title: A visual screen of protein localization during sporulation identifies new components of prospore membrane-associated complexes in budding yeast.
abstract: During ascospore formation in Saccharomyces cerevisiae, the secretory pathway is reorganized to create new intracellular compartments, termed prospore membranes. Prospore membranes engulf the nuclei produced by the meiotic divisions, giving rise to individual spores. The shape and growth of prospore membranes are constrained by cytoskeletal structures, such as septin proteins, that associate with the membranes. Green fluorescent protein (GFP) fusions to various proteins that associate with septins at the bud neck during vegetative growth as well as to proteins encoded by genes that are transcriptionally induced during sporulation were examined for their cellular localization during prospore membrane growth. We report localizations for over 100 different GFP fusions, including over 30 proteins localized to the prospore membrane compartment. In particular, the screen identified IRC10 as a new component of the leading-edge protein complex (LEP), a ring structure localized to the lip of the prospore membrane. Localization of Irc10 to the leading edge is dependent on SSP1, but not ADY3. Loss of IRC10 caused no obvious phenotype, but an ady3 irc10 mutant was completely defective in sporulation and displayed prospore membrane morphologies similar to those of an ssp1 strain. These results reveal the architecture of the LEP and provide insight into the evolution of this membrane-organizing complex.
authors.affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Chien
authors.initials: C
authors.lastname: Lam
authors.forename: Ethan
authors.initials: E
authors.lastname: Santore
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lavoie
authors.forename: Leor
authors.initials: L
authors.lastname: Needleman
authors.forename: Nicholas
authors.initials: N
authors.lastname: Fiacco
authors.forename: Carey
authors.initials: C
authors.lastname: Kim
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Neiman
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D011485:Protein Binding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013172:Spores, Fungal / Q000166:cytology / Q000378:metabolism*
chemical_list: C000593011:ADY3 protein, S cerevisiae; D018797:Cell Cycle Proteins; C000593010:IRC10 protein, S cerevisiae; D008565:Membrane Proteins; C051095:SSP1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins