Bacterial genomes are composed of chromosomes, from one up to three, and numerous plasmids. How these replicons are faithfully segregated at cell division and inherited in each daughter cell is not yet understood at the molecular level. Amongst the three main types of bacterial segregation systems, the type I is overrepresented on low copy number plasmids and is the only type present on chromosomes. Our project aims at deciphering the molecular mechanism of the most widespread type of partition systems, using the archetypical ParABS system of the plasmid F.
We are focusing on the molecular assembly that assembles on centromere sites and interacts dynamically with the Walker A Cytoskeletal ATPase (ParA) which patterns the nucleoid. We are applying a combination of molecular genetics, biochemistry, epi-fluorescence microscopy and modeling to understand how centromeres are separated after DNA duplication and relocated from mid- to quarter-cell positions.
Our current approaches are centered on the characterization of the partition assemblies in live cells using genome-wide analyses (high resolution ChIP-sequencing) and, in collaboration with the team of M. Nollmann (CBS, Montpellier), 3D super-resolution (3D SIM and MLM) and single-molecule super-resolution (PALM) microscopy. We are also strongly involved in the physical modeling of the partition process through an ongoing collaboration with theoretical physicists from the Laboratoire Charles Coulomb (LCC, Montpellier) and the Laboratoire de Physique Théorique (LPT, Toulouse).