The group

Frédéric Boccard, Senior scientist, CNRS

Camille Cibot, PhD student

Stéphane Duigou, Researcher CNRS

Pauline Dupaigne, Postdoctoral fellow

Michèle Valens, Engineer, CNRS

Isabelle Vallet-Gély, Senior scientist, CNRS

Our address

CNRS - Centre de Génétique Moléculaire - UPR 3404

Avenue de la Terrasse - Bât. 26

91198 GIF-SUR-YVETTE Cedex

FRANCE

Phone : 33 (0)1 69 82 32 14

Telecopy : 33 (0)1 69 82 31 50

First topic

Frédéric Boccard, Axel Thiel, Michèle Valens

Conformation and dynamics of the bacterial chromosome during cell cycle

The way bacteria compact their chromosome remains elusive even though a number of factors involved in DNA condensation have been identified.

A genetic analysis of bacterial conformation in E. coli allowed us to reveal the existence of Macrodomains; large regions of about 1 Mb. Using fluorescence microscopy, we demonstrated that DNA dynamics correlates the macrodomain topography of the chromosome. We recently identified the factor MatP that, by interacting with a repeated motif, organizes one of the macrodomain. Proper conformation and insulation of macrodomains are important for chromosome management as inactivation of the structuring factor or chromosome rearrangements that affect macrodomain configuration are highly detrimental.

The main goal of our project is to characterize the molecular mechanisms used to structure macrodomains and to identify the role they play in chromosome management. To achieve this goal, four aspects are studied: i) MatP Structuring of the Ter MD, ii) Structuring processes of other MDs, iii) role of Macrodomains in chromosome management, iv) modulation of DNA dynamics

Selected publications

Espéli, O., Borne, R., Dupaigne, P., Thiel, A., Gigant, E., Mercier, R., Boccard, F. (2012) A MatP-divisome interaction coordinates chromosome segregation with cell division in E. coli. EMBO J., in press.

Thiel, A., Valens, M., Vallet-Gely, I., Espéli, O., Boccard, F. (2012) Long range chromosome organization in E. coli: A site-specific system isolates the Ter macrodomain. PLoS Genet., in press.

Mercier, R., Petit, M.-A., Schbath, S., Robin, S., El Karoui, M., Boccard, F. and Espéli, O. (2008) The MatP/matS site-specific system organizes the terminus region of the E. coli chromosome into a macrodomain. Cell, 135 (3) 475-85.

Espeli, O. Mercier, R. and Boccard, F. (2008) DNA dynamics vary according to macrodomain topography in the E. coli chromosome. Mol Microbiol, 68 (6) 1418-27.

Esnault, E., Valens, M., Espéli, O. and Boccard, F. (2007) Chromosome Structuring Limits Genome Plasticity in Escherichia coli. PLoS Genet, 3 (12) e226.

Espeli, O. and Boccard, F. (2006) Organization of the Escherichia coli chromosome into macrodomains and its possible functional implications. J Struct Biol, 156 (2) 304-10.

Boccard, F., Esnault, E., and Valens, M. (2005). Spatial arrangement and macrodomain organization of bacterial chromosomes. Molecular Microbiology 57, 9-16.

Moulin, L., Rahmouni, A. R., and Boccard, F. (2005). Topological insulators inhibit diffusion of transcription-induced positive supercoils in the chromosome of E. coli. Molecular Microbiology 55, 601-610.

Valens, M., Penaud, S., Rossignol, M., Cornet, F., and Boccard, F. (2004). Macrodomain organization of the E. coli chromosome. EMBO J 23(21):4330-41

Second topic

(in collaboration with the team of Bruno Lemaitre)

Host-pathogen interactions in Drosophila

Pathogens have developed multiple strategies that allow them to exploit host resources and resist the immune response. Drosophila has been shown to be a valuable model for the investigation of host–pathogen interactions. Study of the Drosophila immune response has been hampered, however, by the lack of true Drosophila pathogens.

To study how Drosophila flies deal with infectious diseases in a natural context, we investigate the interactions between Drosophila and two different bacteria: Erwinia carotovora Ecc15 and Pseudomonas entomophila. Ecc15 is able to persist in the gut of Drosophila larvae and induce both a local and a systemic immune response. Activation of the immune response eradicates Ecc15 bacteria. Flies infected with P. entomophila rapidly succumb despite the induction of both local and systemic immune responses, indicating that this bacterium has developed specific strategies to escape the fly immune response.

Selected publications

Vallet-Gely, I., Opota, O., Boniface, A., Novikov, A., Lemaitre, B. (2010) A secondary metabolite acting as a signaling molecule controls Pseudomonas entomophila virulence. Cell Microbiol, 12 (11) 1666-79.

Vallet-Gely, I., Novikov, A., Augusto, L., Liehl, P., Bolbach, G., Péchy-Tarr, M., Cosson, P., Keel, C., Caroff, M., Lemaitre, B. (2010) Association of hemolytic activity of Pseudomonas entomophila, a versatile soil bacterium, with cyclic lipopeptide production. Appl Environ Microbiol, 76 (3) 910-21.

Quevillon-Cheruel, S., Leulliot, N., Acosta Muniz, C., Vincent, M., Gallay, J., Argentini, M., Cornu, D., Boccard, F., Lemaitre, B. and van Tilbeurgh, H. (2008) Evf, a virulence factor produced by the Drosophila pathogen Erwinia carotovora is a S-palmitoylated protein with a new fold that binds to lipid vesicles. J Biol Chem, 284 (6) 3552-3562.

Vallet-Gely, I., Lemaitre, B. and Boccard, F. (2008) Bacterial strategies to overcome insect defences. Nat Rev Microbiol, 6 (4) 302-13.

Acosta Muniz, C., Jaillard, D., Lemaitre, B. and Boccard, F. (2007) Erwinia carotovora Evf antagonizes the elimination of bacteria in the gut of Drosophila larvae. Cell Microbiol, 9 (1) 106-19.

Vodovar, N., Vallenet, D., Cruveiller, S., Rouy, Z., Barbe, V., Acosta, C., Cattolico, L., Jubin, C., Lajus, A., Segurens, B., Vacherie, B., Wincker, P., Weissenbach, J., Lemaitre, B., Médigue, C. and Boccard, F. (2006) The complete genome sequence of the entomopatogenic and metabolically versatile soil bacterium Pseudomonas entomophila Nature Biotech, 24 (6) 673-9.

Liehl, P., Blight, M., Vodovar, N., Boccard, F. and Lemaitre, B. (2006) Prevalence of local immune response against oral infection in a Drosophila/Pseudomonas infection model. PLoS Pathog, 2 (6) e56.

Vodovar, N., Vinals, M., Basset, A., Degrouard, J., Spelmann, P. T., Boccard, F., and Lemaitre, B. (2005). Drosophila host defense after oral infection by an entomopathogenic Pseudomonas species. Proc Natl Acad Sci USA 102, 11414-11419

Vodovar N, Acosta C, Lemaitre B, Boccard F. (2004) Drosophila: a polyvalent model to decipher host-pathogen interactions.Trends Microbiol. 12(5):235-4.

All the publications of the group since 1996