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117 | 2019
Annuaire du Collège de France 2016-2017
Résumé des cours et travaux 117e année
Autres enseignements et recherches
III. Équipes accueillies au Collège de France
Centre interdisciplinaire de recherche en biologie (CIRB)

Dynamique des chromosomes / Chromosome dynamics

Centre international de recherche en biologie (CIRB)
Olivier Espéli
p. 626-627

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Responsable : Olivier Espéli

Recherche

1Bacteria are highly organized cells that can multiply rapidly when the environment is favorable. To reach a fast growth rate bacteria rely on a strongly regulated cell cycle that coordinate the genome replication, chromosome segregation, cell elongation and division. However when the environment is less favorable the bacteria adapts their growing regime to protect themselves. The lack of nutrients or the presence of stress (reactive oxygen species, acid pH, genotoxic compound, etc.) induce gene expression response that will helps to cope with the stress [7]. The fact that these stress response also involve modulation of the cell cycle is an emerging topics. Most of the work performed in my group concerns cell cycle regulation and its adaptation to changing environment.

2The first axis of research concerns the regulation of chromosome segregation and organization [1, 2, 3, 5, 6]. Our group has been involved in collaborative works with the group of Romain Koszul in the Pasteur institute to characterize the chromosome organizations of the E. coli bacteria [2] and the S. cerevisiae yeast [1]. From these work also emerged the intriguing observation that chromosome conformation might be profoundly changed by the presence of environmental stress. We have developed a project to survey chromosome conformation in different conditions and decipher the respective roles the stress response itself and the change in the gene expression program on chromosome conformation. We have also demonstrated that chromosome segregation is under the control of a topoisomerase (TopoIV) which highly regulated activity is the key element to initiate chromosome segregation [3, 5]. Interestingly in the presence of genotoxic drugs that create double strand breaks on the replicative chromosome this segregation program is perturbed and sister chromatids become attached by a cohesin like protein induced by the SOS regulon [6]. The control of chromosome segregation in response to genotoxic stress is an important process for DNA repair and appears to be conserved in other bacteria and eucaryotes.

3The second axis of our research concerns the cell cycle adaptation to environment that bacteria might encounter when they colonize a host [4, 7]. We have focused our interest on a particular type of E. coli that has been found in the gut of Crohn disease’s patients. This E. coli strains, called AIEC, can invade epithelium and colonize macrophages. Inside macrophages they are growing in a highly stressing environment. We recently demonstrated that in the macrophage AIEC bacteria cope with the stress by a profound adaptation of their cell cycle. A large part of the population halt their cell cycle and enter in a dormant like stage that help them to resist to the stress and also to antibiotic treatments. Some AIEC bacteria nevertheless are able to growth inside the macrophage and this might correspond to their ability to find nutrients in their immediate environment. Our efforts are dedicated to the understanding of the mechanisms involved in these cell cycle adaptations and the interplay between the bacteria and its host.

Publications

4[1] Muller H., Scolari V.F., Agier N., Piazza A., Thierry A., Mercy G., Descorps-Declere S., Lazar-Stefanita L., Espeli O., Llorente B., Fischer G., Mozziconacci J. et Koszul R., « Characterizing meiotic chromosomes’ structure and pairing using a designer sequence optimized for Hi-C », Molecular Systems Biology, vol. 14, no 7, 2018, e8293, DOI : 10.15252/msb.20188293.

[2] Lioy V.S., Cournac A., Marbouty M., Duigou S., Mozziconacci J., Espéli O., Boccard F. et Koszul R., « Multiscale structuring of the E. coli chromosome by nucleoid-associated and condensin proteins », Cell, vol. 172, no 4, 2018, p. 771-783, DOI : 10.1016/j.cell.2017.12.027.

[3] El Sayyed H. et Espéli O., « Mapping E. coli topoisomerase IV binding and activity sites », Methods in Molecular Biology, vol. 1703, 2018, p. 8794, DOI : 10.1007/978-1-4939-7459-7_6.

[4] Demarre G., Prudent V. et Espéli O., « Imaging the cell cycle of pathogen E. coli during growth in macrophage », Methods in Molecular Biology, 2017, vol. 1624, p. 227236, DOI : 10.1007/978-1-4939-7098-8_17.

[5] Vickridge E., Planchenault C. et Espéli O., « Revealing sister chromatid interactions with the loxP/Cre recombination assay », Methods in Molecular Biology, vol. 1624, 2017, p. 2937, DOI : 10.1007/978-1-4939-7098-8_3.

[6] Vickridge E., Planchenault C., Cockram C., Junceda I.G. et Espéli O., « Management of E. coli sister chromatid cohesion in response to genotoxic stress », Nature Communications, vol. 8, 2017, 14618, DOI : 10.1038/ncomms14618.

[7] Leh H., Khodr A., Bouger M.C., Sclavi B., Rimsky S., Bury-Moné S., « Bacterial-chromatin structural proteins regulate the bimodal expression of the locus of enterocyte effacement (LEE) pathogenicity island in enteropathogenic Escherichia coli », MBio, vol. 8, no 4, 2017, pii : e00773-17, DOI : 10.1128/mBio.00773-17.

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Olivier Espéli, « Dynamique des chromosomes / Chromosome dynamics », L’annuaire du Collège de France, 117 | 2019, 626-627.

Référence électronique

Olivier Espéli, « Dynamique des chromosomes / Chromosome dynamics », L’annuaire du Collège de France [En ligne], 117 | 2019, mis en ligne le 04 juin 2020, consulté le 14 août 2022. URL : http://journals.openedition.org/annuaire-cdf/14716 ; DOI : https://doi.org/10.4000/annuaire-cdf.14716

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Olivier Espéli

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