Rachid Menouni; Geoffrey Hutinet; Marie-Agnès Petit; Mireille Ansaldi. 2015. "Bacterial genome remodeling through bacteriophage recombination." FEMS Microbiology Letters 362, no. 1: 1-10.

Journal article
Published: 12 August 2013 in Proceedings of the National Academy of Sciences
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Prophages represent a large fraction of prokaryotic genomes and often provide new functions to their hosts, in particular virulence and fitness. How prokaryotic cells maintain such gene providers is central for understanding bacterial genome evolution by horizontal transfer. Prophage excision occurs through site-specific recombination mediated by a prophage-encoded integrase. In addition, a recombination directionality factor (or excisionase) directs the reaction toward excision and prevents the phage genome from being reintegrated. In this work, we describe the role of the transcription termination factor Rho in prophage maintenance through control of the synthesis of transcripts that mediate recombination directionality factor expression and, thus, excisive recombination. We show that Rho inhibition by bicyclomycin allows for the expression of prophage genes that lead to excisive recombination. Thus, besides its role in the silencing of horizontally acquired genes, Rho also maintains lysogeny of defective and functional prophages.

ACS Style

Rachid Menouni; Stéphanie Champ; Leon Espinosa; Marc Boudvillain; Mireille Ansaldi. Transcription termination controls prophage maintenance in Escherichia coli genomes. Proceedings of the National Academy of Sciences 2013, 110, 14414 -14419.

AMA Style

Rachid Menouni, Stéphanie Champ, Leon Espinosa, Marc Boudvillain, Mireille Ansaldi. Transcription termination controls prophage maintenance in Escherichia coli genomes. Proceedings of the National Academy of Sciences. 2013; 110 (35):14414-14419.

Chicago/Turabian Style

Rachid Menouni; Stéphanie Champ; Leon Espinosa; Marc Boudvillain; Mireille Ansaldi. 2013. "Transcription termination controls prophage maintenance in Escherichia coli genomes." Proceedings of the National Academy of Sciences 110, no. 35: 14414-14419.

Journal article
Published: 24 October 2012 in Viruses
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Recombination directionality factors (RDFs), or excisionases, are essential players of prophage excisive recombination. Despite the essentially catalytic role of the integrase in both integrative and excisive recombination, RDFs are required to direct the reaction towards excision and to prevent re-integration of the prophage genome when entering a lytic cycle. KplE1, HK620 and numerous (pro)phages that integrate at the same site in enterobacteria genomes (such as the argW tRNA gene) all share a highly conserved recombination module. This module comprises the attL and attR recombination sites and the RDF and integrase genes. The KplE1 RDF was named TorI after its initial identification as a negative regulator of the tor operon. However, it was characterized as an essential factor of excisive recombination. In this study, we designed an extensive random mutagenesis protocol of the torI gene and identified key residues involved in both functions of the TorI protein. We show that, in addition to TorI-TorR protein-protein interaction, TorI interacts in solution with the IntS integrase. Moreover, in vitro, TorR and IntS appear to compete for TorI binding. Finally, our mutagenesis results suggest that the C-terminal part of the TorI protein is dedicated to protein-protein interactions with both proteins TorR and IntS.

ACS Style

Gaël Panis; Nathalie Franche; Vincent Méjean; Mireille Ansaldi. Insights into the Functions of a Prophage Recombination Directionality Factor. Viruses 2012, 4, 2417 -2431.

AMA Style

Gaël Panis, Nathalie Franche, Vincent Méjean, Mireille Ansaldi. Insights into the Functions of a Prophage Recombination Directionality Factor. Viruses. 2012; 4 (11):2417-2431.

Chicago/Turabian Style

Gaël Panis; Nathalie Franche; Vincent Méjean; Mireille Ansaldi. 2012. "Insights into the Functions of a Prophage Recombination Directionality Factor." Viruses 4, no. 11: 2417-2431.

Journal article
Published: 01 April 2012 in Journal of Biological Chemistry
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Temperate phages mediate gene transfer and can modify the properties of their host organisms through the acquisition of novel genes, a process called lysogeny. The KplE1 prophage is one of the 10 prophage regions in Escherichia coli K12 MG1655. KplE1 is defective for lysis but fully competent for site-specific recombination. The TorI recombination directionality factor is strictly required for prophage excision from the host genome. We have previously shown that DnaJ promotes KplE1 excision by increasing the affinity of TorI for its site-specific recombination DNA target. Here, we provide evidence of a direct association between TorI and DnaJ using in vitro cross-linking assays and limited proteolysis experiments that show that this interaction allows both proteins to be transiently protected from trypsin digestion. Interestingly, NMR titration experiments showed that binding of DnaJ involves specific regions of the TorI structure. These regions, mainly composed of α-helices, are located on a surface opposite the DNA-binding site. Taken together, we propose that DnaJ, without the aid of DnaK/GrpE, is capable of increasing the efficiency of KplE1 excision by causing a conformational stabilization that allows TorI to adopt a more favorable conformation for binding to its specific DNA target.

ACS Style

Tania Puvirajesinghe; Latifa Elantak; Sabrina Lignon; Nathalie Franche; Marianne Ilbert; Mireille Ansaldi. DnaJ (Hsp40 Protein) Binding to Folded Substrate Impacts KplE1 Prophage Excision Efficiency. Journal of Biological Chemistry 2012, 287, 14169 -14177.

AMA Style

Tania Puvirajesinghe, Latifa Elantak, Sabrina Lignon, Nathalie Franche, Marianne Ilbert, Mireille Ansaldi. DnaJ (Hsp40 Protein) Binding to Folded Substrate Impacts KplE1 Prophage Excision Efficiency. Journal of Biological Chemistry. 2012; 287 (17):14169-14177.

Chicago/Turabian Style

Tania Puvirajesinghe; Latifa Elantak; Sabrina Lignon; Nathalie Franche; Marianne Ilbert; Mireille Ansaldi. 2012. "DnaJ (Hsp40 Protein) Binding to Folded Substrate Impacts KplE1 Prophage Excision Efficiency." Journal of Biological Chemistry 287, no. 17: 14169-14177.

Review
Published: 01 January 2012 in Frontiers in Bioscience
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Cellular biology has long been restricted to large cellular organisms. However, as the resolution of microscopic methods increased, it became possible to study smaller cells, in particular bacterial cells. Bacteriophage biology is one aspect of bacterial cell biology that has recently gained insight from cell biology. Despite their small size, bacteriophages could be successfully labeled and their cycle studied in the host cells. This review aims to put together, although non-extensively, several cell biology studies that recently pushed the elucidation of key mechanisms in phage biology, such as the lysis-lysogeny decision in temperate phages or genome replication and transcription, one step further.

ACS Style

Mireille Ansaldi. Cell biology perspectives in phage biology. Frontiers in Bioscience 2012, E4, 1823 -9.

AMA Style

Mireille Ansaldi. Cell biology perspectives in phage biology. Frontiers in Bioscience. 2012; E4 (1):1823-9.

Chicago/Turabian Style

Mireille Ansaldi. 2012. "Cell biology perspectives in phage biology." Frontiers in Bioscience E4, no. 1: 1823-9.

Journal article
Published: 01 November 2011 in Journal of Biological Chemistry
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Temperate bacteriophage lytic development is intrinsically related to the stress response in particular at the DNA replication and virion maturation steps. Alternatively, temperate phages become lysogenic and integrate their genome into the host chromosome. Under stressful conditions, the prophage resumes a lytic development program, and the phage DNA is excised before being replicated. The KplE1 defective prophage of Escherichia coli K12 constitutes a model system because it is fully competent for integrative as well as excisive recombination and presents an atypical recombination module, which is conserved in various phage genomes. In this work, we identified the host-encoded stress-responsive molecular chaperone DnaJ (Hsp40) as an active participant in KplE1 prophage excision. We first show that the recombination directionality factor TorI of KplE1 specifically interacts with DnaJ. In addition, we found that DnaJ dramatically enhances both TorI binding to its DNA target and excisive recombination in vitro. Remarkably, such stimulatory effect by DnaJ was performed independently of its DnaK chaperone partner and did not require a functional DnaJ J-domain. Taken together, our results underline a novel and unsuspected functional interaction between the generic host stress-regulated chaperone and temperate bacteriophage lysogenic development.

ACS Style

Stéphanie Champ; Tania Puvirajesinghe; Elsa Perrody; Rachid Menouni; Pierre Genevaux; Mireille Ansaldi. Chaperone-assisted Excisive Recombination, a Solitary Role for DnaJ (Hsp40) Chaperone in Lysogeny Escape. Journal of Biological Chemistry 2011, 286, 38876 -38885.

AMA Style

Stéphanie Champ, Tania Puvirajesinghe, Elsa Perrody, Rachid Menouni, Pierre Genevaux, Mireille Ansaldi. Chaperone-assisted Excisive Recombination, a Solitary Role for DnaJ (Hsp40) Chaperone in Lysogeny Escape. Journal of Biological Chemistry. 2011; 286 (45):38876-38885.

Chicago/Turabian Style

Stéphanie Champ; Tania Puvirajesinghe; Elsa Perrody; Rachid Menouni; Pierre Genevaux; Mireille Ansaldi. 2011. "Chaperone-assisted Excisive Recombination, a Solitary Role for DnaJ (Hsp40) Chaperone in Lysogeny Escape." Journal of Biological Chemistry 286, no. 45: 38876-38885.

Research article
Published: 01 September 2011 in PLOS ONE
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Ramlibacter tataouinensis TTB310(T) (strain TTB310), a betaproteobacterium isolated from a semi-arid region of South Tunisia (Tataouine), is characterized by the presence of both spherical and rod-shaped cells in pure culture. Cell division of strain TTB310 occurs by the binary fission of spherical "cyst-like" cells ("cyst-cyst" division). The rod-shaped cells formed at the periphery of a colony (consisting mainly of cysts) are highly motile and colonize a new environment, where they form a new colony by reversion to cyst-like cells. This unique cell cycle of strain TTB310, with desiccation tolerant cyst-like cells capable of division and desiccation sensitive motile rods capable of dissemination, appears to be a novel adaptation for life in a hot and dry desert environment. In order to gain insights into strain TTB310's underlying genetic repertoire and possible mechanisms responsible for its unusual lifestyle, the genome of strain TTB310 was completely sequenced and subsequently annotated. The complete genome consists of a single circular chromosome of 4,070,194 bp with an average G+C content of 70.0%, the highest among the Betaproteobacteria sequenced to date, with total of 3,899 predicted coding sequences covering 92% of the genome. We found that strain TTB310 has developed a highly complex network of two-component systems, which may utilize responses to light and perhaps a rudimentary circadian hourglass to anticipate water availability at the dew time in the middle/end of the desert winter nights and thus direct the growth window to cyclic water availability times. Other interesting features of the strain TTB310 genome that appear to be important for desiccation tolerance, including intermediary metabolism compounds such as trehalose or polyhydroxyalkanoate, and signal transduction pathways, are presented and discussed

ACS Style

Gilles De Luca; Mohamed Barakat; Philippe Ortet; Sylvain Fochesato; Cécile Jourlin-Castelli; Mireille Ansaldi; Béatrice Py; Gwennaele Fichant; Pedro M. Coutinho; Romé Voulhoux; Olivier Bastien; Éric Maréchal; Bernard Henrissat; Yves Quentin; Philippe Noirot; Alain Filloux; Vincent Méjean; Michael S. Dubow; Frédéric Barras; Valérie Barbe; Jean Weissenbach; Irina Mihalcescu; André Verméglio; Wafa Achouak; Thierry Heulin. The Cyst-Dividing Bacterium Ramlibacter tataouinensis TTB310 Genome Reveals a Well-Stocked Toolbox for Adaptation to a Desert Environment. PLOS ONE 2011, 6, e23784 .

AMA Style

Gilles De Luca, Mohamed Barakat, Philippe Ortet, Sylvain Fochesato, Cécile Jourlin-Castelli, Mireille Ansaldi, Béatrice Py, Gwennaele Fichant, Pedro M. Coutinho, Romé Voulhoux, Olivier Bastien, Éric Maréchal, Bernard Henrissat, Yves Quentin, Philippe Noirot, Alain Filloux, Vincent Méjean, Michael S. Dubow, Frédéric Barras, Valérie Barbe, Jean Weissenbach, Irina Mihalcescu, André Verméglio, Wafa Achouak, Thierry Heulin. The Cyst-Dividing Bacterium Ramlibacter tataouinensis TTB310 Genome Reveals a Well-Stocked Toolbox for Adaptation to a Desert Environment. PLOS ONE. 2011; 6 (9):e23784.

Chicago/Turabian Style

Gilles De Luca; Mohamed Barakat; Philippe Ortet; Sylvain Fochesato; Cécile Jourlin-Castelli; Mireille Ansaldi; Béatrice Py; Gwennaele Fichant; Pedro M. Coutinho; Romé Voulhoux; Olivier Bastien; Éric Maréchal; Bernard Henrissat; Yves Quentin; Philippe Noirot; Alain Filloux; Vincent Méjean; Michael S. Dubow; Frédéric Barras; Valérie Barbe; Jean Weissenbach; Irina Mihalcescu; André Verméglio; Wafa Achouak; Thierry Heulin. 2011. "The Cyst-Dividing Bacterium Ramlibacter tataouinensis TTB310 Genome Reveals a Well-Stocked Toolbox for Adaptation to a Desert Environment." PLOS ONE 6, no. 9: e23784.