Regulation of meiosis I chromosome segregation by Spol3 and Cdc5 in Saccharomyces cerevisiae

Abstract

Meiosis is a specialized cell cycle that generates gametes for the purpose of disseminating genetic material to the next generation. The reduction of chromosome number by half is brought about two chromosome segregation phases following a single DNA replication phase. In the first division, homologs segregate away from each other and in the second division the sister chromatids separate. These two consecutive meiotic divisions necessitate innovations in chromosome dynamics and hence the involvement of both meiosis-specific modulators and regulators of the mitotic cell cycle. The work described herein characterizes the roles of two essential meiosis I regulators, a mitotic protein kinase, Cdc5 and a meiosis-specific gene, Spol 3. The conserved polo-like kinase Cdc5 regulates many essential aspects of meiosis I including the removal of cohesion between sister chromatids for homolog segregation, sister-kinetochore co-orientation and exit from meiosis I. Spol3 likely cooperates with Cdc5 to regulate some of these processes. SpoI3 controls kinetochore co-orientation and the retention of centromeric cohesion which is essential for accurate sister chromatid segregation in meiosis II. In sum, this work elucidated the roles of two important regulators of the meiotic cell cycle and defines a component of the complex regulatory circuit necessary for the specialized meiotic divisions.