SPO71 Mediates Prospore Membrane Size and Maturation in Saccharomyces cerevisiae

The mechanisms that control the size and shape of membranes are not well understood, despite the importance of these structures in determining organelle and cell morphology. The prospore membrane, a double lipid bilayer that is synthesizedde novo during sporulation inS. cerevisiae , grows to surround the four meiotic products. This membrane determines the shape of the newly formed spores and serves as the template for spore wall deposition. Ultimately, the inner leaflet of the prospore membrane will become the new plasma membrane of the cell upon germination. Here we show that Spo71, a pleckstrin homology domain protein whose expression is induced during sporulation, is critical for the appropriate growth of the prospore membrane. WithoutSPO71 , prospore membranes surround the nuclei but are abnormally small, and spore wall deposition is disrupted. Sporulatingspo71 Δ cells have prospore membranes that properly localize components to their growing leading edges yet cannot properly localize septin structures. We also found thatSPO71 genetically interacts withSPO1 , a gene with homology to the phospholipase B gene that has been previously implicated in determining the shape of the prospore membrane. Together, these results show thatSPO71 plays a critical role in prospore membrane development.