Chromosome Dynamics
The ability of cells to efficiently and accurately segregate its genetic material is crucial for the production of healthy progeny. Eukaryotic chromosome segregation is known to be driven by mitotic apparatus that utilize kinetochore, centromeric DNA and spindles. While a remotely similar mechanism involving centromeres and cytoskeletal filaments is employed by some bacterial plasmids to segregate plasmids, a direct mechanism for bacterial chromosome segregation remains to be identified.
In addition to mechanisms for chromosome segregation, successful passage of chromosomes from generation to generation also requires the dynamics of chromosomes to be well regulated and the three major cell cycle events, chromosome replication, segregation and cell division are well coordinated.
During vegetative growth, like many other rod-shaped bacteria, Bacillus subtilis divide at mid-cell by binary fission to produce two identical daughter cells. However, when B. subtilis cells grow as L-forms, division occurs in several different modes and produce daughter cells of different sizes and shapes. Little is known about the behaviours of chromosomes and how chromosome segregation and cells division is coordinated in L-forms.
Bacillus subtilis is able to form spores when it is starved for nutrients. During spore formation, the cells divide asymmetrically close to the cell pole. Initially, the chromosome destined for the spore is ‘trapped’ only for around 30% in the prespore compartment - centred around the origin of replication. This phenomenon provides a very useful experimental handle to study chromosome segregation and organization. Using genetics combined with cell biology and fluorescent microscopy methods, we are trying to unravel the exact mechanisms of chromosome organization during spore development..
Key papers from the lab
Wu LJ and Errington J. (1994) Bacillus subtilis SpoIIIE protein required for DNA segregation during asymmetric cell division. Science 264, 572-575.
Sharpe ME and Errington J. (1995) Postseptational chromosome partitioning in bacteria. Proc. Natl. Acad. Sci. USA 92, 8630-8634.
Glaser P, Sharpe ME, Raether R, Perego M, Ohlsen K and Errington J. (1997) Dynamic, mitotic-like behaviour of a bacterial protein required for accurate chromosome partitioning. Genes Devel. 11, 1160-1168.
Thomaides HB, Freeman M, El Karoui M and Errington J. (2001) Division-site-selection protein DivIVA of Bacillus subtilis has a second distinct function in chromosome segregation during sporulation. Genes Devel. 15, 1662-1673.
Murray H and Errington J (2008) Dynamic control of the DNA replication initiation protein DnaA by Soj / ParA. Cell 135, 74-84.
Gruber S, Errington J. (2009) Recruitment of the SMC complex to replication origin regions by Spo0J/ParB bound to parS sites in Bacillus subtilis. Cell 137, 685-696.
Su'etsugu M, Errington J. (2011) The replicase sliding clamp dynamically accumulates behind progressing replication forks in Bacillus subtilis cells. Mol. Cell 41, 720-732.
Gruber S, Veening JW, Bach J, Blettinger M, Bramkamp M, Errington J. (2014) Interlinked sister chromosomes arise in the absence of condensin during fast replication in B. subtilis. Curr Biol. 24, 293-298.
Kloosterman TG, Lenarcic R, Willis CR, Roberts DM, Hamoen LW, Errington J, Wu LJ. Complex polar machinery required for proper chromosome segregation in vegetative and sporulating cells of Bacillus subtilis. Molecular Microbiology 2016, 101(2), 333-350.
