Accurate chromosome segregation is vital for cell proliferation. The spindle pole body (SPB), the functional equivalent of the centrosome in budding yeast Saccharomyces cerevisiae, is important for chromosome segregation and cell division. SPB duplication is coupled with DNA replication; duplicated SPBs separate to form a bipolar spindle that partitions chromosomes into daughter cells. Mps3, a SUN-domain protein, plays an important role in SPB duplication and separation. To study Mps3 and its interactions with other relevant proteins, we have conducted both genetic and cellular biology based experiments. We previously observed through live-cell microscopy that Mps3 localizes to the SPB as well as the nuclear envelope and acts as the “molecular glue†that links the duplicated SPBs. We have since found through a combined biochemical and genetic approach that protease activity exists to potentially regulate the function of Mps3 at the SPB and nuclear envelope. We propose that cleavage of the Mps3 protein initiates SPB segregation, which catalyzes or parallels Mps3 oligomer disassembly in the nuclear envelope. Then a bipolar spindle pushes the SPBs apart. Understanding the mechanism of SPB separation will contribute to our knowledge of chromosome segregation and cell division, which has implications in developing treatments for chromosomal birth defects.
