High fidelity meiotic chromosome segregation is required for the propagation of sexually reproducing organisms. Meiosis is fundamentally the same in species as divergent as the yeast, Saccharomyces cerevisiae, and humans. Studies in yeast have provided general insights into the mechanisms of meiosis and will continue to build a framework for understanding this fundamental process. Earlier studies have indicated that there is a link between meiotic DNA synthesis and homologous chromosome pairing. This project is aimed at elucidating the relationship between these critical meiotic processes. The yeast MUM2 gene was identified in a genetic screen for meiotic mutants proficient for the induction of meiotic recombination. Analyses of mum2 mutants indicate that MUM2 is essential for both meiotic DNA synthesis and homologous chromosome interactions. The specific role of the MUM2 gene will be investigated by analyzing the Mum2 protein using cell biological and biochemical approaches. These studies will help define the function of this protein in meiotic chromosome metabolism. Meiotic DNA synthesis and homologous chromosome interactions will also be assessed in mutants defective at various stages of mitotic DNA replication. This will determine whether mum2 mutants define a unique aspect of, or reveal a previously uncharacterized role for, meiotic DNA synthesis. Finally, genetic approaches will be used to identify additional genes important for meiotic DNA replication and homologous chromosome interactions. These studies should provide valuable new information about the role of these processes in ensuring proper chromosome segregation during meiosis.
