The precise distribution of newly replicated genomes to progeny cells is crucial for stable transmission of genetic information. Bacteria and Archaea employ dedicated DNA segregation factors that drive and deliver low copy number plasmids and chromosomes to specific subcellular locations.

Segregation mechanisms of a multidrug resistance plasmid

One of the model systems under investigation is the multidrug resistance plasmid TP228 that replicates at low copy number in Escherichia coli. This mobile genetic element specifies resistance to a range of antibiotics, including tetracycline, streptomycin and sulphonamides. The plasmid harbours a partition cassette encoding two proteins that are crucial for plasmid inheritance: ParF, a ParA Walker-type ATPase, and ParG, a site-specific DNA-binding protein. We have employed multidisciplinary approaches, spanning from genetics to biochemistry, from cell biology to biophysics, to investigate the role and interactions of these proteins in mediating plasmid segregation. Two discoveries have made significant contributions to the field of bacterial genome segregation:

the observation that ParF assembles into higher-order structures [EMBO J 2005, 24:1453-1464] the finding that ParG stimulates ParF ATP hydrolysis via an arginine finger- like motif in a fashion analogous to eukaryotic RasGAPs [Proc Natl Acad Sci USA 2007, 104: 1811-1816].