07 oct
Jeudi 07 Octobre 10h30, amphi Lwoff

Making more than two daughter cells: the strategy of a predatory bacterium (Géraldine Laloux)

Géraldine Laloux (Institut de Duve, Université de Louvain, Belgique) présente un séminaire au MAP invitée par MTSB et Agnès Rodrigue


Making more than two daughter cells: the strategy of a predatory bacterium

In bacteria, the dynamics of chromosome replication and segregation are tightly coordinated with cell cycle progression, and largely rely on specific spatiotemporal arrangement of the chromosome. Whereas these key processes are mostly studied in species that divide by binary fission, they remain mysterious in bacteria producing larger number of descendants. We used the predatory bacteriumBdellovibrio bacteriovorus as a model to investigate the non-binary processing of a circular chromosome. We applied live fluorescence microscopy to monitor, at the single-cell level, the spatio-temporal organisation of the chromosome throughout the lifecycle of Bdellovibrio, from its freely swimming stage to its growth and division inside other bacteria. Our data reveal the unusual polarity and compaction of the predator’s nucleoid, the dynamics of multiple rounds of DNA replication and segregation, and a new cell cycle-dependent behaviour of the conserved centromeric protein ParB. Altogether, our findings support a model of complex chromosome choreography leading to the generation of variable numbers of daughter cells, and highlight the adaptation of conserved mechanisms to achieve non-binary reproduction in bacteria.