title: The fission yeast pleckstrin homology domain protein Spo7 is essential for initiation of forespore membrane assembly and spore morphogenesis.
abstract: Sporulation in fission yeast represents a unique mode of cell division in which a new cell is formed within the cytoplasm of a mother cell. This event is accompanied by formation of the forespore membrane (FSM), which becomes the plasma membrane of spores. At prophase II, the spindle pole body (SPB) forms an outer plaque, from which formation of the FSM is initiated. Several components of the SPB play an indispensable role in SPB modification, and therefore in sporulation. In this paper, we report the identification of a novel SPB component, Spo7, which has a pleckstrin homology (PH) domain. We found that Spo7 was essential for initiation of FSM assembly, but not for SPB modification. Spo7 directly bound to Meu14, a component of the leading edge of the FSM, and was essential for proper localization of Meu14. The PH domain of Spo7 had affinity for phosphatidylinositol 3-phosphate (PI3P). spo7 mutants lacking the PH domain showed aberrant spore morphology, similar to that of meu14 and phosphatidylinositol 3-kinase (pik3) mutants. Our study suggests that Spo7 coordinates formation of the leading edge and initiation of FSM assembly, thereby accomplishing accurate formation of the FSM.
authors.affiliation: Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Nakamura-Kubo
authors.forename: Aiko
authors.initials: A
authors.lastname: Hirata
authors.forename: Chikashi
authors.initials: C
authors.lastname: Shimoda
authors.forename: Taro
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D015825:Chromosomes, Fungal / Q000378:metabolism; D055786:Gene Knockout Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008540:Meiosis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D013170:Spores / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D008565:Membrane Proteins; C483712:Meu14 protein, S pombe; D008869:Microtubule-Associated Proteins; D018129:Phosphatidylinositol Phosphates; C510389:Psy1 protein, S pombe; D050765:Qa-SNARE Proteins; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; C406741:Spo15 protein, S pombe; C569189:Spo7 protein, S pombe; C060974:phosphatidylinositol 3,4,5-triphosphate; D049452:Green Fluorescent Proteins