Bacterial chromosomes are actively segregated and condensed by the ParABS system and condensin. In B. subtilis, this machinery is physically targeted to the origin proximal region of the chromosome by eight palindromic DNA sequences called parS to which the ParB (Spo0J) protein binds. These nucleoprotein complexes act as a positional marker of the origin and earmark this region for segregation in a manner somewhat analogous to eukaryotic centromeres and their binding partners.
ParB is an unusual DNA binding protein. In addition to sequence-specific interactions with the parS sequence, the protein also spreads extensively around the site for about 18 kbp. However, the mechanistic basis for this behaviour is not well understood and a matter of active debate. We have used our single-molecule tools to investigate the binding of B.subtilis ParB to DNA in vitro.
Topic-related papers of the group
Gemma LM Fisher*, Cesar L Pastrana*, Victoria A Higman* et al. Elife Dec 15;6 (2017) pii: e28086. doi: 10.7554/eLife.28086. The structural basis for dynamic DNA binding and bridging interactions which condense the bacterial centromere. LINK
Taylor*, Pastrana* et al. Nucleic Acids Research 43(2), 719-731 (2015). Specific and non-specific interactions of ParB with DNA: implications for chromosome segregation. LINK
University of Bristol: Mark Dillingham Group