Mechanisms for Sister Chromatid Cohesion Establishment at the Replication Fork

Sister chromatid cohesion describes the state of attachment between the two arms that constitute replicated chromosomes. It is crucial for accurate chromosome segregation during cell division and involves the topological entrapment of sister chromatids by the ring-shaped protein complex, cohesin. Two parallel pathways of cohesion establishment have been identified: de novo loading and conversion, both requiring DNA replication. However, their molecular mechanisms remain poorly understood. This project will investigate how cohesin and the cohesin loading complex interact with the DNA replication machinery to generate cohesion, with a particular focus on the de novo loading pathway and comparisons between mitosis and meiosis. To this end, I will use a budding yeast model to identify these interactions via in vitro and in vivo methods, including co-IP with purified proteins and IP-MS. I will also characterise genome-wide cohesion patterns using sister-pore-C, a novel 3C sequencing method. By combining biochemical, structural, and functional investigations, this project will deliver insights into the mechanisms and roles of the cohesion establishment pathways. Anomalies in cohesion establishment can lead to abnormal chromosome segregation, which may manifest as cancer, infertility, developmental disorders, etc. Thus, my findings will contribute towards a fuller understanding of a fundamental step in cell division.