Remodeling of the secretory pathway is coordinated withde novomembrane formation in budding yeast gametogenesis

Abstract

Gametogenesis in budding yeast involves large-scale rearrangement of membrane traffic to allow de novo formation of a membrane, called the prospore membrane (PSM). However, the mechanism underlying this event is not fully elucidated. Here, we show that the number of endoplasmic reticulum exit sites (ERES) per cell fluctuates and switches from decreasing to increasing upon the onset of PSM formation. Reduction in ERES number is accompanied by a transient stall in membrane traffic, resulting in loss of the preexisting Golgi apparatus from the cell, as well as local ERES regeneration, leading to Golgi reassembly in nascent spores. We have revealed that protein phosphatase-1 (PP-1) and its development-specific subunit, Gip1, promote ERES regeneration through Sec16 foci formation. Furthermore, a mutant with impaired ERES formation showed defects in PSM growth and spore formation. Thus, ERES regeneration in nascent spores facilitates the segregation of membrane traffic organelles, leading to PSM growth.

Meiotic Cytokinesis in Saccharomyces cerevisiae: Spores That Just Need Closure

“…Additionally, the Glc7-Gip1 phosphatase complex is required for prospore membrane extension similar to the requirement for the Spo71-Spo73-Vps13 complex, although the two seem to operate in parallel [103]. Gip1 and Glc7 are also required for the generation of endoplasmic reticulum exit sites (ERESs), which are regenerated within the developing spores during the time of membrane extension [104]. SPO71 is required for the localization of the sporulationspecific septin Spr28, indicating a possible link between septins and prospore membrane elongation [27].…”