title: SSP2 and OSW1, two sporulation-specific genes involved in spore morphogenesis in Saccharomyces cerevisiae.
abstract: Spore formation in Saccharomyces cerevisiae requires the synthesis of prospore membranes (PSMs) followed by the assembly of spore walls (SWs). We have characterized extensively the phenotypes of mutants in the sporulation-specific genes, SSP2 and OSW1, which are required for spore formation. A striking feature of the osw1 phenotype is asynchrony of spore development, with some spores displaying defects in PSM formation and others spores in the same ascus blocked at various stages in SW development. The Osw1 protein localizes to spindle pole bodies (SPBs) during meiotic nuclear division and subsequently to PSMs/SWs. We propose that Osw1 performs a regulatory function required to coordinate the different stages of spore morphogenesis. In the ssp2 mutant, nuclei are surrounded by PSMs and SWs; however, PSMs and SWs often also encapsulate anucleate bodies both inside and outside of spores. In addition, the SW is not as thick as in wild type. The ssp2 mutant defect is partially suppressed by overproduction of either Spo14 or Sso1, both of which promote the fusion of vesicles at the outer plaque of the SPB early in PSM formation. We propose that Ssp2 plays a role in vesicle fusion during PSM formation.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Seema
authors.initials: S
authors.lastname: Agarwal
authors.forename: G Shirleen
authors.initials: GS
authors.lastname: Roeder
mesh_terms: D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D020090:Chromosome Segregation; D015966:Gene Expression Regulation, Fungal; D005798:Genes, Bacterial / Q000502:physiology*; D008540:Meiosis; D009024:Morphogenesis; D010739:Phospholipase D / Q000502:physiology; D050765:Qa-SNARE Proteins / Q000502:physiology; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013172:Spores, Fungal / Q000235:genetics* / Q000378:metabolism
chemical_list: D050765:Qa-SNARE Proteins; C084006:SSO1 protein, S cerevisiae; C460039:SSP2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D010739:Phospholipase D; C471177:SPO14 protein, S cerevisiae