The yeast centrosome, also called the spindle pole body, organizes microtubules required for a variety of cellular processes that include cell division. During meiosis, the centrosome is duplicated when chromosomes replicate. Duplicated centrosomes separate to form a bipolar spindle required for homolog separation during the first division of meiosis. Centrosomes duplicate again in the absence of chromosome replication to establish two spindles for sister chromatid separation in the second meiotic division. Coordination of centrosome duplication and separation with the two chromosome segregation cycles in meiosis is fundamental to maintain genome integrity in eukaryotes. The goal of this project is to determine the molecular mechanism by which the Aurora kinase Ipl1 and the Polo-like kinase Cdc5 act antagonistically to regulate centrosome duplication and separation. Using creative yeast genetics in combination with live-cell microscopy and biochemical methods, the temporal and spatial requirements of Ipl1 and Cdc5 in centrosome duplication will be determined. In addition, their phosphorylated substrates will be identified by a novel phosphoproteome approach and characterized for their biochemical activities in regulation of centrosome dynamics. These studies will provide a mechanistic view of protein phosphorylation mediated by Ipl1 and Cdc5 in yeast centrosome duplication and have general implications for understanding the mechanism of centrosome dynamics in animals.
Broader impacts This project will train graduate and undergraduate students in genetics and cell biology, and will also provide unique opportunities for underrepresented and minority students to design and conduct goal-oriented experiments in their classroom. Students enrolled in the Experimental Biology course, which the PI teaches once a year, will tag centrosome components with the green fluorescent protein and screen for genetic abnormalities of the centrosome in yeast. This research will provide molecular insights into the regulation of centrosome duplication and contribute to society by educating those who will be part of our future work force as scholars and scientists.