The molecular mechanism of chromosome condensation mediated by cohesin and condensing

The condensation of chromosomes in the eukaryotic nucleus is essential for life and cells cannot faithfully segregate chromosomes without it. It is well known that the highly conserved condensin and cohesin protein complexes are the key factors for DNA condensation, but the mechanism for condensation remains unknown. One theory is that distant DNA segments in one molecule interact with each other mediated by cDNA bound condensin and/or cohesin. While methods, such as sister chromatid cohesion, have been established to study inter-DNA interaction no techniques have been established to investigate biochemical properties of proposed intra-DNA interactions, required for chromosome condensation. It is essential that new technologies are developed to understand how chromosomes are organised by condensation.

Condensation in Saccharomyces cerevisiae has been studied using repetitive rDNA sequences as a model for conserved DNA condensation. I have established a novel genetic system to isolate of condensed chromatin formed in vivo by intra-rDNA interactions. Using Cre recombinase condensed native rDNA, discrete chromatin circles can be liberated for biochemical characterisation.

These studies will help us formulate a hypothesis on how cohesin/condensin organises rDNA, to build up a solid foundation for further grant application.