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

Abstract

AbstractGametogenesis in budding yeast involves large-scale rearrangement of membrane traffic to allowde novoformation 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.