PP2A (Cdc)⁵⁵ is required for multiple events during meiosis I

Protein phosphatase 2A (PP2A) is a heterotrimer consisting of A and B regulatory subunits and a C catalytic subunit. PP2A regulates mitotic cell events that include the cell cycle, nutrient sensing, p53 stability and various mitogenic signals. The role of PP2A during meiosis is less understood. We explored the role of Saccharomyces cerevisiae PP2A during meiosis. We show a PP2A (Cdc)⁵⁵ containing the human B/55 family B subunit ortholog, Cdc55, is required for progression through meiosis I. Mutant cells lacking Cdc55 remain mononucleated. They harbor meiotic gene expression, premeiotic DNA replication, homologous recombination and spindle pole body (SPB) defects. They initiate but do not complete replication and are defective in performing intergenic homologous recombination. Bypass alleles, which allow cells defective in recombination to finish meiosis, do not suppress the meiosis I defect. cdc55 cells arrest with a single SPB lacking microtubules, or duplicated but not separated SBPs containing microtubules. Finally, the premeiotic replication defect is suppressed by loss of Rad9 checkpoint function. We conclude PP2A (Cdc)⁵⁵ is required for the proper temporal initiation of multiple meiotic events and/or monitors these events to ensure their fidelity.