The molecular mechanism of centromeric chromatin assembly and recognition

• Applicant: Dr. Christian de Groot
• Subject Area: Cell Biology
• Term: from 2011 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 194368604

Kinetochores are large multiprotein complexes that assemble on chromosomes during mitosis to mediate their segregation on the microtubule-based spindle. Kinetochores form in specific chromosomal regions on a base of specialized centromeric chromatin, defined by the fact that a proportion of the nucleosomes contain the histone variant CENP-A instead of histone H3. Accurate localization and propagation of CENP-A containing chromatin is essential to guarantee propagation of genomic information through cell division. It is known that CENP-A containing nucleosomes are exclusively present in active centromeres, and that CENP-A targeting is not directed by specific DNA sequences. However, the mechanisms that restrict the incorporation of CENP-A nucleosomes into centromeric chromatin remain an important open question. My sponsor lab identified a conserved protein, KNL-2, that is essential for CENP-A targeting. To understand the molecular mechanisms underlying centromeric chromatin assembly, I plan to take a combined in vivo/in vitro approach to investigate the key role of KNL-2 family proteins in the incorporation of CENP-A nucleosomes into centromeric chromatin. I will analyze the function of KNL-2 in centromeric chromatin assembly in vivo using the one-cell embryo of Caenorhabditis elegans as a model system. Specifically, I will identify the role of KNL-2 domains in chromosome segregation and chromosome condensation. To gain insights into the molecular mechanism of KNL-2-mediated CENP-A targeting I will analyze their interaction using in vitro reconstituted nucleosomal complexes and attempt to obtain structural information of KNL-2 to reveal the KNL-2/CENP-A interaction mode. The proposed work will help to elucidate conserved mechanisms of centromeric chromatin assembly and recognition on a cellular and molecular level.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Arshad Desai