title: The fission yeast synaptobrevin ortholog Syb1 plays an important role in forespore membrane formation and spore maturation.
abstract: Synaptobrevin, also called vesicle-associated membrane protein (VAMP), is a component of the plasma membrane N-methylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, which plays a key role in intracellular membrane fusion. Previous studies have revealed that, similar to synaptobrevin in other organisms, the fission yeast synaptobrevin ortholog Syb1 associates with post-Golgi secretory vesicles and is essential for cytokinesis and cell elongation. Here, we report that Syb1 has a role in sporulation. After nitrogen starvation, green fluorescent protein (GFP)-Syb1 is found in intracellular dots. As meiosis proceeds, GFP-Syb1 accumulates around the nucleus and then localizes at the forespore membrane (FSM). We isolated a syb-S1 mutant, which exhibits a defect in sporulation. In syb1-S1 mutants, the FSM begins to form but fails to develop a normal morphology. Electron microscopy shows that an abnormal spore wall is often formed in syb1-S1 mutant spores. Although most syb1-S1 mutant spores are germinated, they are less tolerant to ethanol than wild-type spores. The syb1-S1 allele carries a missense mutation, resulting in replacement of a conserved cysteine residue adjacent to the transmembrane domain, which reduces the stability and abundance of the Syb1 protein. Taken together, these results indicate that Syb1 plays an important role in both FSM assembly and spore wall formation.
authors.affiliation: Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Yamaoka
authors.forename: Kazuki
authors.initials: K
authors.lastname: Imada
authors.forename: Kana
authors.initials: K
authors.lastname: Fukunishi
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Yamasaki
authors.forename: Chikashi
authors.initials: C
authors.lastname: Shimoda
authors.forename: Taro
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002467:Cell Nucleus / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D000431:Ethanol / Q000494:pharmacology; D008540:Meiosis; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D050683:R-SNARE Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013172:Spores, Fungal / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure
chemical_list: D050683:R-SNARE Proteins; D029702:Schizosaccharomyces pombe Proteins; C472866:Syb1 protein, S pombe; D000431:Ethanol